RDA or Recommended Dietary Allowance of vitamin C is less than half of what it ought to be, argue scientists in a recent report.
This is because, the scientists said, medical experts insist on evaluating this natural, but critical nutrient in the same way they do pharmaceutical drugs and reach faulty conclusions as a result.
The researchers pointed out that there's compelling evidence that the RDA of vitamin C should be raised to 200 milligrams per day for adults, up from its current levels in the United States of 75 milligrams for women and 90 for men.
Rather than just prevent the vitamin C deficiency disease of scurvy, they said, it's appropriate to seek optimum levels that will saturate cells and tissues, pose no risk, and may have significant effects on public health at almost no expense - about a penny a day if taken as a dietary supplement.
"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," said Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University, and one of the world's leading experts on the role of vitamin C in optimum health.
"Significant numbers of people in the U.S. 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," the researcher noted.
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 are already 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 suggested just the opposite, that higher levels of vitamin C could help reduce the chronic diseases that today kill most people in the developed world - 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. And the benefit-to-risk ratio is very high. A 200 milligram intake of vitamin C on a daily basis poses absolutely no risk, but there is strong evidence it would provide multiple, substantial health benefits," Frei said.
An excellent diet with the recommended five to nine daily servings of fruits and raw or steam-cooked vegetables, together with a six-ounce glass of orange juice, could provide 200 milligrams of vitamin C a day.
Their argument appeared in Critical Reviews in Food Science and Nutrition.