KIN 346Module 3 Flashcards
What are vitamins?
Essential, organic micronutrients
How do vitamins differ from macronutrients?
1) Structure: found in individual units 2) Function: don’t yield energy 3) Food contents: amounts ingested and required are usually measured in micrograms and milligrams
What affects bioavailability of vitamins?
1) efficiency of digestion and previous nutrient intake 2) method of preparation (some are easily destroyed) 3) source of the nutrient (supplement, food, fortification) 4) Other foods consumed at the same time (may help or hunder)
What are precursors or previtamins?
Inactive form of vitamins that must be activated in the body to be useful
What are the fat soluble vitamins?
A,D,E,K
What are the water soluble vitamins?
The Bs and Vitamin C
How are fat soluble vitamins absorbed?
into lymph, requires bile
How are fat soluble vitamins transported?
require protein carriers
How are fat soluble vitamins stored?
in fat compartments
How are fat soluble vitamins excreted?
tend to be stored
Are fat soluble vitamins toxic?
More likely than water soluble
What are the requirements for fat soluble vitamins?
periodic doses
How are water soluble vitamins absorbed?
directly into the blood
How are water soluble vitamins transported?
travel freely
How are water soluble vitamins stored?
in water compartments
How are water soluble vitamins excreted?
usually excess is removed in urine
Are water soluble vitamins toxic?
Less likely, but possible from supplements
What are the requirements for vitamins?
frequent doses
What are the RDAs for Vitamin A for men and for women?
Men (19-30): 900 micrograms/ day. Women (19-30) = 700 micrograms per day
Three active forms of reinoids in the body?
Retinol, retinal, and retinoic acid
How is vitamin A absorbed and where is it stored?
Absorbed into the lymph and stored in the liver
Animal foods supply what form a vitamin A?
Supply retinyl esters, absorbed as retinol
Food sources of retinol/retinyl esters?
liver, fish oils, eggs, milk, milk products, and fortified foods such as margarine
Plan foods supply what type of Vitamin A?
Carotenoids
Food sources of carotenoids?
Leaft greens (kale, spinach), and orange veggies and some orange fruits (squash, sweet potato, cantaloupe, apricots, and papaya)
What are cartenoids?
Orange pigments found in foods in which some have vitamin A activity (called prescursors)
What carentoid has the highest vitamin A activity?
Beta-carotene
What does beta carotene consist of?
Two molecules of retinol
12 micrograms of beta-carotene = ?
1 microgram vitamin A (retinol)
How is vitamin A activity measured?
Retinol Activity Equivalents (accounts for active forms and precursors)
What is an important role of Vitamin A?
regulation of gene expression
What is an important role of retinal?
promoting vision
What is an important role of retinoic acid?
Protein synthesis and cell differentiation (maintenance of epithelial tissues) and growth (bone remodelling)
Important role of retinol?
Supports reproduction
Important role of beta carotene?
acts as anantioxidant
What are the two indispensable roles of vitamin A in vision?
maintenance of the cornea and conversion of light energy into nerve impulses in the retine
Steps in vision?
Retina contains rhodopsin, a molecule composed of opsin (a protein) and cis-retinal (vitamin A). Light hits rhodopsin and retinal becomes trans-retinal, causing it to detach from opsin, sending nerve impulses to the brain to cause vision.
How does vitamin A deficiency cause blindness?
When trans-retinal is being converted back into cis-retinal, some of it is oxidized to retinoic acid, which cannot be turned back into retinal, so more retinal is needed either directly or from converting retinol to retinal.
What does vitamin A adequacy depend on?
stores (liver) and protein status
Where is vitamin A mainly stored?
The liver
What are the 2 stages of blindness caused by vitamin A deficiency?
Night blindness (retina) and progressive blindess called xeropthalmia (cornea)
What is keratinization, and deficiency in what vitamin causes it?
The hardening and thickening of skin. Faltering of digestion and absorption. Weakened defenses because of weakened epithelial tissue. Caused by a vitamin A deficiency.
Why do WHO and UNICEF recommend routine vitamin A supplementation?
Severity of measles often correlated with degree of deficiency, and a deficiency in vitamin A increases vulnerability to infectious disease.
UL for vitamin A?
3000 micrograms/d of PREFORMED vitamin A
Consumption of what increases the risk of vitamin A toxicity?
Eating lots of liver, supplements, and fortified foods
Free vitamin A damages the tissues when?
Binding proteins are swamped
What characterizes vitamin A toxicity?
Over-stimulated cell-division (bone abnormalmities (weakening), birth defects (teratogen), liver failure, and death)
Excess beta carotene intake from foods?
high intake from foods is harmless…causes yellowing if the skin (not eyes)
Excess beta-carotene from supplements causes?
