Are You Getting Enough of the Right Vitamin D?
When it comes to vitamin D, the "sunshine vitamin," not all forms are nutritionally equal. According to a study conducted by researchers at the University of Surrey in the United Kingdom, vitamin D3 is twice as effective as D2 for maintaining healthy levels of this important nutrient in the body. Some experts are suggesting a revision of vitamin D guidelines based on this and other recent research.
Vitamin D is found in a few foods—fish, eggs, mushrooms, and fortified flours or milk, for example—and in dietary supplements. While we get most of our supply from the sun’s rays, that amount is often inadequate. Research suggests more than 40 percent of Americans are vitamin-D deficient.
For the British study, researchers measured vitamin D levels in 335 women over two winter periods. The women were divided into five groups: two groups were given D3 (in biscuits or juice drinks), two were given D2 (in biscuits or juice drinks), and one group received a placebo. Vitamin D3 supplements raised levels of vitamin D 74 percent (biscuits) and 75 percent (juice), while vitamin D2 supplements raised levels 33 percent (biscuits) and 34 percent (juice). In those who took a placebo, vitamin D levels fell 25 percent.