Notes 3/18/13 - 3/22/13

Vitamin A Notes

- a vitamin an organic molecules that is consumed in small quantities (less than a gram) but is necessary for normal function
- ex. A, D, E, K - fat soluble vitamins - can be stored but also can build up and become toxic with time and overconsumption
- B vitamins, C - water soluble vitamins - cannot be easily stored and overconsumption usually leads to excretion

- Vitamin A - aka retinol
 - beta-carotene is a closely related precursor to vitamin A

- daily requirements - women - 700 micrograms/day - men - 900 micrograms/day

- sources of vitamin A - liver, oils from animals, milk fat, spinach, carrots, broccoli, sweet potatoes

- functions - vitamin A is involved in vision (In order to see, proteins in the cells of your retina need to change shape in order to send a signal to your brain. A form of vitamin A makes this protein) , epithelial cell integrity, immune response, RBC production, skeletal growth, fertility, and embryogenesis

- deficiency - With vitamin A deficiency, cells lose their columnar shape and ‘dry out’ (keratinization)
- Deficiency can have very severe consequences - most noticeably in the eye - In children Vitamin A deficiency can also cause growth retardation. Between 100 and 140 million children are vitamin A deficient. An estimated 250,000 to 500 000 vitamin A-deficient children become blind every year, half of them dying within 12 months of losing their sight. (World Health Organization)

- interventions to control vitamin A deficiency 
 - Supplementation –Vitamin A capsules – contain 100x RDA and are well absorbed and stored
 - Fortification / genetic engineering – Ex.  Sugar or golden rice
 - Diet diversification Diversifying diet will provide more natural sources of Vitamin A
 - Promotion of breastfeeding Breastfeeding – if mother is supplemented and has proper stores, she can give the baby all the vitamin A he/she needs for the first six months of life
 - Infectious disease control - Less disease --> less death due to deficiency and fewer children excreting vitamin A above normal