Problematic. Toxic levels can be reached by overriding body’s usual protective mechanisms, can become pro-oxidant, destroys Vitamin A in cells.
Other name for Vitamin D?
Calciferol
RDA for vitamin D for males (19-30) and females?
15 micrograms/day for males and females (600IU)
What is the active form of vitamin D?
1,25-dihydroxycholecalciferol (calcitriol)
Why is vitamin D considered non-essential or “conditionally essential?”
It can be synthesized endgenously from the precursor 7-dehydrocholesterol, made in the liver
What are some animal foods that supply vitamin D?
egg yolks, liver, fatty fish and their oils
What type of vitamin D do animal foods supply?
cholecalciferol (vitamin D3)
What type of vitamin D do plant foods supply? Are there good sources of this?
Supply ergocalciferol (vitamin D2), and no good sources exist
What are some fortified foods that are a source of vitamin D?
milk and margarine (mandatory), butter, juices, cereals
Steps in vitamin D synthesis and activation
1) 7-dehydrocholesterol (a precursor made in the liver from cholesterol) in the skin gets hit with UV light 2) Forms previtamin D3 or Vitamin D3 comes from foods (inactive form) 3) In the liver, hydroxylation turns it in 25-hydroxy vitamin D3 (calcidiol) 4) Hydroxylation in the kidneys turns it into the active form, 1,25-dihydroxy Vitamin D3/calcitriol
How many hydroxylations must occur to get active vitamin D3, and where do they occur?
2, in the liver and the kidneys
Active form of vitamin D3 is a ___
hormone
How does vitamin D participate in bone growth and maintenance?
By maintaining concentrations of calcium and phosphorus through action at the intestine, kidneys, and bone
How does vitamin D maintain blood concentrations of phosphorus and calcium through the intestine, kidneys, and bone?
Intestine: increases absorption when diet is adequate. Kidneys: increases REabsorption with parathyroid hormone. Bone: increases mobilzation with parathyroid hormone. Many other roles are being studied.
Vitamin D is needed to produce a protein that binds calcium in intestinal cells, what is this protein called, and what does vitamin D deficiency cause with respect to it?
Calbindin, deficiency means that dietary calcium absorption is limited. This creates a secondary deficiency that leads to bone abnormalities such as rickets in childrem, osteomalacia in adults, and increased risk of osteoporosis.
What are some reasons why people become vitamin d deficient from lack of sunshine?
older age, northern latitude, pollution, sunscreen, clothing, skin pigmentation
Percentage of Canadians that are vitamin D deficient in winter and summer?
40%, 25%
For all Canadians, what is recommended to guarantee vitamin D requirement is met?
2 cups of fortified milk daily…supplements for older adults, as well
What is the UL for vitamin D?
100 micrograms/day (4000 IU)
What is vitamin D toxicity usually due to?
Excess supplementation. Dietary excess from food sources is unlikely. Endogneous production from sunlight cannot reach toxic levels–precursors in skin are degraded with long sun exposure.
What does vitamin D toxicity cause?
Elevated blood concentration (hypercalcemia) leading to calcification of soft tissues (kidney stones and calcification of blood vessels)
What is another name for Vitamin E?
Tocopherol
RDA for 19-30 males and females for vitamin E?
15 mg/day…those with high PUFA intakes may need more
Why do people with high PUFA intakes need more vitamin E?
Vitamin E is an antioxidant that prevents the oxidation of PUFAs, so more in your diet, the more protection you need from oxidation
How many tocopherol compounds are there, what is hthe biologically active form?
4 different forms differentieated by positions of their methyl groups. Alpha-tocopherol is the biologically active form, other forms cannot be converted to alpha-tocopherol
Is vitamin E widespread in the food supply?
Yes
What are the main sources of vitamin E in the food supply?
Vegetale oils and products made from them (margarine, salad dressings)
What are some food sources of vitamin E in food?
vegetable oils and products made from them, wheat germ (ground), whole grains, nuts and seeds, liver, egg yolkd, leafy green vegetables
Is vitamin E easily destroyed?
YES! by heating process (deep fried foods)
What are the roles of vitamin E?
ANtioxidant (prevents oxidation of PUFAs and other lipids and protects cell membranes from oxidative damage), and may protect against heart disease by protecting LDL against oxidation and reducing inlfammation
Where is vitamin E deficiency primarily seen?
premature infants (transfer of vitamin E in last few weeks of pregnancy) and in conditions of fat malabsoprtion (CF, Chron’s)
What is the acute effect of vitamin E deficiency?
Hemolytic anemia (RBC explode becaues loss of PUFAs in membrane)
What is the long term effect of vitamin E deficiency?
