Vitamins and Minerals Flashcards
1
Q
What are the characteristics of vitamins (5)?
A
Organic compounds
Do not yield energy
Micronutrients
Vital to life
Indispensable to body functions
2
Q
What do precursors, or provitamins do?
A
Transform chemically to one or more active vitamin forms.
Measure of vitamin in a food, generally includes:
- Vitamin and the vitamin activity potential from its precursors
- Example: beta-carotene
3
Q
What is bioavailability?
A
The rate and extent to which a nutrient is absorbed and used
4
Q
What is malnutrition?
A
any condition caused by excess or deficient food energy or nutrient intake or by an imbalance of nutrients
5
Q
What is undernutrition?
A
deficient in energy or nutrients
6
Q
What is overnutrition?
A
Excess energy or nutrients
7
Q
What is a primary deficiency?
A
a nutrient deficiency caused by inadequate dietary intake of a nutrient
8
Q
What is a secondary deficiency?
A
a nutrient deficiency caused by something other than inadequate intake such as a disease condition or drug interaction that reduces absorption, accelerates use, hastens excretion or destroys the nutrient
9
Q
What is a subclinical deficiency?
A
a deficiency in the early stages, before the outward signs have appeared
10
Q
What are the fat-soluble vitamins?
A
A, D, E and K
11
Q
Name the water-soluble vitamins
A
B vitamins, C
12
Q
What are the characteristics of fat-soluble vitamins (7)?
A
Absorbed into the lymph
Require bile for absorption
Travel in blood in association with protein carriers
Stored in tissues – Liver and fatty tissues – until needed
May be toxic in excess
Found in fats & oils of foods
Body can survive weeks without eating these vitamins (diet as a whole provides average amounts that meet requirements)
13
Q
What are the characteristics of water-soluble vitamins?
A
Absorbed directly into bloodstream
Travel freely in bloodstream
Most are not stored to any great extent
Excess excreted in urine
Lower risk of toxicity than fat-soluble vitamins
14
Q
Which fat-soluble vitamins can easily reach toxic levels, with supplements?
A
A and D
15
Q
What happens with deficiency of fat-soluble vitamins?
When is it more likely to happen?
A
- Likely if consistently low in fat-soluble vitamins
- Fat malabsorption
- Mineral oil laxatives can cause vitamin loss
- Extraordinarily low-fat diets interfere with absorption
16
Q
What are the three forms of vitamin A active in the body?
A
Retinol
Retinal
Retinoic acid
17
Q
What is the plant-derived precursor of vitamin A?
A
Beta-carotene (found in dark orange vegetables (carrots, pumpkins))
Most abundant of the carotenoid precursors
18
Q
What are the roles of vitamin A?
A
- Vision
- Cell differentiation
- Gene expression
- Maintenance of body linings and skin
- Immunity
- Growth of bones and of the body
- Normal development of cells
- Critical importance to reproduction
19
Q
How does vitamin A help with eyesight in the back of the eye (describe this process)?
A
Light passes through the cornea before striking the retina
Retina contains light-sensitive nerve cells
Light bleaches the vitamin A-containing pigment rhodopsin
This breaks off the vitamin**, initiating an impulse to the optic center in the brain
The vitamin reunites with the pigment, & there is a little vitamin A destruction
Vitamin A must regenerate the supply
20
Q
What happens if vitamin A supply runs low?
A
Night blindness
21
Q
How does vitamin A affect eyesight (front of the eye) (deficiency)?
A
- Keratin accumulation (keratinization) of the cornea can occur with vitamin A deficiency
- Can lead to xerosis (drying) & then to dryness and thickening (xerophthalmia) causing permanent blindness
- If detected early - can be reversed with vitamin A supplementation or regular consumption of vegetables and fruit
22
Q
Which tissues need vitamin A and why?
A
All epithelial tissues
These tissues serve as protection from pathogens as well as to other damage (protective layer)
23
Q
How does vitamin A affect the control of gene expression?
A
Retinoic acid activates or deactivates certain genes thereby affecting protein production
24
Q
How does vitamin A affect immunity?
A
- Plays a role in the regulation of genes that produce immune system proteins
- Deficiency can lead to a spiral of malnutrition and infection
25
How does vitamin A have a role in growth?
Assists in growth of bone & teeth -- needed in the dismantling step of old bone structure
26
What happens when vitamin A deficient (outside of eye sight)?
- Cell differentiation & maturation are impaired
- failure of mucus-producing cells to produce mucus
- a subsequent increase in keratin-producing cells
- tissues more vulnerable to infection
- ie: respiratory infection
27
Vitamin A toxicity is not very likely from food, but what can cause this?
Supplements, fortified foods, liver (especially polar bear liver)
28
What happens with vitamin A toxicity?
May weaken bones, bone and joint pain, abdominal pain, stunted growth, liver damage
Early symptoms: loss of appetite, blurred vision, growth failure in children, headache, skin itching, irritability
Long-term symptoms: bone weakening and hip fracture
Focus: growth, bones, liver
29
What happens in vitamin A toxicity with pregnant women?
Fetal malformation -- teratogenic. Caused either by:
- Chronic use of supplements exceeding recommendation
- Single large dose (100x need)
30
Who is most prone to toxicity of vitamin A?
- Children who mistake chewable vitamin pills for candy
- Adolescents who take large doses for acne (Accutane is derived from vitamin A but vitamin A supplements do not help with acne)
31
Beta-carotene will not cause vitamin A toxicity. What happens with excess of this?
Can turn yellow/orange due to deposition in subcutaneous fat
32
Vitamin A activity for vitamin A precursors is measured in what?
RAE -- retinol activity equivalents
around 12 mcgs of beta-carotene is equal to 1 microgram of RAE
33
Does eating carrots really promote good vision?
Bright (deep) orange fruits & vegetables and dark green vegetables - rich in beta-carotene - have a role in healthy eyesight.
Does not improve vision if vitamin A intake is already adequate
34
What diseases is a lack of beta-carotene associated with? What can be said about supplements and smokers?
- Lack of foods rich in beta-carotene increases the risk of **macular degeneration**
- Beta-carotene from foods & elevated beta-carotene in the blood are associated with reduced **cancer risk**
- Benefit not seen with supplements
- Beta-carotene **supplements associated with increased risk of cancer in smokers**
35
What are the major dietary antioxidants?
Beta-carotene, Vitamin E, vitamin C, selenium, and many other phytochemicals
36
Where do we get vitamin A from?
Foods of animal origin
- Liver and fish oil
- Fortified milk and milk products
- Eggs
Beta-carotene is found in plants
- Dark green leafy foods (spinach, bok choy)
- Rich yellow and deep orange foods (carrots, sweet potato, pumpkin, and apricots)
Grain products have none
37
What is the tolerable upper intake level of vitamin A? What is the RDA for men and women?
3000 micrograms
900 for men, 700 for women
38
Which vitamin is not really essential?
Vitamin D -- the body can make all it needs with the help of sunlight
Many people may border on vitamin D deficiency
39
What are the roles of vitamin D?
- Regulation of blood calcium and phosphorous levels & therefore maintains bone integrity
- Functions as a hormone
-
40
When more calcium is needed, vitamin D acts to raise blood calcium levels. How does it do this? *
- Promotes calcium absorption
- Promotes calcium retention by the kidneys
- Draws calcium from bone
41
How does vitamin D function as a hormone (what does it play a role in)?
Plays a role in the brain, heart, stomach, pancreas, skin, reproductive organs, some cancer cells, stimulates cell maturation (including immune system cells)
42
It is possible that deficiency in vitamin D promotes what?
- high blood pressure
- some cancers
- type 1 diabetes
- heart disease
- rheumatoid arthritis
- inflammatory bowel disease
- multiple sclerosis
43
What does deficiency in vitamin D cause in children?
