WEST LAFAYETTE, Ind. -- Many people who claim to be lactose intolerant really aren't, says Dennis Savaiano, dean of Purdue University's School of Consumer and Family Sciences.
The problem, Savaiano says, is that dairy foods can be difficult to digest, and people who don't eat these foods often enough haven't acclimated themselves to the foods.
According to the National Institutes of Health, as many as 50 million Americans are lactose intolerant. Although lactose intolerance itself isn't harmful -- it may result in gas, bloating or nausea -- it does affect a person's health in the long-term because avoiding dairy foods reduces calcium intake. According to Savaiano, three-fourths of all calcium in diets in the United States come from dairy foods.
Too little calcium in a diet can reduce bone growth, which can lead to osteoporosis later in life. Osteoporosis, which affects 35 million Americans, can result in weakened bones, causing fractures and injuries. Patients in the United States spend $13 billion a year on osteoporosis treatments.
A big problem with both calcium intake and lactose tolerance, nutritionists say, is that most people, especially teen-age girls, don't consume enough dairy products.
"If you only consume dairy products once in awhile, you are more likely to have symptoms from them," Savaiano says. "Also, if you consume them by themselves, as opposed to as part of a meal, they tend to be transported throughout the intestine more rapidly and are more likely to cause symptoms."
Savaiano has four tips to improve digestion of milk and dairy products. "These approaches can improve lactose tolerance to the point that people can consume diets that are quite rich in calcium and in milk and experience no difference in their symptoms from eating a diet without the milk," he says. His tips:
- Don't overeat dairy foods, and eat them only in moderation.
- Eat dairy foods as part of a meal, such as a cup of milk over cereal with fruit.
- If necessary, use over-the-counter digestive aids.
- Eat yogurts. "Yogurts are very well tolerated because they contain a lactase that helps digest lactose in the intestine."
Lactose is a form of sugar, or carbohydrate, found in milk and dairy products. This sugar is too large to be absorbed by the intestine, and is broken down by an enzyme, lactase, produced by the body. Most adults don't produce enough lactase to completely break down the lactose. In fact, up to three-fourths of the world's population doesn't produce enough lactase.
However, Savaiano says it is possible to train one's own digestive system to break down the lactose.
"Our studies have shown a really amazing adaptation of the large intestine of humans," Savaiano says. "The large intestines contain bacteria that help digest lactose. By altering the diet over time, bacteria more effectively digest lactose, making milk better tolerated.
"The bacteria are very fastidious and very adaptable. An individual who may produce excessive gas may feel uncomfortable after eating milk products. But if they adapt to small amounts of milk for a couple of weeks, at the end of that period, they are producing far less gas than they were two weeks ago from the same amount of milk, and they tolerate dairy products extremely well."
Research studies on calcium metabolism have shown the effectiveness of this form of treatment, Savaiano says.
"We've found that if you do controlled clinical blind trials, where people don't know what they are consuming, and you take out that placebo effect, you can give subjects a glass of milk with breakfast and another with dinner and they exhibit almost no symptoms.
"Further, we just completed a study at Purdue last summer with a group of African-American adolescent girls who were part of a calcium diet study. On the first day of the study many complained about having to drink the milk -- they said they didn't like the milk and that they were intolerant. When we tested them they had only a very modest level of symptoms, though -- almost incidental. Two weeks later, after they had been consuming a dairy-based, high-calcium diet, we tested them again. Every one of these girls had absolutely no symptoms."
According to Savaiano, although many people think that some babies are lactose intolerant, actually this isn't the case. "Milk allergy is often confused with lactose intolerance, but they are physiologically different," Savaiano says. "Babies do not develop lactose intolerance until they are 3 to 5 years old. The intestinal lactase remains high in all infants, except the very rare situation where there is a genetic lack of the enzyme from birth."
Savaiano says milk allergies appears in 5 percent of newborns, but that almost all infants outgrow this allergy by their first birthday. "The best way to deal with this is to continue breast feeding," he says.