Causes neuromuscular dysfunction (loss of muscle coordination and relfexes, impaired vision and speech)
UL of vitamin E?
1000 mg/day…can’t achieve through foods alone
Why is vitamin E toxicity rare?
blood concentration is tightly regulated by the liver.
What do extreme intakes of vitamin E cause?
Hemorrhage because it interferes with clotting action of vitamin K and enhances the action of anti-clotting drugs
AI for vitamin k for males and females?
120 micrograms/d and 90 micrograms/day
Where does about 50% of our vitamin K intake come from?
Synthesized endogenously by GI bacteria as a product of fermentation, the rest must be suppled from dietary sources (i.e. it remains essential)
Is vitamin K essential?
YES
Where is vitamin K stored?
The liver
What does animal food supply in terms of vitamin K, and what foods supply it?
Supply menaquinone…liver and milk
What do plant food supply in terms of vitamin K, and what foods supply it?
Supply phylloquinone…leafy green vegetables, cabbage-type vegetables (brussel sprouts, brocolli, and cauliflower), vegetable oils (canola and soybean)
Roles of Vitamin K
involved in the cascade of reactions that lead to blood clotting *required to repair damage to blood vessels and tissues). Participates in bone health (metabolism of osteocalcin to actiavte carboxylase, decreases bone turnover, protects against fracture)
What is osteocalcin?
A bone proten that binds calcium to bone…helps activate carboxylase, which is needed to bind the calcium. Protects against fracture.
Although primary vitamin K deficiency is rare, when can it happen, and what does it cause?
Can be found in conditions of fat malabsorption, newborn infants and those on antibiotics. Causes poor wound healing and hemorrhage/
What are the water soluble vitamins?
B family and C
Another name for vitamin C
ascorbic acid
Vitamin C requirements?
90 mg/day for males, 75 mg/d females
Why do smokers require an extra 35 mg/d of vitamin C?
Lots of oxidation takes place, so extra vitamin c is needed for more antioxidants
What are some sources of vitamin C?
citrus, strawberries, bell peppers…fruits and veggies
How is vitamin C easily destroyed?
Heat (cooking) and oxygen exposure
How much vitamin C does one cup of orange juice provide?
> 100 mg (more than the RDA)
Roles of vitamin C
Works as antioxidant because it can easily donate electrons to unstable free radicals (can be restored to its active form by accepting an electron, key to limiting losses and maintaining antioxidant reserve, in the SI, it protects Fe from oxidation, enhancing absoprtion). Cofactor in the formation and maintenance of collagen (connective tissue serving as a matrix on which bones and teeth are fored, involved in wound healing). Cofactor in the synthesis of a number of compounds (carnitine, NTs, thyroxin)
What does vitamin c deficiency cause?
Loss of integrity of blood vessels causes bleeding (scorbutic) gums, pinpoint hemorrhages. Long-term inadequacy leads to scurvy (hemorrhage, dry and rough skin, impaired wound healing, bone abnormalities, anemia and infection, sudden death
UL for vitamin c?
2000 mg/d
What can vitamin c toxicity result from?
overzealous supplementation (often for the common cold)
Symptoms of vitamin c toxicity?
GI distress, diarrhea, can interfer with anticlotting medications, causes kidney stones, can become a pro-oxidant and contribute to Fe overload (increases absorption of Fe in GI tract and increaes release of Fe from iron stores)
Can vitamin C cure the common cold?
No. Modest, consistent reduction in duration and severity and reduced risk after periods of physical stress, though.
As a group, what do the B vitamins do?
Work as coenzymes in energy metabolism
What are the B family vitamins?
Thiamin, riboflavin, niacin, folate, pyridoxine, cobalamin, biotin, pantothenic acid
As a group, what are common signs of vitamin B deficiencies?
Glossitis (shiny tongue from it being swollen) and Cheilosis (corners of mouth become cracked)
RDA for Thiamin for men and women?
1.2 mg/d an 1.1 mg/day
What is thiamin?
vitamin B1
What is thiamin deficiency a result of?
A result of malnourishment (diet less than 1200 cals, homeless, poor)
What does prolonged thiamin inadequacy result in?
Beriberi (dry = damage to nervous system, muscle wasting, wet = damage to cardiovascular system - edema)
What is Wernicke-Korsakoff syndrome?
Thiamin deficiency in alcoholics…disorientation, memory loss, jerky eye movements, staggering gait
What is the upper limit for thiamin?
Toxicity is not observed, so no UL
What is riboflavin?
Vitamin B2
RDA of riboflavin for men and women?
1.3 mg/d for men, 1.1 mg/day for women
Role of riboflavin?