Rickets
- Characterized by abnormal bone growth
- Bowed legs, outward-bowed chest, knobs on ribs
44
Risk for bone loss later in life due to potential lack of vitamin D is more common in who?
- Adolescents who consume soft drinks rather than vitamin D-fortified milk or alternatives and prefer indoor to outdoor activities
- Older individuals may have painful joints & muscles due to low vitamin D levels
45
What is the adult form of rickets? In who does this most often occur?
Osteomalacia
In women with all three of the following:
- Low calcium intake
- Little exposure to the sun
- Who go through repeated pregnancies & periods of lactation
46
Vitamin D is the most toxic vitamin in excess. What are some of these symptoms?
- Toxicity symptoms include appetite loss, nausea, vomiting, increased urination and increased thirst, severe psychological depression (effects on the CNS)
- Continued overdoses cause dangerously high blood calcium level, forcing calcium to be deposited in soft tissues
- Such as the heart, blood vessels, lungs, kidneys
47
You cannot reach toxic levels of vitamin D in the sun. How can people make a vitamin from sunlight?
- UV exposure to a cholesterol compound in the **skin** transforms it into a **vitamin D precursor** which is absorbed into the **blood**
(The **liver & kidneys** then convert precursor to **active form of vitamin D**)
- Skin synthesis of vitamin D poses no risk of toxicity
(The sun begins breaking down excess vitamin D made in the skin)
- Generally, just being outdoors when the sun is overhead, even in lightweight clothing, promotes sufficient skin synthesis of vitamin D
Focus: Skin, liver, and kidneys
48
What can affect vitamin D synthesis?
- Skin colour, air pollution, city living, clothing, geography, indoor lifestyle, season, sunscreen, time of day
- Sunscreens with SPFs of 8 or above can reduce sun risks, but also prevent vitamin D synthesis
49
What is vitamin D measured in?
International Units (IU)
50
What are the sources of vitamin D?
- Sunlight
- Small amounts from butter, cream, fortified margarine
- Fortified milk
- Egg yolks, liver, fatty fish and fish oil
- Only certain fortified plant sources exist: margarines & some plant-based beverages (i.e. soy beverage)
- Mushrooms
Milk and alternatives, meat and alternatives
51
Why do recommendations for vitamin D intake increase with age?
- Organs capabilities decrease with age
- Higher risk for bone loss
52
Vitamin E consists of 4 tocopherol compounds. What are they?
Alpha, beta, gamma, and delta.
We only ever talk about alpha-tocopherol
53
For vitamin E, what is its main role and why is it important?
Antioxidant activity
- Antioxidant defending the body against oxidative damage
- Vitamin E is preferentially oxidized, thus protecting cells
- Oxidative damage results from free radicals which are formed during normal metabolism disrupt the structure of cellular lipids, DNA and proteins. Free radical activity may lead to cancer, heart disease, or other diseases
54
What is vitamin E's antioxidant effect especially crucial for?
- In the lungs -- cells are exposed to high oxygen concentrations
- Protects red blood cells, white blood cells
55
What are some of vitamin E's other roles?
- May play other roles in immunity
- Plays a role in nerve development
56
What happens in infants if deficient in vitamin E?
Infants born before transfer of vitamin E from the mother to the infant
- Erythrocyte hemolysis is a rupturing of the red blood cells which results in anemia
57
What happens in adults if deficient in vitamin E?
Nerve damage (loss of muscle coordination & reflexes with impaired movement, vision, and speech)
- Associated with fat malabsorption diseases: damaged liver, gallbladder or pancreas
Why:
- Low intake with extremely-low-fat diet for years
- People who rely solely on fat replacers rather than fat
- Vitamin E is destroyed by food processing & heating (even though present in many fatty foods)
58
What can be said about vitamin E toxicity?
- No toxicity has been seen with natural food sources
- Large doses may increase the effects of anticoagulant medications
- May be an increased risk of death in those taking greater than 400 IU from a supplement
59
What are some food sources of vitamin E?
- Destroyed by heat processing & oxidation
- Vegetable oils (including salad dressing, shortening)
- Avocados are a good source
- Wheat germ is a good source (fatty part of the grain)
- Smaller amounts from meat, poultry, fish, eggs, milk products, nuts, seeds
- Animal fats have almost no vitamin E
- Supplements generally do NOT provide health benefits unless deficient
60
What are the functions of vitamin K?
Synthesis of blood clotting proteins
- Does not improve clotting in those with diseases such as hemophilia
- Interferes with the function of certain anticoagulant medications (blood thinners) Warfarin/Coumadin
Synthesis of normal form of bone proteins that bind minerals to bone (hip fractures can be caused by deficiency)
61
Someone who takes drugs like Warfarin/Coumadin (blood thinners), what do they need to do?
- CONSISTENT intake of vitamin K rich foods (moderate amounts)
- Avoid drastic changes and self-prescription of vitamin K supplements
62
What are some sources of vitamin K?
- Intestinal bacteria (cannot meet the body's need)
**Leafy green vegetables – Dark green generally richest: Spinach, collard greens, beet greens, Swiss chard
- Lettuce, broccoli, Brussels sprouts, cabbage and other members of the cabbage family
- Canola & soybean oils
- Eggs and milk contain small amounts
- Liver is the only rich animal source
(Dark green leafy is the one we need to know, not the rest)
63
Who is most at risk for deficiency for vitamin K?
- Unlikely in adults
- Newborns' intestinal bacteria have not established themselves (sterile GI tract)
- Antibiotic treatment (kills both the beneficial & harmful bacteria in their intestinal tract
- Fat malabsorption
64
What can be said about toxicity in vitamin K?
No UL
- Rare among healthy adults
- Infants & pregnant women: toxicity can result from over-supplementation with synthetic vitamin K
- Leads to jaundice and bilirubin in the brain of an infant can cause brain damage or death
65
Water soluble vitamins can easily be leached out through cooking & washing with water, are easily absorbed, but also excess is readily excreted in urine. What are the general advice for meeting needs?
Choose foods daily that are rich in water-soluble vitamins to achieve the recommended intakes regularly
66
What can be said about toxicity in water-soluble vitamins?
- Not from food
- Can occur from the large doses concentrated in some vitamin supplements (expensive urine)
- Athletes with an appropriate diet generally don't need vitamin supplements -- increased energy needs therefore more food
67
Short trips near the Mediterranean Sea didn't lead to scurvy but there were high death rates on long voyages. Why was this?
Scurvy -- fruits and vegetables were used up early on long trips
James Lind, a British doctor performed the first nutrition experiment on humans in the mid 1700s to find a cure for scurvy (lime juice)
68
What are the roles of vitamin C?
Maintenance of connective tissues
- Formation & maintenance of collagen (component of bones, teeth, skin, tendons, scar tissue, capillaries)
Antioxidant
69
What are the deficiency symptoms of vitamin C?
- Most scurvy symptoms are due to collagen breakdown (Loose teeth, bleeding gums, pinpoint hemorrhages, anemia, tenderness to touch, weakness, swollen ankles & wrists, loss of appetite, growth cessation)
70
Risk of scurvy is low in North America. Who are more susceptible?
- Some elderly people: Low intakes of veg/fruit and a poor appetite
- People with food insecurity
- People addicted to alcohol or other drugs
- Infants fed cow’s milk who do not receive breast milk or formula - Breast milk & infant formula supply vit. C
71
What is the thing we need to know about vitamin C and colds?
There is no consensus as to whether it helps or not
- Vitamin C supports immune system function & so protects against infection
- Vitamin C has not been shown to prevent colds and results are inconsistent in benefitting a cold
- One group of researchers have found the following:
Some small benefit from vitamin C in high doses (1 gram) taken at the onset of a cold
- May shorten the duration of colds by about 1/2 day & reduce the severity of symptoms by about 40%
- Placebo effect has happened
72
Is too much vitamin C hazardous to health?
