2024 September Board Book

CAN’T TOLERATE LACTOSE BUT LOVE DAIRY PRODUCTS?

Researchers: Dr. Danielle Lemay and Dr. Mary Kable, USDA WHRNC

lactose consumption. Lactic acid bacteria types, such as Lactobacillus , were higher in abundance in gut microbes from LNP individuals that consumed more than 10 grams of lactose per day compared with those who consumed fewer than 3.3 grams of lactose per day. Those who experience lactose intolerance may be able to reap health benefits of dairy foods The study findings suggest that despite their genes, LNP individuals may be able to tolerate lactose con sumption through a shift in the composition of their gut microbiomes. This is a remarkable finding as it suggests that humans can adapt to lactose consumption through dietary choices. The study also found that consumption of alternative milks by LNP individuals was associated with lower levels of fecal short chain fatty acids. LNP individu als that are selecting alternative milks over cow milk may be missing out on the gut health benefits associated with microbial-produced short chain fatty acids, including suppressing inflammatory responses in the gut, halting the growth of dangerous pathogens, and helping to maintain the integrity of the intestine’s epithelial barrier. This study was observational in design rather than experimental, which means that the results can only speak to associations rather than a causal relationship between lactose consumption, lactase genotype, and gut microbes. Results from this study are helpful for future researchers in generating hypotheses about specific bacterial families and the quantities of lactose needed to observe a beneficial effect on gut microbial populations. Lemay and Kable recommend that future research includes intervention studies where the researchers can control how much lactose each participant consumes and then look at how these dietary changes influence the gut microbe populations. These types of studies will demonstrate the potential health benefits for lactose on LNP populations. NEW STUDY SUGGESTS THAT PEOPLE WHO EXPERIENCE LACTOSE INTOLERANCE MAY BE ABLE TO ADAPT AND IMPROVE THEIR TOLERANCE WITH INCREASED DAIRY CONSUMPTION

Milk and dairy products contain lactose, a milk sugar that naturally adds sweetness to dairy products. Lactose is broken down in the body during digestion by the enzyme lactase. Adults who are “lactase non-persistent” do not make the enzyme needed for lactose digestion in their intestines. Without this genetic adaptation, many lactase non- persistent individuals avoid consuming milk and other dairy foods due to uncomfortable symptoms associated with lactose maldigestion. CDRF-funded study suggests there may be more than one way to adapt to lactase non-persistence Researchers found that adults who are lactase non- persistent but still consumed more than 10 grams of lactose each day have gut microbiomes that are adapted to increased dairy consumption. Rather than avoid dairy foods, this study suggests that regular dairy consumption by lactase non-persistent individuals could be associated with the ability to consume dairy more comfortably and reap health benefits. USDA researchers Dr. Danielle G. Lemay and Dr. Mary Kable, working with a group of 300 multi-ethnic adults in California, measured recent dairy and lactose intake, lactase persistence genotype—Lactase non-persistent (LNP) or lactase persistence (LP)—fecal microbes, and fecal short chain fatty acids. Based on results from a previous study funded by CDRF, Lemay suspected “that some LNP individuals were con suming quite a bit of lactose in their diet. So the question became, did the gut microbiome adapt to enable LNP individuals to become lactose tolerant?” Lemay and Kable predicted lactase non-persistent adults that were high lactose consumers would have more lactic acid and lactate-utilizing bacteria in fecal samples, as well as higher levels of fecal short chain fatty acids. Short chain fatty acids, are produced when lactic acid gut bacteria break down indigestible dietary carbohydrates like lactose. Consistent with their predictions, the researchers found that the individuals who were consuming lactose, even though lactase non-persistent, had gut bacterial popula tions that were shifted toward microbes that metabolize lactose into lactic acid and short chain fatty acids. They identified 90 different bacterial types that were signifi cantly associated with lactase persistent genotype and

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