Vitamin D seems to be touted as a wonder pill everywhere in the media lately. The truth is we do not yet have conclusive proof that vitamin D deficiencies cause disease, but it is an area ripe for research. Unfortunately, we’ve been here before with other nutrients, where promising observational data was not borne out by subsequent clinical trials.
We do have preliminary data suggesting that vitamin D can be of benefit in the prevention of some cancers, insulin resistance, vascular conditions and gastrointestinal health. Until we have stronger evidence one way or another, as physicians, we should be honest with patients about the current state of evidence and help them to make an informed decision on the use of vitamin D supplements.
Are you at risk?
The Institute of Medicine (IOM) found that the majority of Americans are getting sufficient vitamin D, which can be consumed through fortified dairy foods, orange juice, fatty fish, and D-containing dietary supplements, or produced by the skin during sun exposure.
While most U.S. adults may achieve reasonable blood levels of vitamin D through diet and sun light, national data show that persons with darker skin, particularly African Americans, commonly have D levels believed to be suboptimal. This is particularly true among those who are lactose intolerant and avoid vitamin D fortified milk products. Research is sorely needed among this group to firmly establish optimal levels.
Last year I published an observational study suggesting a link between vitamin D deficiency and a higher number of heart and stroke-related deaths among blacks compared to whites. This study confirms that vitamin D represents one piece of the complex puzzle of race and blood pressure. And, since black-white differences in blood pressure represent thousands of excess deaths due to heart disease and stroke among blacks, simple interventions such as taking vitamin D supplements might have a positive impact on racial disparities.
Studies also performed here at the University of Rochester showed that a lack of vitamin D may explain a higher death rate in colon cancer among blacks compared to whites, and there may be a possible link between lower vitamin D levels among black women and more aggressive breast cancer.
I’m at risk, now what?
The Endocrine Society recommends that people in high-risk groups should be screened for vitamin D deficiencies. These groups are African Americans, obese children and adults, and pregnant and nursing women. The Food and Drug Administration and the IOM recommend the maximum daily dosage of vitamin D for adults as follows:
- Ages 1 to 70 – 600 international units (IU) daily.
- Adults 70 and older – 800 IU to optimize bone health.
- The safe upper limit for everyone older than 8 is 4,000 IU daily.
These doses will resonate differently with health providers and patients. Physicians are most likely to be a bit more conservative in terms of testing for vitamin D deficiencies and prescribing supplements, so you should always discuss this with your doctor.
Kevin Fiscella, M.D., is a professor of Family Medicine at URMC. He is associate director of the Rochester Center to Improve Communication in Health, co-director of Community Engagement for the Rochester Clinical Translational Science Institute, co-director of the Greater Rochester Practice Research Network and HIV Clinical Coordinator for Westside Community Health Center. Dr. Fiscella takes 1,000 units of vitamin D every day.