There Are Multiple Forms Of Folate In The Diet

The active form of folic acid (pteroyl glutamate) is tetrahydrofolate (Figure 45-15). The folates in foods may have up to seven additional glutamate residues linked by y-peptide bonds. In addition, all of the one-carbon substituted folates in Figure 45-15 may also be present in foods.

The extent to which the different forms of folate can be absorbed varies, and this must be allowed for in calculating folate intakes.

Homocysteine h3c — S I

COO-Methionine

Methyl — H4 folate

H4 folate

Figure 45-14. Homocysteinuria and the folate trap. Vitamin B12 deficiency leads to inhibition of methionine synthase activity causing homocysteinuria and the trapping of folate as methyltetrahydrofolate.

Methyl — H4 folate

H4 folate

Figure 45-14. Homocysteinuria and the folate trap. Vitamin B12 deficiency leads to inhibition of methionine synthase activity causing homocysteinuria and the trapping of folate as methyltetrahydrofolate.

O COO

H Tetrahydrofolate (THF) CH

JyNL CH2"H" ^N CH2"N"

h2n^nV 5-Formyl THF h^nV 10-Form^ THF

hc=nh

CH2 N

Ï I I 5-Formimino THF Î 1 I 5,10-Methylene THF H2N N N H2N N N

Figure 45-15. Tetrahydrofolic acid and the one-carbon substituted folates.

5-Methyl THF H2N^N^I

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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