Folate and B12 2011

Folate and B12 2011 - Folate(Folic Acid – Also called B9...

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Unformatted text preview: Folate (Folic Acid) – Also called B9 Discovery – Megaloblastic Macrocytic Anemia Unknown factor isolated from spinach by Hershel K Mitchell in 1941 (The University of Texas) Found to be in other green vegetables Lucy Wills MD – India (1928)– pregnant women suffering from megaloblastic anemia Steps of research: 1) ruled out infectious disease 2) looked for nutritional cause – found common characteristic to be poor diet 3) first tried to add VA and VC – no change 4) replicated in animal model – rhesus monkey – used Marmite 5) successfully transferred treatment to women (also used extract of liver) 6) returned to England to figure out nutrient responsible originally called Wills factor Discovery continued Labeled folate from the Latin folium : leaf Structure determined in 1943 and developed method to synthesize Discovered could also treat megaloblastic anemia caused by B12 deficiency • Problem: “masked” the B12 version by “curing” the anemia but not the neurological • developed controversial discussion about fortification • Several decades after Dr. Wills work, folate was linked to neural tube defects in infants Megaloblastic anemia affected mother later in pregnancy; however, damage would already have been done to infant resulting in NTDs. • 1998 manufacturers required to add folic acid to grain products – staples of diet Fig. 9-27, p. 349 Structure • 3 distinct parts: 1) pteridine 2) PABA 3) glutamic acid • in the body: metabolically active folate has multiple glutamic acid residues attached • humans can synthesize all the components but lack the enzyme needed to attach pteridine to PABA to make pteroic acid Sources Good sources: mushrooms, spinach , brussel sprouts, broccoli, asparagus , turnip greens Okra, peanuts, legumes (especially lima , pinto and kidney beans), lentils, fruit (especially strawberries and oranges) and beef liver . >150 forms of polyglutamated folate found in foods. In supplements and fortified forms – folic acid provided as pteroylmonglutamate- the most oxidized and stable form Issue for absorption is the bioavailability of the various forms – ranges from 10 – 98% general bioavailability for mixed diet = 50% DRI μg/day 1-3 150 4-8 300 Males 9 – 13 300 14 - >70 400 Females 9 – 13 300 14 - >70 400 Factors affecting: intestinal conditions such as pH genetic variations on enzymatic activity inhibitors: ability of conjugases to hydrolyze to the monoglutamate form aids: folate in milk found bound to high-affinity-folate-binding-protein Dietary inhibitors: zinc deficiency, chronic alcohol consumption, conjugase inhibitors found In: legume, lentils, cabbage and oranges. Absorption Hydrolysis of the polyglutmate forms of folate are performed by conjugases found in jejunum mucosa and the intestinal brush border (this one is zinc dependent)....
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Folate and B12 2011 - Folate(Folic Acid – Also called B9...

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