Increase in RDA for Vitamin C could help reduce Heart Disease, Stroke, Cancer
The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy.
A wide body of metabolic, pharmacokinetic, laboratory and demographic studies suggests 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.
RDA should be 200mg per day
“We believe solid research shows the RDA should be increased,” 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.
“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.”
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. But most Americans and people around the world do not have an excellent diet.
Even at the current low RDAs, various studies in the U.S. and Canada have found that about a quarter to a third of people are marginally deficient in vitamin C, and up to 20 percent in some populations are severely deficient – including college students, who often have less-than-perfect diets. Smokers and older adults are also at significant risk.
Even Marginal Deficiency can lead to Malaise, Fatigue, and Lethargy
Healthier levels of vitamin C can enhance immune function, reduce inflammatory conditions such as atherosclerosis, and significantly lower blood pressure, researchers note.
- A recent analysis of 29 human studies concluded that daily supplements of 500 milligrams of vitamin C significantly reduced blood pressure, both systolic and diastolic. High blood pressure is a major risk factor for heart disease and stroke, and directly attributes to an estimated 400,000 deaths annually in the U.S.
- ·A study in Europe of almost 20,000 men and women found that mortality from cardiovascular disease was 60 percent lower when comparing the blood plasma concentration of vitamin C in the highest 20 percent of people to the lowest 20 percent.
- Another research effort found that men with the lowest serum vitamin C levels had a 62 percent higher risk of cancer-related death after a 12-16 year period, compared to those with the highest vitamin C levels.
Laboratory studies with animals – which may be more accurate than human studies because they can be done in controlled conditions and with animals of identical genetic makeup - can document reasons that could explain all of these findings, Frei said.
The RDA of vitamin C is less than half what it should be, scientists argue in a recent report, because 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 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 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.
The above story is based on the July 16, 2012 news release by Oregon State University
The paper was first published on line 14 Jun 2012 in the Critical Reviews in Food Science and Nutrition:
Frei B, Birlouez-Aragon I, Lykkesfeldt J. Authors' Perspective: What is the Optimum Intake of Vitamin C in Humans?, Crit Rev Food Sci 2012; 52 (9): 815 DOI: 10.1080/10408398.2011.649149