By Raji Edayathumangalam, PhD
The answer to that question depends on whether your daily vitamin D intake is adequate or whether you have any risk factors for vitamin D deficiency and adverse effects on bone health.
Factors that place individuals in the high-risk category include obesity, very dark skin, not spending adequate time in the sun daily, habitually wearing sunscreen (which reduces skin’s capacity to make vitamin D), always wearing protective clothing, osteoporosis, taking anti-seizure medications that accelerate vitamin D clearance from the body, inflammatory bowel disorder with distal small bowel removed (where much of the vitamin D is absorbed), and other vitamin D malabsorption disorders.
If one or more of these risk factors applies to you, then the Institute of Medicine (IOM) and expert researchers collectively recommend that your healthcare provider measure your blood vitamin D levels to determine what your daily vitamin D intake should be. Further, they recommend that your clinician re-measure levels every couple of months and adjust your daily supplement accordingly to make sure that your blood vitamin D reaches optimum levels.
The Vitamin D Debate
Last year, the IOM announced an increased daily recommendation of 600 international units (IU) for children and adults less than 70 years, 800 IU for adults over age 70, and an increased daily, safe upper limit from 2,000 IU to 4,000 IU.
At a recent lecture and panel discussion at Brigham and Women’s Hospital, vitamin D researchers disputed the IOM’s conclusion that most of the US population has adequate vitamin D levels. The featured speaker was Bess Dawson-Hughes, MD, Senior Scientist and Director of Bone Metabolism Laboratory at Tufts
University, who was joined by a panel of BWH vitamin D experts including Scott T. Weiss, MD, Joann Manson, MD, and Meryl S. LeBoff, MD, who moderated the discussion.
Based on her scientific evidence, Dr. Dawson-Hughes recommended that individuals at average risk for vitamin D deficiency should take 800-1000 IU of vitamin D daily and need not be clinically tested. She also pointed out that a significant proportion of the US population satisfies one or more of the above-mentioned high-risk criteria (like obesity) and cautioned that the IOM’s public recommendations are therefore still too dangerously low for the high-risk individuals.
Despite the ongoing debate between the IOM and the scientific community on what daily vitamin D intake levels should be and precisely what proportion of the US population is at high risk for vitamin D deficiency, all parties agree on the importance of vitamin D and calcium in maintaining bone health. As to the role of vitamin D deficiency in cardiovascular disease, certain cancers and other non-skeletal diseases, the evidence is preliminary and controversial, and more research and clinical trials need to be done to provide definitive recommendations.