Yvette C. Terrie, BSPharm, RPh
Approximately 50 million individuals in the United States are affected by lactose intolerance. Pharmacists are in a key position to ensure that patients receive the essential nutrients that may be lost by not consuming milk and dairy products.
Lactose intolerance is defined as the inability or insufficient ability to digest lactose—a sugar found in milk and other dairy products.1,2
Lactose intolerance is very common among American adults but can begin at different times in life. Pharmacists are in a prime position, as front-line health care professionals, to first help determine whether a patient is indeed intolerant of lactose (and refer him or her to their primary care physician). Pharmacists can also provide education on lactose intolerance, including how it occurs, how it can be treated, and how to ensure that patients obtain essential vitamins and nutrients that they may not be receiving from milk or other dairy products.
Lactose intolerance is the result of a deficiency of the enzyme lactase, which is produced by the cells lining the small intestine. Lactase breaks down lactose into 2 simpler forms of sugar known as glucose and galactose, which are then absorbed into the bloodstream.1,2
Lactose intolerance is most likely to occur in the adult population, with a greater prevalence among older adults, and occurs most frequently in certain ethnic populations, including >60% of African Americans and >85% of Asian Americans.1-3
Other ethnic groups affected include Hispanic Americans and Native Americans. Lactose intolerance is least prevalent among Americans of northern European descent.1-3
Statistics indicate that partial or complete lactose intolerance affects an estimated 50 million individuals in the United States to some extent, and approximately 30 million adults in the United States are affected by some degree of lactose intolerance by 20 years of age.2
The exact number of affected individuals is unknown, however.
The symptoms associated with lactose intolerance result from bacterial fermentation of undigested lactose in the colon.4
The most common symptoms associated with lactose intolerance include diarrhea, abdominal pain, bloating, and flatulence and may appear within 30 minutes to 2 hours from ingestion of food products containing lactose.4-7
The development of symptoms is dependent on various factors, which include how much lactose is consumed, whether food is eaten along with lactose, the level of residual lactase activity in the small intestine, fecal bacterial metabolites, and intestinal transit.4,7
In late February 2010, the National Institutes of Health (NIH) Consensus Development Conference Panel met to review the current state of knowledge regarding lactose intolerance and to provide critical information to ensure that patients do not needlessly lack important nutrients found in milk and other dairy products.4-7
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. The onset of these symptoms is due to deficient levels of lactase, an enzyme necessary to break down lactose.4-7
The 14-member panel was unable to estimate the incidence of lactose intolerance from a systematic review of 54 studies. The panel was able to conclude, however, that a significant proportion of individuals who have little or no lactase activity may not have clinical lactose intolerance, but may be missing out on the health benefits provided by essential nutrients, such as calcium and vitamin D, in dairy foods.4-7
Inadequate levels of these nutrients may increase an individual’s risk for osteoporosis and other adverse health outcomes, especially if these individuals are not adequately taking in essential nutrients.4-7
In addition to concerns about bone health, the panel stated that the results of various studies have suggested a correlation between increased calcium intake and decreased blood pressure and a reduced risk of adenomatous colon polyps.4,7
According to the NIH panel, determining the amounts of lactose that can be tolerated is a key step in determining evidence-based dietary guidelines.4-7
Results from various studies suggest that many adults and adolescents diagnosed as lactose intolerant may be able to tolerate up to 12 g of lactose daily (the amount in 1 cup of milk) with no or minimal symptoms. 4-7
The panel experts also reported that the health effects of lactose intolerance in people who avoid the consumption of dairy foods have not been adequately studied to ascertain if such individuals have any nutritional deficiencies or long-term clinical effects on bone and cardiovascular health.7
It is also important for lactose-intolerant individuals to obtain sufficient intake of calcium and other nutrients through dietary sources and supplementation. The panel also suggested that educational and behavioral approaches be developed to promote a better understanding for both patients and health care providers and that these approaches be implemented to aid those with lactose intolerance.7
