BOSTON -- Researchers from Boston University School of Medicine have discovered that eating mushrooms containing vitamin D2 can be as effective at increasing and maintaining vitamin D levels (25-hydroxyvitamin D) as taking supplemental vitamin D2 or vitamin D3.

These findings will be presented Monday, April 22, at the annual meeting of the American Society for Biochemistry and Molecular Biology, which is being held in conjunction with the Experimental Biology 2013 meeting in Boston. The findings also will appear concurrently as an open-access article in the journal Dermato-Endocrinology.

Vitamin D is crucial for good bone health and muscle strength; adequate amounts help the body maintain bone density, reducing the risk of fracture, osteomalacia, osteoarthritis and osteoporosis. The nutrient also plays an integral role in modulating the immune system to help fight infections like the flu and reduces the risk of many common diseases, including cancer, cardiovascular disease, depression and diabetes.

For the randomized study, 30 healthy adults took capsules containing 2,000 International Units (IU) of vitamin D2, 2,000 IU of vitamin D3 or 2,000 IU of mushroom powder containing vitamin D2 once a day for 12 weeks during the winter.

Baseline serum 25-hydroxyvitamin D [25(OH)D], a measure to determine a person's vitamin D status, were not significantly different among the groups.

The levels among the three groups gradually increased and plateaued at seven weeks and were maintained for the next five weeks. After 12 weeks of the vitamin D supplements, the levels were not statistically significantly different than those who ingested the mushroom powder.

"These results provide evidence that ingesting mushrooms that have been exposed to ultraviolet light and contain vitamin D2 are a good source of vitamin D that can improve the vitamin D status of healthy adults," said Michael F. Holick, the principal investigator. "Furthermore we found ingesting mushrooms containing vitamin D2 was as effective in raising and maintaining a healthy adult's vitamin D status as ingesting a supplement that contained either vitamin D2 or vitamin D3."

Holick added: "These results confirm other studies that have demonstrated that ingesting vitamin D2 either from fortified orange juice, a supplement or a pharmaceutical formulation were all capable of increasing total circulating 25(OH) D concentrations for at least three months and up to six years."

According to Holick and his coauthors, ingesting mushrooms containing vitamin D2 can be an effective strategy to enhance a persons' vitamin D status. "The observation that some mushrooms when exposed to UVB light also produce vitamin D3 and vitamin D4 can also provide the consumer with at least two additional vitamin Ds," Holick said.

In a second poster presentation at the same meeting, the researchers will report how mushrooms make vitamin D2 using a process similar to what occurs in human skin after sun exposure.

"Although it has been previously reported that mushrooms have the ability to produce both vitamin D2 and vitamin D4, through our own research we were able to detect several types of vitamin Ds and provitamin Ds in mushroom samples, including vitamin D3, which is also made in human skin," added Holick.

According to the researchers, the meeting presentations as well as the published study demonstrate that mushrooms are another good natural food source for vitamin D that can easily be found in one's local grocery store.

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Funding for this research was provided in part by the Mushroom Council.

About Experimental Biology 2013

Experimental Biology's mission is to share the newest scientific concepts and research findings shaping future and current clinical advances - and to give scientists and clinicians an unparalleled opportunity to hear from colleagues working on similar biomedical problems using different disciplines. With six sponsoring societies and another 20 U.S. and international guest societies, the annual meeting brings together scientists from throughout the United States and the world, representing dozens of scientific areas, from laboratory to translational to clinical research. The meeting also offers a wide spectrum of professional development sessions.

About the American Society for Biochemistry and Molecular Biology