- Vitamin C from food is safe
- Adverse effects include digestive upsets, such as nausea, abdominal cramps, excessive gas, diarrhea
- Massive doses may interfere with medications to prevent blood clotting
- May be dangerous for people with an overload of iron
73
What is an interesting fact about smokers and vitamin C that you need to know?
- Smoking introduces oxidants that deplete vitamin C. So, RDA set 35 mg higher for smokers
74
What are some food sources of vitamin C?
- Citrus fruits, dark green vegetables (bell peppers and broccoli), cabbage type vegetables, strawberries, cantaloupe, lettuce, tomato, papaya, mangos, red bell pepper
- Potatoes contain vit C - scurvy became evident in Ireland during the potato famine
- Vitamin C in fruits & vegetables are prone to destruction by heat & oxygen
- Fresh, raw & quickly cooked are best
- Store properly & consume promptly
Mostly from vegetables and fruits
75
What are the DRI recommendations for vitamin C?
Women: 75 mg/day
Men: 90 mg/day
+ 35 for smokers
76
What can be said about B vitamins overall?
B vitamins act as part of **coenzymes**
- Coenzyme combines with & activates an enzyme
Role in **Metabolism**
- Metabolism of carbohydrates, lipids & amino acids
- Thiamin, riboflavin, niacin, pantothenic acid & biotin all help **release the energy stored in the energy-yielding nutrients**
- Vitamin** B6 helps the body make protein**
- **Folate** & vitamin **B12 help cells to multiply**
77
What happens with B vitamin deficiencies overall?
Every cell is affected
- Cell renewal depends on energy & protein which depend on the B vitamins
- Digestive tract & blood are damaged
- In children, full recovery may be impossible (A thiamin deficiency during growth can cause permanent brain damage)
78
What can be said about deficiency of any one B vitamin?
Rarely shows up alone, because people eat foods that contain mixtures of nutrients
79
What is the role of thiamin?
Energy metabolism
Nerve processes and their responding tissues (muscle)
80
What is the deficiency disease of thiamin?
Beriberi:
- First observed with polishing of rice in Asia
- Loss of sensation in the hands & feet, muscular weakness, advancing paralysis, abnormal heart action
- Wet beriberi (edema present)
- Dry beriberi (no edema)
81
What is the name of the deficiency disease that shows up with alcohol abuse and severe deficiency?
Wernicke-Korsakoff Syndrome
- Alcohol displaces food in the diet, impairs thiamin absorption, promotes thiamin excretion in the urine
- Symptoms: mental confusion, disorientation, loss of memory, jerky eye movements, staggering gait, apathy, irritability
- Treatment: thiamin by IV or orally (alcohol withdrawal protocol in hospitals)
82
What are the sources of thiamin?
** Widespread in healthy foods
- Pork products, sunflower seeds, whole grain cereals, legumes are rich sources
83
What is the role of riboflavin (similar to thiamin)
Energy metabolism of all cells
84
What is the deficiency disease of riboflavin?
Ariboflavinosis
- Inflammation of the membranes of the mouth, skin, eyes and GI tract; smooth, purplish red tongue
- May go undetected because thiamin def. symptoms more severe
- Children who lack milk products & meat are at risk
- Treatment: A diet that treats a riboflavin deficiency also resolves a thiamin deficiency
- Often accompanies thiamin deficiency
85
What are the sources of riboflavin?
** Widespread in healthy foods
- Milk & milk products
- Leafy green vegetables
- Whole-grain breads
- Enriched/fortified grain products
- Some meats & eggs
86
What is the main role of niacin?
Energy metabolism
87
What is the deficiency disease of niacin?
Pellagra -- the four Ds
- Diarrhea, dermatitis (develops on skin exposed to light), dementia, and death
Came to Europe from North America
At risk for pellagra:
- Poorly nourished people living in poverty, particularly those with alcohol addiction
88
What are the sources of niacin? What can be converted to niacin?
** High protein foods
Tryptophan, which is abundant in almost all proteins, can be converted to niacin
If eating adequate protein, will not be deficient in niacin
- Milk, eggs, meat, poultry, fish, whole grains, fortified and enriched grains, nuts and seeds
89
What are niacin equivalents (NE)?
Food containing 1 mg niacin and 60 mg tryptophan would contain 2 mg NE
90
What can be said about toxicity & niacin?
Caused from supplements (that aren't that high -- 2-3x the RDA)
- Large doses can cause **niacin flush – painful tingling, flush and hives** – niacin supplements **2-3x RDA**
- Large doses of niacin can **injure the liver and cause blurred vision**
- Large doses of a form of niacin (nicotinic acid) may be prescribed to lower blood lipids
91
What is the role of folate?
DNA synthesis
Part of coenzymes for new cell synthesis
92
What does deficiency of folate lead to in adults?
Because immature red & white blood cells & cells of the GI tract divide rapidly, they are most vulnerable to a deficiency
- Anemia - megaloblastic anemia or macrocytic anemia (Large, immature red blood cells. Related to anemia of vitamin B12 deficiency)
- Diminished immunity
- Abnormal digestive function
- Folate deficient diet may increase risk of CVD, colon and cervical cancer
93
What are neural tube birth defects (NTDs)?
Problems with spinal cord, mental delay, severely diminished brain size or even death shortly after birth
Arise in the first few days or weeks of pregnancy
Most women eat too few fruits & vegetables to supply folate needed (especially since it is forming so early in pregnancy, when so many women are unaware of their pregnancy)
- Why bleaches white grain products are all fortified with folic acid since late 1990s (which has seen a significant drop after fortification)
94
What does folate toxicity look like?
- Folate can mask B12 deficiency (anemia)
- Excess folate may be antagonistic to the actions of some anticancer drugs
95
What is the unit of measure of folate?
Dietary Folate Equivalent (DFE) converts all forms of folate into units that are equivalent to the folate in food
96
Why is DFE important?
Synthetic folate in enriched foods & supplements is absorbed more readily than naturally occurring folate (so, natural is not always better)
- Bioavailability ranges from approx 50% (foods) to 100% (supplements taken on an empty stomach). So, folate from foods is given full credit & fortified foods & supplements are given extra credit (1.7 times more available)
97
What are the sources of folate?
- Leafy green vegetables
- Fresh, uncooked vegetables and fuits (the heat of cooking & oxidation occurs during storage destroy much of the folate in foods
- Eggs
- Orange juice and legumes
98
What is the RDA of folate?
Healthy adults: 400 mcg DFE/d
Pregnancy: 600 mcg DFE/d
Heath Canada recommends women who could become pregnant: 400 mcg/day of folic acid from supplements plus a healthy diet
99
What is the role of B12?
Close relationship with folate
- Activated by folate
- Folate is activated by B12
Maintenance of the sheaths that surround and protect nerve fibres
100
What happens with deficiency of B12?
- Damaged nerve sheaths
- Creeping paralysis (tips of finger/toes and can be permanent)
- General malfunctioning of nerves and muscles
101
Deficiency of vitamin B12 results in failure of folate to make red blood cells. What type of anemia can be caused then?
Vitamin B12 deficiency same anemia as folate
Large, immature red blood cells (macrocytic or megaloblastic anemia)
102
What is not good about the relationship between folate and B12 with anemia?
Folate will clear up anemia but B12 deficiency continues. Give vitamin B12 as well if there is are symptoms of folate deficiency – incase of B12 deficiency
103
Who is at risk of B12 deficiency?
- Elderly (absorption problems due to decreased stomach acidity and decreased intrinsic factor)
- Atrophic gastritis (inherited gene defect for intrinsic factor production (mid-adulthood)
- Vegans (deficiency symptoms take time: body stores up to 6 years' worth of the vitamin. All strict vegetarians (vegans) must be sure to use B12-fortified products or supplements)
104
What can be said about absorption of B12?
