After earning a Ph.D. degree in biochemistry, a medical degree, and completing a research postdoctoral fellowship at the University of Wisconsin–Madison, Holick completed a residency in medicine at the Massachusetts General Hospital in Boston.
He is an endocrinologist and professor of medicine, physiology and biophysics and director of the Bone Health Care Clinic and the Heliotherapy, Light, and Skin Research Center at Boston University Medical Center, providing 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 imperfecta, and Ehlers Danlos Syndrome. He has been director of the General Clinical Research Unit at Boston University for several years.
Holick serves as chair of NASA's "Human Health Countermeasures Element" Standing Review Panel, chair of the Endocrine Practice Guidelines Committee for Vitamin D, and editor-in-chief of the medical journal Clinical Laboratory.
Holick made discoveries in the field of vitamin D that have led to novel therapies for metabolic bone diseases, hypocalcemic disorders, and psoriasis. He is author of more than 400 publications about the biochemistry, physiology, metabolism and photobiology of vitamin D and the pathophysiology of vitamin D deficiency.
His scientific work increased awareness in the pediatric and medical communities regarding vitamin D deficiency, and its role in causing not only metabolic bone disease, and osteoporosis in adults, but increasing risk of children and adults developing common deadly cancers, autoimmune diseases, including type 1 diabetes, multiple sclerosis and heart disease, as discussed in his review article.
He has been quoted and his scientific work has been referenced in The New York Times, Forbes, Newsweek, Men's Health, Scientific American and Time. He wrote several books about the importance of vitamin D and its beneficial health effects to the broad public, and discussed the benefits of sensible and the risks of excessive sun exposure.
As a graduate student, he identified the major circulating form of vitamin D, 25-hydroxyvitamin D3, which is the vitamin D metabolite that is measured by physicians worldwide to determine a patient's vitamin D status. He also identified the active form of vitamin D, 1,25-dihydroxyvitamin D3, as well as other metabolites including 24,25-dihydroxyvitamin D3, 1,24,25-trihydroxyvitamin D3 and 25,26-dihydroxyvitamin D3.
As a fellow, he participated in the first chemical synthesis of 1,25-dihydroxyvitamin D3 and 1α-hydroxyvitamin D3 to treat renal osteodystrophy, hypoparathyroidism, vitamin D dependent rickets type I, and osteoporosis. Furthermore, he elucidated the pathophysiology of hereditary vitamin D-dependent rickets which involves defective vitamin D metabolism, and the pathophysiological mechanisms of X-linked hypophosphatemic rickets.
Holick helped develop the first clinical assays for 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, determined how vitamin D3 is made in the skin from sun exposure, and established how season, time of day, skin pigmentation, sunscreen use, and latitude influenced this vital cutaneous process. He established that the skin was not only the organ responsible for making vitamin D3 but was also a target tissue for its active form, 1,25-dihydroxyvitamin D3. He determined the extremely inhibitory effects of 1,25-dihydroxyvitamin D3 on keratinocyte proliferation and the promoting effects on differentiation, and translated these seminal observations by demonstrating that the topical application of 1,25-dihydroxyvitamin D3 and several of its analogs were effective for the treatment of psoriasis.
He demonstrated that macrophages and prostate cells have the enzymatic machinery to produce 1,25-dihydroxyvitamin D3, and established that the extrarenal production of 1,25-dihydroxyvitamin D3 may play a crucial role not only in cancer prevention but also in regulating the immune system.
He developed a vitamin D absorption test and demonstrated that vitamin D was bioavailable in orange juice, leading to fortification of juice products in the United States. He also used the test to demonstrate the major cause of vitamin D deficiency in obesity is due to sequestration of vitamin D in the fat.
He helped perform dose escalation studies establishing how much vitamin D is required to maintain blood levels of 25-hydroxyvitamin D in the sufficient range for adults. These studies also demonstrated that up to 10,000 IU of vitamin D a day for 5 months did not cause toxicity.
Holick was awarded for his outstanding contributions to the field of vitamin D research with many prizes, including the Merit Award from the National Institute of Health, the first ASBMR Fuller Albright Award, the Mead Johnson Award, the Osborne and Mendel Award, the McCollum Award, the Robert H. Herman Award from the American Society for Clinical Nutrition, ACN Award from the American College of Nutrition, the NIH’s General Clinical Research Center's Program Award for Excellence in Clinical Research, the Psoriasis Research Achievement Award from the American Skin Association, the DSM Innovation in Nutrition Award, the Van Slyke Award from American Association for Clinical Chemistry, the Linus Pauling Prize In Human Nutrition, the Delbert A Fisher Research Scholar Award from the Endocrine Society, and the American College of Nutrition's Communication Media Award.Holick, MF (2011). The Vitamin D Solution: A 3-Step Strategy to Cure Our Most Common Health Problems. Plume 1st edition. ISBN 978-0452296886.
Holick, MF; Dawson-Hughes, B (2010) . Nutrition and Bone Health. Humana Press. ISBN 978-1617374517.
Holick, MF, ed. (2010). Vitamin D: Physiology, Molecular Biology, and Clinical Applications (2nd ed.). Humana Press. ISBN 978-1603273008.
Holick, MF; Jenkins, Mark (2005). UV Advantage (2nd ed.). IBOOKS. ISBN 978-1596879003.
Holick, MF (2007). "Vitamin D deficiency". N Engl J Med. 357 (3): 266–81. PMID 17634462. doi:10.1056/NEJMra070553.
Holick, MF (2006). "Resurrection of vitamin D deficiency and rickets.". J Clin Invest. 116 (8): 2062–72. PMC 1523417 . PMID 16886050. doi:10.1172/JCI29449.
Pietras, SM; Obayan, BK; Chai, MH; Holick, MF (2010). "Vitamin D2 treatment for vitamin D deficiency and insufficiency for up to 6 years.". Arch Intern Med. 169 (19): 1806–8. PMID 19858440. doi:10.1001/archinternmed.2009.361.
Biancuzzo, RM; Young, A; Bibuld, D; Cai, MH; Winter, RM; Klein, EK; Ameri, A; Reitz, R; Salameh, W; Chen, TC; Holick, MF (2010). "Fortification of orange juice with vitamin D(2) or vitamin D(3) is as effective as an oral supplement in maintaining vitamin D status in adults.". Am J Clin Nutr. 91 (6): 1621–6. PMC 2869510 . PMID 20427729. doi:10.3945/ajcn.2009.27972.
Holick, MF; Binkley, NC; Bischoff-Ferrari, HA; Gordon, CM; Hanley, DA; Heaney, RP; Murad, MH; Weaver, CM; et al. (2011). "Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline.". J Clin Endocrinol Metab. 96 (7): 1911–30. PMID 21646368. doi:10.1210/jc.2011-0385.