NIH Study Suggests That 200 mg Is The Optimal Daily Dose of Vitamin C

BETHESDA, Md--Although only 10 mg/day of vitamin C is enough toprevent deficiency, the optimal daily intake is probably 200 mg,according to results of a new NIH-sponsored study. The currentRecommended Dietary Allowance (RDA) is 60 mg.

In this study, vitamin C was given in various amounts to sevenhealthy young male volunteers who lived in a hospital ward forthe duration of the study so that intake could be strictly controlled.The NIH researchers, led by Dr. Mark Levine, found that the 200mg level was best absorbed by the body; absorption levels fellas the dose was raised above 200 mg.

Daily doses higher than 400 mg offer no additional value, Dr.Levine said, since, at that level, a large amount of the doseis excreted from the body. The research also suggests that veryhigh doses could be dangerous: At 1,000 mg/day, the urine wasfound to contain oxalate, a breakdown product of the vitamin thatcould lead to kidney stone formation in some people.