Manual of Clinical Nutrition

Nutrition Management in Bariatric Surgery

Manual of Clinical Nutrition Management B- 19 Copyright © 2013 Compass Group, Inc.

is connected directly to the final segment of the small intestine, thus completely bypassing both the

duodenum and jejunum. In the biliopancreatic diversion with duodenal switch, the distal stomach,

duodenum, and entire jejunum are bypassed, leaving only a 50-cm distal ileum common channel for

nutrients to mix with pancreatic and biliary secretions. This procedure has a substantial increase in the

risk of nutritional and metabolic complications (1,3). Although this procedure successfully promotes

weight loss, it is not commonly used because of the high risk of nutritional deficiencies, especially with

the biliopancreatic diversion with duodenal switch (1).

Because gastric bypass operations cause food to bypass the duodenum, where most iron and calcium are
absorbed, the risks of nutritional deficiencies are higher in these procedures (1,3,5,6). Iron deficiency is
common secondary to the lack of contact of food iron with gastric acid and the consequently reduced
conversion of iron from the relatively insoluble ferrous form to the more absorbable ferric form (1). Vitamin
B 12 deficiency may result from the lack of contact between food and the gastric intrinsic factors, decreases in
acid and pepsin digestion of protein-bound cobalamins from foods, and the incomplete release of vitamin B 12
from R binders (1). Vitamin D and calcium absorption may also be reduced since the duodenum and proximal
jejunum, which are the preferential sites of absorption, are bypassed by this procedure (1). Anemia may result
from malabsorption of vitamin B 12 and iron in menstruating women, and decreased absorption of calcium
may lead to the development of osteoporosis and metabolic bone disease (1,3,5,6). Shikora (7) studied the
nutritional consequences of gastric bypass surgery and found deficiencies in vitamin B 12 (26% to 70% of
patients), folate (33% of patients), vitamin A (10% of patients), potassium (56% of patients), and magnesium
(34% of patients). Patients are required to take nutritional supplements that usually prevent these
deficiencies. Lifelong supplements of multivitamins, vitamin B 12 , iron, and calcium are mandatory following
this procedure (1,5).

Gastric bypass operations often cause dumping syndrome (1). Dumping syndrome occurs when stomach
contents move too rapidly through to the remaining small intestine (1). Symptoms include tachycardia,
weakness, sweating, and abdominal pain that usually occur immediately after eating. Diarrhea may also
occur, especially if the patient eats concentrated sweets. Patients with dumping syndrome will need to lie
down until the symptoms pass. Refer to Section IB: Dumping Syndrome Diet for appropriate medical nutrition
therapy intervention and treatment.

Rationale
The Bariatric Diet meal plan is for severely obese patients specifically being treated for weight management.
The primary outcome of the diet approach is to compliment the surgical procedure by promoting substantial
weight loss through reductions in food volume and energy intake. This diet is not intended for use with other
types of gastric surgery, such as gastrectomy, that are used as the primary treatment for other conditions or
diseases such as cancer of the gastrointestinal tract, peptic ulcer disease, or trauma. Refer to Section IB:
Dumping Syndrome Diet or other transitional diets as needed.

Nutritional Adequacy
During the first 6 weeks after surgery, energy, protein, vitamin, and mineral needs are difficult to meet.
However, the combination of diet and multivitamin and mineral supplementation can be planned to meet the
DRIs as outlined in Section IA: Statement on Nutritional Adequacy. The adequacy of the diet will depend on
the type and extent of surgery and on the postoperative progression of food based on the individual’s
tolerance. Up to 3 months after surgery, deficiencies in proteins, vitamins, and minerals may occur (1). Due to
the small volume of food in the Bariatric Diet, vitamin and mineral supplementation is necessary to meet
specific vitamin and mineral needs (1). Two to 3 days after surgery, patients should begin a multivitamin and
mineral supplement regimen to meet 100% of the DRIs, including iron, B-complex vitamins (B12, folate), and
1,200 to 2,000 mg of calcium (1). Additional supplementation is often required for patients who have had
Roux-en-Y gastric bypass or biliopancreatic diversion with duodenal switch (1). The vitamin and mineral
regimen should be consumed daily and considered necessary for lifelong maintenance of nutritional health
(1,5). Chewable forms of supplements may be better tolerated in the initial stages after surgery (1-5). Refer to
the discussion of vitamins and minerals later in this section under “Medical Nutrition Therapy and Nutrition
Intervention After Bariatric Surgery” and “Strategies for Vitamin and Mineral Supplementation Following
Bariatric Surgery”.

How to Order the Diet
Order as “Bariatric Diet.” One or more features of the diet may be individually ordered based on the
postoperative stage, for example, Bariatric Clear Liquids, Bariatric Full Liquids, Bariatric Pureed, or Bariatric