Requires intrinsic factor, which is a compound made by the stomach. The stomach's acid liberate vitamin B12 from food; intrinsic factor then binds to the vitamin. The complex is then absorbed from the small intestine into the blood
105
What is pernicious anemia?
A vitamin B12 – deficiency disease, caused by a lack of intrinsic factor and characterized by large, immature red blood cells
Treatment: B12 injections
106
What are the sources of B12?
Animal sources are the only significant sources
Bioavailability greatest in milk and fish
Fortified plant foods - ex - soy beverage
107
What are the roles of B6?
- 100+ reactions in the tissues
- assists in conversion of one amino acid to another needed amino acid – protein synthesis
- Aids in the conversion of tryptophan to niacin
- Neurotransmitter synthesis: conversion of tryptophan to serotonin
- Hemoglobin synthesis
- Assists in release of stored glucose from glycogen, contributing to the regulation of blood glucose
- Immune function
- Steroid hormonal activity
- Fetal brain & nervous system development
108
What happens in B6 deficiency?
General symptoms: Weakness, Psychological depression, Confusion, Irritability, Insomnia
Other symptoms:
Anemia, Greasy dermatitis
Advanced cases of deficiency:
convulsions, May weaken the immune system
Evidence that low intakes may be related to increased risk of heart disease
109
What can be said about toxicity of B6?
Seen in women took 2+ g/day for 2+ months
Numb feet
Lost sensation in their hands
Eventually became unable to walk or work
Recovered after they stopped taking the supplements
110
A single B6 supplement can deliver 2g of the vitamin, the equivalent of what?
3,000 bananas
1,600+ servings of liver
or 3,800+ servings of chicken breast
Stick with food
111
What can be said about the need of B6?
Due to its roles in protein metabolism, need is proportional to protein intake
112
What is the most important thing to remember for B6 (disregard other extensive lists for this vitamin)?
Unlike other water soluble vitamins it is stored extensively in muscle tissues
113
What are the sources of B6?
Protein-rich foods: meats, fish, poultry
Legumes & peanut butter
Potatoes, leafy green vegetables, some fruits
114
What can be said about homocysteine, an amino acid?
- Elevated homocysteine may be an indicator of **CVD risk**
- **Deficiencies of folate, vitamin B12 or vitamin B6 cause excess homocysteine to build up in the blood**
- Supplements of these vitamins lead to a significant drop in homocysteine level
- It is unknown how this affects a person’s CVD risk
115
What is the role of biotin?
Energy metabolism
Cofactor for several enzymes in the metabolism of carbohydrate, fat, protein
116
What can be said about deficiency of biotin?
May occur with some rare diseases
Consumption of dozens of raw egg whites per day, which contain a protein that binds biotin (avidin), will result in a deficiency
- Cooking eggs denatures this protein
117
What are the sources of biotin?
Widespread in foods
118
What is the role of pantothenic acid?
Energy metabolism
Coenzyme that plays a role in the release of energy from the energy nutrients
Plays a role in 100+ steps concerned with the synthesis of lipids, neurotransmitters, steroid hormones & hemoglobin
119
What are the sources of pantothenic acid?
Widespread in foods
120
What do the experts say about taking vitamin and mineral supplements?
- Some say healthy people might benefit from a multiple vitamin supplement taken every day or two
- Others say potential risks outweigh the unproven benefits - supplements should only be taken when there is a risk of deficiency
121
Who may likely need supplements?
**People with nutrient deficiencies
- Habitual dieters
- Vegans or those with atrophic gastritis
- Lactose intolerance or milk allergy
- People in certain stages of the life cycle (Infants need iron; Newborn- vitamin K; Women who could become pregnant need folate; Pregnant women need Iron and Folate; Elderly need B12 and Vitamin D)
- Injuries or infections that impair intake, absorption, excretion or metabolism of nutrients
- People taking medications that interfere with nutrient absorption
122
What are the major minerals?
Calcium
Sulphur
Phosphorus
Potassium
Sodium
Chloride
Magnesium
123
What is the most abundant mineral in the body?
Calcium
124
Only 1% of calcium is in body fluids but has important roles. What are they?
Muscle contraction and relaxation
Nerve functioning
Blood clotting
125
What are good calcium sources?
Milk and milk products *
Fortified soy beverage and other fortified milk alternatives
Fish with bones (ex. canned salmon, sardines)
Calcium set tofu
Broccoli, some leafy greens and legumes
Fortified juices
On average, Canadians are not consuming enough calcium
126
When is peak bone mass reached?
By the late 20s (10 years after adult height is reached)
127
After around 40, what happens to bones?
Begin to reduce density. Loss can be slowed by a diet rich in calcium and sufficient physical activity
128
To protect against bone loss, a diet rich in calcium is recommended early in life. Why?
A calcium-poor diet during the growing years may prevent a person from achieving peak bone mass
Insufficient bone calcium increases the risk of osteoporosis (adult bone loss – bones become brittle and fragile)
129
What happens with a calcium deficiency?
Adult - bone loss
Children - stunted growth and weak bones
Consumption of milk has declined
Consumption of beverages such as soft drinks has greatly increased
130
What happens with toxicity of calcium?
Constipation
Kidney stones
Interferes with absorption of other minerals
131
How much calcium is stored in bones and teeth?
99%
132
What are the two major roles of calcium in bones?
Integral part of bone structure
Bone serves as a calcium reserve
- Bone minerals are in constant flux
133
People who do not use milk because of lactose intolerance, preference, dislike, or allergy must obtain calcium from other sources. Children who don't drink milk often have what?
Lower calcium intakes
Poorer bone health than those who drink milk regularly
134
Some vegetables are good sources of calcium. Name some
Rutabaga, broccoli, mustard and turnip greens, collards, and kale
135
Some vegetables are poor sources. Name some.
Spinach, Swiss chard, rhubarb * (because of the very very low absorption)
Calcium content similar to milk
Provide little calcium
Binders in some vegetables
inhibit calcium absorption
136
What can be said about the benefits of spinach and dark greens of all kinds?
Still a good food to eat
Iron-rich
Beta-carotene rich
Rich in phytochemical
Dark greens of all kinds:
Superb sources of riboflavin
Indispensable for the vegan or anyone else who does not drink milk
137
What is osteomalacia?
Vitamin D deficiency disease leads to impaired mineralization of bone. Characterized by an overabundance of unmineralized bone protein.
The ratio of bone mineral to matrix is low.
Symptoms include bending of the spine and bowing of the legs
138
What is osteoporosis?
A reduction in bone mass of older persons in which the bone becomes porous and fragile.
The bone mineral to matrix ratio is normal
139
According to the Osteoporosis Society of Canada, how many Canadians suffer from osteoporosis
According to the Osteoporosis Society of Canada
2 million people Canadians suffer from osteoporosis
1 in 3 women - osteoporotic fracture
1 in 5 men - osteoporotic fracture
Treatment costs of osteoporosis $2.3 billion annually
140
What type of fractures are the most serious?
Hip fractures
The break is rarely clean - the bone breaks into fragments that cannot be reassembled
Hip replacement requires major surgery
Many elderly people with hip fractures never walk or live independently again
About 1/5 die within the year of having a hip fracture
141
What are the risk factors for osteoporosis (high correlation)? *
Advanced age
Female
Heavy drinking
Chronic steroid use
Rheumatoid arthritis
Being underweight/significant weight loss
Removal of ovaries or testes
White race
Genetics – Family history
142
Why is osteoporosis called the silent thief?
Osteoporosis is slowly decreasing bone density until many years later, the hip gives way
Break a hip and fall
143
What are some of the moderate correlation risk factors for osteoporosis?
Chronic thyroid hormone use
Smoking
Type 1 diabetes
Insufficient dietary calcium and vitamin D
Inadequate vitamin K
Physical inactivity/sedentary lifestyle
Excessive antacid use
144
Risks of osteoporosis differ by age. What can be said about black women?
