metabolismtest1 - FOLATE - - - - - - - FOLIC ACID RDA: 400...

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FOLATE FOLIC ACID - RDA: 400 ug DFE/day- Adults 600 ug DFE/day- pregnant women 500 ug DFE/day- lactating women - Upper Level : 1000ug/day folic acid - Folate is necessary in DNA synthesis and metabolism of several amino acids. - Folic Acid is the synthetic form of folate. It does not occur naturally in food. It is more stable than reduced folates (dietary folate) - Occurs naturally in orange juice, asparagus, strawberries, peanuts, legumes, black beans. - Monoglutamate is the term for Folic Acid. During digestion in the intestines, enzymes cleave off glutamates. The result is polyglutamate monoglutamate. - Dietary folate is primarily in reduced polyglutamate form . - Folic acid is in oxidized monoglutamate form. - When naturally occurring food folate is consumed, it must first be converted from its polyglutamate form monoglutamate form o The enzyme FGCP-folypoly-y-glutamate-carboxypeptidase aka “folate conjugase/hydrolase” is located in the jejunal brush border membrane and deconjugates the monoglutamate prior to absorption o pH affects digestion of folate. Optimum pH in jejunum is 6.5-7.0. - Absorption/Uptake of folate is a carrier-mediated process. Reduced Folate Carrier RFC is the major folate uptake system functional in intestinal epithelial cells. - When high doses of folic acid are absorbed in pharmacological quantites, folate is absorped by diffusion and its non-saturable . - Alcohol and drugs can effect absorption of folate. o Chronic Alcohol decreases the activity of FGCP and inhibits the expression of reduced folate carrier RFC. Alcohol inhibits folate absorption and cellular uptake. It also increases renal excretion of folate. This causes an increase in folate requirements with alcohol consumers. o Sulfasalazine (Aztilfidine) is a drug used for treatment of ulcerative colitis. It inhibts folate absorption. - Before folate is uptaken into portal blood, folic acid is o Reduced to THF o Converted to methyl folate o THF is folate’s primary coenzyme form. It serves as an enzyme complex that transfers 1 Carbon compounds that arise during metabolism - When heavy doses of folic acid are consumed (~200ug), folic acid can be found in blood and urine because the reducing enzymes are easily saturated. - Endogenous Intestinal Folate occurs as folate is secreted into the intestine as bile or in pancreatic secretions . Enterohepatic recirculation is very efficient between the liver and intestines. o Very little folate is excreted. When food is eaten, bile is secreted along with bile folate- some is reabsorbed o Excess folate is disposed of by the liver which excretes it as bile and ships it to the gallbladder for storage. It then returns to the intestines in enterohepatic circulation.
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- Food Folate ~50% absorbed (variable and often incomplete bioavailability) - Folic Acid ~100% absorbed from supplements ~85% absorbed from fortified foods - Factors the May affect Efficiency of Intestinal Absorption o Entrapment of folate in food matrix o FGCP inhibitors o
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metabolismtest1 - FOLATE - - - - - - - FOLIC ACID RDA: 400...

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