Image courtesy of Prevention

The validity of vitamin D supplements has been called into question a few times over the last couple months (see here and here), and a new study review released today in The Lancet Diabetes & Endocrinology doesn't offer any reprieve. The latest conclusion: Vitamin D supplements don't help prevent many common diseases.

French researchers reviewed nearly 300 studies that looked at the link between blood levels of vitamin D and diseases linked to D-deficiency, like cardiovascular disease, diabetes, certain cancers, as well as mood disorders and weight gain. The majority of those studies showed that people with higher D levels were less likely to develop disease. However, when comparing those results to randomised clinical trials where people were given D supplements, researchers failed to find any actual reductions of risk. Which means the 50 percent of American adults who take the "sunshine pill" aren't doing their health as big a favor as they thought. The study authors write that low vitamin D levels may be a consequence of -- not a cause of -- disease.

But that doesn't mean you should toss your supplements just yet, especially since research shows that D supplements boost bone health. It just means it's time to consider other places to get the nutrient, like your diet. "In my practice," says Brian Clement, PhD, co-director of the Hippocrates Health Center, "it has been our clinical observation after working with hundreds of thousands of people that the foremost way the body obtains nutritional sustenance is through an organic, plant-based diet." (Learn how to Choose The Right Multivitamin For You.)

"Studies done at Washington University," Dr. Clement continues, "showed that people eating unheated varieties of vegetables had a significantly lower vitamin D deficiency rate than those consuming a Western diet. Food and food-based supplements contain subcultures and gatherings of unidentified nutrients that allow thorough and full absorption to occur."

This is an especially good idea for those who spend a lot of their time indoors, adds Dr. Clement, since the body makes vitamin D through sun exposure. A list of D-rich foods includes fatty fish such as salmon and sardines, fortified milk and cereal, beef, and egg yolks.

It's important to note that it's difficult to meet all of your daily D requirements strictly through food. If you're worried your levels are low, check with your doctor for alternative options. (Overwhelmed by the supplement aisle? Here's how to find out the supplements you actually need -- and what you don't.)

Source: Brian Clement, PhD, The Real Truth About Health