Vitamin C intake should increase
Linus Pauling Institute director leads study on increasing RDA for vitamin C
Published: Tuesday, July 31, 2012
Updated: Tuesday, July 31, 2012 23:07
An article in the scientific journal Critical Reviews in Food Science and Nutrition has analyzed a set of studies and concluded that the recommended dietary allowance for vitamin C should be increased from 90 milligrams to 200 milligrams, and that there is strong evidence from many studies that increasing vitamin C intake can have a protective effect against heart disease, stroke and cancer.
The study was authored by Balz Frei, the director of OSU’s Linus Pauling Institute in association with researchers in France and Denmark. Frei is also a professor of biochemistry and biophysics.
RDAs are the nutritional statistics on food labels, decided by the Institute of Medicine’s Food and Nutrition Board. In the case of vitamins, they are commonly expressed on the label as a “percent daily value per serving.”
“The discussion is as follows: Is vitamin C’s only function to prevent the deficiency disease scurvy, or does it have other functions as well?” Frei said.
Current RDAs are engineered only to prevent scurvy, which is characterized by the body having trouble synthesizing working connective tissue, which occurs at critically low vitamin C levels.
Linus Pauling himself was a strong advocate for the other health effects of vitamin C, and got his body used to eating large amounts of it throughout his life by slowly building up his intake. In his later years, he ate 18 grams of the vitamin per day — 200 times more than the current RDA. Most animals are able to produce vitamin C, but humans are among those who cannot and need to acquire it through their diet.
Vitamin C is also a known antioxidant, a compound that could guard against oxidative stress in the body. Oxidative stress has been implicated in contributing to the above chronic diseases, though this alone does not prove the vitamin’s efficacy. The researchers cited a wide range of studies that produced evidence supporting the idea that vitamin C intake can lessen the severity of risk factors for those diseases, and proposed several alternative mechanisms unrelated to vitamin C’s antioxidant activity by which the vitamin may affect chronic disease risk factors.
Official trials have not found vitamin C to decrease chronic disease risks; however, the authors argue that the current method for determining the RDA for a vitamin is flawed, primarily because it is the same trial used for testing newly developed drugs, which are handled differently by the body than vitamins.
“Medicines are foreign compounds that are very quickly metabolized and excreted,” Frei said. “It’s completely different for essential [micro]nutrients. The body retains these compounds because they are essential for normal biological functions.”
“The medical community has essentially concluded that vitamins have no role in chronic disease prevention.”
According to Frei, even very high levels of vitamin C are rarely, if ever, dangerously toxic because the body’s regulatory mechanisms ensure cells don’t overdose on this particular vitamin.
Frei first got involved with vitamin C research as a postdoctoral research associate in 1986. In 1999, he was first invited to give a presentation at the Food and Nutrition Board’s discussions on vitamin C RDAs.
“It’s an ongoing process. The RDA used to be only 60 milligram per day for both men and women.”
Michael Mendes, news writer