July 2017 Issue
Prebiotics' Role in Treating Lactose Intolerance — What Dietitians Need to Know
By Constance Brown-Riggs, MSEd, RD, CDE, CDN
Vol. 19, No. 7, P. 18
The simple pleasures of drinking a tall glass of ice-cold milk or enjoying a large scoop of ice cream can cause great digestive discomfort for many. Up to 70% of the human population has a reduced ability to digest lactose after infancy.1
After age 2, there's a gradual reduction of the enzyme lactase that breaks down the lactose in milk and other dairy products.2 The prevalence of lactase deficiency varies widely in the different geographic locations around the world. In the United States, 20% of white people have a lactase deficiency, while 80% to 100% of Asians have a lactase enzyme deficiency.1 The prevalence of lactase deficiency is about 70% to 95% in Africa and 15% to 70% in Europe.1 People who have a lactase deficiency are at risk of lactose intolerance.3 Current management of lactose intolerance depends on the degree of lactase deficiency and may include avoidance of lactose, restricted amounts of lactose, lactase enzyme supplementation, or the use of probiotics. New evidence suggests prebiotics may be another option for management of lactose intolerance.
This article will describe lactose intolerance, differentiate between prebiotics and probiotics, discuss the latest research on prebiotics as a treatment for lactose intolerance, and provide strategies for nutrition professionals counseling clients and patients with lactose intolerance.
Lactose Intolerance Defined
Lactose intolerance often is misunderstood. It's a condition in which people have gastrointestinal (GI) disturbances after eating or drinking milk or milk products.
During digestion of dairy products, lactase from the small intestine breaks down the lactose into two smaller sugars, glucose and galactose, which are more easily digested in the body.1
In people who have a lactase deficiency, the small intestine produces low levels of lactase and can't digest much lactose.1,3 Lactase deficiency may, in turn, cause lactose malabsorption. In lactose malabsorption, undigested lactose passes to the colon. Left undigested, lactose is fermented by colonic microflora in the intestinal tract.1,3 This fermentation produces uncomfortable symptoms such as bloating, abdominal distention, excessive flatulence, nausea, and abdominal pain. Some individuals also may experience diarrhea.1
Lactase deficiency and lactose malabsorption, also known as lactose maldigestion, can lead to lactose intolerance, since lactase levels are decreased, which can occur due to primary lactase deficiency, secondary lactase deficiency, developmental lactase deficiency, or congenital lactase deficiency.3
• Primary lactase deficiency, also called adult type lactase deficiency, is the most common type of lactase deficiency. In people with this condition, lactase production declines gradually over time after age 2.1 However, symptoms may not begin until adolescence or adulthood.1,3 Researchers have discovered that some people inherit genes from their parents that can cause a primary lactase deficiency.3
• Secondary lactase deficiency results from injury to the small intestine secondary to diseases such as celiac disease, Crohn's disease, or episodes of gastroenteritis.1 Treating the underlying cause usually improves the level of lactase and lactose tolerance.1
• Developmental lactase deficiency can occur in infants born prematurely. This condition usually lasts for only a short time after they're born.3
• Congenital lactase deficiency is an extremely rare genetically inherited disorder3 usually described in reports from Finland. In congenital lactase deficiency, the small intestine produces little or no lactase enzyme from birth. Symptoms of lactose intolerance occur shortly after birth and subside with a lactose-free diet.1
Probiotics and Prebiotics
The use of probiotics and prebiotics continues to grow in the United States. According to data from the 2012 National Health Interview Survey, probiotic and prebiotic use quadrupled between 2007 and 2012. In fact, 4 million US adults had used probiotics or prebiotics in the 30 days before the survey.4
Probiotics were first described in 1908 by Élie Metchnikoff—sometimes described as "the father of natural immunity," who proposed regular ingestion of lactobacilli—the forerunner of contemporary probiotics.5,6 In the late 1800s and early 1900s, Metchnikoff theorized that by manipulating the intestinal microbiome with "host-friendly" bacteria found in yogurt, health could be enhanced and senility delayed.7
In 2001, the Joint Food and Agriculture Organization/World Health Organization Working Group defined probiotics as live microorganisms that, when administered in adequate amounts, confer a health benefit to the host.8 The International Scientific Association for Probiotics and Prebiotics reinforced this definition as relevant in an issued 2014 consensus statement.9
Probiotics are available in dietary supplements and yogurts, as well as in suppositories and creams.4 The FDA defines yogurt as a fermented dairy product derived from the fermentation of milk by two species of bacterial cultures: Streptococcus thermophilus and Lactobacillus bulgaricus.10 "The two starter cultures [S thermophilus and L bulgaricus] used to make yogurt produce β-galactosidase, which aides in lactose digestion in the gut," says Jo Ann Hattner, MPH, RDN, of Hattner Nutrition in San Francisco and coauthor of Gut Insight: Probiotics and Prebiotics for Digestive Health and Well-Being. "That's why people who are lactose intolerant can often tolerate eating yogurt more than drinking milk," Hattner says.
