1. Vitamins: An Overview

2. Vitamins Essential organic substances (contain carbon)
Not synthesized
Inadequate synthesis
Yield no energy, but facilitate energy-yielding chemical reactions
If absent from a diet, it will produce deficiency signs and symptoms

3. Body Needs Vitamins for Normal
Function
Growth
Maintenance
Reproduction

4. Two Forms of Vitamins Precursor/Provitamin Active form
Dietary form inactive
Activated in body
Active form
Dietary form active
Not changed in body

5. Vitamins Often Serve as Coenzymes

6. Vitamin Classification
Fat-soluble vitamins
Dissolve in substances such as ether and benzene but not readily in water
Include vitamins A, D, E, and K
Water-soluble vitamins
Vitamins that dissolve in water
Include B vitamins and vitamin C

7. Vitamin Classification
Category determines
Food sources
How handled in body
Best preservation methods

8. Vitamin History
First discovered: fat soluble substance essential for health in (vitamin A)
B complex: (water soluble nutrient)
Vitamin C: isolated 1912
Vitamin D, Vitamin E: 1922
Last vitamin (B12) discovered in 1948
Likely all vitamins have been discovered, since people can be maintained on IV solutions fortified with known vitamins

9. Vitamin Facts
Megadose (>10x needs) proved useful in treating certain conditions
Plant and animal foods provide vitamins
Synthesized vitamins work equally well in the body

10. Fat-Soluble Vitamins Dissolve in organic solvents
Not readily excreted; can cause toxicity
Absorbed along with fat
Deficiency with fat malabsorption
Fat blockers (Orlistat/Xenical)
Mineral oil

11. Fat Soluble Vitamins Requires protein carrier
Transported like fat in chylomicrons, VLDL, LDL
Stored in body (except Vitamin K)
Fat tissue/liver
Can cause toxicity
Vitamin D and A most likely to be toxic

12. Fat Soluble Vitamin Preservation
Not easily destroyed
Fat addition in cooking vegetables
Fat soluble vitamins leach out
Lost if liquid discarded
Add fat after vegetables drained, just before serving
Baking soda
Used to preserve color of green vegetables
Destroys Vitamin D

13. Water Soluble Vitamins
Found in grains, fruits, vegetables, meat
Low risk of toxicity
Not stored in large amounts
Excess excreted inurine
Need daily intakes
Easily destroyed
Heat – increases enzyme activity
Light – destroys riboflavin
Oxygen: breaks down

14. Water Soluble Vitamins - Preservation
Cooking
Heat – destroys vitamins
Water – leaches out vitamins
Baking soda – destroys thiamin
Conserve vitamins
Store foods covered in refrigerator
Consume soon after purchase (freshest possible)
Minimal cooking/minimal liquid
Freezing preserves vitamin content

15. Vitamin A
Deficiency is most common cause of non-accidental blindness worldwide
Up to 500,000 children in developing nations especially Asia, become blind each year because of Vitamin A deficiency

16. Functions of Vitamin A Prevents night blindness
Prevents xerophthalmia (dry eye)
Maintains cell health (epithelial cells)
Growth, development, reproduction
Cardiovascular disease prevention
Cancer prevention

17. Night Blindness Vitamin A is needed for dark vision
Rhodopsin in retina
Light destroys
Constantly reformed
Allows for a chemical process to signal the brain that light is striking the eye
Allows eyes to adjust to dark vision

18. Xeropthalmia
In Vitamin A deficiency, the cells that line the cornea lose their ability to produce mucus
When dirt particles scratch the dry surface of the eye, becomes infected
Leads to blindness
Worldwide public health efforts are fortifying sugar, margarine, MSG, giving large doses of Vitamin A 2x year

19. Macular Degeneration
Leading cause of legal blindness among North American adults over 65
Changes in the macular area of the eye
Age, smoking, and genetics are risk factors
Macula contains carotenoids lutein and zeaxanthin
High intakes of carotenoids associated with lower risk (but may be fruit and vegetable intake)
Also may reduce risk of cataracts
Multivitamins are adding lutein

20. Cell Health
Vitamin A maintains health of cells that line internal and external surfaces (epithelial cells)
Barriers to bacterial infections
Epithelial cells produce mucus
Without vitamin A, these cells do not produce mucus
Increases infections and decreases immune system

21. Growth Vitamin A binds to DNA Assists in protein synthesis
Affects growth, reproductive system, and bone growth

22. Cancer and Cardiovascular Disease
Role in cell development and immune-system
Role as an antioxidant
Lower risk of breast cancer with vitamin A supplements
Megadoses are not recommended
Mixed results in cancer/vitamin A studies
Foods rich in vitamin A and other phytochemicals are advised

23. Prostate Cancer and Carotenoids
One of the most common cancers among North American men
Lycopene (tomatoes, watermelon, other fruits) seems to protect against it, possibly due to antioxidant activity

