May 2, 2013
Myth Debunked: More Vitamin D Is Not Better
Alan McStravick for redOrbit.com — Your Universe Online
It is believed vitamin D is beneficial for our epidermal and osteo health. The primary purveyor of this vitamin is our Sun. You won´t find vitamin D occurring naturally in too many foods, but many commercially sold milks will fortify their product with it. And we have seen, especially over the past few years, a plethora of information regarding the benefits of this all-important vitamin and how it can protect against everything from hypertension to hardening of the arteries to diabetes.
New research out of Johns Hopkins University School of Medicine and supported by grant funding from the National Heart, Lung and Blood Institute was undertaken to refute the contradictory and anecdotal information surrounding this so-called “sunshine vitamin.” This study examined the blood levels of individuals presenting levels of vitamin D above the top range suggested by the Institute of Medicine (IOM) and found excessive supplementation offered no additional health benefit. When viewed in concert with previous research by this same group, which noted potential harm to health in individuals due to elevated levels of vitamin D in their system, the investigators felt a flag of caution should be raised.
“Healthy people have been popping these pills, but they should not continue taking vitamin D supplements unchecked,” claims study leader Muhammed Amer, MD, MHS, an assistant professor in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine. “At a certain point, more vitamin D no longer confers any survival benefit, so taking these expensive supplements is, at best, a waste of money.”
A person´s location, with respect to the equator, along with our societal propensity to first apply sunscreen to our skin before stepping into the sun has raised concern too many individuals are becoming vitamin D-deficient. According to Amer, however, there is no set amount of supplementation that can bring someone up to 21 nanograms per milliliter because the way people process vitamins varies.
Amer is careful to note some groups of people do require supplementation of the vitamin. Among them are the elderly, postmenopausal women and individuals with kidney disease. Amer points out these groups do experience a benefit from higher blood levels of a vitamin that is vital to bone health.
Amer, along with study colleague Rehan Qayyum, MD, MHS, and also of Johns Hopkins, published their article online in the American Journal of Medicine. In it, they describe their intensive review of data from more than 10,000 participants in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2004. The duo then matched those data with mortality data from the National Death Index through December of 2006.
The team looked at deaths from all causes, and cardiovascular disease specifically. They found individuals who presented blood levels of 21 nanograms per milliliter of 25-Hydroxyvitamin D — considered to be what the IOM regards as being at the top range of ℠adequate´ and the low end of ℠normal´ — cut their risk of death in half. However, as the blood levels of the vitamin rose above 21 nanograms, the data suggest the protective effect simply wears off.
The team´s previous research, published in the January 2012 edition of the American Journal of Cardiology, found increasing levels of vitamin D in the blood are linked with decreased levels of a popular marker for cardiovascular inflammation — c-reactive protein (CRP). As the blood levels of vitamin D increased beyond 21 nanograms, the team noted an association with an increase in CRP. Increased CRP has been linked to stiffening of the blood vessels and an increased risk of cardiovascular problems. Additionally, their previous research suggested a link between excess vitamin D and elevated homocysteine levels. This is another danger sign for cardiovascular disease.
Amer cautions that individuals should consult with their physician before starting a supplementation regime that includes vitamin D. A doctor should perform blood work to ascertain the current levels of vitamins in a patient´s system. Even with this advice, Amer states, “most healthy people are unlikely to find that supplementation prevents cardiovascular diseases or extends their lives,” and there is currently no consensus among physicians on what is the proper level of vitamin D in the blood for a healthy individual.
"There are a lot of myths out there and not enough data," he concludes.