March 3, 2025, 2:12 pm | Read time: 5 minutes
The state of the gut microbiome, i.e., the entirety of the bacteria found in the gut, plays a decisive role in general health. Researchers are, therefore, also investigating which lifestyle factors, and in particular dietary habits, influence the composition of the gut microbiota. A new study has now provided surprising findings in this context.
“Dairy products are a rich source of nutrients,” states the introduction to the recently published study.1 Among other things, they contain proteins, calcium, potassium, zinc, and various vitamins that can contribute to healthy physical functions. However, the link between the consumption of dairy products and the development of certain diseases (e.g., cancer and stroke) is not yet fully understood. The term ‘dairy products’ encompasses a broad range of foods. The research team from Houston, therefore, investigated the individual types of food that fall under it and found differences in the effects of milk and cheese on the gut.
Overview
Why the Effects of Diet on the Gut Are So Important
The bacteria in the human gut perform a variety of important tasks. Among other things, they play a key role in digestion. They also support the immune system in fighting diseases by preventing the colonization of unwanted pathogens. An imbalance of the microbiome — i.e., an unfavorable distribution of good and less good intestinal bacteria — can, in combination with genetic predispositions and unhealthy lifestyle factors, promote the development of various diseases. FITBOOK explains the function and importance of the gut microbiome in more detail here.
The authors of the study explain that the influence of dairy products on the microbiota associated with the intestinal mucosa (the entirety of all microorganisms) has not yet been researched. With their study, they wanted to specifically investigate the question of how (differently) milk and cheese, for example, affect the composition of bacteria in the gut.
Influence of Cheese, Milk, and Co. on the Gut — Study Details
The study was a cross-sectional study. This means that data was collected at a specific point in time, allowing a snapshot to be taken. In this case, the researchers used data from US war veterans — including only one woman — with an average age of 62.7 years who underwent a colonoscopy between 2013 and 2017. The examinations were “planned,” explain the study authors. This can be interpreted to mean that they were not carried out due to any symptoms of illness but as part of a check-up.
The Data Considered
Subjects with various pre-existing conditions were excluded from the study, including bowel diseases such as Crohn’s disease or ulcerative colitis, as well as certain types of cancer, severe mental disabilities, and kidney and infectious diseases. Of the total of 612 subjects recruited, 562 completed the colonoscopy. In 172 of them, the colonoscopy revealed no changes in the intestinal mucosa. When analyzing the findings, the researchers took into account further data based on information provided by the test subjects, such as various lifestyle and health factors. The researchers obtained information on the veterans’ diet using the Food Frequency Questionnaire (FFQ), a recognized 110-item questionnaire that is often used in nutrition research to assess the daily nutrient intake of subjects or patients.
Result: Milk Is Good for the Gut, Cheese Less So
The researchers found a greater diversity of bacterial species and a more even distribution of microorganisms in the intestines of the test subjects who consumed more dairy products overall. The authors consider the more frequent occurrence of the bacterium Faecalibacterium, which is said to have an anti-inflammatory effect on the body, to be particularly beneficial. People whose intestines are richly colonized with this bacterium are also said to suffer less frequently from coronary heart disease and anxiety disorders. A lack of Faecalibacterium, on the other hand, is associated with an increased risk of inflammatory bowel disease.
According to the analysis, cheese consumption was associated with a lower microbial diversity in the gut. This could be related to the method of production. Fermentation is generally considered to be beneficial to health, and the consumption of products such as buttermilk and kefir is recommended.2 However, in the current study, the researchers associated non-fermented dairy products, in particular, with a lower risk of various diseases. They did not have enough data to make a conclusive assessment of the possible influence of yogurt.
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Significance of the Study and Limitations
The limited scope of the data prevents the drawing of reliable, universally applicable conclusions about the impact of dairy products, especially cheese, on gut health. In addition, the study is based on information provided by the participants about their own eating habits, which always entails the risk of inaccuracies — whether due to an error or because participants prefer to conceal the frequent consumption of fast food, such as a cheesy pizza.
Finally, it should be noted that the consumption of dairy products among the study participants was rather low overall. The average values were 0.57 portions of dairy products per day, broken down to around 0.24 cups of milk and 0.27 portions of cheese per day. Yogurt made a minimal contribution to the participants’ diets, amounting to only 0.002 cups. In addition, only two participants stated that they consumed low-fat cheese. This suggests certain assumptions about the participants’ overall dietary habits and does not exclude the influence of other dietary or lifestyle factors on the gut microbiome of the subjects.