Lecture 6 Flashcards
provitamins
transform chemically to one or more active vitamin forms
bioavailability
the rate and extent to which a nutrient is absorbed and used
malnutrition
excess or deficient food energy or nutrient intake
undernutrition
deficient in energy or nutrients
overnutrition
excess energy or nutrients
primary deficiency
nutrient deficiency caused by inadequate dietary intake of a nutrient
secondary deficiency
nutrient deficiency cause by something other than inadequate intake such as a disease condition or drug interaction that reduces absorption, accelerates use, hastens excretion or destroys nutrient
fat-soluble vitamins
A,D,E,K
where are fat-soluble vitamins absorbed
into the lymph
- require bile for absorption
fat-soluble vitamins characteristics
- travel in blood with protein carriers
- stores in tissues (liver and fat)
- may be toxic in excess
water-soluble vitamins
- B vitmins
- Vitamin C
where are water-soluble vitamins absorbed
directly into the bloodstream
water-soluble vitamins characteristics
- travel freely in bloodstream
- not stored mostly
- excess excreted in urine
- lower risk of toxicity than fat-soluble vitamins
which vitamins have higher risk of toxicity?
fat-soluble vitamins
where are fat-soluble vitamins found?
in fats and oils of foods
how long can the body survive without fat-soluble vitamins?
weeks
excess vitamin A and D from supplements
can easily reach toxic levels
fat-soluble vitamin deficiency
- if consistently low in fat-soluble vitamins
- fat malabsorption
- mineral oil laxatives can cause vitamin loss
- very low-fat diets interfere with absorption
3 active forms of vitamin A in the body
- retinol
- retinal
- retinoic acid
plant-derived precursor of vitamin A
beta-carotene
vitamin A roles
- vision
- gene expression
- maintenance of body linings and skin
- immunity
- growth of bones and body
- normal development of cells
- critical importance to reproduction
eyesight
- light passes through cornea before striking retina
- retina contains cells
eyesight and vitamin A
light bleaches the vitamin A-containing pigments RHODOPSIN
rhodopsin
- breaks of vitamin A, initiating an impulse to optic centre in brain
- vitamin reunited with pigment with little destruction of the vitamin
- vitamin A must regenerate the supply
what happens if vitamin A supply runs low?
night blindness
vitamin A deficiency
keratin accumulation (keritinization)
keritinization
can leads to xerosis (drying) and xerophthalmia (thickening) which can cause permanent
skin/body linings and vitamin A
- vitamin A is needed by all epithelial tissues
- vitamin A promotes cell differentiation
epithelial tissues
serve as protection from pathogens as well as to other damage
cell differentiation
each type of cell develops to perform a specific function
control of gene expression and vitamin A
retinoic acid activates or deactivates certain genes thereby affecting protein production
immunity and vitamin A
- regulates genes that produce immune system proteins
- deficiency can lead to a spiral of infection
growth and vitamin A
vitamin A assists in growth of bone and teeth
vitamin A deficiency
- cell differentiation and malnutrition impaired
- failure of mucus-producing cells to produce mucus
- increase in keratin-producing cells
- vulnerable to infection
what worsens vitamin A deficiency
diarrhea and reduced food intake
vitamin A supplementation
may benefit those suffering complications from disease such as malaria, lung disease and HIV
vitamin A toxicity
- supplements or fortified foods
- may weaken bones, bone and joint pain, abdominal pain, stunted growth, liver damage
early symptoms of vitamin A toxicity
- loss of appetite
- blurred vision
- headache
- skin itching
long-term symptoms of vitamin A toxicity
bone weakening and hip fracture
vitamin A toxicity and pregnant women
fetal malformation (teratogenic)
accutane
derived from vitamin A
- but vitamin A supplements do not help with acne
what organ might be affected most by vitamin A toxicity?
the liver (especially polar bear)
beta-carotene and vitamin A toxicity
will not cause vitamin A toxicity
- can turn yellow/orange due to deposition in subcutaneous fat
beta-carotene
- most abundant of the carotenoid precursors
- major dietary antioxidants
how is vitamin A activity for vitamin A precursors measured?
