Abstract
Bariatric surgery is becoming increasing prevalent. Multiple meta-analyses and systematic reviews have shown it to be more effective than other obesity treatments.5,6 Bariatric surgery should be considered for obese patients at high risk of morbidity and mortality who have not achieved adequate weight loss with lifestyle and medical management. Specifically, patients with a body mass index (BMI) of ≥35 with comorbidities or a BMI of ≥40 should be considered. 7 More than 5% of U.S. adults—that is, more than 15 million patients—meet the criteria of a BMI of ≥40 for obesity surgery. In reality, only a small fraction of this group undergoes surgery. Healthcare system dynamics play a large role in who receives surgery and the required aftercare. 8
Growing evidence suggests that the demographic characteristics of patients who undergo surgery do not reflect individuals with severe obesity in the United States. For example, nearly 84% of patients who undergo surgery are women, >90% are white, and most have higher income levels. On the contrary, blacks and Hispanics, who represent some of the most overweight of all racial/ethnic groups, are much less likely to undergo surgery for weight loss, and account for <10% of bariatric surgery patients. Obesity among these groups may have greater devastating social and clinical consequences. Despite this, the rate of bariatric surgery over the past 10 years for Medicaid beneficiaries has decreased, and in some states, few (or even no) bariatric centers perform surgery on Medicaid beneficiaries. Over the past 10 years, the prevalence of more extreme levels of obesity (BMI of ≥50) has increased fivefold, while lower levels of obesity have increased at a much less rapid rate. It is therefore surprising that patients with a BMI of ≥50 account for a relatively small fraction of those undergoing surgery. 8
Bariatric surgery has traditionally been classified into three groups: restrictive, malabsorptive, and combination. Restrictive procedures produce weight loss solely by limiting intake, such as gastric banding. Malabsorptive procedures induce weight loss by interference with digestion and absorption, such as jejunal ileal bypass. Procedures that limit intake and produce malabsorption, like the Roux-en-Y gastric bypass (RYGB), are considered combination procedures.9,10
The two most commonly used bariatric surgery procedures are the RYGB and the adjustable gastric band (AGB). Recent data extracted from the Bariatric Outcomes Longitudinal Database (BOLD) indicates that the most commonly performed bariatric surgical procedure was gastric bypass (54.68%), followed by gastric banding (39.62%), sleeve gastrectomy (2.29%), and biliopancreatic diversion (0.89%). 11 A new procedure being performed, laparoscopic gastric plication (LGP), is still considered investigational. 12 Some procedures that were once popular but are not performed routinely include intestinal bypass, vertical banded gastroplasty (VBG), and minigastric loop bypass.
Bariatric surgery is not without complications. Morbidity associated with surgery varies depending on the type of surgery and proximity in time to the surgical procedure. Various nutritional deficiencies are among the list of complications. While they are less common in purely restrictive procedures, they have been associated with all procedures. In order to obtain the most successful postoperative outcomes for bariatric surgery patients, the importance of nutritional management and patient education cannot be overstated.
