Compared to much of the world, we lack vacation days and the ability to find most countries on a map. Additionally, Americans lack vitamin D.
James Dowd, MD, blames the deficiency on our indoor, sedentary lifestyle in this video clip.
Dowd, the author of "The Vitamin D Cure," is a clinical associate professor of medicine at Michigan State University and the founder and director of both the Arthritis Institute of Michigan and the Michigan Arthritis Research Center.
People are much less physically active today than they were 50 years ago, and physical activity is tied directly to vitamin D levels according to the CDC, he says. “When we don't get out in the sun, we don't make vitamin D,” he says.
There are a few high risk groups who should be particularly concerned, according to Dowd. The first, people with darker skin. More than 90 percent of African Americans and more than 75 percent of latinos are D deficient. The melanonin in darker skin acts as a sunscreen, so dark-skinned people need more sunshine to make enough vitamin D. Obese people with body masses above 30 are at higher risk, as are women. Breast-fed infants often don't get enough vitamin D, as their mothers are not likely to have enough in their bodies either, and are unable to pass it on through their milk.
The advent of sunscreen has also impacted our D levels. “If used correctly, sunscreen with SPF 8 witll block 90 percent of our vitamin D production,” says Dowd. “All these things tell us that most of us probably need to be supplementing with vitamin D,” he adds. “There are just too many obstacles in the way of us getting enough sunshine to make it ourselves.”