retinol activity equivalents (RAE)
deep bright orange fruits and veggies and dark green veggies
rich in beta-carotene and have a role in healthy eyesight
does eating carrots promote good vision
doesn’t improve vision if vitamin A intake is already adequaete
carotenoids and diseases
- beta-carotene is associated with reduced cancer risk
- benefits not seen with supplements (only on food in blood)
lack of foods rich in beta-carotene
increases risk of macular degeneraton
beta-carotene supplements
associated with increased risk of cancer in smokers
where is vitamin A found?
foods of animal origin
where is beta-carotene found?
in plants
good food sources of vitamin A
- liver and fish oil
- fortified milk and milk products
- eggs
- beta-carotene (dark greens, rich yellow and deep orange foods)
vitamin D characteristics
- body can make all it needs with help of sunlight (not essential)
- many people may border on vitamin D insufficiency
roles of vitamin D
- regulation of blood calcium and phosphorus (maintains bone integrity)
- raises blood calcium when needed
- functions as a hormone
vitamin D and role in calcium
- promotes calcium absorption
- promotes calcium retention by kidneys
- draws calcium from the bone
how does vitamin D function as a hormone?
plays a role in brain, heart, stomach, pancreas, skin, reproductive, organs, some cancer cells, stimulates cell maturation
vitamin D deficiency results
- high blood pressure
- some cancer
- type I diabetes
- heart disease
- rheumatoid arthritis
- inflammatory bowel disease
- multiple sclerosis
rickets
- vitamin D deficiency in children
- characterized by abnormal bone growth
symptoms of rickets
- bowed legs
- outward-bowed chest
- knobs on ribs
risks with vitamin D deficiencies for adolescents
bone loss later in life
risks with vitamin D deficiencies for older adults
painful joints and muscles
osteomalacia
adult for of rickets
what population of women does osteomalacia typically occur for?
- low calcium intake
- little exposure to sun
- who go through repeated pregnancies and periods of lactation
what population of adolescents are at risk for vitamin D deficiencies?
- consume beverages with no vitamin D
- prefer indoor to outdoor activities
what vitamin is the most toxic?
vitamin D
vitamin D toxicity symptoms
- appetite loss
- nausea
- vomiting
- increased urination and thirst
- severe psychological depression (effects CNS)
continued overdose of vitamin D
causes dangerously high blood calcium level, forcing calcium to be deposited in soft tissue (heart, lungs, kidneys)
how can people make a vitamin from sunlight?
- UV exposure to cholesterol compound in skin transforms it into a vitamin D precursor which is absorbed in blood
- liver and kidneys convert precursor to active form of vitamin D
is there a risk of vitamin D toxicity with skin synthesis?
NO
factors effecting sun exposure and vitamin D synthesis
- skin color
- air pollution
- city living
- clothing
- geography
- indoor lifestyle
- season
- sunscreen
- time of day
sunscreen with SPF of 8
reduce sun risks, but also prevent vitamin D synthesis
canadian cancer society
believes it is better to get vitamin D from food or supplements because sun is dangerous
vitamin D RDA
400 IU
- recommendation may increase with age
sources of vitamin D
- sunlight
- small amounts from butter, cream, fortified margarine
- fortified milk
- egg yolks, liver, fatty fish, fish oil
- mushrooms
4 tocopheral compounds of vitamin E
- alpha
- beta
- gamma
- delta
what is the gold standard for vitamin E activity
alpha-tocopherol
antioxidant activity
defends the body against oxidative damage
- vitamin E is oxidized, protecting cells
oxidative damage
results from free radicals
free radicals
- formed during metabolism disrupt the structure of cellular lipids, DNA and proteins
- free radical activity may contribute to development of cancer, heart disease, etc.
vitamin Es antioxidant effect
- crucial in the lungs - cells are exposed to high oxygen concentrations
- protects red and white blood cells
vitamin E roles
- antioxidant activity
- roles in immunity
- a role in nerve development
do vitamin E supplements provide health benefits?