Prebiotics often are confused with probiotics. Unlike probiotics, prebiotics aren't bacteria; they stimulate the growth of healthy bacteria in the gut. "Prebiotics are nondigestible food ingredients that selectively feed probiotic microbes that reside in our gut," says Kate Scarlata, RDN, a New York Times best-selling author and digestive health expert based in Massachusetts. They're also described as fermentable ingredients that alter the composition and activity in the gut microflora in a beneficial way.11 Common prebiotics include the fructooligosaccharides, galactooligosaccharides (GOS), lactulose, and inulin.1
Prebiotics also may have a role to play in lactose intolerance. Andrea Azcarate-Peril, PhD, an assistant professor of medicine at the University of North Carolina (UNC) School of Medicine and director of the UNC Microbiome Core Facility, says, "prebiotics [and specifically pure GOS] have been shown to impact the gut microbiome of lactose-intolerant individuals."
In a multicenter, randomized, double-blinded, placebo-controlled trial designed to determine the impact of short-chain GOS on lactose intolerance, subjects with a self-reported history of lactose intolerance were assessed via a hydrogen breath test. Eighty-five individuals were randomly assigned to either GOS or placebo treatment groups (2:1). The placebo group received corn syrup (Sweetose). GOS and placebo were escalated in five-day increments from 1.5 g to 15 g consumed once per day. The subjects avoided dairy during the 35-day treatment. After completion of the treatment period, subjects were instructed to reintroduce dairy foods into their diets.12 Fecal samples were taken from study participants over the course of the study to determine changes in the gut microbiome. "The objective of the study was to investigate whether the gut microbiota of lactose-intolerant people would change in response to prebiotics and dairy, decreasing symptoms of lactose intolerance," Azcarate-Peril says. At the end of the study period, abdominal pain was reduced by 70% among those who consumed GOS, and 90% showed a significant increase in lactose-fermenting bifidobacteria, known as a bifidogenic response.12
Azcarate-Peril's and colleagues' analysis concluded that the study demonstrated modulation of the gut microbiome by prebiotics in lactose-intolerant individuals. "We were able to correlate Bifidobacterium with symptoms. Specifically, the individuals that reported pain and cramping had less bifidobacteria. Approximately 70% of people stated they felt better, and about 90% showed increases in beneficial Bifidobacterium," Azcarate-Peril says.
Hattner says, "This was a well-designed human trial that demonstrated the benefits of fermentation. In this study, they demonstrated modulation of the gut microbiome in lactose-intolerant people. However, studies do need duplication." To broaden the sample size and take a deeper look at what changes occur to the microbiome by consumption of GOS and dairy products, and how durable those changes are over time, a 377-subject phase 2b/3 trial was conducted. Topline results of this trial are consistent with those of the initial trial and are scheduled to be released later this year.13
Many nutrition professionals encourage clients to avoid GOS due to digestive discomfort such as in irritable bowel syndrome (IBS). "GOS, a family of poorly absorbed short-chain carbohydrates found in beans (kidney, soybeans) and nuts such as cashews and pistachios, are known to cause gas. For those troubled with a visceral hypersensitivity of the gut, as occurs in irritable bowel syndrome, a diet high in GOS can exacerbate gas pains and debilitating cramping," Scarlata says.
