Vitamin A: -Elmer McCollum found vitamin A: fat soluble factor A required for the health of rats -Animals fed butter fat and egg yolks would drive and animals fed lard or olive oil died -Vitamin A is a mixture of compounds but all interconvertible in the body -Found in animal food e.g. liver-Liver is rich in retinoids-But not necessary to eat animal food for vitamin A -Pro vitamin A can be converted into vitamin A = beta carotene. Carotenoids are found in plant products. Beta-carotene can give rise to vitamin A. -You can get vitamin A from eating beta-carotene but you would have to eat more beta-carotene than you have to eat vitamin A -1 IU (international unit)= 0.3 mcg of retinol = 0.6 mcg of beta-caroteneVitamin A needed for:-bone growth, reproduction, health of the immune system -Appearance of the skin and the mucous membranes -Mucous membranes repel bacteria and viruses -Essential to vision-retinol (another form of vitamin A) is important in the functioning of the eye-Can aid people with retinitis pigmentosa -The story of carrots and vision: carrots have vitamin A in the form of beta-carotene-In developing countries:-Children are affected by vitamin A deficiency -Blindness, impairment of immune function—> leads to death -Over 600000 children are dead and up to half a million go blind every year -Solved by golden rice(genetically modified rice)= made with enzymes that will produce beta-carotene in the rice -But hasn’t taken offdue to the fear of unwarranted genetically modified foods
-Golden potato:developed the same way as golden rice (relatively new) -Why not take pills?: have to take them in a regular basis which is hard for people-Rice and potatoes are the staple foods so people are foreign to carrots or sweet potatoes (crops high in vitamin A) -For smokers taking large doses of beta carotene, beta-carotene increases the risk of lung cancer -with excess of beta-carotene, you turn orange (Carotenemia) but nothing really more than that.-But overdosing on preformed vitamin A (found in meat):-Polar bear liver is high in vitamin A and is toxic that it could kill people -Nobody should exceed 10,000 IU a day -4000-5000 IU a day would be fine -Vitamin A has a dramatic effect on acne (Tretinoin, trans-retinoic acid, or isoretinoic acid)-Vitamin A acid gel/ Retin-A can be found to apply-Accutane/ isotretinoin can be magical in cleaning up acne (taken as a drug) -BUT should not be taken during pregnancy due to a very powerful teratogenic effect (affects embryo in a negative way) -Vitamin A is fat solubleand fat-soluble vitamins can build up int eh body and be overdosed. 2-2Elmer McCollum discovered vitamin D in 1921-prevented a disease called rickets -Rickets:malformations of the bones -Found when children were forced to work in mines with no sunshine -Cod river oil treated rickets: contains vitamin D-Vitamin D is also called “sunshine vitamin” -Sunshine can trigger a host of chemical reactions that take place in the body by which vitamin D is formed -Chemicals reacted by sunlight—> reactions that causes formations of vitamin D-Lack of vitamin D causes rickets and osteoporosis (weak bones) -Dairy products are supplemented with vitamin D (about 100 IU in every glass of milk) to prevent osteoporosis -Many “claims” of benefits of Vitamin D-Reduces respiratory tract infections (like cold) ?
- Spring '11