Gastric bypass is the most common type of bariatric surgery for weight loss and improving weight-related conditions like diabetes or high blood pressure. It induces weight loss by reducing the size of the stomach and malabsorption. At the same time, these very same factors can cause nutritional deficiencies that can lead to protein malnutrition, metabolic bone disease and neurologic abnormalities. Due to limited food intake and malabsorption, vitamin supplementation is essential in maintaining health. It is common practice to recommend a multivitamin that provides 200% of daily values.
B Vitamins
The B vitamins comprised of cyanocobalamin (vitamin B12), thiamine (vitamin B1), pyridoxine (vitamin B6), folate (vitamin B9) and riboflavin (vitamin B12) have all been shown to be low postoperatively.
Vitamin B12 deficiency is the most common problem in weight loss surgery due to decreased stomach size and acid secretion. Foods that are good sources of vitamin B12 like beef, poultry, fish and eggs are usually not well tolerated after surgery. The amount of vitamin B12 in standard multivitamins is not enough to prevent deficiency, therefore an additional B12 supplement of 100 to 350 mcg is recommended daily. If blood work still shows a low vitamin B12 level, intramuscular injections of 1,000 to 3,000 mcg of B12 will be given and then repeated every 6 to 12 months. For all other B vitamins, a B complex vitamin taken prophylactically is sufficient to avoid deficiency.
Iron
Iron deficiency, particularly women, is very common in patients postoperatively. In addition to a multivitamin, a separate iron supplement is recommended for all patients. One such regimen is 40 to 65 mg of ferrous iron such as gluconate, sulfate, or fumarate, three times per day. The addition of vitamin C to an iron supplement may increase absorption.
Calcium and Vitamin D
Adequate calcium and vitamin D are vital to bone health. Decreased absorption and tolerance of dairy products are main reasons for reduced levels in the body. Weight loss from the surgery also independently causes bone loss. Daily supplementation of at least 1200 mg of calcium and 800 IU of vitamin D in addition to dietary sources are recommended. Calcium supplements in the citrate form is recommended as its absorption is less affected by the lower acidity of the stomach post-surgery. Vitamin D3 is the natural form of vitamin D that is synthesized from our skin from UVB sunlight, and therefore is the preferred form of vitamin D supplement.
References
- Gastrointestinal and Nutritional Complications after Bariatric Surgery: Nutritional Complications; G.A. Decker et al.; The American Journal of Gastroenterology, 2007, 102(11)
- Nutritional Deficiencies Following Bariatric Surgery; Liz Goldenberg, MPH, RD, CDN; Gastroenterology & Endoscopy News Special Edition, September 2008
- True Fractional Calcium Absorption Is Decreased after Roux-en-Y Gastric Bypass Surgery; C.S. Riedt et al.; Obesity, 2006, 14(11)
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