Individuals with IBS weren't included in the above study, although the results suggested that GOS might have potential therapeutic benefits in IBS.14
"The notion of modulating the colonic microbiota via diet to improve health and tolerance to foods is interesting and a noted area of expanding research," Scarlata says. "Using prebiotics may offer another solution for those who suffer from lactose intolerance; however, I would exert these approaches [use of GOS] gently and cautiously in patients with a history of food intolerance or IBS to avoid protracted pain," she says.
Counseling Individuals With Lactose Intolerance
When it comes to counseling patients with lactose intolerance, it's best to make it a team approach—particularly for someone with secondary lactase deficiency, where healing of the gut typically restores lactose tolerance. "Dietitians should work with the patient and the gastroenterologist to gain a better understanding of the potential cause of the lactose intolerance to provide a tailored approach to patient care. For instance, the lactose intolerance may be transient due to small intestinal bacterial overgrowth (SIBO). Treatment of SIBO with antibiotics could result in improved lactose digestion," Scarlata says. For those with primary lactase deficiency, the team should work together to encourage the patient to try small amounts of dairy with a meal to slow down and improve lactose digestion. For example, make soups, pancakes, and oatmeal with low-fat milk or yogurt.
Know the Lactose Content
Individuals vary in the amount of lactose they can tolerate. In general, adults and adolescents with a diagnosis of lactose malabsorption can tolerate at least 12 g lactose.3 "RDNs working with this population need to be knowledgeable about various lactose-free and low-lactose options," says California-based Vandana Sheth, RDN, CDE, a spokesperson for the Academy of Nutrition and Dietetics who specializes in diabetes, weight management, eating disorders, prenatal nutrition, food allergies, and various disorders. Generally, hard cheeses such as cheddar or Swiss have less than 1 g lactose and are more likely to be tolerated than an 8-oz glass of milk, which contains 11 to 13 g lactose.15 People with lactose intolerance also are more likely to tolerate yogurt than milk, although they may have similar amounts of lactose.15 Sheth attributes this to yogurt's live cultures. "Yogurt contains live cultures that break down lactose from the milk in the yogurt. This helps minimize symptoms of GI discomfort including bloating and gas among people with lactose intolerance," Sheth says. In addition, Sheth suggests providing clients with a list of foods and their lactose content.
There's a common misconception that clients following a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet for IBS should limit lactose. This is true only if they're also diagnosed as lactose intolerant. However, because lactose is a disaccharide, it's eliminated during the elimination phase of a low-FODMAP diet. The elimination phase may last two to six weeks, after which time lactose gradually is reintroduced to determine tolerance. Over time, tolerance to FODMAPs including prebiotics can change. Scarlata says, "When working with patients with FODMAP sensitivity, periodic food trials are encouraged to help patients incorporate more prebiotic fibers into their diet. Incorporating prebiotic fibers into their diet is done per their personal threshold to help manage symptoms while potentially enhancing gut health."
"Given that each and every one of us has our own personal gut microbial 'fingerprint,' I anticipate diet therapies in the future will likely become more personalized," Scarlata says. Current management of lactose intolerance depends on the degree of lactase deficiency and may include avoidance of lactose, restricted amounts of lactose, lactase enzyme supplementation, or the use of probiotics. The science on prebiotics and lactose digestion is limited, but may represent another therapeutic option for adults with lactose intolerance.
— Constance Brown-Riggs, MSEd, RD, CDE, CDN, is nutrition advisor for the Dannon One Yogurt Every Day Initiative; a past national spokesperson for the Academy of Nutrition and Dietetics, specializing in African American nutrition; and author of The African American Guide to Living Well With Diabetes and Eating Soulfully and Healthfully with Diabetes.
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WGOHandbookonDietandtheGut_2016_Final.pdf. Published 2016. Accessed May 2, 2017.
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13. Ritter Pharmaceuticals announces lactose intolerance treatment, RP-G28, demonstrated efficacy and clinically meaningful benefit in phase 2b/3 clinical trial. Market Wired website. http://www.marketwired.com/press-release/ritter-pharmaceuticals-announces-lactose-intolerance-treatment-rp-g28-demonstrated-efficacy-nasdaq-rttr-2206020.htm. Published March 28, 2017. Accessed May 2, 2017.
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