Approaches to Providing Nutritional Guidance after Vertical Sleeve Gastrectomy: Do We Consider the VSG as Purely Restrictive or Something More?

by Lillian Craggs-Dino, MS, RD, LDN, CLT
Cleveland Clinic Florida, Weston, Florida

Bariatric Times. 2013;10(4):24–26.

FUNDING: No funding was provided.

DISCLOSURES: Ms. Craggs is on the Advisory Board of Bariatric Fusion, a bariatric supplement company.

ABSTRACT
The vertical sleeve gastrectomy is gaining popularity worldwide as a stand-alone bariatric procedure. While the literature describes this procedure as purely restrictive, assumption that nutrient deficiencies are less likely to occur in patients who have undergone vertical sleeve gastrectomy is neither prudent nor supported by current research. Evidence shows that vitamin and mineral deficiencies occur postoperatively, some of which may be induced by malabsorptive mechanisms. In absence of long-term data to support a standardized nutrition protocol for vertical sleeve gastrectomy, medical nutrition therapy should be based on a patient-centered approach to address specific pre-, peri-, and post-macro- and micronutrient needs of the patient. This article suggests that healthcare professionals working with vertical sleeve gastrectomy patients look beyond the procedure as merely restrictive. Patients who have undergone vertical sleeve gastrectomy should be encouraged to participate in regular follow-up visits with their interdisciplinary bariatric team, and a comprehensive nutrition assessment should be performed to identify, prevent, or correct deficiencies.

Introduction
Bariatric surgery is recognized as a safe and long-term treatment for patients with obesity, and it is gaining popularity worldwide as benefits extend beyond weight loss and reflect favorable metabolic alterations and resolution of comorbid conditions.[1,2] The precise mechanism of action of bariatric surgery is not fully understood; however, some studies suggest that weight loss and resolution of comorbid conditions are influenced by the type of surgical procedure performed.[3–5] Bariatric surgery is classified broadly to include restrictive, malabsorptive, or combination restrictive-malabsorptive procedures.[6,7] Literature describes the history of the jejunoileostomy and biliopancreatic diversion as purely malabsorptive procedures, although the jejunoileostomy procedure has been abandoned mainly because of severe malabsorption complications.[6]

Literature describes further the biliopancreatic diversion with duodenal switch (BPD-DS) and Roux-en-Y gastric bypass (RYGB) as combined restrictive-malabsorptive procedures, and adjustable gastric banding (AGB), vertical sleeve gastrectomy (VSG), and gastroplasty as purely restrictive procedures whereby a reduced size of the stomach leads to early satiety with reduced oral consumption.[6] No alteration of the normal passage of food into the intestinal tract is produced in these restrictive procedures, thereby supporting the assumption that malabsorption of nutrients is not precipitated.

While the RYGB remains the most commonly performed bariatric procedure, the VSG as a stand-alone bariatric procedure is gaining popularity in part because of the enthusiasm expressed by both the medical community and patients. The VSG is attractive to surgeons because of the relative ease of surgical technique, low rate of complications, and positive reported patient outcomes.[8] From the patient perspective, the VSG is enticing because the procedure does not require implantation of a foreign device that requires periodic adjustments, alleviating the additional burden of cost and time commitment. In addition, the belief that the VSG does not cause dumping syndrome or severe malabsorptive complications makes this an appealing procedure. Interestingly, a study by Tzovaras et al[9] contradicts the notion that dumping syndrome is not seen with VSG. Tzovaras et al demonstrated patients with VSG can experience clinical symptoms of early dumping syndrome with provocation with an oral glucose challenge as early as six weeks postoperatively, and this may be a consequence of accelerated gastric emptying.

