Vitamin D Status May Influence Bariatric Surgery Outcomes

Leigh A. Peterson, PhD, MHS Post-doctoral fellow Department of Surgery - Bayview Johns Hopkins School of Medicine

Dr. Leigh Peterson Interview with:
Leigh A. Peterson, PhD, MHS

Post-doctoral fellow
Department of Surgery – Bayview
Johns Hopkins School of Medicine

Medical Research: What is the background for this study? What are the main findings?
Dr. Peterson: From our previous study published in Obesity Surgery earlier this year, we knew that vitamin D deficiency and insufficiency was very common in our bariatric surgery candidates (71.4% < 20 ng/ml and 92.9% < 30 ng/ml). We wanted to explore the effect of this deficiency on adverse outcomes after bariatric surgery such as wound healing, infection, and extended hospital stay.

We turned to the Nationwide Inpatient Sample to answer this question, as it would contain enough surgeries to detect changes in even less frequent outcomes such as wound infection. But blood concentration of vitamin D is not available, so we used a traditional method to estimate group vitamin D status with season and geography. Vitamin D comes from the sun, so people have the most vitamin D in summer and in sunnier places.

In 932,091 records of bariatric surgeries from 2001 to 2010, we saw that more adverse outcomes occurred during winter—January to March, the time of lowest vitamin D status—compared to summer or even spring or fall. Additionally, most adverse outcomes occurred in northern latitudes (≥ 37°N) compared to sunnier southern latitudes.

Medical Research: What should clinicians and patients take away from your report?

Dr. Peterson: Many people do not get enough vitamin D, especially those at risk of vitamin D deficiency such as those who are overweight / obese, have darker skin, spend most of the day inside, or use sunscreen daily. It is important to screen those who are at risk for vitamin D deficiency and treat them with supplements. Treating vitamin D deficiency prior to surgery may improve your ability to heal, so speak with your doctor about getting screened if you are planning to have surgery.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Peterson: The next step is to perform a study measuring vitamin D status prior to surgery to strengthen the case for vitamin D preventing adverse surgical outcomes and to attempt to determine the desired vitamin D status (blood concentration) required to elicit benefit.


Peterson, L. A., Canner, J. K., Cheskin, L. J., Prokopowicz, G. P., Schweitzer, M. A., Magnuson, T. H., and Steele, K. E. (2015) Proxy measures of vitamin D status – season and latitude – correlate with adverse outcomes after bariatric surgery in the Nationwide Inpatient Sample, 2001–2010: a retrospective cohort study. Obesity Science & Practice, 1: 88–96.

doi: 10.1002/osp4.15.

Leigh A. Peterson, PhD, MHS (2015). Vitamin D Status May Influence Bariatric Surgery Outcomes 

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