1. Kin 110 Lecture 6
Vitamins Ch. 7

2. Vitamins
Vitamin – essential organic (contains carbon) substances needed in small amounts in diet
Normal function, growth, maintenance of body
Yield no energy, but participate in energy yielding reactions
ADEK – fat soluble
B vitamins and C – water soluble
B vit. And Vit K – co-enzymes – help enzymes function
Fig. 7-1

3. Vitamins To be classified as vitamin Body unable to synthesize enough
Absence for a defined period of time must produce deficiency
symptoms, if caught in time, are cured when substance is reintroduced to diet
Have they all been found?
People living on intravenous solutions of Protein, Carbohydrates, Fat and all known vitamins and minerals survive, grow, reproduce and fight disease

4. Storage of Vitamins Fat soluble vitamins A and D not readily excreted
Water soluble - lost from body quite rapidly (B12 stored)
Limited storage – should be consumed daily

5. Vitamin Toxicity Toxicity theoretical for all vitamins
Fat soluble more frequently observed (A and D)
E, Niacin, B-6 and C – very large amounts - toxicity
Only possible from supplements
A and D times daily need
A – important to minimize in early pregnancy
Once a day vitamins, less than 2 times daily value – not a risk
Consult physician – as medications can be counteracted

6. Fat soluble Vitamins ADEK Absorbed along with dietary fat
Travel in bloodstream along with fat to reach body cells
Stored in liver and fatty tissue
40-90 % of fat sol. vit. absorbed
Can be reduced further – interference in normal digestion and absorption of fats.
Eg. Mineral oil laxatives

7. Vitamin A Easy to over dose (toxic) and be deficient
Both cause sever problems
Variety of forms
Eg. Retinol
Preformed vitamin A – retinoids
animal foods
Carotenoids – pro-vitamin A
plants
Yellow-orange pigment in carrots
Turned into vitamin A as needed
Most potent – beta-carotene
Both pre and pro – referred to as VitaminA

8. Functions of Vitamin A Many roles – not all well understood
Role in vision – best known and most clearly understood
Performs important functions is both light (day) and dark (night) vision
in dim light, one form of A is required to start the chemical process that signals the brain that light is striking the eye.
Without A – night blindness
Prolonged deficiency – cells unable to produce mucus
Dry, dirty, scratched, infected
Xeropthalmia
Less-developed nations – children
Blindness. Infection, death

9. Health of Cells
Vitamin A – maintains health of all cells that line internal and external surfaces
Lungs, intestines, stomach, eyes, skin (epithelial cells)
Cells secrete mucus – lubricant
Without A – decrease activity of immune cells, increased infection
Needed for growth, Development and Reproduction
Synthesis of proteins that stimulate proper growth and ddevelopment
Resorption and production of bone

10. Cancer and Vitamin A Skin, lung, bladder and breast cancer
Adequate intake of vitamin A can lower risk of breast cancer
Mega dose NOT recommended
Carotenoids – trap energy in free radicals – oxidation can initiate cancer process
Supplements of B-carotene not effective
Variety of fresh fruits and vegetables
Acne – topical and internal derivatives
Birth defects in pregnant women

11. Vitamin A in Food Preformed
liver, fish oils, fortified milk and cereal, butter, margarine, eggs
Pro-vitamin – dark green and orange vegetables
Carrots, spinach, winter squash, papaya, apricots
RDA – RE- retinol equivalent
1000 RE (males)
800 RE (females)
Risk of deficiency – children, poor, alcoholics
Dietary sources table – p. 214

12. Toxicity of Vitamin A
3 times the RDA can cause problems if continued for prolonged periods
Early pregnancy (preformed)
Fetal malformations, birth defects, spontaneous abortion
Non-pregnant – skin, hair, internal organs and CNS
Permanent damage can occur
Vit A is stored for months
Women in childbearing years – limit to 100% intake
Carotenoids(pro) not toxic
Rate of conversion is slow
Efficiency of absorption decreases as intake increases

