A great many of us are low in vitamin D. Indeed, some 42 percent of adults in the U.S. are vitamin-D-deficient, according to a 2010 Nutrition Journal study. The vitamin modulates the immune system and helps the body absorb calcium, maintaining bone density and overall bone health, thereby lowering risks of fracture and bone diseases like rickets and osteoporosis.

You can get vitamin D through the skin, through supplements or through diet. After sunlight exposure, the body produces vitamin D naturally. Trouble is, overdoing it can lead to wrinkles, or worse, skin cancer.

There may a new, simpler and safer option for getting vitamin D right in the produce aisle. Get this: Munching on mushrooms containing vitamin D2 may increase and maintain vitamin D levels as effectively as supplements (of vitamin D2 or vitamin D3) according to new research from the Boston University School of Medicine.

When 30 healthy adults took capsules with 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 daily for three months, researchers found that all three methods increased levels of serum 25(OH)D levels. After 12 weeks, none of the groups had significantly different levels.

“Ingesting mushrooms which 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 lead researcher on the abstract, Michael Holick, PhD, MD, in a statement. “We found ingesting mushrooms containing vitamin D2 as effective in raising and maintaining a healthy adult’s vitamin D status as ingesting a supplement containing either vitamin D2 or vitamin D3.”

The results confirm past studies finding that ingesting vitamin D2 from fortified orange juice, a supplement, or a pharmaceutical formulation can each raise total circulating 25(OH)D concentrations for at least 3 months.

Mushrooms are usually grown in the dark, and therefore do not typically have vitamin D. Some brands now grow mushrooms in ultraviolet light so that the vegetables will be vitamin-D rich. Check labels and look for brands such as Dole’s Portobello Mushrooms, each 3-ounce serving of which contains 400 IUs of vitamin D.

Other foods naturally containing vitamin D include egg yolks, liver, and saltwater fish. Milk and cereals also may contain vitamin D. Most Americans require at least 1,000 IU of vitamin D daily, according to the Harvard School of Public Health, even though the US Dietary Guidelines of 2010 recommend just 600 IU for children and most adults. Some experts, such as Dr. Andrew Weil, recommend 2,000 IU of vitamin D daily.

Are You getting enough vitamin D?