How Vitamin D From the Sun Affects Success of Weight Loss Surgery

Published on: 

Bariatric surgery is becoming a more popular method to address obesity, so physicians and surgeons should be more aware of how time of year affects outcomes.

A study published this month highlights how getting more time outside can offset the effects of weight loss surgery on vitamin D levels, which have been shown to drop after the procedure.

The study, published in the December issue of Obesity Science & Practice, showed that patients who had bariatric surgery between January and March, when sun exposure and vitamin D levels are the lowest, had more complications than those who had surgery in the summer.

US patients who lived in the North also fared worse than those who lived in the South.


Researchers led by Leigh Peterson, PhD, MHS, of Johns Hopkins Center for Bariatric Surgery, reviewed records of more than 930,000 patients who had operations in the United States between 2001 and 2010. Generally, complications are rare, with less than 1% developing infections. A more typical outcome was a need to spend a few more days in the hospital.

The team found that a higher share of patients who needed extra hospital days lived north of latitude 37 degree, which runs through South Carolina, than areas south of that line. Researchers found 150,000 more patients living north of the parallel needed more than 3 days in the hospital than those living south of the line.

Adverse outcomes, such as nonhealing wounds, were more common during colder seasons with less sunshine. More than twice as many patients, 349 of them, had these kinds of complications in the winter, compared with 172 in the summer.

Is the use of supplements a solution? Researchers cannot say, although these are often prescribed because the surgery itself can reduce the ability of the gut to absorb this nutrient in food. Experts believe that patients can get vitamin D in brief, regular amounts of sun exposure and through an overall healthy diet.

The key is to screen patients and identify those with reduced vitamin D levels, according to researchers.

“The growing rates of obesity and increased popularity of bariatric surgeries mean that primary care clinicians and bariatric surgeons should consider screening their patients and correcting any confirmed vitamin D deficiency,” Peterson said.


Peterson LA, Canner JK, Cheskin LJ, et al. Proxy measures of vitamin D status—season and latitude—correlate with adverse outcomes after bariatric surgery in nationwide patient sample, 2001-2010 [published online December 22, 2015]. Obes Sci Pract. 2015; doi:10.1002/osp4.15.