no, only if deficient
vitamin E deficiency in infants
some infants born before transfer of vitamin E from mother to infant
erythrocyte hemolysis
a rupturing of the red blood cels which results in anemia
vitamin E deficiency in adults (causes and results)
- nerve damage
- fat malabsorption diseases (damaged liver, gallbladder or pancreas)
- low intake with low fat diets for years
- people who rely on fat replacers rather than fat
how is vitamin E destroyed?
by food processing and heating
vitamin E toxicity
- no toxicity with natural food sources
- large doses may increase effects of anticoagulant medications
- increased risk of death for those taking greater than 400 IU from supplement
food sources of vitamin E
- veggie oils (salad dressing, shortening)
- avocados
- wheat germ
- smaller amounts from meat, poultry, fish, eggs, milk products, nuts, seeds
- animal fats have almost no vitamin E
functions of vitamin K
- synthesis of blood clotting proteins
- synthesis of normal form of bone proteins that bind minerals to bone
blood clotting proteins
interferes with the function of certain anticoagulant medications (blood thinners)
sources of vitamin K
- intestinal bacteria
- leafy green veggies (dark)
- cabbage family
- canola and soybean oils
- eggs and milk contain small amounts
- liver is only rich animal source
vitamin K and newborns
newborns are given a dose of vitamin K
- sterile Gi tract
- vitamin K producing bacteria establish themselves
when are you at risk for vitamin K deficiency?
- newborns
- antibiotic treatment (kills beneficial and harmful bacteria in intestinal tract)
- fat malabsorption
- unlikely in adults
vitamin K toxicity
no UL
- infants and pregnant women can result from over-supplementation with synthetic vitamin K
what does vitamin K toxicity lead to?
jaundice and bilirubin in brain of an infant
- can cause brain damage or death
water-soluble vitamins
- cooking and washing water leaches them out of food
- easily absorbed
- excess readily excreted in urine
toxicity from water-soluble vitamins
- not from food
- can occur from large doses concentrated in vitamin supplements (expensive urine)
vitamins for athletes
athletes with an appropriate diet don’t generally need supplements
- increased energy = more food
vitamin C experiment
those who received citrus quickly recovered from scurvy
scurvy
- vitamin C (ascorbic acid) deficiency
- to avoid scurvy, British sailors were given lim juice
roles of vitamin C
- maintenance of connective tissues
- antioxidant
vitamin C and connective tissue maintenance
formation and maintenance of collagen
- component of bones, teeth, skin, tendons, scar tissue, capillaries
vitamin C antioxidant function
- protects substances found in food and body
- protects iron from oxidation
- protects blood constituents from oxidation and helps protect vitamin E (returns to active form)
vitamin C supplements
- useful to treat a deficiency disease
- not been shown to protect against heart disease, cancer or other disease
vitamin C deficiency symptoms
- loose teeth
- bleeding gums
- pinpoint hemorrhages
- anemia
- tenderness to touch
- weakness
- swollen ankles and wrists
- loss of appetite
- growth cessation
how can scurvy be cured?
100 mg of vitamin C per day for 5 days - easily with food
vitamin C and colds
- supports immune system function
- does not prevent colds or benefit cold
- one study said if taken at high doses may shorten duration of cold about 1/2 a day and reduce symptoms by 40%
blood histamine
substance responsible for sneezing, runny or stuffy nose, swollen sinuses
what dose of vitamin C reduces blood histamine?