Coenzyme in a number of reactions, including energy metabolism as flavin mononuleotide (FMN) and flavin adenine dinucleotide (FAD), accept and donate hydrogen
Sources of riboflavin?
mostly milk products, liver, also whole and enriched grains
Why is milk packaged in a certain way in regards to riboflavin?
To avoid its destruction by UV light and irradiation
Riboflavin deficiency is known as? What does it cause?
Ariboflavinosis…inflammation of membranes (mouth, skin, eyes, GI tract), glossitis and cheilosis
UL for riboflavin?
Toxicity is not observed, no UL
What is niacin?
Vitamin B3
RDA for niacin?
16 mg NE/ d for men, 14 mg NE/d women
How can niacin be produced endogenously?
Using the AA tryptophan…60 mg of tryptophan is needed to produce 1 mg niacin…requirements are expressed in niacin equivalents (NE)
What are the two forms of niacin? Where are they found?
Nicotinic acid (synthetic) and nicotinamide (major form in blood)
Roles of niacin?
involved in energy transfer reactions as coenzymes nicotinamide adenine dinucleotide and its phosphate form (NADP). Protects against neurological degeneration. High doses of nicotonic acid may produce a pharmacological effect (raise HDL and lower LDL)
Sources of Niacin?
milk, eggs, legumes, enriched and whole grains, all protein containing foods (supply tryptophan)
Why was niacin deficiency prevalent in the southern US? How was it fixed?
Due to reliance on low protein, corn-based diets, which are low in tryptophan and niacin. Greater than 70% of niacin in corn is bound to complex CHO and small peptides high in leucine. Treatment with LIME increases bioavailability.
What is niacin deficiency known as, and what is it characterized by?
Pellagra, the four Ds…diarrhea, dermatitis, dementia, death
UL for niacin toxicity?
Nicotinic acid (synthetic)
Does naturally occurring nicotinamide cause toxicity?
Nope
How does excess niacin intake occur, and what does it cause?
Excess intake from supplements (energy drinks) results in niacin flush (dilation of capillaries leading to tingling sensation, painful flushing of skin, rash)
RDA for folate for men and women?
400 micrograms per day for men and women. Needs increase during pregnancy
Two forms of folate?
Naturally occurring folacin, and Synthetic folic acid.
requirements for folate are expressed in?
dietary folate equivalents, accounting for differences in bioavailability
Which form of folate is more bioavailable?
Synthetic form (folic acid) is 1.7x more bioavailable
Roles of folate
Transfer of 1-C compounds arising during metabolism, involved in synthesis of DNA, conversion of B12 to one of its coenzyme forms
Sources of folate?
Leafy green vegetables, legumes, seeds, liver, and enriched grains
Two types of folate deficiency?
Primary (inadequate intakes) or secondary (impaired absorption, unusual metabolic need)…higher amounts are needed for times of rapid cell division (pregnancy). Adequate intake before and during pregnancy prevents neural tube defects.
Folate deficiency causes?
Impaired cell division and protein synthesis…replacement of RBCs and GI tract cells falters, leads to megaloblastic anemis, and glossitis
What is megaloblastic anemia?
Large, immature RBCs
When did folate fortification of grains become mandatory, and by how much did neural tube defects decrease?
1998, 46%
UL for folate?
1000 micrograms/day (fortified foods and supplements). Naturally occurring folate is not harmful, but supplements and fortified foods can lead to excess
What is the main concern of folate toxicity?
Masks a B12 deficiency symptoms…both folate and B12 deficiencies cause megaloblastic anemia, supplementing with folate will cure the anemia but not the other symptoms of B12 deficiency
What is cobalamin?
B12
RDA for cobalamin?
2.4 micrograms/day
Roles of cobalamin?
Coenzyme in methyl transfer reactions in metabolism, maintenance of the myelin sheath protecting nerve cells, conversion of folate to one of its coenzyme forms, involved in synthesis of DNA, regenerates methionine from homocysteine
What is homocysteine?
AA occurring naturally in blood and high levels increase the risk of CVD
Sources of vitamin B12?
almost exclusively in animal foods, with greatest bioavailability from milk and fish. Vegans must seek out fortified foods (soy beverage)
Digestion and absorption of cobalamin?
Stomach: HCl and pepsin release B12 from proteins Stomach to small intestine: B12 binds with stomach secretion called intrinsic factor End of small intestine: recognizes complex and is absorbed
What is required for cobalamin to be absorbed?
Intrinsic factor
Why is primary B12 deficiency rare?
It enters the enterohepatic circulation, so it is recycled like bile…take about 3 years to deplete your B12, possible in vegans
What are most B12 deficiencies from, and what do they cause?
