FNDH 400

Folate - correct answer reduced, natural, polyglutamate, less stable Folic acid - correct answer oxidized, synthetic, monoglutamate, more stable Purpose of dietary folate equivalents (DFE) - correct answer Bioavailability of folate is lower than folic acid. To account for these differences, the DRI committee created dietary folate equivalents cofactor of folate - correct answer THF (tetrahydrofolate) Why does the US fortifies foods with folic acid? - correct answer Maternal folate deficiency can lead to neural tube defects in infants. Neural tube closes 24-28 days after conception, and with 50% of pregnancies unplanned, many women are not aware they are pregnant during this period. Recommended women of childbearing age consume 400 ug of folic acid daily. Difficult for women of low socioeconomic status or young mothers because they might not be able to afford or not know to take the supplement. Megaloblastic (macrocytic) anemia - correct answer Large, nucleated, and immature red blood cells. Occurs because THF is needed for DNA synthesis. Without it, red blood cells are not able to divide properly = fewer and poorer functioning red blood cells are produced that cannot carry oxygen as efficiently as normal red blood cells. How does folate and vitamin B12 deficiency lead to megaloblastic anemia? - correct answer In vitamin B12 deficiency, this anemia can occur because there is not enough cobalamin to convert 5-methyl THF to THF as it normally would by donating a methyl group. Thus, THF is not available for normal DNA synthesis and the red blood cells do not divide correctly. scientific name for vitamin B12 - correct answer cobalamin Why is vitamin B12 deficiency an issue for vegans? - correct answer Vegans do not consume animal products, and vitamin B12 is found almost exclusively in animal products. Why are the most reliable sources of B12 animal-based foods? - correct answer Animals consume microorganisms in soil or microorganisms in the GI tract of ruminant animals produce vitamin B12 that can then be absorbed. Plant products contains a pseudo vitamin B12 compound which is not bioavailable. pernicious anemia - correct answer Potential cause of some vitamin B12 deficiency. A condition of inadequate intrinsic factor production that causes poor vitamin B12 absorption. Common in people over the age 50 because of atrophic gastritis. atrophic gastritis (B12) - correct answer a chronic inflammatory condition that can lead to the loss of glands in the stomach. Loss of glands leads to decreased intrinsic factor production. Intrinsic factor - correct answer In the duodenum, intrinsic factor binds to vitamin B12. Intrinsic factor + B12 continues to the ileum. In ileum, intrinsic factor + B12 is endocytosed by intrinsic factor binding to cubulin, intrinsic factor receptor, forming an endosome inside the enterocyte. Intrinsic factor is broken down in the enterocyte. How does folate/folic acid mask a vitamin B12 deficiency? - correct answer Large dose of folate can correct macrocytic anemia, by providing enough folate that there is enough THF for red blood cell division to occur even without cobalamin available, which is normally needed to accept a methyl group from 5-methyl THF. Corrects the anemia, but not the neurological problems which is the issue. How does the intake of folate and vitamin B12 decrease homocysteine levels? Is it a good way to decrease cardiovascular disease risk? - correct answer Homocysteine is a sulfur containing, non-proteinogenic amino acid. Elevated circulating levels have been found in people with cardiovascular disease. Folate, vitamin B6, and vitamin B12 contribute to the conversion of homocysteine to methionine by providing methyl groups, thereby decreasing homocysteine concentrations. However, studies have not found that it decreases cardiovascular disease risk. Why is vitamin D conditionally essential? - correct answer Vitamin D is part vitamin, part hormone. We have the ability to synthesize it. It has hormone-like functions. The amount synthesized is not enough to meet our needs so we need to consume this vitamin under certain circumstances. How is vitamin D synthesized? - correct answer Vitamin D2 - correct answer Ergocalciferol Has double bond in tail along with a metterm-16hyl group Produced mainly by plants and yeast Vitamin D3 - correct answer cholecalciferol No double bond in tail Mainly made by animals Vitamin D DRIs - correct answer They are thought to be equivalent, but research has found that vitamin D3 supplementation increases 25(OH)D concentrations more than D2 supplementation. How environmental factors affect vitamin D synthesis: Latitude - correct answer Increased distance from equator (increased latitude) = decreased UV light exposure and vitamin D3 synthesis How environmental factors affect vitamin D synthesis: Seasons - correct answer Vitamin D3 is synthesized by cholesterol in the skin when UV-B light interacts with it. Not occurring during fall/winter months because not enough UV-B reaches earth's surface to synthesize Vitamin D during these months. How environmental factors affect vitamin D synthesis: Time - correct answer Vitamin D3 synthesis increases in the morning before peaking at noon, then declines the rest of the day. How environmental factors affect vitamin D synthesis: Skin Pigmentation - correct answer Increased production of melanin and darker skin color can provide a sun protection factor (SPF) 8-30. These people need 5 to 10 times greater sunlight exposure than light-skinned, white people to produce the same amount of vitamin D3. How environmental factors affect vitamin D synthesis: Age - correct answer Aging results in decreased 7-dehydrocholesterol concentration in the skin à about 75% reduction in the vitamin D3 synthesis capability by age 70. How environmental factors affect vitamin D synthesis: Clothing - correct answer More clothing = less sun reaches s