24. Vitamin A and Your Skin Topical treatment and oral drug
Accutane (oral) and Retin-A (topical)
Can induce toxicity symptoms
Contraindicated in pregnant women
Use only under supervision of a physician

25. Sources of Vitamin A Preformed Provitamin
Liver, fish oils, fortified milk, eggs
Contributes to half of vitamin A intake in North America
Provitamin
Dark leafy green, yellow-orange vegetables/fruits; carrots, spinach and other greens, winter squash, sweet potatoes, broccoli, mangoes, cantaloupe, peaches and apricots
Contributes to half of all the vitamin A intake

26. Vitamin A from the Food Guide Pyramid

27. Deficiency of Vitamin A
Night blindness
Decrease mucus production leading to bacterial invasion in the eye
Irreversible blindness

28. Deficiency of Vitamin A
Follicular hyperkeratosis
Keratin protects the inner layers of skin and maintains moisture
Kertinized cells replaces the normal epithelial cells in the underlying skin layers
Hair follicles become plugged
Bumpy, rough, and dry skin

29. Measuring Vitamin A
International unit (IU)-crude method of measurement
Retinol activity equivalent (RAE) -current, more precise method of measurement
1 ug of retinol = 1 RAE = 3.3 IU =12 ug beta-carotene = 24 ug of other provitamin A

30. RDA for Vitamin A for Adults
900 mcg REA for men
700 mcg REA for women
Average intake meets RDA
Daily value used on food and supplement labels is 1000 mcg
Much stored in the liver
Vitamin A supplements are unnecessary
No separate RDA for carotenoids

31. Who is at Risk For Deficiency
Breast fed infants
Preschooler with poor vegetable intake
Urban poor
Elderly
Alcoholics and people with liver disease
Individual with fat malabsorption
HIV, AIDS

32. Toxicity of Vitamin A
Large intake of vitamin A over a long period: supplements, liver, fish oil
Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting
Possible permanent damage
Discontinue supplement

33. Toxicity of Vitamin A
May produce fetal malformations and spontaneous abortions in pregnant women
May occur with as little as 3 x RDA of preformed vitamin A
Pregnant women and women who may become pregnant should limit to 100% DV
Upper Level for Vitamin A
3000 ug for adults
Fatal dose -12 g of vitamin A can be fatal

34. Toxicity of Carotenoids
Don’t produce toxic effects because
Rate of conversion to Vitamin A is slow and regulated
Efficiency of absorption decreases as oral intake increases

35. Carotenoids High amounts of carotenoids in the bloodstream
Excessive consumption of carrots/squash/beta-carotene supplements
Skin turns a yellow-orange color

36. Vitamin D Prohormone Derived from cholesterol
90% of needs is synthesized from sun exposure
Insufficient sun exposure makes this a vitamin

37. Sun Exposure to Prevent Vitamin D Deficiency
~15 minutes 2-3 times a week
Between 8 a.m. and 4 p.m.
Hands, face, arms
Light skin
No sunscreen greater than SPF8

38. Activation of Vitamin D
To become the active hormone, Vitamin D must be
Acted on by the liver to produce 25-hydroxyvitamin D
Acted on by the kidney to produce 1,25 dihydroxyvitamin D (active hormone form)

39. Functions of Vitamin D Regulates blood calcium
Regulates calcium and phosphorus absorption from the intestine
Reduces kidney excretion of calcium
Regulates calcium deposition in bones
Serum calcium involved in nerve transmission and muscle contraction

40. Functions of Vitamin D Influences cell differentiation
Linked to reduction of breast, colon, and prostate cancer
Controls the growth of the parathyroid gland, aids in immune function, contributes to skin cell development

41. Role in Bone Formation
Vitamin D causes Ca + Phos to deposit in the bones
Strengthen bones

42. Food Sources of Vitamin D
Fatty fish (salmon, herring)
Fortified milk and yogurt
10 mcg per quart in US and Canada
Some fortified cereal

43. The Adequate Intake (AI) for Vitamin D
5 ug/d (200 IU/day) for adults under age 51
10-15 ug/day ( IU/day) for older Americans
Light skinned individuals can produce enough vitamin D to meet the AI from casual sun exposure
Infants are born with enough vitamin D to last ~9 months of age.

