Vitamin C - there's a new RDA.

If you listen carefully, you might hear a chorus ringing up "I told you!" as the Food and Nutrition Board of the National Academy of Sciences increases the recommended dietary allowance for vitamin C. Until now it has been 60 mg a day, less than the vitamin C found in one medium kiwi fruit--an absurdly low amount to vitamin C fans everywhere. Ever since Linus Pauling came Out with his theory that the vitamin could prevent and cure the common cold, people everywhere have been downing megadoses of the vitamin found naturally in fruits and vegetables without any convincing research to support doing so.

Before you jump to any conclusions, read carefully. The new recommendation arose from research that showed lower rates of cancer among individuals consuming 200 mg or more vitamin C a day from dietary sources like fruits and vegetables. Study subjects who took the same amount of vitamin C in supplement form did not enjoy the same protection. And, the new recommendation, which will be between 100 mg and 200 mg, still does not justify large doses. The Academy will issue the new recommendation with a warning that scant medical research supports amounts greater than 1,000 mg, and larger doses may pose health threats for some individuals.

With few exceptions (notably calcium and folate) most vitamins are better consumed in whole food. This research suggests that other components of fruits and vegetables may be responsible for the health benefits or that vitamin C needs to be associated with other plant components for the benefits to accrue. You cannot go wrong eating more fruits and vegetables and in doing so you will certainly consume larger quantities of vitamin C than the new recommended daily allowance suggests you need.

(Journal of the American Medical Association, 1999, Vol. 281, No. 15, pp. 1415-1423)