For information on vitamin D and mushrooms from the United States Depart of Agriculture (USDA) and the National Institutes of Health (NIH) on vitamin D and mushrooms, see the following resources:

Vitamin D helps build and maintain strong bones by helping the body absorb calcium. Vitamin D is available via diet, supplements and sunlight, which is why D is also referred to as the “sunshine vitamin.” Increased debate about the extended health benefits and required quantities of vitamin D prompted the Institute of Medicine (IOM) to conduct a 24-month review on dietary reference intakes (DRIs) for vitamin D and calcium. Results validated the importance of vitamin D for its role in promoting bone growth and maintenance, and for the first time ever, the committee set a recommended intake level for vitamin D – 600 IU.1

The current recommended intake level of 600 IU is triple the value from 1997 that was previously considered adequate for most adults (200 IU).2 With a little more attention to food sources of vitamin D, Americans can achieve their D requirements through diet. When building your plate to maximize vitamin D, consider mushrooms. USDA’s National Nutrient Database – the foundation of most food and nutrition databases in the U.S. – includes the vitamin D values of many foods, but mushrooms stand out as the only source of vitamin D in the produce aisle and one of the few non-fortified food sources. In fact, the IOM recognizes them as the exception to the rule that plant foods don’t naturally contain vitamin D.

3 Values are based on a single serving, which is 84 grams.

The excerpt above from the USDA National Nutrient Database shows the vitamin D values for multiple mushroom varieties. All mushrooms contain vitamin D, but growers also have the ability to increase D levels by exposing mushrooms to ultraviolet light. Similar to humans, mushrooms naturally produce vitamin D following exposure to sunlight or a sunlamp: mushrooms’ plant sterol – ergosterol – converts to vitamin D when exposed to light. Exposing mushrooms to as little as five minutes of UV light can produce a significant quantity of vitamin D, demonstrating that this process could provide a significant, unique plant source of vitamin D for vegetarians and individuals who do not drink milk, the major fortified food source.4 While all mushrooms contain vitamin D at various levels, retailers currently offer a variety of light-exposed mushrooms which can provide close to 400 IU of vitamin D per serving (approximately 4-5 white button or crimini mushrooms, or one portabella).

Additional Resources:

For more on Dietary Reference Intakes (DRIs), click here to access the Nutrition Information Resource Center (NIRC) fact sheet on the USDA website.

References
¹ IOM (Institute of Medicine). 2010. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC, National Academies Press.² IOM (Institute of Medicine). 1997. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC, National Academy Press.³ U.S. Department of Agriculture, Agricultural Research Service, USDA Nutrient Data Laboratory. 2010. USDA National Nutrient Database for Standard Reference, Release 23. www.ars.usda.gov/nutrientdata

4 Calvo M, Garthoff LH, Raybourne RB, Babu US, Kelly C, Lodder S, et al. FDA’s Center for Food Safety and Applied Nutrition and the Mushroom Council Collaborate to Optimize the Natural Vitamin D Content of Edible Mushrooms and to Examine their Health Benefits in Different Rodent Models of Innate Immunity. Presented at 2006 FDA Science Forum A Century of FDA Science: Pioneering the Future of Public Health. April 18-20, 2006, Washington Convention Center. Abstract, http://www.accessdata.fda.gov/scripts/oc/scienceforum/sf2006/search/preview.cfm?keyword=Calvo&abstract_id=733&type=coauthor&backto=search