Bariatric surgery is highly effective for significantly obese patients, but it often leads to nutritional deficiencies. Most of the time, these deficiencies can be predicted ahead of time, making prevention or treatment easier.
A 2006 paper, written by Dr. Malinowski and published in the American Journal of the Medical Sciences, explains which bariatric procedures are most likely to cause nutritional deficiencies and how patients can reduce their risk.
Nutritional Deficiencies: Lap Band vs. Gastric Bypass vs. Biliopancreatic Diversion
Nutritional deficiencies depend on the type of bariatric surgery. Weight loss surgery procedures consist of a restrictive and/or malabsorptive component. Laparoscopic gastric banding is an example of a restrictive procedure whereas gastric bypass (Roux-en-y) involves both gastric restriction and intestinal malabsorption. Biliopancreatic Diversion (BPD) is basically a malabsorptive procedure.
During a lap band procedure, a small silicone band is used to create a small pouch at the top of the stomach (gastric restriction). The patient is unable to eat very much at mealtime, so his or her daily calorie intake is greatly reduced. Food slowly proceeds to the rest of the stomach, where it is broken down the same as before surgery. The patient’s intestines are undisturbed, so the body can continue absorbing nutrients in the usual way. As long as the patient gets enough nutrients from healthy foods, there’s a low chance of nutritional deficiency.
Gastric bypass procedures also create a stomach pouch (restrictive component), but part of the small intestine is attached to the pouch (malabsorptive component). Because food is prevented from passing through the rest of the stomach and much of the small intestine, fewer calories are absorbed—but fewer nutrients are, too. Gastric bypass procedures are most likely to cause nutritional deficiencies afterward.
Biliopancreatic Diversion (BPD) involves an extensive bypass of the small intestine (malabsorption) and therefore is associated with high risk of nutritional complications.
Gastric bypass and BPD, which cause weight loss by preventing the body from absorbing as much food in the intestines, can lead to protein malnutrition due to malabsorption. Because red meat isn’t tolerated very well, those patients will have to take greater care to get enough protein from alternative sources, Eating protein-rich foods like eggs, fish poultry, yogurt and milk is a good way to avoid suffering from malnutrition. Protein malnourishment is not an issue with gastric banding.
Causes of Vitamin and Mineral Deficiencies
Vitamin B12 and iron are extracted from food in the stomach and absorbed in the small intestine. Because lap band patients still use their entire digestive tract, they are unlikely to suffer from vitamin or mineral deficiency. Gastric bypass and BPD patients, however, lack the stomach acidic environment to remove enough vitamins and minerals from food. The body also has less opportunity to absorb what is removed, because food is routed around much of the small intestine.
As a result, gastric bypass patients and BPD are likely to experience deficiencies in vitamins, A, B12, D, and K, iron, calcium, folate and thiamine. Lap band patients instead have a small chance of developing calcium and thiamine deficiency, but this is mainly because they eat less food after surgery and not because of food malabsorption.
Prevention and Treatment
Bariatric patients are likely to need nutritional supplements, particularly of iron and calcium. According to the author, supplementation is the best way to prevent nutritional complications. Patients who have undergone gastric bypass surgery and BPD are most in need of supplements.
Some nutritional deficiencies take time to develop, because the body can use nutrients that it stored up before the surgery. In order to avoid malnutrition or vitamin deficiency, it’s important to have frequent doctor visits in the first two years after surgery. The visits can become less frequent over time, but to ensure that the patient stays healthy, they’ll have to continue for life.