Black women have far fewer hip fractures than white women
Asian women also tend to have lower hip fractures (bone structure is slightly different -- angle of the bones)
Black race is correlated with being protective against osteoporosis
Black women have denser bones and lose density more slowly than white women
145
What can be said about gender and hormones and osteoporosis?
Women account for more than 2/3 of cases of osteoporosis
Men have greater bone density than women at maturity
Women experience greater bone loss during menopause
- Accelerated losses continue for 6 - 8 years following menopause & then tapers off
Men produce only a little estrogen, yet they resist osteoporosis better than women
Testosterone may play a role: Men experience more fractures with reduced testosterone ex. after removal of diseased testes or decreased function with aging
146
What can be said about physical activity and osteoporosis?
Without physical activity, bones lose strength (swimming isn't against gravity in the same way though, so not necessarily great for preventing it)
Muscle use seems to promote bone strength
- The bones of active people are far denser than those of sedentary people
- Hormones that promote synthesis of new muscle tissue also favour the building of bone
- Flexibility & muscle strength gained through physical activity also improve balance & help prevent falls from occuring
So, to keep bones health & to prevent falls, include weight bearing activities every day: calisthenics, dancing, jogging, vigorous walking, weight training
147
What can be said about body weight and osteoporosis?
Being underweight or losing weight increases risk
Heavier body weights & higher body fatness stress the bones & promote their maintenance – but obesity may have negative effect
148
What can be said about tobacco smoke and alcohol and osteoporosis?
Bones of smokers are less dense
People addicted to alcohol experience more frequent fractures
149
What can be said about protein and calcium?
Excess dietary protein causes the body to excrete calcium in the urine
Research is not entirely clear as to whether or not a high-protein diet causes bone loss
Sufficient dietary protein is essential to bone health
150
What can be said about sodium's influence on calcium?
High sodium intake is associated with urinary calcium excretion
Lowering sodium intakes seems to lessen calcium losses
To lower sodium & increase potassium intake choose a diet:
- Rich in unprocessed foods such as fruits & vegetables
- Restricted in highly processed, convenience, or fast foods
151
What can be said about caffeine and calcium?
Some evidence linking the heavy consumption of caffeinated beverages & osteoporosis but there is also contradicting evidence
Almost anything you read about caffeine is like that statement -- some say negative, some say beneficial
152
What can be said about soft drinks and osteoporosis?
May have adverse effects on calcium but why is unclear
- High concentration of fructose sweetener or phosphoric acid may cause calcium loss?
- Displace milk from the diet especially in children & adolescents?
153
What can be said about vitamin K and osteoporosis?
Plays important roles in the production of at least one bone protein (osteocalcin) that participates in bone maintenance *
People with hip fractures often have low vitamin K intakes
154
What can be said about magnesium and osteoporosis?
Helps maintain bone density
155
What can be said about vitamin A and osteoporosis?
Needed in bone-remodeling process
Too much may be associated with osteoporosis (break down too much bone)
156
Cells need continuous access to calcium therefore the body maintains a constant calcium concentration in the blood. How is that regulated?
Blood calcium is regulated by hormones not by daily intake
When calcium intake is inadequate, normal blood calcium is maintained at the expense of the bones
157
When does calcium need increase?
Calcium absorption from the intestine increases (e.g., infants and children - around 60%, pregnant women - around 50%, and adults - around 25% of dietary calcium)
Loss of calcium via the kidneys is reduced
Percent absorbed increases as dietary intake decreases (with the help of vitamin D -- helps with calcium absorption *)
158
Calcium and phosphorous are essential to bone formation. Why?
Calcium phosphate salts crystallize on collagen, forming hydroxyapatite crystals that add rigidity to bone
Fluoride may also displace the “hydroxy” part of the crystals, making fluorapatite - A mineral that resists bone-dismantling
159
Formation of teeth is similar to bone formation. What happens?
Fluoride hardens and stabilizes the crystals of teeth and makes the enamel resistant to decay
160
What are the characteristics of major and trace minerals?
Major: Essential nutrients, amounts exceed 5 grams
Trace: Essential nutrients, amounts less than 5 grams
Don't need to know what is a major vs trace mineral
161
Upon death, what happens to the body?
The carbon in carbohydrates, fats, proteins & vitamins combine with oxygen to produce carbon dioxide
The hydrogen & oxygen combine to form water - evaporates
All that is left behind is minerals (about 2.3kg)
162
What are minerals?
Chemical elements
Inorganic
Not energy yielding
Micronutrients
163
What is hard and soft water?
Hard water – “Water with high calcium & magnesium concentrations”
Soft water – “Water with high sodium concentration”
may aggravate hypertension & heart disease
164
What is the AI for females and males for water?
AI total water is 2.7L/day for females
AI total water is 3.7L/day for males
165
According to the DRI committee, what does the total water intake include?
both caffeinated and non-caffeinated beverages
Food
About 80 percent from liquids ( 2.2 L and 3 L) – textbook incorrect
Water content of foods (approximate):
- Meat and cheese - 50%
- Vegetables and fruit - 80-95%
166
Phosphorus is the second most abundant mineral in the body. Where is the majority found in the body?
Bones and teeth
167
What are some of the roles of phosphorus?
Helps maintain **acid–base balance (buffers)**
Part of DNA and RNA
**Metabolism** of energy yielding nutrients
Assist many enzymes and vitamins in extracting **energy**
Form part of the molecules of the **phospholipids**
168
What can be said about phosphorus need?
Needs are easily met by almost any diet
169
What happens with toxicity of phosphorus?
Calcification of soft tissues
170
What are some sources of phosphorus?
Animal proteins are best source
Also found in cola drinks
171
Where is magnesium stored in the body?
Half of body’s magnesium is in the bones
Remainder in muscles, heart, liver and other soft tissues
Only 1% in body fluids
172
To maintain concentration of magnesium in the blood, what happens?
Magnesium can be taken from bones
Kidneys can act to conserve magnesium
Body fights really hard to not allow low calcium, magnesium deficiency is more common
173
What are some of the roles of magnesium?
Assists in the functioning of more than 300 enzymes
Release & use of energy from energy-yielding nutrients
Works with calcium for the proper functioning of muscles *
- Calcium promotes contraction
- **Magnesium helps muscles relax afterwards**
Involved in **bone mineralization** and promotes **resistance to tooth decay** **by holding calcium in tooth enamel**
174
What are some sources of magnesium?
Easily washed & peeled away from foods during processing: unprocessed foods (or only slightly processed foods) are the best sources
Nuts, legumes, whole grains, dark green vegetables, seafood and chocolate.
Most Canadians reach the EAR but below RDA
175
Deficiency in magnesium could occur as a result of what?
Inadequate intake, vomiting or diarrhea
Alcoholism, protein energy undernutrition (malnutrition)
Hospital clients who have been fed magnesium-poor TPN or using diuretics (medication to take fluid out of the body)
176
What are some of the deficiency symptoms of magnesium?
Muscle weakness
May be related to cardiovascular disease, heart attack, high blood pressure
Even with intakes above EAR and below RDA, overt deficiency symptoms are rare in healthy people
177
What happens with magnesium toxicity?
Magnesium laxatives and antacids can cause diarrhea and acid base imbalance
Toxicity is rare but can be fatal (very very rare)
Only occurs with high intakes from nonfood sources such as supplements or magnesium salts
178
Does cooking or storing destroy minerals?
No. You may lose it (like if you are boiling something for a long time and it dissolves into the water or during processing, but you won't destroy them)
179
What is sodium?
Positive ion in sodium chloride (table salt)
40 % of the weight of sodium chloride
180
What are some of the roles of sodium?
Fluid and electrolyte balance
Acid-base balance
Muscle contraction and nerve transmission
About 30-40% stored on bone crystals – easily accessible to maintain blood levels
181
What happens with deficiency of sodium?