Nutritional Impact of Bariatric Surgery
Bariatric procedures change the gastrointestinal system and therefore affect the ingestion, digestion, and absorption of food and its nutrients. All types of bariatric surgery lead to an extreme reduction in total calorie intake, especially in the first six postoperative months, typically ranging from 700–900 calories per day.13,14 Many bariatric procedures reduce digestion time and nutritional absorption in the small intestine, resulting in an increased risk of nutritional deficiency. This restriction has the potential to impact food tolerance, which consequently affects the quality of the postoperative diet. Preoperative nutrition counseling, as well as ongoing medical and nutritional follow-up visits, are important in preventing nutritional and metabolic complications. Long-term nutritional counseling, encouraging patients to engage in active participation in their weight-loss journey, as well as reinforcing the long-term lifestyle changes, are key to optimal outcomes. The ultimate long-term success of bariatric surgery relies a great deal on patients' ability to make sustained lifestyle changes in nutrition and physical activity. Living with bariatric surgery will require patients to make permanent changes in what, how, and why they eat. Failure to do this may result in inadequate weight loss, nutritional deficiencies, and can even cause weight gain over the years following surgery.15–17
Nutritional Needs of Bariatric Surgery Patients
The nutritional status of bariatric surgery patients is important, as it may impact both the short- and long-term outcomes. Good nutritional status is essential for normal wound healing, immunity, and recovery times. The early weeks and months following bariatric surgery present patients with varying degrees of challenges in nutrient intake. This may be further complicated by episodes of vomiting and dumping syndrome. Over time, there is continued risk for nutrient deficiency in patients with malabsorptive procedures. Increasing the healthcare workers' understanding of postoperative nutrition can lead not only to better patient health and improved recovery, but also to predictive modes of which patients may be at greatest risk for early onset of postoperative nutritional deficiencies. Information of this nature could ultimately assist in addressing questions about why some patients develop acute nutritional problems, while others remain healthy for longer. 18
Dietary progression following gastric bypass surgery can be divided into phases and can vary depending on the surgeon and the type of procedure. One resource on dietary progression following RYGB suggests a four-phased approach. Phase I lasts up to 1 week, during which time the patient takes in only clear liquids. The significant goal of the first 1 to 2 weeks postop is to keep the patient well hydrated. Phase II lasts from 2–3 days to 1 month, and involves eating pureed food, which should be the consistency of baby food to facilitate chewing and ingestion. Phase III lasts 1–2 months, at which time the patient progresses to more solid food. This may include soft foods, such as tuna fish, mashed potatoes, unstrained oatmeal, cooked vegetables, and canned fruits. Phase IV begins after 2 months, during which the patient can eat foods of regular consistency. A restricted diet such as this can easily result in nutritional deficiencies if careful planning and monitoring is not undertaken. 19
Nutritional Deficits
Changes in the anatomy and function of the gastrointestinal tract after bariatric surgery significantly change patients' eating patterns. One significant risk associated with all bariatric procedures is malnutrition, which may subsequently lead to dangerous nutritional deficiencies. However, if patients are availed to thorough preoperative nutrition education and postoperative nutritional follow-up, these deficiencies are largely preventable. As a rule, most Americans do not meet their basic nutritional needs through diet. Specific diseases like obesity create further nutritional challenges. While surgery helps to limit the food intake, improved eating habits and nutrient supplementation following surgery can lead to long-term positive outcomes. With appropriate supplementation and diet, most nutritional deficiencies can be avoided or corrected. Patients who engage in poor diet postop are at risk for significant nutritional deficiencies. 19
Bariatric surgery patients are commonly at risk for deficiencies of vitamins B1, B12, folate, C, A, D, E, and K, as well as the minerals iron, zinc, selenium, calcium, magnesium, and copper. Deficiencies of vitamin B12 and iron (occurring in 12% to 47% of patients) are perhaps the most commonly observed.13,14,20 If these deficiencies exist prior to the weight loss, bariatric procedures only serve to increase the nutritional risk to the patient. Diminished food intake, in addition to malabsorption and altered food profiles, establishes an environment where deficiencies become increasingly likely. 18
Long-term nutritional deficiencies related to bariatric surgery expose the patient to increased risk for neurological dysfunction (5–9% of patients), anemia (10–74% of patients), and possible bone loss. Unmonitored deficiencies can leave patients vulnerable to both acute and, in some cases, permanent physical damage. 18
Nutritional Resources
A variety of nutritional resources are available to support healthcare workers and patients. Healthcare workers often access journals for information, but patients are more likely to access books and online resources. A MEDLINE search using the search terms “bariatric nutrition” found several key resource articles. A Google search using the search terms “bariatric nutrition” returned 139 million results, many of which had inaccurate information. Various resources found to be accurate and useful for bariatric nutrition are listed.
