Folic acid Dietary Reference Intakes

The authors of the Dietary Reference Intakes (15) have concluded that reports of the effect of folic acid supplementation on the intestinal absorption of zinc are controversial, but that the recent literature shows that folic acid supplementation has either no effect or an extremely weak effect on zinc supply. 

In many animals, dietary deprivation of choline leads to liver dysfunction and growth retardation, and some patients maintained on choline-free total parenteral nutrition develop liver damage that resolves when choline is provided, suggesting that endogenous synthesis may be inadequate to meet requirements (Zeisel, 2000). There is inadequate information to permit the setting of reference intakes, but the Acceptable Intake for adults is 550 mg (for men) or 425 mg (for women) per day (Institute of Medicine, 1998). In experimental animals choline deficiency is exacerbated by deficiency of methionine, folic acid, or vitamin B12, which impairs the capacity for de novo synthesis. 

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