Most are due to inadequate absorption…lack of HCl or intrinsic factor or atrophic gastritis in those >50 years old. Supplements must bypass the stomach or be enteric coated. Causes pernicious anemia (megaloblastic) and neerve damage
What 2 vitamins cause megaloblastic anemia when deficient?
Folate toxicity and B12 deficiency
What is atrophic gastritis?
a process of chronic inflammation of the stomach mucosa, leading to loss of gastric glandular cells and their eventual replacement by intestinal and fibrous tissues. As a result, the stomach’s secretion of essential substances such as hydrochloric acid, pepsin, and intrinsic factor is impaired, leading to digestive problems, vitamin B12 deficiency, leading to megaloblastic anemia or malabsorbtion of iron, leading to iron deficiency anaemia
What are minerals?
Naturally occurring inorganic elements (micronutrients)
Structure, function, and food contents of minerals?
Found as elements, retain chemical structure. Do not yield energy. Amounts ingested and required are usually measured in micorgrams to grams
Requirements of minerals are affected by?
Bioavailability…efficiency of absorption and previous nutrient intake, sources of the nutrient, other foods sunsumed at same time (may help of hinder)
4 classes of minerals
major, trace, electrolytes, ultratrace
RDA for iron?
men = 8 mg/d. Women = 18 mg/d
How is iron transported in the blood?
Attached to the protein transferrin
Where and how is iron usually stored?
Primarily stored in the liver, attached to the protein ferritin and excess is stored as hemosiderin
Roles of iron?
Accepts, carries and releases oxygen (bound to Hb and myoglobin), cofactor in oxidation-reduction reactions be swtiching between its oxidized (Fe3+) ferric form and reduced (Fe2+) ferrous form. Forms part of the e- carriers in the ETC
Usual diet supples about how many mg of iron per 1000 kcal?
6-7 mg
Animals food supply what type of iron?
Heme and non-heme iron
What type of iron is best absorbed? Where is it found?
heme iron, found ONLY in animal foods
Sources of heme iron?
red meat, fish, poultry, eggs, clam, liver
Plant foods supply what type of iron?
Non-heme iron
Sources of non-heme iron?
legumes, whole and enriched grains, dried fruit
What type of iron is the greatest in our diets?
Non-heme iron (90%), heme (10%)
How is iron absorption regulated?
In times of need, iron absoprtion is enhanced. When stpres are full, absorption is reduced.
Enhancers of NON-HEME iron absorption?
MFP factor (meat, poultry, fish peptide) and vitamin C (prevents oxidation of iron)
Inhibitors of NON-HEME iron absorption?
Phytates (legumes and grains), vegetable proteins (legumes, nuts), calcium, tannic acid (tea, coffee), excess Zn
How is iron recycled?
Most of the iron attached to transferrin goes to bone marrow to be incorporated into Hb of RBC and excess iron is stored in ferritin and hemosiderin. Spleen then dismantles RBC (after about 4 months), packages Fe into transferrin and stores excess iron in ferritin and hemosiderin/
What is the most prevalent dietary deficiency in the world?
Iron
Populations most vulnerable to iron deficiency?
women in reproductive years (blood losses), pregnant women (increased blood volume, growth, losses in birth), infants and young children (high milk diets and rpaid growth), adolescents (rapid grwoth, typically poor diet quality), vegetarians (consuming only non-heme Fe, needs are 1.8x higher)
Stages of iron deficiency?
- Diminishing stores (low serum ferritin) 2. Decreasing transport iron (low serum iron + increase in transferrin = decreased transferrin saturation) 3. Limited hemoglobin production (low Hb and hematocrit). Over time, severe depletion results in iron deficiency anemia (RBCs are small (microcytic) and pale (hypochromic)
Signs of iron deficiency anemia?
Weakness and fatigue, pallor, cold sensitivity, pica, and koionychia
What is pica, and when is it common?
Desire to eat non-food things…iron deficiency
What is koilonychia, and when is it common?
Spoon shaped nails…very advanced iron deficiency
UL of iron?
45 mg/d…in general, diet poses no risk because the body absorbs less when stores are full, high risk from supplement intake
What is hemachromatosis?
Genetic disorder, common in men when the body continues to absorb iron even when stores are full. Leads to hemosiderosis and free radical damage
RDA for calcium, established in 2010
1000 mg/d for males and females. Higher in adolescents and older adults/
What aids calcium absorption?
Aided by the stomach’s acidity and requires calcium binding protein (calbindin, which needs vitamin D)
Calcium absorption is inhibited by?
Lack of stomach acid and vitamin D, high P intake, phytates and oxalates
In a usual diet, how much of dietary Ca is absorbed?
about 30%
What are the single highest source of Ca?
Milk products
1 food guide serving of milk products has how many mg of Ca?
