[Nutritional deficiencies associated with bariatric surgery]

Morbidly obese patients often have nutritional deficiencies, particularly in fat-soluble vitamins, folic acid and zinc. After bariatric surgery, these deficiencies may increase and others can appear, especially because of the limitation of food intake in gastric reduction surgery and of malabsorption in by-pass procedures. The latter result in more important weight loss but also increase the risk of more severe deficiencies. The protein deficiency associated with a decrease in the fat-free mass has been described in both procedures. It can sometimes require an enteral or parenteral support. Anemia can be secondary to iron deficiency, folic acid deficiency and even to vitamin B12 deficiency. Neurological disorders such as Gayet-Wernicke encephalopathy due to thiamine deficiency, or peripheral neuropathies may also be observed. Malabsorption of fat-soluble vitamins and other nutrients, especially if diagnosed after by-pass surgery, rarely cause clinical symptoms. However, some complications have been reported such as bone demineralization due to vitamin D deficiency, hair loss secondary to zinc deficiency or hemeralopia from vitamin A deficiency. A careful nutritional follow-up should be performed during pregnancy after obesity surgery, because possible deficiencies can affect the health of both the mother and child. In conclusion, increased awareness of the risk of deficiency and the systematic dosage of micronutrients are needed in the pre- and postoperative period in obese patients undergoing bariatric surgery. The case by case correction of these deficiencies is mandatory, and their systematic prevention should be evaluated.