Researchers: Vitamin C RDA should be raised; pharmaceutical trials for vitamins faulty


CORVALLIS, Ore. — Researchers argue there is compelling evidence that the recommended dietary allowance of vitamin C should be raised to 200 mg per day for adults, up from its current levels of 75 mg for women and 90 mg for men, in a recent report published in Critical Reviews in Food Science and Nutrition.

The recommended dietary allowance of vitamin C is less than half what it should be, according to the researchers, because medical experts insist on evaluating vitamin C in the same way they do pharmaceutical drugs and reach faulty conclusions as a result.

“It’s time to bring some common sense to this issue, look at the totality of the scientific evidence and go beyond some clinical trials that are inherently flawed,” stated Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University. “Significant numbers of people in the [United States] and around the world are deficient in vitamin C, and there’s growing evidence that more of this vitamin could help prevent chronic disease,” Frei said. “The way clinical researchers study micronutrients right now, with the same type of so-called ‘phase three randomized placebo-controlled trials’ used to test pharmaceutical drugs, almost ensures they will find no beneficial effect. We need to get past that.”

Unlike testing the safety or function of a prescription drug, the researchers said, such trials are ill suited to demonstrate the disease prevention capabilities of substances that already are present in the human body and required for normal metabolism. Some benefits of micronutrients in lowering chronic disease risk also show up only after many years or even decades of optimal consumption of vitamin C — a factor often not captured in shorter-term clinical studies.

A wider body of metabolic, pharmacokinetic, laboratory and demographic studies suggest just the opposite, that higher levels of vitamin C could help reduce chronic diseases, including heart disease, stroke, cancer and the underlying issues that lead to them, such as high blood pressure, chronic inflammation, poor immune response and atherosclerosis.

“We believe solid research shows the RDA should be increased,” Frei said. “And the benefit-to-risk ratio is very high. A 200 mg intake of vitamin C on a daily basis poses absolutely no risk, but there is strong evidence it would provide multiple, substantial health benefits.”

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