Dark Winters Put People at Risk for Vitamin Deficiency

Weak ultraviolet rays mean that people’s bodies cannot produce vitamin D from sunlight
Lack of sun’s rays from November to February means
New Englanders lose out on nature’s most common
source of Vitamin D.


New England’s dark winter days not only chill you to the bone, they can damage your bones as well. From November to February, the sun’s weak ultraviolet rays mean that people’s bodies cannot produce vitamin D from sunlight, the main source of the critical nutrient. Without vitamin D, bones can become weak and brittle.


“Ninety percent of people’s vitamin D requirement comes from exposure to sunlight, and Mother Nature cleverly designed our bodies so that any excess vitamin D that we produce in the spring, summer and fall months is stored in our body fat and then released in the wintertime,” says Michael F. Holick, Ph.D., M.D., director of the Bone Health Care Clinic and the General Clinical Research Unit at BMC and professor of medicine, physiology and biophysics at Boston University School of Medicine. “However, many people are not receiving an adequate amount of vitamin D during these months to compensate for the lack in winter.”


Vitamin D is crucial for good bone health and muscle strength; adequate amounts help the body maintain bone density reducing the risk of fracture, osteomalacia, osteoarthritis and osteoporosis. The nutrient also plays an integral role in modulating the immune system and reduces the risk of many common diseases including cancer, cardiovascular disease, depression and diabetes.


A healthy diet does not ensure adequate intake of vitamin D. Very few foods provide sufficient amounts, although oily fish such as wild salmon, mackerel and herring, cod liver oil and sun-dried mushrooms are good sources. Surprisingly the liberal use of sunscreen also increases the risk of vitamin D deficiency as it filters the sun’s ultraviolet rays. To maintain good health throughout the year, Dr. Holick recommends people take a daily 1,000 IU vitamin D supplement and enjoy some sun during the spring, summer and fall.


“Moderation is the message. You should never bake in the sun, but a little bit of sensible sun exposure on your arms and legs, a couple of times a week, for both children and adults is really important for your health,” says Dr. Holick.


Dr. Holick is a leading expert in the field of bone metabolism and vitamin D and heads BMC’s Bone Health Care Clinic, which emphasizes the prevention and treatment of metabolic bone disorders including osteoporosis, rickets and osteomalacia. The clinic offers state-of-the-art DEXA scans to make immediate assessments of bone status. Dr. Holick’s new book, “The Vitamin D Solution,” is set to be released in April. More at www.bmc.org/endocrinology.