Bioavailability and Biological Effects of Vitamin D2 Contained in Mushroom

Poor vitamin D status is now considered epidemic in North America. In addition to its effects on bone metabolism, Vitamin D has several other important biological effects including modulating the immune system, stimulating the production of insulin and decreasing renin production in the kidney. Furthermore, the active metabolite of vitamin D, 1,25 dihydroxyvitamin D (1,25(OH)2D), is a very potent inhibitor of cellular proliferation and inducer of terminal differentiation and vitamin D deficiency has been associated with higher prevalence of cancer, autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, type 1 diabetes and hypertension.

The current recommendations for dietary vitamin D in North America are much too low to maintain optimal levels of 25(OH)D associated with disease prevention. The majority of circulating 25(0H) D originates from cutaneous synthesis upon exposure to adequate sunlight. However, seasonal changes, living at high latitudes or low polluted altitudes, dark skin pigmentation and aging are among the many factors that can impede this process requiring periodic reliance on dietary sources to supply the precursor to 25(OH)D.

In November of 2010, the Institute of Medicine (IOM) of the National Academy of Science established new DRI values for vitamin: EAR (Estimated Average Requirement) of 400 IU (10 µg; RDA ( Recommended Daily Intake) of 600 IU (15µg) for adults up to 70 years of age, and an UL of 4000 IU (50µg) (21). The IOM also discourages the taking of dietary supplements to achieve the RDA for vitamin D and encourages Americans to achieve their needed vitamin D through food sources.

The proposed study will be to provide meals with one serving of fresh mushroom per day that could have two different levels of vitamin D2 in it (600 IU or 4,000 IU/day, which are the 2011 currently recommended RDA to age 70 AI and UL, respectively) for four months and test both the bioavailability of vitamin D in mushroom, as reflected in blood 25(OH)D levels, as well as the effect of vitamin D on markers of disease (e.g. C-reactive protein (CRP), Hemoglobin A1c, etc). The vitamin D2 amount in mushrooms can easily be manipulated just by adjusting the time and distance of their UVB exposure. Two groups will be compared with controls who will receive the same dose of vitamin D3 in the form of tablets commercially available (600 IU or 4000 IU/day).

Inclusion criteria

• Adult non-smoking subjects from ages 30 to 90, any race or gender
• Presence of at least two of the following characteristics:

• Waist circumference:

Men: > 102 cm Women: > 88 cm

• Blood pressure: > 130/85 mm Hg (or use of anti-BP medication)
• HDL-cholesterol:

Men: < 40 mg/dL Women: < 50 mg/dL

• Triglycerides: > 150 mg/dL (or use of medications for high triglycerides such as fibrates or nicotinic acid)
• Fasting blood sugar > 100 mg/dl (or use of metformin), but a HbA1c < 6.5%

Exclusion criteria

• Blood levels of 25(OH)D > 50 nmol/L
• Regular intake of vitamin D fortified milk exceeding approximately 3 glasses/day
• Lack of the ability to comprehend instructions and/or sign the consent form
• Inability to comply with the potential requirement to eat a daily portion of provided mushroom together with meals
• Inability to comply with the rule of avoiding any beach days during the duration of the study
• Any projected trip to sunny places such as Puerto Rico and the Caribbean during the period of study
• Any attendance to tanning studios during the period of study
• Women who regularly use a veil over their heads
• Any history of kidney stone formation
• Non-traumatic bone fracture over the past 3 years
• Any form of vitamin D supplement intake, including combined calcium and vitamin D products
• Active smoking