This study will investigate whether mushrooms treated with ultraviolet (UV) light to increase their vitamin D2 content are actually a good source of vitamin D when consumed daily with a meal (lunch). The mushrooms will be provided cooked along with a meal which will be a standard, pre-packaged frozen meal. We also hope to learn if the resulting improvement in vitamin D status affects the immune system by decreasing it's level of activation, which may be abnormally elevated in vitamin D deficiency.

Volunteers will be asked to consume a standard meal (lunch) containing one serving of mushrooms daily for six weeks (7 days per week). With the meal, they will also need to take one capsule. The capsule will be either a placebo or will contain vitamin D. The purpose of the vitamin D in the capsule is to determine if the vitamin D from the mushrooms is absorbed as well as vitamin D from a capsule. The total dose of vitamin D that volunteers will receive each day from mushrooms and capsule together will always be the same and will be one of three doses: (1) little or no vitamin D (placebo); (2) 400 IU, which is near the current recommended intake and (3) 1,000 IU, which is up to five-fold higher than the current recommended intake, depending on your age. Both levels of vitamin D are safe. In addition to consuming the meals and taking the capsules, up to 20 mL (4 teaspoons) of blood will be drawn at three times during the study just before the mushroom-containing lunch is provided: (1) at the beginning of the study before the first meal; (3) after three weeks; (3) at the end of the study. The purpose of the blood draw is to measure vitamin D in your blood and to measure the level of activation of your immune system by measuring markers of immune activation.

Inclusion Criteria:

• willing to consume a lunch meal 7 days per week for 6 weeks containing mushrooms
• willing to stop eating other sources of mushrooms
• willing to discontinue taking vitamin D and other dietary supplements
• estimated low vitamin D status based on dietary questionnaire, skin reflectance, and sun behavior

Exclusion Criteria:

• women who are pregnant or breastfeeding
• volunteers with anemia
• volunteers with evidence of underlying disease affecting vitamin D metabolism
• volunteers taking medications altering vitamin D metabolism