Lactose intolerance is a real and important clinical syndrome, but quantifying its public health burden is challenging. An NIH Consensus Development panel was convened this week to assess the available evidence on lactose intolerance and health across the age spectrum and across racial and ethnic groups.
The panel will hold a telebriefing to highlight their findings today. Many individuals with diagnosed or perceived lactose intolerance avoid dairy products, which constitute a readily accessible source of calcium, other nutrients, and vitamin D (when fortified). Inadequate consumption of these nutrients may increase the risk for chronic health problems, including osteoporosis and decreased bone health.
The panel defined lactose intolerance as the onset of gastrointestinal symptoms—diarrhea, abdominal pain, flatulence, and/or bloating—after ingesting lactose-containing foods and beverages; this is due to deficient levels of lactase, an enzyme necessary to break down lactose. Lactose malabsorption occurs when lactose is incompletely broken down in the intestine, which may or may not result in gastrointestinal symptoms after eating dairy products. Reduction of lactase in humans occurs in childhood and persists through the lifespan in most individuals (lactase nonpersisters). These individuals may or may not have the gastrointestinal symptoms of lactose intolerance. Understanding the distinction and interplay between these conditions is important when considering ways to meet nutritional needs.
"A lot of people who think they have lactose intolerance don't," said panel and conference chairperson Dr. Frederick J. Suchy, chief of pediatric hepatology at Mount Sinai School of Medicine. "They may have other conditions, or they may just need to consume smaller amounts of dairy products. Whether they are truly lactose intolerant or not, it is important that they meet recommended intakes of calcium and other essential nutrients."
Many individuals mistakenly ascribe symptoms of a variety of intestinal disorders, including irritable bowel syndrome and inflammatory bowel disease, to lactose intolerance and avoid lactose-containing foods without undergoing testing. This misconception becomes intergenerational when self-diagnosed lactose-intolerant parents place their children on lactose-restricted diets in the mistaken belief that they will experience symptoms.
"It is startling and disappointing to learn how little we know about the consequences of avoiding lactose-containing products," Dr. Suchy added. "Health care providers are concerned, but we don't have good data on bone health outcomes in people who have lactose intolerance or who avoid dairy products for other reasons."
For diagnosed lactose intolerant individuals, multiple management strategies have been proposed. These include distributing lactose intake throughout the day and/or combining it with other foods, choosing non-dairy foods rich in the nutrients found in dairy products, taking nutritional supplements, ingesting incremental amounts of dairy products over time to increase tolerance, consuming reduced-lactose dairy products, and using probiotics (in supplements and foods). The panel emphasized the need for additional research to better understand the effectiveness of these approaches for decreasing symptoms, optimizing nutritional intakes, and improving health outcomes, with special emphasis on diverse populations.
The panel encouraged health care providers to offer personalized, culturally-sensitive management strategies based on individual preferences. Depending on a variety of factors, some affected individuals could be counseled on ways to increase dairy intake while others could be urged to meet nutrient requirements from other sources. For example, studies show that when consumed with other foods, even individuals diagnosed with lactose malabsorption can consume at least one cup of milk with few or no symptoms.
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