Vitamin D Research
Vitamin D, Skin, and Bone Research Laboratory
Michael F. Holick, Ph.D, M.D., Professor of Medicine, Physiology and Biophysics and his team of researchers continue to be leaders in the fields of vitamin D, osteoporosis, metabolic bone disease, psoriasis and hair research.
Studies are underway to evaluate how mushrooms are able to produce vitamin D when exposed to ultraviolet radiation. Mushrooms exposed to ultraviolet radiation are potentially a good dietary source for vitamin D. A randomized controlled trial is underway to determine the bioavailability of vitamin D2 in mushrooms compared to vitamin D2 and vitamin D3 supplements. Dr. Holick’s laboratory has pioneered studies on the photobiology of vitamin D that have provided guidelines worldwide for sensible sun exposure as a major source for vitamin D. Recent studies have suggested that as many as 10 vitamin D like photoproducts are produced in human skin when exposed to sunlight. An investigation is underway to determine whether any of these photoproducts have unique biologic properties. Results from these studies could provide important new information as to whether producing vitamin D and its photoproducts from sensible sun exposure is more efficacious than taking a vitamin D supplement.
Vitamin D deficiency has been linked to increased risk for prostate cancer. A variety of prostate cancer cell lines have been evaluated for their responsiveness to 1,25-dihydroxyvitamin D. An in vivo nude mouse model was developed demonstrating that vitamin D deficiency increases prostate tumor growth. Molecular and cellular studies are underway to understand how vitamin D reduces prostate cancer cell growth.
It is well known that body fat is the major storage site for vitamin D. Cultured human adipocytes have been shown to have a vitamin D receptor and the capacity to produce 1,25-dihydroxyvitamin D3. Studies are underway to understand how adipocytes utilize vitamin D and the effect of vitamin D and its metabolites on adipocyte function and maturation.
Clinical research studies are comparing the effectiveness of exposure to ultraviolet radiation on serum vitamin D levels in comparison to taking an oral dose of vitamin D. A double blind controlled trial evaluating the effect of broad-spectrum sunscreen use on the cutaneous production of vitamin D is underway. An NIH funded study evaluating a vitamin D producing Sperti lamp for improving the vitamin D status of patients with inflammatory bowel disease and who have had gastric bypass surgery has just been initiated.
Dr. Holick and his team provide extensive evaluation and treatment programs for children and adults with various metabolic bone diseases including osteoporosis, osteomalacia, stress fractures in young athletic women and men and minimum trauma and nontraumatic fractures in infants, children and adults with hypermobility syndromes, osteogenesis imperfecti and Ehlers Danlos syndrome.
Rahul Ray, Ph.D., Associate Professor of Medicine, continues to study structure-activity of binding proteins and nuclear transcriptional factors related to the vitamin D endocrine system: protein crystallography; molecular modeling; biochemical and mutational studies; gene regulation; molecular targeting of steroid hormone receptors for selective delivery of toxins to cancer cells; development of anti-cancer agents, small molecules and proteins; and identification and characterization of breast cancer-specific antigens.
The production of photoproducts of previtamin D3 and vitamin D3 was investigated. At least six photoproducts have been isolated and are being evaluated for their structure and biologic activity. To better understand how 1,25-dihydroxyvitamin D3 is produced in non-renal tissues such as the prostate, colon, and skin, the promoter region of the enzyme’s gene was cloned. It is being evaluated for its regulatory sequences. In addition an alternative spliced variant of the mRNA has been identified. Studies are underway to determine its function, gene regulation and use for gene therapy. Studies were conducted to determine the prevalence of vitamin D deficiency in cancer patients.