People generally eat more salt than is needed – far more. Deficiency is very rare
Occasionally a very strict low-sodium diet for hypertension, kidney disease, or congestive heart failure can deplete the body of sodium
Vomiting, diarrhea, or extremely heavy sweating could be a cause
Endurance athletes can lose so much salt and drink so much water they become hyponatremic.
Symptoms: headache, confusion, stupor, seizures, coma
182
How does the body maintain sodium?
Body absorbs sodium freely
Kidneys filter excess sodium out of the blood into the urine
Kidneys will also conserve sodium
Small sodium losses occur in sweat
The amount of sodium excreted in a day equals the amount ingested that day
183
What can be said about salt and "water weight"?
As blood sodium rises, a person gets thirsty. Thirst leads a person to drink until sodium-to-water ratio is restored
The kidneys then excrete the extra water which removes the excess sodium
Some dieters think too much salt or too much water will make them gain weight. Not a fat gain – it’s excess water which a healthy body then excretes. Body salt & water weight can be kept under control by controlling sodium intake & increasing water intake
184
What is the AI of sodium for those 14 and up?*
1500 mg/day
185
What is the Chronic Disease Reduction Risk (CDRR) for 14 and up?*
2300mg/day.
Mean Canadian Intake is above this
186
What is the daily value of sodium?
Was 2400 mg -- now 2300 mg on new food labels
187
What can be said about hypertension and sodium?
Salt (NaCl) seems to have a greater effect on blood pressure than either sodium or chloride alone
188
What age group tends to have the highest average daily sodium intake?
19 to 30 for both makes and females. Especially males (more food intake)
189
What is the major food category to the average daily sodium intake of Canadians in 2017?
Bakery products
Mixed dishes
Due to the quantity -- tend to have a lot of bakery products in their diet, even if they are not high individually, they add up over the day
190
What can be said about sodium and blood pressure?
High salt intakes associated with higher rates of hypertension, cardiovascular disease & cerebral hemorrhage
There is a relationship between sodium and blood pressure
- More salt = higher blood pressure
- Increasing blood pressure= increasing risk of death from cardiovascular disease
191
Some individuals are more sensitive to the blood pressure-raising effects of sodium than others. In salt-sensitive people, the more salt they eat, the higher their blood pressure. Who tends to be the most salt sensitive?
People with diabetes, hypertension, or kidney disease
People of African descent
Family history of high blood pressure
Anyone over the age of 50
192
What is some advice for high blood pressure?
Can be argued that only salt-sensitive people should be advised to cut down on salt - but who is salt sensitive?
Critics: Non-salt-sensitive people with hypertension are unlikely to benefit from restricting dietary sodium & salt
Try reasonable weight loss, adding vegetables, fruits, fatty fish & milk/milk products to the diet. Reducing processed foods (without targeting sodium)
Reducing alcohol consumption
193
A dietary approach that may help salt-sensitive and non-salt-sensitive people is the ___ diet
DASH (Dietary Approaches to Stop Hypertension) -- the diet often achieves a lower blood pressure than restriction of sodium alone.
Greatly increased intake of vegetables and fruits
Adequate amounts of nuts, fish, whole grains, low-fat dairy products
Occasional small portions of red meat, butter, & other high-fat foods and sweets
Salt & sodium are greatly reduced
194
When the diet changed to provide abundant magnesium, potassium, and calcium, as well as adequate protein and fibre, the average blood pressure drops even lower at each level of sodium intake. Research shows DASH diet with reduced sodium -- blood pressure falls responsively (3450 mg, 2300mg, 1150mg). What are some sources?
whole grains, fruits, vegetables, seeds, nuts, legumes
195
What can be said about what lowers or raises blood pressure (potassium and physical activity)?
Low potassium intake found to raise blood pressure
High potassium intake appears to both help prevent & correct hypertension
Physical activity also lowers blood pressure
196
What are some other reasons for reducing salt intake?
Older people without clinical hypertension can die of stroke
- Reducing dietary sodium may lower their blood pressure enough to reduce stroke risks
Excessive salt may:
- stress a weakened heart (congestive heart failure)
- aggravate kidney problems
- may be potential contributor to stomach cancer
Labelling regulations also allow a health claim linking sodium & potassium to hypertension
197
What happens with prolonged vomiting or diarrhea?
Could result in fluid and electrolyte imbalance
Life-threatening disruption of heartbeat
198
What are some characteristics of water in the body (4)?
60% of an adult's body weight
Found in blood, cells, tissues, and organs
Participates in many chemical reactions
Delivers nutrients and removes waste from cells
199
What can be said about the body's need for water?
The body needs more water per day than any other nutrient
May survive deficiency of any other nutrient for potentially months or years
May survive a few days or slightly more without water
In less than a day, a lack of water alters the body’s chemistry and metabolism
200
What are some of the roles and functions of water?
Water is a nearly universal solvent
Water is the body's cleansing agent
Water's incompressibility
Water lubricates
Water plays a role in thermoregulation
201
How is water a nearly universal solvent?
Dissolves amino acids, glucose, minerals, etc. for transport; Fatty substances get packaged with water-soluble proteins for transport in the blood & lymph
202
How is water the body's cleansing agent?
Nitrogen wastes dissolve in blood & must be removed; Kidneys filter these wastes from the blood, mix them with water and excrete them as urine
203
What does water's incompressibility do for the body?
Enables it to act as a lubricant & cushion for joints; Cushions sensitive tissues (i.e., spinal cord and fetus); Fills the eye keeping optimal pressure
204
What does water lubricate?
The digestive tract, respiratory tract & all tissues that are moistened with mucus
205
How does water play a role in thermoregulation?
Sweat cools the body - evaporation; Blood routed through capillaries in the skin gets rid of excess heat. The cooled blood then flows back to the body's core
206
What is water balance?
Water intake needs to equal water loss
Otherwise dehydration or water intoxication or overhydration can occur
207
What is the progression of symptoms of dehydration and what are its effects?
Progression of symptoms: thirst → weakness → exhaustion & delirium → death
Loss of < 5% bodyweight: headache, fatigue, confusion, forgetfulness, and an elevated heart rate
208
What may result with chronic low fluid?
May increase likelihood of:
Bladder and colon cancer
Heart attack
Gallstones
Kidney stones
Urinary tract infections
209
How does water intoxication happen? What are its symptoms?
Dangerous dilution of body fluids resulting from excessive water ingestion – usually gallons or more in a few hours
Symptoms: headache, muscular weakness, lack of concentration, poor memory, loss of appetite – convulsions & death
210
What can be said about body's water content?
Varies by kilograms at a time
High-salt meal leads to water retention
Water is lost over a 1-2 day period as the sodium is excreted
Fluctuation in water weight does not reflect gain or loss of body fat
211
Thirst lags behind lack of water. So, what can be said about water deficiency?
Dehydration can threaten survival
A water deficiency that develops slowly can switch on drinking behaviour in time to prevent serious dehydration
A water deficiency that develops quickly may not
Ignoring thirst leads to dehydration
Drink whenever thirsty to replace lost fluids
Older adults - thirst blunted - should drink regularly throughout the day
212
How is the hypothalamus related to blood concentration?
Major role in monitoring blood concentration
High blood concentration (salt and other substances) or low blood pressure signals thirst
213
What can affect a mineral's bioavailability?
Binders, such as phytates in legumes, bind with minerals decreasing their absorption
214
What are the key contributors to sodium in the diet (percentages)?
Unprocessed foods (15%)
Salt (10%)
Processed Foods (75%)
215
1 tsp of salt has how many mg of sodium?
2300
216
What are some processed foods known for being a source of sodium?
Canned soup and dried soup mixes
Cured meats, deli meats, hot dogs
Cheese -- especially processed
Foods in a brine -- pickles, coleslaw
TV dinners and fast food
Canned pasta sauce
Salt
Soy sauce
Onion salt
Garlic salt
Worcestershire sauce
217
Chloride is a major negative ion in the body. It therefore has what roles?
