University:
MacEwan University
Course:
HEED 110 | Introduction to Personal Health and Well-Being
Academic year:

2023
Views:

348

Pages:

3
Author:

Arthur M.

Chp 8: Vitamins Factors that Affect Bioavailability Digestion efficiency & GI track transit time Previous nutrient intake & nutrition status Other foods consumed at the same time Method of food preparation & processing Nutrient source: naturally occurring, synthetic, fortified Vitamins Overview Precursors (provitamins) must be converted to active form Organic nature can be destroyed vulnerable to heat, light, & oxygen exposure Solubility water soluble: B & C vitamins fat soluble: A, D, E, & K solubility affects absorption, transport, storage Fat Soluble Vitamins A, D, E, & K Stored in liver & fatty tissue Vitamin A Beta-Carotene Vision: maintains cornea, rhodopsin light detection in retina, early deficiency can cause night blindness Gene expression: retinoic acid helps activate/deactivate genes Protein synthesis & cell differentiation Immunity, reproduction, antioxidant Vitamin A deficiency All epithelial surfaces: cells harden and flatten Major cause of preventable blindness via damage to cornea ↑ susceptibility to disease Vitamin A & Beta-Carotene Toxicity Vitamin A toxicity teratogenic risks, weakens bone Beta-carotene conversion & toxicity retinol activating enzymes high intake from foods is not hepatotoxic Vitamin D Body can synthesize w/ help of sunlight Two major forms D2: Plants D3: Animal foods, human skin Requires conversions from liver & kidneys Roles of Vitamin D Brain, nerve, muscle, immune cells Adipose tissue Decrease type 2 diabetes, high blood pressure Bone growth & Ca absorption D-deficiency Factors include dark skin, breastfeeding, sunlight exposure Diseases: Rickets, osteomalacia, osteoporosis Stored in liver & fatty tissue Sources: Fatty fish, milk, cheese, egg yolks, liver, fatty fish Vitamin D Toxicity Excess blood calcium & calcification Vitamin D from sun less risk of cancer DRI assumes no skin synthesis Vitamin E (alpha-tocopherol) Antioxidant Prevents oxidation of polyunsaturated fatty acids & other lipids Protects the lungs, may reduce LDL oxidation while reducing atherosclerosis Sources Vegetable oils, wheat germ oil, whole grains, fruits, vegetables, nuts Vitamin E deficiency Erythrocyte hemolysis in infants Adults Loss of muscle coordination, reflexes, impaired vision, impaired speech Vitamin E toxicity Supplement use Interferes with blood clotting Vitamin K Roles in blood clotting & bone protein synthesis Blood clotting Needed for activation of several proteins involved in clotting Intestinal synthesis by bacteria Insufficient as sole source Deficiency Poor absorption Antibiotics/anticoagulants Toxicity Rare, high doses interfere with anticoagulants Newborns receive single dose at birth Folate Active in cell division Alcohol & drugs Negative impact on folate status Alcohol impairs absorption, medications, aspirin, oral contraceptives, smoking Neural tube defects Prevented by supplements At least 400 mcg/day from fortified foods