For people who fail to meet intake recommendations for essential vitamins and minerals, dietary supplements, such as vitamin C, are a welcomed addition compared to dieting and exercise. However, a string of recent studies have discredited the seemingly beneficial aspects of a daily vitamin regimen. A recent study out of the Linus Pauling Institute at Oregon State University revealed that research that denotes the healthy qualities of vitamins or even lists them as harmful is flawed by an unsound methodology.

"If a person already has adequate amounts of a particular vitamin or nutrient, then a supplement will probably provide little or no benefit," said director of the Linus Pauling Institute, Professor Balz Frei. "That's common sense. But most of our supposedly scientific studies take results from people with good diets and healthy lifestyles and use them to conclude that supplements are of no value to anyone."

Professor Frei and his colleagues from the institute combed through a string of recent studies that have linked vitamin C and other micronutrients to adverse health conditions. One of the research team’s criticisms against these studies is that they are usually focused on healthy test subjects who diet regularly and engage in a sufficient amount of exercise each day. The majority of these studies are also missing a baseline analysis that includes each participant’s specific health complications and how vitamins helped to remedy these complications.

"One of the obvious problems is that most large, clinical studies of vitamins have been done with groups such as doctors and nurses who are educated, informed, able to afford healthy food and routinely have better dietary standards than the public as a whole," Professor Frei added. "It's fine to tell people to eat better, but it's foolish to suggest that a multivitamin, which costs a nickel a day, is a bad idea."

Modern clinical studies that rely on healthy test subjects are flawed by design simply because people who fail to diet regularly or meet daily exercise recommendations are the ones who actually benefit from vitamins, antioxidants, and folic acid. Many studies have relied on animal test subjects or a cell culture which can skew results since micronutrient’s effect on the human body is not being tested. The research team suggests future studies include blood plasma measurements, an even study sample of healthy and unhealthy participants, a baseline analysis that includes any health complications, along with a follow-up analysis to gauge a vitamin regimen's effect on these complications.

"In cell culture experiments that are commonly done in a high oxygen environment, vitamin C is unstable and can actually appear harmful," said Alexander Michels, an LPI research associate and lead author on this report. "And almost every animal in the world, unlike humans, is able to synthesize its own vitamin C and doesn't need to obtain it in the diet. That makes it difficult to do any lab animal tests with this vitamin that are relevant to humans."

Researchers from OSU also compared recommendations that advise against multivitamins to withholding a drug that can support normal body function, metabolism, and growth from the general public. One of largest and longest clinical trials conducted on multivitamins and micronutrients found that these supplements were able to effectively reduce the number of cancer and cataract reports in male physicians over the age of 50. Professor Frei concluded that adding a daily regimen of vitamins could “prevent up to 130,000 new cases of cancer each year.”

"More than 90 percent of U.S. adults don't get the required amounts of vitamins D and E for basic health," Frei said. "More than 40 percent don't get enough vitamin C, and half aren't getting enough vitamin A, calcium, and magnesium. Smokers, the elderly, people who are obese, ill, or injured often have elevated needs for vitamins and minerals.”

Source: Michels A, Frei B. “Myths, Artifacts, and Fatal Flaws: Identifying Limitations and Opportunities in Vitamin C Research.” Nutrients. 2013.