Patients at risk for trace element deficiencies: bariatric surgery

Obesity is a worldwide epidemic associated with diseases such as diabetes mellitus and cardiovascular disease. Current methods for weight loss are not very effective, particularly for those with morbid obesity. Surgical therapy may be recommended for those with a BMI≥40kg/m(2), or BMI≥35kg/m(2) with co-morbidities. This therapy can produce significant weight loss and improve/resolve co-morbidities including hypertension and hyperlipidemia. Yet successes may be tempered by adverse effects on trace element absorption and status. A PubMed literature search identified studies from January 1980 to February 2013 for inclusion in a meta-analysis. Publications that contained keywords 'bariatric surgery or gastric bypass,' 'trace element or mineral or zinc or iron or copper or iodine or manganese', and 'absorption or status or rate or level' were identified. Inclusion criteria were human markers that reflect changes in trace element status before and after bariatric surgery. The meta-analysis found a decrease in blood copper, zinc, hemoglobin, as well as an increase in iron, regardless of the type of surgery. The pooled effect sizes and 95% confidence intervals were 0.17 and -0.09 to 0.43 for plasma/serum iron (p=0.20); -0.49 and -0.67 to -0.31 for blood hemoglobin (p=0.00); -0.47 and -0.90 to -0.05 for plasma/serum copper (p=0.03); -0.77 and -1.20 to -0.35 for plasma/serum zinc (p=0.00). Differences in levels of these minerals pre- and post-surgery may have been influenced by the time period after surgery, a pre-existing deficiency, type and dose of vitamin-mineral supplements, and malabsorption due to elimination of parts of the gastrointestinal tract.