2 grams per day for 2 weeks
- acts as a weak antihistamine
placebo effect and vitamin C
there is a placebo effect with vitamin C
vitamin C toxicity
- vitamin C from food is safe
- may be dangerous for those with an overload of iron
- massive doses may interfere with medications to prevent blood clotting
adverse effects of vitamin C
digestive upsets such as nausea, abdominal cramps, excessive gas and diarrhea
smoking and vitamin C
smoking introduces oxidants that deplete vitamin C
- RDA set 35 mg higher for smokers
food sources of vitamin C
- citrus fruits, strawbs, cantaloupe, lettuce, tomato, papaya, mangoes, red pepper
- dark green veggies
- cabbage veggies
- potatoes
what fruits and veggies are the best source of vitamin C
fresh, raw, and quickly cooked
vitamin B function
- coenzyme function
- metabolism
B vitamins role as coenzymes
combines with and activated an enzyme
b vitamins role in metabolism
- metabolism of carbs, lipids, amino acids
- thiamin, riboflaviin, niacin, pantothenic acid and biotin all help release energy
- B6 helps body make protein
- folate and B12 help cells multiply
B vitamin deficiencies
- every cell affected
- cell renewal depends on energy and protein which depend on B vitamins
- deficiency in any B vitamin rarely shows up alone, cause people eat foods that contain mixtures of nutrients
thiamin deficiency during growth
can cause permanent brain damage
thiamin function
- energy metabolism
- nerve processes and their responding tissues (muscle)
thiamin deficiency
beriberi and wernicke-korsakoff syndrome
beriberi symptoms
- loss of sensation in hands and feed
- muscular weakness
- advanced paralysis
- abnormal heart action
wet beriberi vs dry beriberi
wet: edema present
dry: no edema
where was the first beriberi observed
with the polishing of rice in Asia
wernike-korsakoff syndrome
- alcohol abuse with sever thiamin deficiency
- alcohol displaces food in diet, impairs thiamin absorption, and promotes thiamin excretion in urine
symptoms of wernicke-korsakoff syndrome
- mental confusion
- disorientation
- loss of memory
- jerky eye movements
- staggering gait
- apathy
- irritability
treatment of wernicke-korsakoff syndrome
thiamin by IV or orally
- alcohol withdrawal protocol in hospitals
sources of thiamin
1 .widespread in healthy foods
2. pork products
3. sunflower seeds
4. whole grain cereals
5. legumes
riboflavin function
energy metabolism of all cells
riboflavin deficiency
ariboflavinosis
- accompanies other vitamin deficiencies due to poor diet (mostly thiamin)
ariboflavinosis
- inflammation of membranes of the mouth, skin, eyes, and GI tract
- smooth, purplish, red tongue
- may go undetected cause thiamin def. symptoms are more severe
who are at risk for riboflavin deficiencies?
children who lack milk products and meat
treatment of ariboflavinosis
a diet that treats a riboflavin deficiency also resolves a thiamin deficiency
sources of riboflavin
- milk and milk products
- leafy green veggies
- whole-grain breads
- enriched/fortified grains
- some meats and eggs
niacin function
energy metabolism
niacin deficiency
pellagra (4’Ds)
pellagra 4 D’s
- diarrhea
- dermatitis
- dementia
- death
who is at risk for pellagra?
poorly nourished people living in poverty
- particularly those with alcohol addiction
sources of niacin
- tryptophan (abundant in proteins, can be converted to niacin)
- milk
- eggs
- meat, poultry, fish
- whole grains
- fortified and enriched grains
- nuts and seeds
niacin equivalents (NE)
1 mg of niacin is made from 60 mg of tryptophan
- those with adequate protein, will not be niacin deficient
niacin toxicity
large doses can cause niacin flush and can injure the liver and caused blurred vision
niacin flush
- painful tingling
- flush and hives
- niacin supplements 2-3x the RDA
large doses of niacin (nicotinin acid)
may be prescribed to lower blood lipids
folate functon
- DNA synthesis
- part of co-enzymes for new cell synthesis
folate deficiency
anemia - megaloblastic anemia or macrocytic anemia
anemia
- large, immature red blood cells
- related to anemia of vitamin B12 deficiency
what does a deficiency in folate cause
- diminished immunity
- abnormal digestive function
- increase risk of CVD, colon and cervical cancer
folate deficiency can lead to?