Acid-base balance
Electrolyte balance
Component of hydrochloric acid
218
What are some sources of chloride?
Salt: added & naturally occurring
219
What can be said about chloride deficiency?
No known diet lacks chloride
220
Potassium is known as what?
The principal positively charged ion inside the body's cells
221
What are some roles of potassium?
Maintenance of fluid balance
Maintenance of electrolyte balance (sodium potassium pump)
Maintenance of heartbeat
222
What happens with deficiency of potassium?
Heart failure due to inadequate potassium or potassium loss may cause the sudden deaths that occur with:
- Fasting or severe diarrhea
- In children with kwashiorkor (acute protein energy undernutrition - second sibling)
- People with eating disorders
Dehydration leads to potassium loss from the cell
Some diuretics
With low potassium intake, hypertension becomes worse
223
What can be said about potassium intake?
Generally, for healthy people, a reasonable diet provides enough potassium to prevent dangerously low blood potassium
224
What is the median Canadian intake of potassium, and what can this lead to?
Median Canadian intake provides just under the AIs for each sex
With such a diet, blood potassium may remain normal
However, chronic diseases are more likely to occur
225
What are the richest sources of potassium?
Fresh, whole foods
Oranges (juice), bananas, potatoes, tomatoes, avocados, strawberries, spinach and cantaloupes are particularly rich
Potassium is abundant in cells
Food processing reduces the potassium in foods
226
What can happen with potassium toxicity?
Potassium from food is safe
Potassium injected into a vein can stop the heart (death penalty)
Over-the-counter potassium chloride pills should not be used except on a physician’s/ nurse practitioner’s advice
Salt-substitutes often contain high amounts
Usually, potassium overdoses are not life-threatening as long as the excess potassium is taken orally – vomiting reflex
227
What are some of the roles of sulphate/sulphur?
Required for the synthesis of many important sulphur-containing compounds.
- Sulphur containing amino acids.
These help strands of protein assume their functional shape. Skin, hair, and nails proteins with high sulphur content
228
What are some sources of sulphur?
Protein containing foods
229
What happens with toxicity and deficiencies of sulphate?
D: Unknown
T: Diarrhea
230
What are the trace minerals?
Iodine
Iron
Zinc
Sulphur
Selenium
Fluoride
Chromium
Copper
231
What is the role of iodine?
Integral part of thyroxine (hormone).
Made by the thyroid gland - regulation of basal metabolic rate
232
What happens with deficiency of iodine?
Enlarged thyroid (goiter) – enlarged to trap iodine
Sluggishness
Weight gain
Severe deficiency during pregnancy can cause congenital hypothyroidism
- Extreme irreversible mental & physical developmental delay
- Most preventable causes of intellectual delay
233
What foods contain goitrogens, which inhibit iodine uptake by the thyroid?
Collards, kale, and brussel sprouts
234
What happens with toxicity of iodine?
Enlarged thyroid gland (same as with deficiency)
Can be deadly in very very large amounts (supplements)
235
What are some sources of iodine?
Amount varies with amount in soil in which plants are grown or on which animals graze
Seafood: Iodine from ocean
Iodized salt: less than a half-teaspoon meets an entire day’s recommendation
Sea salt has little iodine
Liberal use of iodized salt in fast-food & other restaurants
Bakery products: use of iodine-containing dough conditioners
Milk: 250 mL (1 cup) supplies nearly ½ of a day’s recommended intake: Most dairies use iodine to disinfect milking equipment
236
What two things contain most of the body's iron?
Hemoglobin and myoglobin
Hemoglobin is the oxygen-carrying protein of red blood cells
Myoglobin is the oxygen-holding protein of muscles
237
What are the roles of iron?
Carries oxygen
Helps many enzymes use oxygen
Iron is needed to make new cells, amino acids, hormones, neurotransmitters
238
How does the body try to preserve iron?
Liver puts iron into red blood cells sent to it from bone marrow
Red blood cells die after about 3 to 4 months and the liver & spleen break them down & recycle their iron
239
Why are many people iron deficient?
Iron balance is maintained mainly through absorption. We are preventing ourselves from getting too much, as that can be very dangerous
240
How do we lose iron?
Small amounts in nail clippings, hair cuttings, shed skin cells
Loss from bleeding can be significant
241
How do we obtain iron?
Food -- only ≈10%-15% absorption
Increases with diminished body supply & with need
Decreases when iron is abundant
242
How is iron stored?
Ferritin -- an iron storage protein stores iron in the mucosal cells of the small intestine
243
If iron is needed, what does the body do? If it is not?
Iron is releasted to transferrin and travels through the blood to the body
Iron is shed with the intestinal cells which are replaced every 3 to 5 days.
244
Why is free iron a powerful oxidant?
Can start free-radical reactions that can damage cells
Therefore, protein carries iron molecules away from vulnerable body compounds
245
What is an iron deficiency?
Result of absorption not compensating for losses or low dietary intakes
Decreased iron stores (stage 1 deficiency)
Depleted iron stores (stage 2 deficiency)
246
What is iron deficiency anemia?
A person can be iron deficient without being anemic
Anemia refers to depletion of iron stores resulting in low blood hemoglobin (stage 3 deficiency)
247
Severe iron deprivation leads to insufficient hemoglobin production to fill new blood cells, which leads to what?
Anemia (red blood cells are smaller - microcytic & lighter red than normal - hypochromic) **
- Cells contain too little hemoglobin & thus deliver too little oxygen - limits cell's energy metabolism, which leads to tiredness, apathy, and a tendency to feel cold
248
What can be said about these symptoms of iron deficiency?
They are often mistaken for behavioural or emotional problems/
Slightly lowered iron levels cause fatigue & can impair physical work capacity & productivity
Pica (craving for non-food substances) sometimes occurs with iron deficiency. They may eat clays and soils, even though they often contain substances that inhibit iron absorption. Nonfood substances displace food substances and have contaminants.
249
What are some causes of iron deficiency and anemia?
Malnutrition, inadequate iron intake (lack of food/high consumption of the wrong foods - rich in sugar & fat & poor in other nutrients)
Non-nutritional causes of anemia (losses or increased need)
- Most often: blood loss - 80% of body's iron stored in blood
- Women in reproductive years - iron loss and generally less food than men
- GI bleed
- Infants over 6 months of age, young children, adolescents, pregnany women have increased iron needs to support growth of new tissue
250
Worldwide, iron deficiency is the most common nutrient deficiency, affecting more than 1.2 billion people. In developing countries, what can be observed?
parasitic infections of the digestive tract and digestive tract ulcers and sores can cause daily blood lost
almost 1/2 of preschool children & pregnant women suffer from iron-deficiency anemia
251
Can a person take in too much iron?
Iron is toxic in large amounts
Difficult to excrete once absorbed
The body defends against iron overload (hemochromatosis) by controlling its entry
252
How does the body defend against hemochromatosis?
Hepcidin – a hormone secreted by the liver that limits iron absorption
Small intestine traps some of the iron & hold it within their boundaries (mucosal cells)
When these intestinal mucosal cells are shed, the excess iron they collected is lost from the body
When iron stores are filled, less iron is absorbed - protects from iron overload
253
Dangers of iron overload are an argument against high-level iron fortification of foods. What can be said about this?
Susceptible people would have trouble following a low-iron diet if most foods were doused with iron
Many Canadians take vitamin C supplements; vitamin C enhances iron absorption
Iron-fortified foods pose no risk for healthy people
254
Iron supplements can reverse iron-deficiency anemia from dietary causes. What can be said about this and children, though?
Iron supplements are a leading cause of fatal accidental poisonings among Canadian children under 6 years old
255
What can be said about men and iron-deficiency anemia?
