vitamin D requirements

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7 Signs You May Have A Vitamin D Deficiency

Sarah Klein | Huffington Post | April 29, 2014

...In fact, about 80 to 90 percent of our vitamin D comes from sun exposure, says Dr. Michael F. Holick, M.D., Ph.D., a professor of medicine, physiology and biophysics at the Boston University Medical Center who has studied and published on vitamin D for decades. "The problem is [many of us] assume if you have a healthy diet that you're getting enough of every nutrient," he says...

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