300
Other sources of calcium besides milk products?
calcium set tofu, fish with bones, nuts
Roles of calcium
99% is found in the bones and teeth (integral part of bones structures and serves as a calcium bank in times of need). 1% is found in intra and extracellular fluids (involved in maintenance of BP, participiates in blood clotting, regulation of muscle contraction, transmission of nerve impulses). May protect against hypertension and overweight
How are blood calcium levels kept stable, and at what 3 sites?
By the action of vitamin D, parathyroid hormone, and calcitonin at the kidneys, intestines, and bones.
Rising blood calcium causes…
Thyroid secretes calcitonin, inhibits the activation of vitamin D, limits Ca absorption from GI, prevents Ca reabsoprtion in kidneys, and inhibits release of Ca from bones. Result = lower blood Ca which inhibts secretion of calcitonin
Falling blood calcium causes…
Parathyroid secretes parathyroid horomone, stimulates the activation of vit D. Vitamin D + PTH = stimulates Ca reabsorption at kidneys, enhance Ca absorption from GI, stimulates release of Ca from bones. Result = higher blood Ca which inhibits secretion of PTH
High blood Ca results in? Low blood Ca results in? Are these related to dietary deficiency or excess?
Calcium rigour. Calcium tetany. Not related to diet.
Inadequate intakes of calcium result in?
bone loss. This is generally not apparent until there are drastic consequenes such as osteoporsis…detected by measuring bone mineral density via DEXA
What is the UL for calcium?
2500 mg/d
Supplements and abnormal secretion of regulatory hormones can cause hypercalcemia, what are the signs of this?
constipation, risk of urinary stones and kidney dysfunction, calcification of soft tiddues, and it interferes with absorption of other minerals, notably Fe.
What is the AI for sodiuM?
1500 mg/d
The AI for sodium is set at 1500 mg/d, although, the body needs much less to function. Why is it set this high?
In order to still be able to maintain adequate intake of other nutrients…low enough to ward off hypertension, though
How is sodium absorbed, and how does it travel in the bloodstream?
Readily absorbed in the intestine and travels freely in the bloodstream
What maintains blood sodium concentrations?
The kidney by filtering Na from the blood…excess is excreted, required Na is returned to the bloodstream
Roles of sodium
Regulates fluid volume as the principle cation in the extracellular fluid (water follows sodium in the body; high Na in the blood leads to thirst–excess Na is excreted with water). Participates in maintaining acid–base balance (kidneys excrete H+ ions in exchange for Na+ ions, increasing pH). Needed for nerve impulse transmission and muscle contraction
% of sodium that comes from veggies, meats, and milk products?
about 10%
% of foods that come from processed foods
accounts for up to 75% of dietary sodium
% of sodium that comes from being added at the table
about 25%
3 sources of sodium
veggies/meat/milk produts, processed foods, added at the table
Main source of sodium in the diet?
Processed foods
1 tsp/5 ml of NaCl = g NaCl = mg NaCl
1 tsp = 6 g = 2300 mg Na
Top 5 sources of Na in the Canadian diet
1) breads and bread like things 2) processed foods 3) vegetable based dishes 4) soups 5) pasta
What effect does food processing have on sodium and potassium?
Increases sodium whilst decreasing potassium
UL for sodium?
2300 mg/d
Acute sodium toxicity results in?
Edema and high blood pressure, however, the greatest concern is long-term excess
What is the main health concern of NaCl intake?
Hypertension (especially in salt responders)…contributes to renal disease, cardiovascular disease, stroke, myocardial infarction. Associated with urinary Ca loss, stomach cancer
Mean intake of sodium for Canadians
3400 mg…although, people are concerned about it
Barriers to reduced intake include:
lack of options, taste, lack of knowledge
Diets low in K cause what?
Play a role in the development of hypertension, especially when combined with high Na intake…intakes among Canadians tend to be low
What is the DASH diet?
Dietary Approaches to Stop Hypertension…emphasizes fruit, vegetables. low fat milk products. Includes whole grains, nuts, poultry, and fish. Low in red meat, butter, high fat foods.
Personal recommendations for lowering sodium intake?
select fresh foods (shop perimeter of the store), add little to no salt in cooking (use herbs and spice for flavour), read labels carefully (choose sodium free or low sodium, not neceaarily reduced)
%DV of sodium reflects a comparison to what number?
2400 mg (>UL of 2300 mg)
How can free radicals can cause damage to body cells?
Attacking lipids in cell membranes and lipoproteins. ALtering DNA, RNA and body proteins
What is oxidative stress?
