1. Kin 110 Lecture 6
Vitamins Ch. 8

2. Learning Objectives Define vitamin
Classify vitamins as fat-soluble or water-soluble
List the major functions and deficiency symptoms for each fat-soluble vitamin
List three important food sources for each fat-soluble vitamin
Describe toxicity symptoms for excess consumption of certain fat-soluble vitamins
Evaluate the use of vitamin supplements - risk / benefit

3. Vitamins
Vitamin – essential organic (contains carbon) substances needed in small amounts in diet
Required for normal function, growth, maintenance of body structures
Yield no energy, but participate in energy yielding reactions
fat soluble vitamins - ADEK
water soluble vitamins-B vitamins and C
co-enzymes – help enzymes function
B vitamins and vitamin K
Fig. 8-1

4. Vitamins To be classified as vitamin Megadoses of Vitamins
Body unable to synthesize enough
Absence for a defined period of time must produce deficiency (fig 8.2)
symptoms, if caught in time, are cured when substance is reintroduced to diet
Megadoses of Vitamins
Requires Medical supervision
Toxicity diseases are possible
Many unproven claims continually being made
Niacin - cholesterol lowering
Vit D - treatment of psoriasis
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

5. Storage of Vitamins
Fat soluble vitamins A, E and D not readily excreted
Water soluble - lost from body quite rapidly (B6 and B12 stored)
In general, limited storage of vitamins
should be consumed daily

6. Vitamin Toxicity Toxicity theoretical for all vitamins
Fat soluble more frequently observe toxicity (A and D)
E, Niacin, B-6 and C – very large amounts needed to result in toxicity
Only possible from supplements
A and D only 3-5 times RDA needed on a regular basis for toxicity
Vit A – important to minimize in early pregnancy
Once a day vitamins, less than 2 times daily value – not a risk
Preserving vitamin content - Table 8.1

7. Fat soluble Vitamins ADEK Absorbed along with dietary fat
Table 8.2
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

8. Vitamin A Easy to over dose (toxic) and be deficient Variety of forms
Both cause severe problems
Variety of forms
Retinoids
Preformed vitamin A –
Only found in animal foods
Carotenoids – pro-vitamin A
plants
Yellow-orange pigment in carrots
Turned into vitamin A as needed
Most potent form is beta-carotene
Both pre and pro – referred to as Vitamin A

9. 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 vit A – night blindness
Prolonged deficiency – cells unable to produce mucus for cornea
Dry, dirty, scratched, infected
Xeropthalmia - dry eye
Less-developed nations – children
Blindness. Infection, death

10. 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
Carotenoids play a role in preventing cardiovascular disease
Needed for growth, Development and Reproduction
Synthesis of proteins that stimulate proper growth and development
Resorbing and producing bone

11. Cancer and Vitamin A Skin, lung, bladder and breast cancer
Adequate intake of vitamin A can lower risk of breast cancer
Megadoses NOT recommended to prevent cancer
Carotenoids – trap energy in free radicals – oxidation can initiate cancer process
Supplements of b-carotene not effective
Variety of fresh fruits and vegetables
Lycopene - tomatoes - may prevent prostate cancer
Acne – topical and internal derivatives
May produce birth defects in pregnant women using treatments
Eg retin-A and accutane

12. Vitamin A in Food Preformed vitamin A
liver, fish oils, fortified milk and cereal, butter, margarine, eggs
Pro-vitamin – dark green and orange vegetables
Carrots, spinach, winter squash, papaya, apricots, sweet potatoes
RDA – RAE- retinol activity equivalent
900 mg RAE (males)
700 mg RAE (females)
Due to difficulty in classifying contributions from preformed and pro-vitamin A sources the labeling has undergone changes recently
Very old - IU, old RA, now RAE
Risk of deficiency – children, poor, alcoholics
Dietary sources table – fig 8.3

13. Toxicity of Vitamin A
3 times the RDA can cause problems if continued for prolonged periods
Early pregnancy (pre-formed)
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 -one ounce of liver - 300%
Carotenoids (pro form) not toxic
Rate of conversion is slow
Efficiency of absorption decreases as intake increases

14. 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

15. 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
Immune system and skin development influenced by vitamin D

16. 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 - reduces fractures
problem with vitamin D activation or absorption

17. Dietary Sources of D
Fatty fish (sardines, salmon), fortified milk, yogurt and cereals
under 51 years - 5 mg/day
over times mg/day
max. 50 mg /day
Young, fair skinned min of sun on face and arms 2-3 times /week
5-10 times recommended on regular basis results in toxicity
calcium over absorption - deposition in kidneys and other organs
high blood calcium
Weakness, loss of appetite, diarrhea, vomiting , mental confusion,
sun exposure does not result in toxicity

18. Vitamin E Fat soluble antioxidant - resides in cell membranes
donates electrons - protection from free radicals
fig 8-4
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 to making good overall health choices

19. Deficiency of vitamin E
Few women getting enough vitamin E from food
Supplements not as potent
Smoking destroys vitamin E
Cell membranes break down
red blood cell breakdown 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

20. Vitamin E in Foods
plant oils, fortified cereals, fruits and vegetables, eggs, margarine
Sunflower seeds and almonds are an excellent source of vitamin E
vitamin E in plant oils - protects unsaturated fatty acids
Animal foods almost no vitamin E
content of vit E depends on harvesting , processing storage and cooking
easily destroyed by oxygen, metals , light , repeated frying
RNI - 15 mg /day
alpha tocopherol - most active form
megadose therapy - not proven
Upper level is 1000mg of supplement
toxicity not a problem, except for people on anticoagulants (CVD) or with a vitamin K deficiency - due to increasesd risk of hemorrhage

21. Vitamin K Family of compounds known collectively as vitamin K
Found in plant oils, fish oils, and meats
One form is synthesized by bacteria in the intestine (10% of need)
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 with poor fat absorption

22. Vitamin K in Food
Liver, green leafy vegetables, broccoli, peas and green beans
Also soybean and canola oils
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 (CVD)

23. Vitamin Supplements
Supplements may be beneficial, and improve health of population
Most unwilling to increase intake of fruits and vegetables
folate (B vitamin)
birth defects
homocystien - risk factor for heart disease
alleviated by adequate folate (and reduction in red meat)
vitamin B12 - risk over 50
synthetic more easily absorbed
Eat right and take a multivitamin
Use supplements in consultation with physician
Potential impacts of medications for CVD and cancer

24. Vitamin Supplements Megadoses of E and B12
trials ongoing, may be beneficial
Vit E not very exciting results
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