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Lactose Intolerance
Lactose Intolerance and Minorities: The Real Story
How Common is Lactose Maldigestion in Minorities?
The prevalence of lactose maldigestion (or lactase non-persistence) varies among different ethnic and racial groups in the U.S.:
- 90% of Asian Americans
- 80% of African Americans
- 62-100% of Native Americans
- 53% of Mexican Americans
- 15% of Caucasians.
In all, about 25% of the U.S. population – or an estimated 30 to 50 million American adults – have low lactase levels or are lactose maldigesters. A diagnosis of lactose maldigestion doesn't necessarily mean that the individual will experience intolerance symptoms.
Many minorities have low levels of lactase, but stereotyping all minorities as lactose intolerant is inappropriate. Why? Gastrointestinal symptoms that mimic lactose intolerance may be explained by factors unrelated to lactose such as culturally-based attitudes toward milk learned at a young age. Many people who say they have trouble digesting milk have actually never been diagnosed as lactose intolerant by a health professional.
"What Americans minorities and non-minorities don't know is that lactose intolerance is not an 'all-or-nothing' condition. It's a matter of degree. Our research shows that many people diagnosed with lactose intolerance can tolerate two cups of milk a day when consumed with meals several hours apart."
Michael Levitt, M.D.
Associate Chief of Staff for Research
Minneapolis VA Medical Center
Minneapolis, MN
Several studies confirm that lactose intolerance is overestimated. One-third of 45 African American adolescents and adults with diagnosed lactose intolerance had some minor symptoms of intolerance after consuming both lactose-containing and lactose-hydrolyzed milk under double-blind conditions. Clearly, the symptoms in some of these African Americans were not due to lactose intolerance. Rather, the symptoms were most likely explained by culturally-determined food preferences developed early in life or learned attitudes that affected their ability to tolerate milk.
In another study, one-half of lactose maldigesters reported gastrointestinal symptoms after consuming a lactose-free milk, or more symptoms after intake of smaller rather than larger intakes of lactose. Again, the symptoms experienced by many of these individuals were due to factors unrelated to lactose intake.
Strong beliefs can contribute to lactose intolerance, according to several studies carried out by a group of Minnesota researchers. When 30 self-described lactose intolerant individuals of diverse ethnic backgrounds (Asians, African Americans, Latinos, as well as Caucasians) received a breath hydrogen test, 30% were diagnosed as lactose digesters. When these same 30 individuals participated in a randomized, double-blind, cross-over trial in which they consumed either 1 cup of lactose-containing milk or lactose-hydrolyzed milk with breakfast for one week, gastrointestinal symptoms were minimal. In fact, there were no significant differences in symptoms when either type of milk was consumed. The researchers concluded that self-described lactose intolerant individuals “may mistakenly attribute a variety of abdominal symptoms to lactose intolerance.” In another study involving adults of varied ethnic background and designed to test tolerance to 2 cups of milk, 31% who said they were severely lactose intolerant comfortably digested lactose.
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