With most people unable to get enough vitamin D from sunlight or foods, scientists are suggesting that a new vitamin D-fortified food — bread made with high-vitamin D yeast — could fill that gap. Their study, confirming that the approach works in laboratory tests, appears in ACS' Journal of Agricultural and Food Chemistry.

Connie Weaver and colleagues cite studies suggesting that up to 7 in 10 people in the United States may not get enough vitamin D, which enables the body to absorb calcium. Far from just contributing to healthy bones, however, vitamin D seems to have body-wide beneficial effects. Vitamin D insufficiency has been linked to an increased risk of heart disease, cancer, allergy in children, and other conditions. With few good natural sources of vitamin D, milk producers long have added it to milk. Weaver explains, however, that dairy products do not provide enough. The body makes its own vitamin D when the skin is exposed to sunlight. But people are not exposed to sun in winter and are avoiding the sun and using sun blocks in summer. Scientists thus have been looking for new ways to add vitamin D to the diet.

Weaver's group did experiments with laboratory rats, a stand-in for humans in such research, that ease doubts over whether bread baked with high vitamin D yeast could be a solution. The doubts originated because yeast produces one form of the vitamin, termed vitamin D2, which has been thought to be not as biologically active as the form produced by sun, vitamin D3. They showed bread made with vitamin D2-rich yeast, fed to the laboratory rats, had effects that seemed just as beneficial as vitamin D3. "Our results suggest that bread made with high vitamin D yeast could be a valuable new source of vitamin D in the diet," they concluded.