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(HealthNewsDigest.com) – Low levels of vitamin D have long been identified as an unwanted hallmark of weight-loss surgery, but now findings of a new Johns Hopkins study of more than 930,000 patient records add to evidence that seasonal sun exposure – a key factor in the body’s natural ability to make the sunshine vitamin – plays a substantial role in how well people do after such operations.
Results of the study, described online December 14 in the journal Obesity Science and Practice, reveal an interplay between vitamin D levels, seasons, geography and surgery outcomes, according to Leigh Peterson, Ph.D., M.H.S., a nutritionist and postdoctoral research fellow at the Johns Hopkins Center for Bariatric Surgery who led the research.
Specifically, the researchers found that patients undergoing bariatric surgery in the northern United States during winter – November to April – fared worse than patients who had procedures in southern areas.
“Sun exposure is critical in the synthesis of vitamin D, so the notion that people living in less sunny northern states may suffer from vitamin D deficiency is not surprising,” says Peterson, “What is surprising is how closely sun exposure, vitamin D and surgical outcomes were linked.”
For the study, researchers reviewed records of more than 930,000 bariatric operations performed in the United States between 2001 and 2010. Overall, they report, postprocedural complications were rare, with fewer than 1 percent of patients developing infections or needing to spend a few extra days in the hospital.
But much to the researchers’ surprise, Peterson says, a disproportionate number of those who fared worse hailed from areas north of latitude 37° (roughly South Carolina) than areas south of it. For example, areas north of latitude 37° yielded almost 150,000 more patients with an extended length of stay (more than three days in the hospital postsurgery) than areas south of that latitude. Considering that more than 300,000 of the operations – over a third of the total in the study – led to extended hospitalization, 71 percent of these surgical complications occurred north of 37°.
Furthermore, the researchers noticed, adverse outcomes such as non-healing wounds, wound infections and delayed wound healing clustered in colder seasons marked by less sunshine. For example, more than twice as many postoperative patients experienced delayed wound healing complications in the winter (349 patients, or 16 percent of operations reviewed) than in the summer (172 patients, or 0.04 percent of operations reviewed).
The investigators caution that this observational study using medical records has limitations, and it is too early to recommend the routine use of vitamin D supplements as a strategy to prevent or reduce the risk of postsurgical complications. Vitamin D supplements are sometimes prescribed after weight-loss surgery because of evidence that the operations reduce the ability of the gut to absorb the nutrient.
The investigators emphasize that further research is needed to determine which patients may warrant such preemptive treatment and at what doses. Experts believe that most people can and should get sufficient Vitamin D from brief, regular sun exposure and regular diets because of the potential ill effects of excessive vitamin D intake, such as nausea, constipation, confusion and abnormal heart rhythm. However, the researchers note, obesity is a well-known risk factor for vitamin D deficiency, and patients preparing to undergo weight-loss operations should be screened for it.
Bariatric surgery serves to reduce weight for obese individuals or patients with diabetes and other conditions by reducing stomach size or removing a portion of the stomach. Nearly 200,000 bariatric surgeries occur annually in the U.S. Costs for the procedure vary from $15,000 to $30,000.
“The growing rates of obesity and concurrent rise in bariatric surgeries performed mandate that primary care clinicians and surgeons treating patients with the condition should consider checking their vitamin D levels and correcting any confirmed deficiency,” says Peterson.
In general, she says, nutritional deficiencies can fuel inflammation, higher infection risk and delayed wound healing.
The researchers say they plan next a study measuring patients’ vitamin D levels before and after surgery to help determine optimal doses for supplementation.
Others participating in the study from Johns Hopkins University were Joseph Canner, Lawrence Cheskin, Gregory Prokopowicz, Michael Schweitzer, Thomas Magnuson, and Kimberley Steele were co-investigators on the study.
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