Digestive tract bypass surgery for weight loss leads to iron deficiency

October 26, 2009

Gastric bypass or gastric banding are the two most common procedures for triggering weight loss in morbidly obese individuals (those who are greater than 100 pounds overweight); these are referred to collectively as Bariatric surgery. These procedures have been shown to greatly improve weight loss and to make diabetes disappear in many patients.

Researchers from the University of Chile in Santiago found that 39% of a sampling of 67 Chilean women who had undergone gastric bypass surgery developed anemia (low blood counts) within 18 months after the surgery and the anemia was mostly due to a lack of iron. By contrast only 2% of these women were anemic before the surgery.

Poor absorption of nutrients occurs due to the nature of the surgery. The gastric bypass procedure involves stapling off the upper portion of the stomach to create a small pouch that restricts the amount of food a person can eat at one time. The surgeon also makes a bypass from the pouch that skirts around the rest of the stomach and a portion of the small intestine, limiting the body's absorption of nutrients.

The new findings suggest that impaired iron absorption, rather than reduced iron intake, is the major cause of long-term deficiency after gastric bypass, according to the researchers. Tests done six months after surgery showed that, on average, women were absorbing just one-third of the iron from food that they had before surgery. What's more, their absorption of iron from supplements showed nearly as great a decline. And many women became deficient in iron despite taking supplements after surgery.

All of the women in the study were put on vitamin and mineral supplements after surgery, though not all took iron pills. Those who did were prescribed 18 milligrams per day -- the standard recommended iron intake for women younger than 50.

That amount, Dr Ruz writes, appears "largely insufficient to prevent iron deficiency and iron deficiency anemia."

The researchers say that some patients may need to take newer more readily absorbed iron formulations, or receive infusions of the mineral to prevent a deficiency. The study is published in the September 2009 issue of the American Journal of Clinical Nutrition, September 2009.

Commentary by Jerry Hickey, R.PH.; research also shows that gastric bypass surgery inhibits the absorption of calcium and Vitamin B12. Chances are that other nutrients are affected also even though the evidence hasn't to date, been uncovered. Individuals who have undergone either stomach bypass or stomach gastric banding should supplement with powdered, liquid, or chewable supplements because nutrients will be more absorbable in these forms for these patients.