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Folate (Folic acid, Folacin):

Consists of pteridine group, para-aminobenzoic acid (PABA), and glutamic acid Coenzyme form: tetrahydorfolic acid ( THFA ) Folate (Folic acid, Folacin )

Food Sources of Folate:

Liver Fortified breakfast cereals Grains, legumes Foliage vegetables Susceptible to heat, oxidation, ultraviolet light Food Sources of Folate

Absorption, Metabolism of Folate:

Absorbed in the monoglutamate form with help of folate conjugase Actively absorbed during low to moderate intake Passively absorbed during high intake Delivered to the liver where it is changed back to the polyglutamate form Mostly stored in the liver Excreted in the urine and bile ( enterohepatic circulation) Absorption, Metabolism of Folate

Functions of Folate:

DNA synthesis Transfer of single carbon units Synthesis of adenine and guanine Anticancer drug methotrexate Homocysteine metabolism Neurotransmitter formation Functions of Folate

Deficiency of Folate:

Similar signs and symptoms of vitamin B-12 deficiency Pregnant women Alcoholics Interferes with the enterohepatic circulation of bile/ folate Deficiency of Folate

Megaloblastic Anemia:

Megaloblastic Anemia

Neural Tube Defects:

Neural Tube Defects Spina bifida Anencephaly Importance of folate before and during pregnancy

Toxicity of Folate:

Epilepsy Skin, respiratory disorder FDA limits nonprescription supplements to 400 ug per tablet for non-pregnant adults OTC Prenatal supplement contains 800 ug Excess can mask vitamin B-12 deficiency Toxicity of Folate

Vitamin B-12:

Cyanocobalamin . methlcobalamin , 5-deoxyadenosylcobalamin Contains cobalt Folate metabolism Maintenance of the myelin sheaths Rearrange 3-carbon chain fatty acids so can enter the Citric Acid Cycle Vitamin B-12

Food Sources of Vitamin B-12:

Food Sources of Vitamin B-12 Synthesized by bacteria, fungi and algae (Stored primarily in the liver) Animal products Organ meat Seafood Eggs Hot dogs Milk

Absorption of Vitamin B-12 (Fig. 10-10) :

Absorption of Vitamin B-12 (Fig. 10-10)

Functions of Vitamin B-12:

Helps convert methylmalonyl CoA to succinyl CoA (citric acid cycle) RBC formation Nerve functions Maintains myelin sheath Megalobalstic anemia Functions of Vitamin B-12

Vitamin B-12 and Homocysteine :

Vitamin B-12 and Homocysteine

RDA for Vitamin B-12:

2.4 ug / day for adults and elderly adults Average intake exceeds RDA B-12 stored in the liver Non-toxic RDA for Vitamin B-12

Who is at Risk For Deficiency?:

Vegans Breastfed infants of vegan moms Elderly Individuals with AIDS or HIV Who is at Risk For Deficiency?

Deficiency of Vitamin B-12:

Pernicious anemia Never degeneration, weakness Tingling/numbness in the extremities ( parasthesia ) Paralysis and death Looks like folate deficiency Usually due to decreased absorption ability Achlorhydria especially in elderly Injection of B-12 needed Takes ~20 years on a deficient diet to see nerve destruction Deficiency of Vitamin B-12

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