ReviewNutritional deficiency after gastric bypass: diagnosis, prevention and treatment
Introduction
In recent years, surgical treatments of morbid obesity have greatly increased worldwide, notably in France where 17,000 operations a year were performed in 2001–2002, compared to only 2000 in 1995 [2], [3]. Several surgical techniques are available, but in France, gastric banding is the most frequently used [2]. However, due to increasing “malabsorptive” operations, such as RYGB, experts were prompted to develop practical recommendations regarding these procedures [4], [5].
RYGB combines two methods, restriction and malabsorption (Fig. 1). The superior part of the stomach is cut to provide a small additional pocket of 20–30 ml, which in return leads to a quantitative decrease in nutritional intake. The inferior part of the stomach and the duodenum stay in place so they are of no more use to the crossing food, but they still secrete substances important for digestion (chlorhydric acid, pancreatic enzymes, biliary salts, hormones…). This is how a certain degree of food maldigestion and malabsorption contributes to weight loss.
The efficacy of the RYGB technique has been proven in terms of weight loss and improvement of comorbidities [6], [7]. However this intervention is not without risk, and a frequent short-term and long-term follow-up is required for several reasons. Firstly, there are potential surgical complications (leaks, fistula, obstruction, anastomotic stenosis, internal hernia etc.) particularly in the case of patients with acute digestive symptoms. In addition, it is essential to follow-up on comorbidities, and to adapt treatments, in particular antidiabetic ones. Finally, the operation might have a deep psychological and social impact on patients, which then require a multidisciplinary support. In any case, the operation results in important changes in digestive physiology: for example, non acid reflux, exclusion of the inferior gastric pocket, asynergia between the different secretions (enzymes, acids, hormones) and the nutrients, malabsorption. Consequently, the operation might induce iatrogenic pathologic symptoms on the overall digestive tube organs [8], [9]: the mouth, the esophagus, the stomach, the intestine, the pancreas, the liver etc. In particular we notice its damaging effect on dental state and mastication, hypoglycemia by pancreatic cell hyperplasia [10], [11], functional complications (vomiting, bowel disorders, dumping syndrome). Lastly, patients experience short-term and long-term nutritional complications which is the topic of this review.
First we are going to review the nutritional malfunctions and deficiencies observed after RYBP, and how to diagnose them through close monitoring. Then we will suggest ways to prevent and supplement these deficiencies, and finally we will discuss the appropriate course of action in case of pregnancy after RYGB.
Section snippets
Nutritional deficiencies and physiopathology mechanisms
The different mechanisms that explain the observed nutritional deficiencies are illustrated in Fig. 1. First, there is insufficient intake due to dietary restrictions and potential intolerance to certain type of food (meat, milk, fiber) (1). The exclusion of the stomach's inferior part results in a decreased secretion of gastric acid, sometimes required to absorb vitamins and minerals (B12 and iron) (2). Dietary restrictions are also accompanied by duodeno-jejunal malabsorption related to the
Diagnosis of the deficiencies and nutritional follow-up
Taking into account the frequency of the nutritional deficits among obese patients (vitamin D, B12, folates, iron), it is imperative to carry out a complete nutritional assessment before surgery. After surgery, we propose a nutritional check-up after 3 months, then every 6 months in the first 2 years, then at least once per year after 2 years.
The assessment should attempt to seek clinical signs of deficiency (Table 1). An example of the complementary examinations to require and rhythm of
Prevention and treatment of the nutritional deficiencies after RYGB
No controlled trial exists to determine the type of supplements and the dosages to be prescribed after RYGB. The majority of the reviews published on post-RYGB deficiencies recommend a multivitamin supplement providing 100% of the ANC (Table 3) [8], [51].
However, in France, no marketed supplement available covers all the requirements. In addition, one does not know the proportion of each vitamin or minerals introduced which is really absorbed, the principal site of absorption remaining the
Specific nutritional needs during pregnancy and breast feeding [1]
The specific ANCs for pregnant women are detailed in Table 3.
The additional protein contribution necessary for foeto-placental growth is estimated at 11 g/day in the third trimester compared to 1.3 g/day in the first trimester.
The consequences of certain specific deficits deserve to be detailed:
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in the event of maternal ferriprive anemia, the risks of prematurity and low-weight birth are increased [85], [86];
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there is a relation between a maternal deficit in vitamin D and the occurrence of
Conclusion
The large increase in the number of gastric surgeries and in particular malabsorptive techniques such as RYGB, as well as the nutritional deficiencies observed after this type of surgery require rigorous medical follow-up and multi-disciplinary collaboration between nutritionists, surgeons, dieticians and obstetricians.
Based on the data in the medical literature, this synthesis suggests practical guidelines for vitamin supplements and post-operative follow-up, but well-designed randomized tests
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