Vitamin A
Getting to know it!
Vitamin A represents a number of related compounds: retinol, retinal, retinoic acid, and a vitamin A precursor beta (b)-carotene. Vitamin A is important for night vision, for fighting infection (body immunity), and for regulating the genes to ensure their proper functioning.
Dietary sources
Orange and yellow vegetables such as carrots, cod liver oil, fortified cereal, cantaloupe, whole milk, spinach, and eggs are examples of vitamin A rich foods.
Deficiency aftermath
Early vitamin A deficiency leads to impaired night vision, and advanced vitamin A deficiency can lead to corneal ulcers and scarring and blindness. In developing countries, vitamin A deficiency is an important cause of blindness among children. These children are also more likely to develop diarrhea and respiratory infections.
Why are supplements beneficial?
There is NO evidence that taking vitamin A supplements can prevent cancer or heart attacks. In the ATBC trial, subjects given beta-carotene had higher incidence of lung cancer than subjects not given beta-carotene.
Toxicity
Vitamin A can be toxic in high doses (Usually 10 times RDA). Symptoms of vitamin A toxicity include nausea, dry itchy skin, headache, and loss of appetite, bone and joint pain. High doses of vitamin A can also cause liver toxicity. Elderly people and people who drink alcohol heavily are more susceptible to vitamin A toxicity.
Tips for supplements
Eat a balanced diet and take one multivitamin daily. (Most multivitamins contain 5000 IU of vitamin A, generally in the form of beta-carotene). Additional vitamin A supplements are currently NOT recommended. Pregnant women should not take additional vitamin A supplements without medical supervision. Pregnant women should also avoid skin acne medications derived from natural and synthetic retinoids such as tretinoin (Retin-a), isotretinoin (Accutane), and psoriasis medications such as etretinate and acitretin.
Vitamins A (retinyl), C (ascorbic acid), and E (tocopherol) all help slow down the natural oxidation process, keeping oil-based applications fresher for longer periods and prolonging their shelf life before they go rancid. Any products that contain a large amount of oil, such as ointments, massage oils, and bath salts, need an antioxidant to prevent them from breaking down and losing their potency. Vitamins A, C, and E also protect skin cells from the damaging effects of free radicals. Do not be fooled by the synthetic version of vitamin C on the market, which goes by a number of aliases such as Alpha Tocopherol and Tocopherol Acetate. Vitamin E is preferable, since certain forms of vitamin C can be unstable.===============**********===============
Vitamin E
Vitamin E represents a family of eight fat-soluble anti-oxidant vitamins. Alpha-tocopherol is the most important vitamin E in humans. Alpha-tocopherol protects the LDL cholesterol in the blood and body cell membranes from oxidation by free radicals. (Oxidation of LDL cholesterol is believed to contribute to atherosclerosis of the arteries that can lead to strokes and heart attacks.) Alpha-tocopherol also inhibits blood clotting.
Dietary sources
Foods rich in alpha-tocopherol include green leafy vegetables, carrots, nuts, olive oil, corn oil, canola oil, safflower oil, sunflower oil, wheat germ, whole grains, and margarines made from plant oils. Meats, fruits, and milk have little vitamin E.
Deficiency aftermath
Severe vitamin E deficiency can lead to muscle weakness and impaired balance and coordination, and anemia. But there have been no reports of severe vitamin E deficiency among healthy adults. Vitamin E deficiency can occur in children and adults with fat malabsorption (conditions that render their intestines unable to absorb fat and fat soluble vitamins A, D, E, and K).
Toxicity
Vitamin E in high doses can impair blood clotting and increase the risks of hemorrhage. Vitamin E can also increase the blood thinning action of warfarin, Coumadin (an anti-coagulant used in preventing blood clotting) and increase the risk of bleeding in patients taking Coumadin. Therefore, patients taking Coumadin, patients with vitamin K deficiency, and patients taking other medications that impair platelet function should take vitamin E supplements under medical supervision.
Tips for supplementation
All adults are recommended to consume vitamin E rich foods and to take a multivitamin daily. (An average multivitamin tablet contains 30-40 IU of vitamin E).
Consult the doctor regarding additional vitamin E supplements. For example some doctors recommend supplementation of 400 IU of vitamin E for all healthy middle age or older adults to prevent strokes, heart attacks, and cancers. Others recommend vitamin E supplements (400 IU) only for patients with small dense LDL cholesterol particles and with familial hypercholesterolemia. These patients are susceptible to oxidation and have higher than normal risks of heart attacks.
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Vitamin D
Getting to know it!
Vitamin D is necessary for the intestines to absorb dietary calcium. Vitamin D comes from food and is also produced by the skin upon exposure to sunlight. Active children and young adults living in sunny regions can produce most of the vitamin D they need from their skin. In areas with insufficient sunlight, or in colder areas in winter, adequate vitamin D cannot be produced by the skin. Vitamin D deficiency is common among the elderly.
Dietary sources
Vitamin D is not present in foods of plant origin except some plants of solanum family. Foods rich in the vitamin include fish liver oils, fortified milk, herring, salmon, fatty fish, milk, eggs, butter, cheese and full fat milk powder.
Deficiency aftermath
Children with prolonged vitamin D deficiency can develop rickets. Children with rickets will develop bowing of the extremities due to weak bones. In adults, vitamin D deficiency can lead to osteoporosis and osteomalacia (both conditions of weakened bones).
ips for supplementation
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Vitamin D deficiency is common among the elderly living in the colder regions. Therefore, it is recommended that the elderly take a multivitamin daily, eat vitamin D rich foods, and have regular exposure to the sun several times a week with sunscreen during spring, summer and fall. ===============**********=============== |