When production of oxidants and free radicals exceeds the body’s ability to defend against them and prevent widespread damage
Oxidative stress causes?
decreased cognitive performance, premature aging and most chronic disease (cancer, diabetes, CVD)
First line of defense against free radicals is? The second line of defense?
First line is a system of enxymes that disarms the most harmful oxidants (depends on the minerals selenium, copper, manganese and zinc. Link of defense weakens when one’s diet is inadequate). The second line of defense is antioxidant vitamins (vitamin E, beta-carotene, vitamin C. SOme phytochemicals also have antioxidant properties)
Ways dietary antixodants protect against oxidative stress?
limiting the formation of free radicals, destroying free radicals or their precursors, stimulating antioxidant and repair enzyme activity, repairing oxidative damage, supporting a healthy immune system. Antioxidant vitamins tend to be stable in both their oxidized and reduced forms–can stop the free radical chain reaction
What are phytochemicals?
non-nutritive compounds in plants that have biological activity that is beneficial to health.
Roles of phytochemicals in the body?
acting as antioxidants, mimicking hormones, stimulating enzymes, destroying bacteria.
phytochemicals roles in foods
impart tastes, aromes, and colours
2 phytochemicals who are through to reduce the risk of cancer
phytoestrogens and lycopene (a carotenoid)
What are phytoestrogens and where are they found?
Phytochemicals that weakly mimic or modulate effects of estrogen. Found in soybeans, flaxseeds, whole grains, veggies and fruits
What is lycopene, and where is it found?
A carotenoid that acts as a powerful antioxidant that inhibits the growth of cancer cells when consumed as part of food (not supplements). Found as a red pigment in tomatoes, papaya, and grapefruit.
What are flavonoids?
Powerful antioxidants that may protect against LDL oxidation, minimize inflammation, and reduce platelet aggregation and blood clotting.
Where are flavonoids found?
Found abundantly in fruits (berries), tea, herbs, spices, nuts, red wine, dark chocolate
What are phytosterols, and where are they found?
Cholesterol-like molecules found in plants that inhibit cholesterol absoprtion in the stomach. Reduce LDL cholesterol while keeping stable HAL. Reduces inflammation and blood pressure. Found in SOYBEANS
What are lignans, and where are they found>
Similar action to phytosterols in terms of CVD. Can be converted to phytosterols in the intestines by bacteria. Found in whole flaxseed
What are dietary supplements?
defined as any pill, capsule, tablet, liquid or powder intended to increased dietary intake of a particular dietary component
Examples of dietary supplements
vitamins, minerals, herbs, botanicals, amino acids, combinations of the above
Percentage of females that use supplements in Canada? Males?
47% females, 34% males
Increased prevalence of supplement use in Canada is associated with?
increasing age, female gender, increasing education, increasing income
Arguments for supplement use?
To correct or prevent overt deficiencies. To support increased nutrient needs that may be difficulr to attain without supplements (iron in women, folate in women, newbowns require a single dose of vitamin K, etc). To improve nutritional status. To improve the body’s defenses
Examples of why supplements are needed for increased nutrient needs that may be difficult to attain without supplements?
Iron in females with high losses. Folate for women of childbearing age. Newborns require a single dose of vitamin K. Vegans and those with atrophic gastritis need B12 supplements. Olders adults need more vitamin D.
Why would supplements be needed to improved nutritional status?
Treating subclinical deficiencies in older people. Habitual dieters with low energy intakes or who restrict entire food groups. Vegetarians in some cases. Food allergies or intolerances.
Arguments against supplement use?
Increased risk of toxicity, life threatening misinformation, can provide a false sense of security, bioavailability/biological activity is different than food sources, and antagonistic effects
What minerals and vitamins have the highest likelihood for toxicity?
Fe, Zn, vitamin A, and niacin
For dietary improvements, what should the first line of defense be?
Dietary improvement
What are the 3 things to look for when taking a multivitamin?
Look for about 100% of the RDA for most vitamins, not more. Look for minimum amount of minerals due to likelihood of interfering with absorption of other nutrients. Take a look at your diet–principles of a healthy diet should eliminate the need for most people.
What is the number one cause of death in Canada?
Cancer (30% cancer, 22% CVD, 6% stroke)
Diet may be linked to as many as ____ of cancer cases
1/3
What is carcinogenesis?
Refers to the growth of malignant tissue which often occurs slowly over several decades. Arises from the mutation of genes controlling cell division in a single cell, which promotes cellular growth, interferes with growth restraint, prevent cellular death. Daughter cells have similar effects.
What is carcinogenesis most often caused by?
Gene-environment interactions. Exposure to carinogens can induce genetic mutations or promote proliferation in cancer cells.
What are cancer initiators/
Initiate cancer development.
Alcohol and low fruit/veggies initiates what type of cancer?
head and neck cancer
Cooking meat at high temps leads to?
