Gastric Bypass Limits Absorption of Food

by Daniel Hurley, M.D.

DEAR MAYO CLINIC:

I had bariatric surgery 3.5 years ago and am doing well. I have been faithful in going to my follow-up appointments and take 200 milligrams of calcium with vitamin D daily. I broke my foot six months ago, and it hasn't healed. What can I do to build back my bones?

ANSWER:

Your situation is not uncommon after bariatric (weight-loss) surgery. Some investigation is necessary to determine why your foot hasn't healed and to decide how best to treat the underlying cause. Perhaps you're not getting enough vitamins and minerals to keep your bones strong. Other factors, however, also should be considered.

Bariatric surgery limits the amount of food a person can eat and digest. Three and one-half years ago, the most common bariatric operations were gastric banding (lap banding) and gastric bypass (Roux-en-Y). The kind of procedure you had is a factor in determining the amount of supplemental vitamins and minerals needed following surgery. Both types of surgery limit food intake, but only gastric bypass limits absorption of food, including vitamins and minerals.

During gastric banding, the surgeon places a band around the upper part of the stomach, creating a small gastric pouch to receive food. The band limits how much you can eat, and even a small amount of food leaves you feeling full.

In gastric bypass surgery, the surgeon creates a small pouch at the top of the stomach that's sealed off from the rest of the stomach. The surgeon then connects the stomach pouch to the small intestine, which allows food to bypass most of the stomach and the first section of the small intestine. As a result, fewer calories are absorbed from the food ingested.

Gastric banding does not change the body's ability to absorb vitamins and minerals. As a result, impaired bone healing is less likely to occur after that type of surgery. Gastric bypass surgery may affect your body's ability to get enough calcium and vitamin D from food and from the supplements you're taking to keep bones healthy.

In either case, first, you need a foot X-ray, which should help show why it isn't healing. You may have a severe fracture that requires additional treatment to heal properly. Second, you should have a bone mineral density test to determine if you have bone loss or osteoporosis -- a disease that makes bones thin and fragile, putting them at risk for fracture. Third, your physician should measure your calcium and vitamin D levels.

Calcium is important because it helps maintain strong bones. The richest sources of calcium are milk and dairy foods fortified with vitamin D. If dairy products cause diarrhea or other digestive problems after gastric bypass, calcium and vitamin D supplements can help ensure adequate intake.

You have to be careful what kind of calcium supplement you take, however. The most common supplement is calcium carbonate. To effectively be absorbed into the body, it must be broken down by stomach acid. After gastric bypass, what you eat doesn't pass through as much stomach acid as usual during the digestion process. Most of that acid is made in the larger, bypassed part of the stomach. So you may not be absorbing as much calcium as you think. Instead, you may want to consider another type of calcium supplement, for example, calcium citrate, which can be absorbed even with reduced levels of stomach acid.

Vitamin D is important because it helps transport calcium from the gut into the bloodstream and then locks it into the bones, making them hard. Without enough vitamin D, bones won't get adequate calcium.

Appropriately evaluating and treating a situation such as yours can be complicated. Your broken foot must be treated successfully. In addition, your physician must determine if underlying problems are increasing your risk of bone loss and bone fractures and must also ensure that you are getting needed vitamins and minerals.

To determine the appropriate treatment and follow-up care, I recommend you consult an endocrinologist or a physician-expert in nutrition who's worked with bariatric surgery patients.

Detailed information about preventing bone loss and treating osteoporosis is available online from the National Osteoporosis Foundation (www.nof.org).

-- Daniel Hurley, M.D., Endocrinology, Mayo Clinic, Rochester, Minnesota

(Medical Edge from Mayo Clinic is an educational resource and doesn't replace regular medical care)

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