Effect of Vitamin B12 and Folic Acid on the Metabolism of Formiminoglutamate, Formate, and Propionate in the Rat

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Abstract
The effects of deficiencies of vitamin B12 on excretion of formiminoglutamate (FIGLU), formate, and propionate were investigated. The excretion of FIGLU was increased in vitamin B12 deficiency and was higher with a 30% soy protein diet than with a 70% soy protein diet, although the vitamin B12 deficiency was more severe with the diet at higher protein level. Excretion of endogenous formate was increased in both folic acid and vitamin B12 deficiencies and roughly paralleled that of FIGLU. Excretion of injected 14C-formate increased in folic acid deficiency but was less affected by vitamin B12 deficiency with a soy protein diet. The excretion of a test dose of 3H-propionate was increased in vitamin B12 deficiency and developed more rapidly with the 70% than with the 30% soy protein diet. The feeding of either 2 or 4% calcium propionate produced a growth depression, but this was not appreciably diminished by vitamin B12. Calcium propionate did not increase FIGLU excretion.