MGTS-312 Lecture Notes - Lecture 21: Sunscreen, B Vitamins
25 Mar 2016
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Document Summary
The water-soluble vitamins: cooking & washing with water, leaches them out of food, easily absorbed, excess easily excreted in urine, some can remain in lean tissues for 1+ months. Deficiency of any one b vitamin rarely shows up alone, because people eat foods that contain mixtures of nutrients. Skin synthesis of vitamin d poses no risk of toxicity. Vitamin d: the sun itself begins breaking down excess vitamin d made in the skin, sunbathers are at risk of skin damage & skin cancer. Sunscreens with spfs of 8 or above can reduce these risks, but they also prevent vitamin d synthesis. In most places, during warmer months, just being outdoors when the sun is overhead, even in lightweight clothing, promotes sufficient skin synthesis of vitamin d. Factors affecting sun exposure & vitamin d synthesis: skin colour, air pollution, city living, clothing, geography, indoor lifestyle, season, sunscreen, time of day.