44. Vitamin D Toxicity Upper level is 50 mcg/day
Vitamin D can be very toxic especially in children
Regular intake of 5-10x the AI can be toxic
Results from excess supplementation (not from sun exposure or milk consumption)

45. Vitamin D Toxicity
Signs/symptoms: overabsorption of calcium (hypercalcemia)
Signs of high blood calcium: weakness, loss of appetite, diarrhea, vomiting, mental confusion, increased urine output
Calcium deposits in kidneys, heart, and blood vessels
Mental retardation in infants

46. Vitamin D Deficiency At risk Dark skinned Lack of sun exposure
Northern climates in wintertime
Breastfed babies

47. Vitamin D Deficiency: Rickets
Is the result of vitamin D deficiency in children
Poor mineralization of bones because of low calcium content
Fortification of milk has greatly reduced rickets in children
Most rickets is associated with fat malabsorption, as in cystic fibrosis

48. Vitamin D Deficiency: Osteomalacia (soft bone)
Is rickets in the adult
Low calcium content in bones due to lack of vitamin D

49. Vitamin E Group of fat-soluble compounds, tocopherols and tocotrienols
Alpha-tocopherol is the most potent
Fat-soluble antioxidant
Resides mostly in cell membranes

50. Redox Agent Vitamin E is able to donate electron to oxidizing agent
Protects the cell from attack by free radicals
Protects PUFAs within the cell membrane and plasma lipoproteins
Prevents cell death
Prevents the alteration of cell’s DNA and risk for cancer development

51. Vitamin E, An Antioxidant

52. The More The Better? Vitamin E is only one of many antioxidants
It is likely that the combination of antioxidants is more effective
Best to diversify antioxidant intake with a balanced and varied diet
Megadose of one antioxidant may interfere with the action of another

53. Vitamin E and Cardiovascular Disease
Epidemiological studies suggest higher intakes of Vitamin E are associated with lower risk of CHD
Clinical trial results have been mixed
American Heart Association states it is premature to recommend vitamin E supplements to the general population
FDA has denied permission for supplement mfr’s to claim that Vitamin E prevents heart disease and cancer

54. Other Functions of Vitamin E
Protects the double bonds in saturated fat
Helps vitamin A absorption
Role in iron metabolism
Inhibits LDL oxidation
Maintenance of nervous tissue and immune function

55. Food Sources of Vitamin E
Plant oils: salad dressings, mayonnaise
Fortified cereals, oatmeal
Wheat germ
Asparagus, tomatoes, green leafy vegetables

56. Food Sources of Vitamin E
Peanuts
Margarine
Nuts and seeds (sunflower seeds)
Actual amount is dependent on harvesting, processing, storage and cooking

57. Food Sources of Vitamin E

58. Vitamin E: Easily Damaged
Oxygen
Metals
Light
High heat
Deep fat frying

59. RDA for Vitamin E 15 mg/day alpha-tocopherol for women and men
(=22 IU of natural source or 33 IU of synthetic form)
Average intake meets RDA
1 mg d--tocopherol = 0.45 IU (synthetic source)
1 mg d--tocopherol = 0.67 IU (natural sources)

60. Deficiency of Vitamin E
Hemolytic anemia
Hemolysis occurs in preterm infants because they did not receive enough vitamin E from their mothers
Preemie formulas and supplements compensate for increased needs

61. Deficiency of Vitamin E: Who’s At Risk?
Smokers are especially at risk (smoking destroys vitamin E in the lungs)
However even megadoses may not prevent damage
Adults on very low fat diets
Fat malabsorption

62. Toxicity of Vitamin E Supplements up to 800 IU probably harmless
Upper Level is 1,000 mg/day of any form of supplementary alpha-tocopherol
Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms)
Inhibits vitamin K metabolism especially in conjunction with anticoagulants
Possible hemorrhage

63. Vitamin K (“Koagulation”)
Family of compounds found in plants, plant oils, fish oils, and meats
Synthesized by the bacteria in the colon and are absorbed (10% of needs)

64. Role of Vitamin K Role in the coagulation process
Contributes to the synthesis of several blood-clotting factors
Helps form proteins present in bone, muscle, and kidneys
Imparts calcium-binding potential
Poor intake linked to increase in hip fractures

65. Vitamin K in Newborns
Newborn’s intestinal tract lacks bacteria to allow blood to clot effectively
Vitamin K is routinely given by injection shortly after birth to bridge the gap
May also occur in adults with chronic malabsorption

66. Drugs and Vitamin K Anticoagulant Antibiotics
Lessens vitamin K reactivation
Lessens blood clotting process
Monitor vitamin K intake
Antibiotics
Destroy intestinal bacteria
Inhibit vitamin K synthesis and absorption
Potential for excessive bleeding

67. Food Sources of Vitamin K
Liver
Green leafy vegetables
Broccoli
Peas
Green beans
Soybeans/canola oil
Resistant to cooking losses
Limited vitamin K stored in the body

68. Adequate Intake for Vitamin K
90 ug/day for women
120 ug/day for men
Amount met by most
Excess vitamins A and E interferes with vitamin K
Newborns are injected with vitamin K (breast milk is a poor source)
Toxicity unlikely; readily excreted

69. Next: Water Soluble Vitamins