Prevalence and correlates of iron, B12 and vitamin D deficiency after Roux-en-Y gastric bypass

Background. Roux-en-Y gastric bypass surgery (RYGB) has become a common treatment for obesity. Predictors and the time course of associated nutrient deficiencies remain unclear. Methods. This study evaluated nutrient levels of post-RYGB patients who had baseline nutrient levels and at least one nutrient level at six months. These levels were examined prior to surgery and at six months, one year, and two years. We then evaluated baseline characteristics, deficiency at previous visits and weight loss to determine factors associated with current deficiency. Results. 792 patients met inclusion criteria. At six months there was a significant decrease in the number of patients with vitamin D deficiency (80% to 60%, n=750, p=0.0001), and an increase in the prevalence of vitamin B12 deficiency (6% to 11%, n=737, p=0.0001) at six months. The prevalence of iron deficiency varied depending of the iron parameter used. Prior to surgery, 30.9% (133/430) of women and 56.7% (72/127) of men had low iron saturation whereas 44.6% (206/462) of women and 2.4% (3/126) of men had low ferritin. Two years after surgery 28.1% of women (55/99) and 53.9% of men (n=13/20) had low iron saturation and 74.3% of women (n=74/99) and 25% of men (n=12/20) had low ferritin. Regardless of the iron parameter used, deficiency at baseline, six months and one year were all found to be associated with deficiency at two years. Conclusion. Nutritional deficiencies are common prior to and after surgery. Vitamin D levels improve after surgery whereas vitamin B12 and iron are decreased after surgery. Previous deficiency is associated with future deficiency for iron and vitamin D at all time points.