Carcinogen release
Red and processed meats initiates what type of cancer?
Colorectal cancer
What are promoters?
May accelerate the development of pre-existing cancers
What are antipromoters?
Defend against cancer
High animal fat intake promotes what type of cancer?
Colon cancer
Non-starchy veggies protect against what type of cancer?
Esophageal and stomach cancer
4 things that can inhibit cancer
Fruit/veggies, high fibre diets, dietary antioxidants, some phytochemicals
Recommendation: be as lean as possible within the normal range of body weight (BMI 21-23 is most protective). Convincing evidence?
Increase body fat leads to an increased risk of colorectal, breast and several other cancers
Recommendation: Be as lean as physically active as part of everyday life (>60 mon moderate or >30 min vigorours PA daily and limit sedentary time). Convincing evidence?
Decreased risk of colorectal cancer
Recommendation: Limit consumption of energy-dense foods and avoid sugary drinks. Consume fast food sparingly if at all. Convincing evidence?
Increased risk of overweight
Recommendation: Eat mostly foods of plant origin. Eat at least 5 servings of non-starch veggies/fruits; eat mostly unprocessed grains that contribute fiber. COnvincing evidence?
Decreased risk of esophageal and stomach cancer (non-starch veggies). Decreaed risk of colorectal cancer (fibre)
Recommendation: Limit intake of red meat and avoid processed meat. Less than 500 g per week, minimally processed. Convincing evidence?
Increased risk of colorectal cancer
Recommendation: Limit alcoholic drinks to less than 2 per day for men and less than 1 per day for women. Convincing evidence?
Increased risk of mouth, esophageal, colorectal (men), and breast cancer
Recommendation: Limit consumption of salt and avoid mouldy cereals and pulses. <2400 mg daily and avoid preserved foods. Convincing evidence?
Increaed risk of stomach cancer (salt) and liver cancer (aflatoxins in mouldy stuff)
Recommendation: Mothers to breast feed and children to be breast fed. Convincing evidence?
Decreased risk of breast cancer (mother). Probable decreased risk of overweight in children.
A diet that prevents cancer is one that is….
adequate in vitamins and minerals, rich in phytochemicals, antioxidants and fibre
The fuel mix during physical activity will depend on?
Intensity and duration of the acitivity and the composition of the diet
In the first 8-10 seconds of exercise, what is used as fuel source?
ATP (small amounts stored in all cells and can deliver immediate energy), CP is stored in the muscle and can be broken down anaerobically and replenish the supplies of ATP
What fuel source predominates in anaerobic activity?
Glucose
What fuel source predominates in aerobic activity?
Increasing dependence on fat
How many kcals does glycogen supply?
About 2000 kncal, enough for about 30 km of running
During endurance activity, glycogen supplies about what % of the fuel mix?
50-60%
Mostly glycogen is used for fuel during the first ____ minutes of moderate activity, after which greater and greater proportions of fat are used.
20 minutes…glyocogen stores will eventually be depleted
How many kcals are available from fat stores?
more than 70,000…virtually unlimited
When is fat the primary fuel?
Activities lasting greater than 20 minutes at moderate intensity
What type of diet spares the use of protein for energy?
When the diet is adequate in energy and rich in CHO, less protein is used than with high fat or high protein diets. Adequate CHO spares protein.
Are athletes’ protein recommendations substantially different than the general population?
No…first priority should be adequate energy intake with a priority on carbs…want to eat closer to 65% carbs versus the lower end of 45%
Protein recommendations for regular adults, power athletes, and endurance athletes?
0.8 g/kg/day, 1.2-1.7 g/kg/day, 1.2-1.4 g/kg/day
Fat recommendations for athletes?
Follow the same AMDR recommendations for fat intake as the general population (20-35%0. Consuming a diet <20% fat may lead to inadequate nutrient and energy intake. Focus on quality vs. quantity.
Adequate hydration is needed for?
temperature regulation
As little as ___% water loss can lead to greatly diminish performance
2%
For short bouts of activity (less than 60 mins), what is the best way to stay hydrated?
Cool water
How much to drink 2-3 hours before activity?
500-750 mL
How much to drink 15 min before activity?
250-500 mL
How much to drink every 15 min during activity?
125 to 250 mL (drink enough to minimize loss of body weight but don’t overdrink)
How much to drink after activity?
500 mL for every half kilogram of body weight lost
What electrolytes are lost in sweat?
Na, Cl, K, and Mg
When should a sports drink be consumed?
In events that last more than 1 hour.
Neglecting to replace Na losses or overhydrating with water along in events that last more than 1 hour can cause?
Hyponatremia (low Na in blood)