13. Vitamin D Also considered a hormone effects kidney and bone
skin cells convert cholesterol like substance into vitamin D using sunlight
effects kidney and bone
10-15 minutes of exposure of arms, face and hands; 2-3 times per week
not effective in winter
must have vitamin intake

14. Functions of Vitamin D
To become active hormone, vitamin D must be activated in liver and kidneys
calcitrol - active form
regulates calcium and bone metabolism along with parathyroid hormone
regulates absorption of calcium and phosphate from intestines
reduces kidney excretion of calcium
regulates deposition of calcium in bones
Cancer cells influenced by vitamin D

15. Vitamin D and Bone Calcium and phosphorus deposition
without vit D bones weaken and bow under pressure
Rickets (children)
fortification of milk -
malabsorption of fat (cystic fibrosis)
osteomalacia - adults - soft bones
calcium withdrawn from bones
inefficient absorption or conservation
vit d deficient
bones porous and weak - break easily
supplement vit D - reduce fractures
problem with vitamin D activation or absorption

16. Dietary Sources of D
Fatty fish (sardines, salmon), fortified milk and cereal
under 51 years - 5 ug/day
over times ug/day
max. 200 ug /day
Young, fair skined min 2-3 times /week
5-10 times recommended on regular basis - toxicity
calcium overabsorptoin - deposition in kidneys and other organs
high bld calcium
weakness loss of appetite, diarrhea, vomiting , mental confusion,
sun exposure does not result in toxicity

17. Vitamin E Fat soluble antioxidant - resides in cell membranes
donates electrons - protection from free radicals
fig 7-3 p 217
DNA oxidation - cancer, cell death
repair mechanisms for damage
impact on cancer, heart disease very minimal compared to proper diet and exercise
not an alternative

18. Deficiency of vitamin E
Cell membranes break down
red blood cells in infants
unsaturated fatty acids susceptible to oxidation
hemolysis- breaking of rbc in absence of vit. E
vit E improves vit A absorption
used to metabolize iron in cell, maintain nervous tissue, and insulin function

19. Vitamin E in Foods
plant oils, fortified cereals, fruits and veg, eggs, margarine
vitamin E in plant oils - protects unsaturated fatty acids
animals almost no vitamin E
content of E depends on harvesting , processing storage and cooking
easily destroyed by oxygen, metals , light , repeated frying
RNI mg /day
alpha tocopherol - most active form
smoking destroys vitamin E
megadose therapy - not proven
toxicity not a problem, except with anticoagulants (cardiovascular disease)

20. Vitamin K Plants, fish oils, and meats
synthesized by bacteria in intestine
role - vital for blood clotting
synthesis of blood clotting factors
formation of proteins in bone, kidney and muscle
impart calcium binding potential
newborns lack bacteria to produce vitamin K
routine injection at birth
deficiency in adults on prolonged antibiotics or wit fat malabsorption

21. Vitamin K in Food
Liver, green leafy vegetables, broccoli, peas and green beans
vitamin K not stored well - one day
abundant in diet, deficiency uncommon
resistant to cooking
RDA mg / day
no risk of toxicity
risk of reduced effectiveness of medications to reduce blood clotting (CV disease)

22. Vitamin Supplements
Supplements may be beneficial, and improve health of population
folate (B vitamin)
birth defects
homocystien - risk factor for heart disease
alleviated by adequate folate (and reduction in red meat)
over 50 - vitamin B12 (synthetic)
easily absorbed
Eat right and take a multivitamin
Table 7-2
Supplements in consultation with physician

23. Vitamin Supplements Megadoses of E and B12
trials ongoing, may be beneficial
Supplements should be taken with or just after meal
no more than 100% of daily values
avoid excess selenium and C
overabsorption of iron
males avoid excess iron
excess zinc - inhibits iron an copper absorption
excess folate - masks b12 deficiency
avoid other products - PABA, inositol, bee pollen, lecithin
Table 7-3, p 224