A recent study announced at the American Society for Biochemistry and Molecular Biology's annual meeting in Boston found that mushrooms are a significant source of vitamin D. Exposing fresh mushrooms to sunlight before eating them can be as effective as taking a vitamin D supplement.
In the 12-week study, scientists from Boston University School of Medicine randomly assigned 30 adult participants into two groups: one group took a daily supplement containing 2000 international units (IU) of vitamin D, and the other group was given a powder made from sun-exposed mushrooms. The results showed that there was virtually no difference in the final vitamin D levels between the two groups.
The researchers explained that the mechanism is similar to that of human skin. When exposed to ultraviolet light from the sun, mushrooms can produce vitamin D, and they continue to do so even after being harvested.