Caution should be practiced when providing nutritional care and guidance to patients with VSG. Despite absence of intestinal rearrangement, assumption that nutrient deficiencies are less likely to occur in patients with VSG is neither prudent nor supported by current research. To begin with, vitamin and mineral deficiencies are commonly seen patient populations with obesity prior to surgery. Deficiencies in the water-soluble B-vitamins (thiamine, cobalamin, folate) and fat-soluble vitamins (vitamin D, E, and A) are seen with obesity and morbid obesity.[10] Damms-Machado et al[11] showed 51 percent of patients undergoing VSG had preoperative microdeficiencies with below normal results in vitamin D, iron, potassium, folate, and vitamins B6 and B12. If not corrected prior to surgery, some of these deficiencies can be exacerbated by decreased food intake, food intolerances, inadequacy of food variety, and the patient’s adherence to proton-pump inhibitors (PPI) protocol. Symptoms post-surgery, including vomiting, diarrhea, and dietary nonadherence have also been reported and can have profound negative effects on vitamin and electrolyte status.[12]

VSG should be considered more than purely a restrictive procedure when providing nutrition counseling because physiologic nutrient absorption of some vitamins and minerals post surgery are compromised, although the severity and duration is not clear. Deficiencies post-VSG are reported as soon as six months postoperatively and as late as 2 to 3 years when suspected food intolerances are typically resolved. Foundational research has shown that deficiencies can arise with B12, folate, vitamin D, iron, and zinc post VSG.[13–15] Vitamin D deficiency was shown persistent even with supplementation with a daily multivitamin, increasing risk for metabolic bone disease at least in the first year post VSG.[14–16] Aarts et al[16] advised screening for anemia post VSG due to risk for iron and B12 deficiency. Classifying the VSG as purely restrictive misrepresents the many physiological changes the surgery induces, some of which may or may not have direct bearing on nutrient absorption or usage. Physiological alterations seen after VSG include neurohormonal changes,[17] increased gastric emptying,[18] decreased ghrelin production due to removal of the oxyntic cells,[19] and decreased hydrochloric acid production and significantly reduced intrinsic factor (IF), directly affecting iron and B12 absorption, respectively.[20] According to the Merriam-Webster online medical dictionary, malabsorption is defined as “faulty absorption of nutrient materials from the alimentary canal.” By this definition alone the VSG may induce a malabsorptive state for some micronutrients and transcends the meaning of purely restrictive.

With limited research on the long-term nutritional effects of the VSG and absence of universal or standardized nutrition practice guidelines for the VSG, nutritionists often use the knowledge from peer-reviewed, scientific literature and expert opinion about other bariatric procedures or other digestive system surgeries, such as total, sub-total, or partial gastrectomy, when providing nutrition counseling. Dietitians are taught to recognize that any alteration of the gastrointestinal tract, including the stomach, and/or intestines or ancillary organs that provide digestive enzymes and metabolites, may affect bioavailability of nutrients. Factors that negatively affect oral intake of food are understood also as affecting absorption by the mere absence of intake. Bariatric programs typically agree that dietary progression for the VSG should include clear liquid to full liquid, pureed to mechanical, and finally, a regular diet. However, many institutions diverge when recommending a vitamin and mineral protocol. Research has shown that while most programs agree that vitamins and minerals are important, a single multivitamin containing more than 100 percent the recommended daily intake (RDI) may be insufficient in providing some necessary micronutrients while concomitantly providing excess of others.[7,12]

As with any patient who has undergone bariatric surgery, those with VSG should be encouraged to attend postoperative follow-up care with their interdisciplinary bariatric team. The dietitian, as a member of that team, should conduct a comprehensive nutrition assessment and provide medical nutrition therapy based on the patient’s specific and individual micro- and macronutrient needs. As the number of VSG surgeries increases each year, providing proper nutrition advice becomes even more critical and contributes to the longevity and durability of this bariatric procedure by influencing positive patient outcomes. However, until more long-term data are acquired on the specific nutritional needs of post VSG patients, patient-centered, conservative approaches to nutrition guidance may prove most advantageous.

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Category: Nutritional Considerations in the Bariatric Patient, Past Articles