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(Last updated 6/28/00)



COLUMBUS, Ohio - Teenage girls who can't adequately digest lactose can still consume enough dairy products every day to provide their recommended daily dose of calcium, new research suggests. And they can do so with minimal symptoms of lactose intolerance.

The key is to slowly add dairy products to the diet, said Steve Hertzler, a study co-author and an assistant professor of medical dietetics at Ohio State.

The study involved 14 African-American girls. Nearly 60 to 80 percent of African Americans cannot adequately digest lactose, according to Hertzler.

At the end of three weeks of eating and drinking dairy products daily, the girls had a marked decrease in common symptoms of lactose intolerance, particularly bloating and gas.

"Eating enough dairy foods to reach 1,300 milligrams of calcium each day - the recommended amount for all teenagers - should not cause considerable discomfort for girls who have a problem digesting lactose," Hertzler said.

The research appears in a recent issue of the Journal of the American Dietetic Association.

"We get 75 percent of our calcium from dairy products. If we stop drinking milk, it is difficult get enough calcium."

Lactose maldigestion means a reduction in the activity of lactase, an enzyme in the small intestine that breaks down lactose. Lactose intolerance refers to the severity of the symptoms (including abdominal pain, diarrhea and headaches) caused by the inability to digest lactose. The inability to adequately digest lactose, however, doesn't necessarily mean that a person will experience symptoms of intolerance, Hertzler said.

All subjects lived in a closely supervised environment on the campus of Purdue University. The researchers closely monitored each girl's intake of dairy foods every day for 21 days. Each subject's daily diet averaged 1,200 mg of calcium. About 1,100 mg came from dairy sources - milk, yogurt and cheese - while the rest came from bread and vegetables. Each subject consumed about four servings of dairy foods throughout each day.

On days 1 and 21, each girl participated in a breath hydrogen test. The researchers took breath samples every hour for eight hours via a syringe and analyzed the hydrogen content in each breath. Excessive breath hydrogen is a sign of the inability to properly digest lactose.

On day 21, breath hydrogen levels were about 32 percent lower than they were on day 1 (101 ppm vs. 148 ppm) indicating that the body has adapted to an increase in lactose consumption.

Each girl was asked to record her symptoms on a chart once an hour during the breath tests and once each evening during the study. Symptoms of lactose intolerance decreased during the course of the study. In addition to a reduction in bloating and flatulence, the girls also reported fewer headaches. There was a slight increase in abdominal pain, but not enough discomfort to warrant keeping dairy products at bay, Hertzler said.

He recommends that lactose-intolerant individuals experiment with their dairy intake. "Start with small amounts of milk - about a half-cup with each meal," he said. "A cup of milk contains about 300 milligrams of calcium, and most people can tolerate that much.

"Once you find the right dose, try taking it several times during the day, with meals," he suggests. "Consuming milk with meals slows the delivery of lactose to the bacteria in the colon, which tends to moderate the symptoms."

Hertzler conducted the study with Berdine Martin, a research associate at Purdue University; Connie Weaver, a professor in the Department of Foods and Nutrition at Purdue; Dennis Savaiano, dean of the School of Consumer and Family Sciences at Purdue; and Bethany Pribila, a former graduate student at Purdue.


Contact: Steve Hertzler, (614) 292-8141; Hertzler.4@osu.edu
Written by Holly Wagner, (614) 292-8310; Wagner.235@osu.edu