Adult men rarely experience it. May have unknown bleed if low iron
256
How much iron should vegetarians obtain?
1.8 times the normal requirement, as iron in plant foods is not well absorbed &
their diets lack factors from meat that enhance iron absorption
257
What can be said about iron supplements?
Food is generally best source – better absorption than supplements
Pregnant women need an iron supplement
258
Iron occurs in 2 forms in foods. What are they?
Heme iron (bound to heme) -- The iron-containing part of hemoglobin & myoglobin found in meat, poultry and fish
Nonheme iron -- found in foods from plants & meat, poultry and fish
259
Which is absorbed better, heme iron or nonheme iron?
Heme iron
Healthy people with adequate iron stores absorb heme iron at a rate of around 23%.
People absorb nonheme iron at rates of 2% to 20%, depending on dietary factors & iron stores
260
What is the MFP factor?
Found in meat, fish & poultry
Promotes the absorption of nonheme iron from other foods eaten at the same time
261
What can be said about vitamin C and iron?
can help absorption of iron from foods eaten in the same meal
262
What impairs iron absorption?
Tannins - Found in tea & coffee
Calcium & phosphorus - Milk
Phytates - Found in the fibre of lightly processed legumes & whole-grain cereals
Black tea is exceptional in its efficiency in reducing iron absorption (advisable for iron overload)
263
What are some general sources of iron?
Red meats, fish, poultry, shellfish, eggs
Legumes, green leafy vegetables, dried fruit
Cooking in an iron pan adds iron to food
264
There is a very small quantity of zinc in the human body. What are some of its roles?
Works with proteins in every body organ
Helps more than 300 enzymes to:
Make parts of the cell’s genetic material
Make heme in hemoglobin
Assist the pancreas with its digestive functions
Help metabolize carbohydrate, protein & fat
Liberate vitamin A from storage in the liver
Assists in immune function
Regulation of gene expression in protein synthesis
Taste perception
Wound healing
Sperm production
Fetal development
Growth & development in children
Affects behaviour & learning
Produces the active form of vitamin A in visual pigments
May have a protective role in oxidative damage
265
What are some zinc deficiency symptoms?
Adverse effects on growth*
Profoundly alters digestive function & causes diarrhea, which worsens the malnutrition already present
Drastically impairs the immune response - Increased infections
Infections of the intestinal tract worsen malnutrition - Including zinc malnutrition
Poor wound healing
Abnormal taste
Abnormal vision in the dark
Even a mild deficiency can result in impaired immunity
266
What can be said about zinc deficiencies overall?
Deficiency often misdiagnosed as general malnutrition & sickness because symptoms are so vast
Severe zinc deficiencies are not widespread in developed countries
Pancreatic juices are rich in zinc so after a meal, the body gets zinc from the food and the pancreatic enzymes
Zinc is primarily lost in the feces
267
What can happen with too much zinc?
Excess supplements can cause serious illness or death
May reduce blood concentrations of HDL
Can block copper absorption & lower the body’s copper content
High doses can also inhibit iron absorption
A protein that carries iron from the digestive tract to tissues also carries zinc
Lozenges with zinc are generally not an issue
268
How much is zinc absorbed?
Varies from 15% – 40% - absorption decreases with increased intake
Absorption limited by phytates
269
What are some food sources of zinc?
Meats, shellfish, poultry, milk & milk products (not good for iron, but good for zinc)
Plant sources of zinc are not absorbed as well as animal sources (some legumes, whole grains)
270
What is the role of selenium?
Works to prevent the formation of free radicals and prevent oxidative harm to cells & tissues * (antioxidant)
Plays roles in activating thyroid hormone
Shares some of the characteristics of sulphur and can therefore sometimes occur in place of sulphur in amino acids
271
What can happen with deficiency of selenium?
Cancer* (low blood selenium correlates with the development of some forms of cancer - especially prostate cancer)
Heart disease (Associated with Keshan disease*: heart enlargement and insufficiency. Keshan disease is likely caused by a virus but a selenium deficiency may predispose people to the disease. First discovered in parts of China from areas which have sodium deficient soil
Adequate selenium seems to prevent Keshan disease
272
What can happen with toxicity?
Long-term supplementation. Symptoms: nausea, abdominal pain, hair loss, nerve abnormalities
273
What are some sources of selenium?
Diet is adequate if mostly unprocessed foods
Widely distributed in foods such as: Meats, shellfish, vegetables & grains grown in selenium-rich soils
Selenium content of soils varies in areas of Canada and the US
No benefits seen from selenium supplements unless selenium deficient
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Is fluoride essential?
No, but it is beneficial
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What is the role of fluoride?
Crystalline deposits in bone and teeth
Forms more decay-resistant fluorapatite in developing teeth
Floride replaces the hydroxy portion of hydroxyapatite.
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What are some sources of fluoride?
Primary source: Fluoridated drinking water
Tea and seafood
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What happens with deficiency of fluoride?
Where fluoride is missing, the incidence of dental decay is very high
Fluoridation is a practical, safe & cost-effective way to help prevent dental caries in the young
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What happens with toxicity of fluoride, and who can this happen to?
Fluorosis - discolouration and pitting of tooth enamel caused by excess fluoride during tooth development - irreversible
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What is the role of chromium?
Works closely with insulin to regulate & release energy from glucose
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What happens with deficiency of chromium?
Impaired insulin action, resulting in a diabetes-like condition of high blood glucose & resolves with chromium supplementation
Supplements cannot cure the common forms of diabetes. Research - role of chromium supplements in the management of type 2 diabetes
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What are the sources of chromium?
Widely distributed in the food supply. Especially in unrefined foods & whole grains. Lost during food processing
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What are the roles of copper?
Formation of hemoglobin & collagen
Many enzymes depend on copper for its oxygen-handling ability
Plays a role in the body’s handling of iron
Assists in reactions leading to the release of energy
One copper-dependent enzyme (superoxide dismutase) helps control damage from free-radical activity in the tissues
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What happens with copper deficiency?
Rare
Excess zinc interferes with copper absorption & can cause deficiency
Menkes disease – intestinal cells absorb copper but can’t release it into circulation causing deficiency
(less important:)
Symptoms:
Can severely disturb growth & metabolism
In adults, can impair immunity and blood flow through arteries
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What happens with copper toxicity?
Unlikely from foods
Can be caused by supplementation
Wilson’s disease* - copper accumulates in the liver and the brain
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In Canada, copper intakes are thought to be adequate. What are some sources?
Organ meats
Seafood
Nuts and seeds
Whole grains
Water may supply copper, especially where copper plumbing pipes are used
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What are some other trace minerals?
Molybdenum, manganese, boron, nickel, silicon, and cobalt
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What is arsenic?
A known poison & carcinogen
May turn out to be essential in small quantities
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What can be said about toxicity of trace minerals overall?
All trace minerals can be toxic in excess
Overdoses are most likely to occur in those who take supplements
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What inhibits iron absorption?
Calcium and Phytates (bind iron)
MFP factor is found in meat fish and poultry. It increases absorption of nonheme iron
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Abnormal taste, poor wound healing, impaired growth and impaired immune response are symptoms of a deficiency in which of the following nutrients?
Zinc
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Menke's disease is associated with a defiency in which of the following?
Copper
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Which of the following groups would generally be at the lowest risk of iron deficiency?
- Infants over 6 months
- Growing children
- Middle aged men
- Women in their reproductive years
- Pregnant women
Middle aged men (some of the lowest iron needs and highest caloric intake)
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How does vitamin C act as an antioxidant?
- Protects substances found in foods & the body
- Protects iron from oxidation promoting its absorption
- Protects blood constituents from oxidation and helps protect vitamin E and return it to its active form
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What can be said about vitamin C supplements?
- Research generally shows supplements have not been proven to protect against heart disease, cancer, or other diseases
- Supplements are useful to treat a deficiency disease