neural tube birth defects (NTDs)
NTDs
problems with spinal cord, mental delay, severely diminished brain size or even death shortly after birth
- arise in first few days or weeks of pregnancy
fortified folate
all bleached white grains are fortified with folate (1990s)
- synthetic folate is better absorbed than folate in foods
folate toxicity
- folate can mask vitamin B12 deficiency
- excess folate may be antagonistic to action of anticancer drugs
dietary folate equivalent (DFE)
converts all forms of folate into units that are equivalent to folate in food
bioavailability of folate
- 50% (foods)
- 100% (supplements taken on empty stomach)
fortified foods and folate supplements
given extra credit because they are 1.7 more times available
calculating DFE
100 mg from food and 100 mg from suuplemennts
= 100 + 100(1.7)
sources of folate
- leafy green veggies
- fresh, uncooked veggies and fruits (heat destroys folate)
- eggs
- orange juice and legumes
RDA for folate - healthy adults
400 mcg DFE/day
RDA for folate - pregnancy
600 mcg DFE/day
- 400 supplement, rest healthy diet
vitamin B12 function
- close relationship with folate
- maintenance of sheaths that surround and protect nerve fibers
vitamin B12 and folate
- vitamin B12 is activated by folate
- folate is activated by vitamin B12
vitamin B12 deficiency symptoms
- damaged nerve sheaths
- creeping paralysis
- general malfunctioning of nerves and muscles
what does vitamin B12 deficiency result in?
failure of folate to make red blood cells
- same anemia as folate (large immature red blood cells)
who is at risk of a vitamin B12 deficiency?
- elderly
- atrophic gastritis
- vegans
why are the elderly at risk for vitamin B12 deficiencies?
absorption problems
- decreased stomach acidity and decreased intrinsic factor
atrophic gastritis
inherited gene defect for intrinsic factor production (mid-adulthood)
vegans and vitamin B12 deficiency
- deficiency symptoms take time (6 years worth is stored)
- must use vitamin B12-fortified products or supplements
vitamin B 12 absorption
requires intrinsic factor
intrinsic factor
- compound made by stomach
- stomachs acid liberated vitamin B12 from food and intrinsic factor binds to vitamin B12
- complex is then absorbed from small intestine into the blood
pernicious anemia
a vitamin B12 deficiency disease, caused by a lack of intrinsic factor
- large, immature red blood cells
treatment of pernicious anemia
B12 injections
sources of vitamin B12
- animal sources = best
- bioavailability greatest in milk and fish
- fortified plant foods (soy beverage)
vitamin B6 function
- 100+ reactions in tissues
- assists conversion of one amino acid to another (protein synthesis)
- aids in conversion of tryptophan to niacin
- neurotransmitter synthesis
- hemoglobin synthesis
- assist in release of stored glucose to glycogen
- immune function
- steroid hormonal activity
- fetal brain and nervous system development
neurotransmitter synthesis
conversion of tryptophan to serotonin
vitamin B6 deficiency general symptoms
- weakness
- psychological depression
- confusion
- irritability
- insomnia
vitamin B6 deficiency weird symptoms
- anemia
- greasy dermatitis
advanced cases of vitamin B6 deficiency
- convulsions
- may weaken the immune system
- increase risk of heart disease
vitamin B6 toxicity in what population?
women who intake 2+g/day for 2+ months
vitamin B6 toxicity symptoms
- numb feet
- loss of sensation in hands
- eventually unable to walk or work
- recovered after stopped taking supplements
vitamin B6 suplements
can deliver 2 g of vitamin
what is a 2 g vitamin B6 supplement equivalent to?
- 3000 bananas
- 1600 liver
- 3800 chicken breasts
vitamin B6 requirement
need is proportional to protein intake, due to roles in protein metabolism
STICK WITH FOOD
sources of vitamin B6
- protein-rich foods: meat, fish, poultry
- legumes and peanut butter
- potatoes, leafy greens, some fruits
homocysteine
elevated homocysteine may be indicator of CVD risk
what causes homocysteine to build up in the blood?
deficiencies of folate, vitamin B12, or vitamin B6
biotin function
- energy metabolism
- cofactor for several enzymes in metabolism of carbs, fat, proteins
biotin deficiency
may occur with some rare diseases
what results in a biotin deficiency?
consumption of dozens of raw egg whites per day - contain a protein that binds biotin (avidin)
- cooking eggs denatures this protein
sources of biotin
widespread in foods
pantothenic acid function
1 .energy metabolism
2. coenzyme that plays a role in release of energy from energy nutrients
3. plays a role in 100+ steps concerned with synthesis of lipids, neurotransmitters, steroid hormones, and hemoglobin
pantothenic acid deficiency
may occur with some rare diseases
pantothenic acid sources
widespread in foods
supplements
should only be taken when there is a risk of deficiency