AACE/TOS/ASMBS guidelines
In 2008, the American Association of Clinical Endocrinologists (AACE), The Obesity Society (TOS), and American Society for Metabolic and Bariatric Surgery (ASMBS) Medical produced clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient. These guidelines are an excellent resource for anyone caring for bariatric surgery patients. The recommendations for nutritional management are divided into screening prior to surgery, early postoperative care, and late post-operative care. The guidelines can be found at http://alt.aace.com/pub/pdf/guidelines/Bariatric.pdf. 21
Micronutrition for the weight-loss surgery patient
This book by Jacquiline Jacques, a Naturopathic Doctor, reviews specific preoperative and postoperative nutritional management for bariatric surgery patients, as well as strategies for risk reduction. Chapters on nutritional deficiency in obesity and nonalcoholic fatty liver disease are discussed in preoperative nutrition. Postoperative nutrition includes chapters on thiamine, folate, B12, A, D, E, K, calcium, iron, magnesium, copper, zinc, and selenium. Appendices include lab testing, multivitamins, supplementation, hair loss, deficiency-related medical conditions, and other resources. 18
www.CalorieKing.com
The CalorieKing website provides a variety of services and resources. A free resource, useful to bariatric surgery patients, is the food search. Patients can enter and compare foods for total calories, total fat, saturated fat, cholesterol, sodium, total carbohydrate, fiber, sugar, protein, calcium, and potassium. In addition, they offer other subscriptions services such as a food and exercise database. The software integrates foods in the CalorieKing database, healthy recipes, sample meal plans, and exercise regimens. Patients are able to personalize the plan. They offer practical tips, provide tutorials, and have a member question and answer section. Topics include: “Calorie control basics,” “Getting and staying motivated,” “Portion control,” and “Binge eating.” An interactive goal setting and motivation program helps members progress according to their personal goals, timelines, needs, and preferences. Registration and a membership fee are required for services other than the food search. Well-respected companies such as Johnson & Johnson, Roche, Sanofi Aventis, Joslin Diabetes Center, and Woman's World magazine endorse CalorieKing.
www.adaevidencelibrary.com
Sponsored by the American Dietetic Association (ADA), the Evidence-Based Dietetics Practice is a synthesis of the relevant scientific evidence on food and nutrition practice. The ADA Evidence Analysis Library (EAL) is an easily accessible, online library. This website may be more appropriate for the healthcare worker than patients, as it provides detailed information on the latest evidence, how the evidence was rated and graded, along with recommendations and algorithms for use. Specific topics related to bariatric surgery are weight loss and weight regain, expectations after bariatric surgery, diet progression in bariatric surgery, nutrition in bariatric surgery, albumin and prealbumin in prolonged protein restriction, and considerations for adolescents. Other available resources are nutrition care manuals, tutorials, presentations, and articles.
www.bariatrictimes.com
This website provides online access to a monthly peer-reviewed publication with up-to-date information on a variety of bariatric surgery topics. The site offers searchable access to the publication. Searching the key terms “nutrition” and “nutritional deficiencies” returned numerous relevant articles. This website does not require pre-registration or a membership fee to access any of this information. It is a site that is equally helpful for both bariatric patients and healthcare workers.
www.asmbs.org/Newsite07/resources/asmbs_items.htm
The website of the American Society of Metabolic and Bariatric Surgery (ASMBS) has a resource section. Within the resources section, there are press releases, statements, and guidelines regarding bariatric surgery. Of particular interest are the ASMBS Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient published in 2008.
http://win.niddk.nih.gov/publications/gastric.htm#complications
The National Institutes of Health Weight-Control Information Network has a webpage dedicated to bariatric surgery. While this website does not provide detailed information regarding bariatric nutrition, it does provide an overview of bariatric surgery and potential risks, including nutritional deficiencies.
www.obesityaction.org
The Obesity Action Coalition (OAC) is a nonprofit organization dedicated to those affected by obesity. The website offers a links to many resources. Specifically, the “Educational Tools” tab links to the OAC magazine, resources articles, and multimedia information. Within the resource articles, there are numerous articles on nutrition, including those specific to bariatric surgery.
Conclusion
Clinicians working with bariatric surgery patients need to use evidence-based nutritional resources to guide their nutritional recommendations. An abundance of information is available on the Internet for bariatric surgery patients; however, caution needs to be taken to make sure patients and healthcare workers are obtaining accurate information. A Google search found that many Internet sites have inaccurate or misleading information. Many proprietary sites offer education, services, support groups, supplements, and food products, but their content is not peer reviewed. In addition, much of the information on nutritional information may be above the reading and comprehension level of bariatric surgery patients. The onus rests on healthcare workers to help patients understand the issues at hand, as it is important to their long-term health, as well as to the success of the weight-loss surgery industry.
Footnotes
Disclosure Statement
No competing financial interests exist.