Vitamin and mineral deficiencies following obesity surgery.

Any obesity operation, whether malabsorptive or based upon the production of early satiety, produces weight loss by causing a net reduction in the delivery of nutrients to the portal circulation. The malabsorption caused by jejunoileal bypass produces numerous severe micronutrient deficiencies along with other potentially damaging conditions. Although there are numerous reports of such deficiencies following gastric restrictive procedures (particularly gastric bypass), the conditions are almost always more easily treated than those after intestinal bypass, and resultant clinical illnesses are rare. Physicians should be aware that any obesity procedure carries a risk of nutritional deficiency.