In addition, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, not getting an adequate amount of calcium is considered one of the primary risk factors for developing osteoporosis. This is of particular concern among many individuals with lactose intolerance, and some studies suggest that this patient population may be at greater risk for osteoporosis.8
Results from various studies investigating the role of lactose intolerance in calcium intake and bone health have conflicting results, however.8
Some studies have found that individuals with lactose intolerance are at higher risk for osteoporosis, but other studies have not.8
In summary, the NIH panel concluded that the majority of those with lactose malabsorption may not have clinical lactose intolerance. The NIH panel also concluded that more research is clearly needed to evaluate the prevalence of lactose intolerance association between bone health and lactose intake, genetic predisposition, lactose malabsorption, and intolerance.6
For more information on the NIH Consensus Development Conference: Lactose Intolerance and Health, visit http://consensus.nih.gov/2010/lactosestatement.htm
There are several methods to diagnose lactose intolerance. The sidebar describes a patient self-test, lactose intolerance blood test, and hydrogen breathing test.1,2,9,10
For patients diagnosed with lactose intolerance, the primary treatment is dietary modifications, which include reducing or restricting the use of food products that contain lactose. Various lactose-free milk and dairy products are available, as well as OTC lactase enzyme supplement products, such as Lactaid (McNeil Nutritionals LLC) or Digestive Advantage (Ganeden Biotech Inc), for reducing or preventing symptoms.9
These supplements make dairy products more digestible and enable individuals to consume dairy products without worrying about onset of symptoms. Patients should be advised to read the labels of food products carefully to identify sources of lactose.1
Lactose-intolerant patients must ensure adequate calcium intake by taking calcium supplements and/or eating nondairy foods with calcium (eg, leafy greens, oysters, sardines, shrimp, broccoli) or by drinking orange juice that has added calcium.3
The Dietary Guidelines for Americans 2005 recommend that people with lactose intolerance choose milk products with lower levels of lactose than regular milk, such as yogurt and hard cheeses.2
Because lactose is also present in an estimated 20% of prescription drugs and 6% of OTC drugs, patients with severe lactose intolerance should also be informed that they may develop symptoms when using some pharmacologic agents that contain lactose, such as oral contraceptives, or certain OTC products.2,10,11
Pharmacists should advise patients who present with symptoms of lactose intolerance to consult their primary health care provider to ascertain if they are truly lactose intolerant and to learn how to properly manage this condition without compromising the intake of essential dietary nutrients.
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
Lactose Intolerance. Ferri’s Clinical Advisor 2010 1st Edition. MD Consult Web site. www.mdconsult.com/das/book/body/207036770-2/0/2088/362.html. Accessed June 18, 2010.
Lactose Intolerance. National Digestive Disease Information Clearinghouse Web site. http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/. Accessed June 18, 2010.
Lactose Intolerance. Medline Plus Web site. www.nlm.nih.gov/medlineplus/ency/article/000276.htm. Accessed June 19, 2010.
Voelker R. NIH panel tackles lactose intolerance. JAMA. 201;303(13):1240, 1242.
Evans J. Impact of lactose intolerance on health is tough to measure, define. MD Consult Web site. www.mdconsult.com/das/news/body/206918312-3/mnfp/1016863051/216629/1.html?nid=216629&date=week&general=true&mine=true. Accessed June 21, 2010.
Hitt E. Lactose Intolerance Management Guidelines Issued by NIH Panel. Medscape Web site. www.medscape.com/viewarticle/717600. Accessed June 20, 2010.
Lactose Intolerance and Health. U.S Department of Health and Human Services National Institutes of Health Web site. http://consensus.nih.gov/2010/lactose.htm. Accessed June 20, 2010.
What People with Lactose Intolerance need to know about osteoporosis. National Institute of Arthritis and Musculoskeletal and Skin Diseases Web site. www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Conditions_Behaviors/lactose_intolerance.asp#b. Accessed June 20, 2010.
Roy P, et al. Lactose Intolerance. Medscape Web site. http://emedicine.medscape.com/article/187249-diagnosis. Accessed June 20, 2010.
Lactose Intolerance. American Gastroenterological Association Web site. www.gastro.org/patient-center/diet-medications/food-allergies-fructose-intolerance-and-lactose-intolerance#Lactose Intolerance. Accessed June 21, 2010.
Lactose Intolerance. Cleveland Clinic Web site. http://my.clevelandclinic.org/disorders/lactose_intolerence/hic_lactose_intolerance.aspx. Accessed June 20, 2010.