Vitamin C studies flawed say OSU researchers
There has been much debate about whether taking vitamins or other supplements cause more harm than good. Researchers from Oregon State University (OSU) have shed some light on vitamin C studies that they say need an overhaul before we can really know whether supplementing is good for human health.
Most vitamin studies useless
In their review, the OSU researchers explain most studies about vitamins have been conducted on people who have access to good nutrition, are well educated and have better dietary standards than the rest of the population.
Indeed, many of the studies are done on nurses and doctors.
The reality, says Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University, in a new review published in the journal Nutrients, is that most vitamin studies have little scientific validity not only because of the study targets but also because many of the studies are done on cell cultures or animals versus humans.
The focus of the reviewers was regarding vitamin C that many people take regularly, despite what researchers have said, to help keep immunity intact. You can find a plethora of comments on the internet about the benefits of vitamin C perceived by consumers.
“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.”
Future study recommendations
If we're to really know if vitamins can help thwart disease, the reviewers say it would be necessary to start with measurements of baseline nutrition in study subjects.
Supplementing with vitamins and minerals could correct deficiencies, but most studies fail to include a baseline nutritional analysis or follow-up to see if supplements work to correct those deficiencies.
“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.
The researchers also point out one of the largest studies done on people over age 50 suggested taking a daily multi-vitamin with minerals might help prevent nearly 130,000 cases of cancer each year.
“The cancer reduction would be in addition to providing good basic health by supporting normal function of the body, metabolism and growth,” Michels said. “If there’s any drug out there that can do all this, it would be considered unethical to withhold it from the general public. But that’s basically the same as recommending against multivitamin/mineral supplements.”
If you are taking a vitamin, mineral or other supplement, speak with your doctor about testing that can help you understand your nutritional needs. It might also be helpful to see a registered dietitian who can review your daily food intake to see if you're getting an optimal amount of vitamins from diet alone.
Do you take a vitamin C supplement? If so, tell us what you think.
Nutrients 2013, 5(12), 5161-5192; doi:10.3390/nu5125161
Image credit: Pixabay