Background: Nutritional deficiencies in patients after Roux-en-Y gastric bypass operations have been mainly attributed to dietary restriction. However, most of these studies have been performed during the period of greatest caloric restriction.
Methods: Two hundred patients who were morbidly obese were followed for 6 to 8 years (mean, 6.7 years) after Roux-en-Y gastric bypass surgery. Each underwent a thorough physical examination and behavioral and nutritional assessments, including hemoglobin, red blood cell indices, serum iron content, iron binding capacity, and serum vitamin B12 and folic acid concentrations.
Results: Data obtained from blood tests disclosed a significant gradual decrease of the mean serum hemoglobin (p less than or equal to 0.0000), mean corpuscular volume (p less than 0.001), and iron saturation (p less than or equal to 0.0000). Mean vitamin B12 concentration improved during the last 3 years of follow-up. The mean values of iron saturation and vitamin B12 were not correlated with the patients' weight loss. Meat intolerance was observed in 51%, 60.3%, 59.5%, and 55.1% of the patients during the 0 to 12 months, 13 to 24 months, 25 to 72 months, and 73 to 96 months after surgery, respectively. A significant correlation was found between the eating habits and the laboratory values. The mean serum iron saturation, vitamin B12, and folic acid were significantly higher in patients who eat meat than in patients who do not eat meat (piron less than 0.0046, pB12 less than 0.0052, folate less than 0.01). In addition, oral vitamin and mineral supplements significantly improved the nutritional status of the patients. The patients had no caloric malnutrition or protein deficiency.
Conclusions: Roux-en-Y gastric bypass induces long-term changes in eating habits, independent of caloric intake. Iron continuously declines 6 to 8 years after surgery, depending (significantly) on the eating behavior, but not on the caloric intake.