Eating Yogurt May Help Reduce Colorectal Cancer Risk

Long-term yogurt consumption may help protect against colorectal cancer by influencing gut bacteria, according to a new study¹ led by researchers at Mass General Brigham. Analyzing decades of data, scientists found that people who ate 2 or more servings of yogurt per week had lower incidence of a specific type of colorectal cancer associated with the bacterial species Bifidobacterium.

People who regularly consumed yogurt had lower rates of colorectal cancer–positive Bifidobacterium. | Image credit: pilipphoto - stock.adobe.com

“Our study provides unique evidence about the potential benefit of yogurt,” said Shuji Ogino, MD, PhD, chief of the Program in Molecular Pathological Epidemiology in the Department of Pathology, Brigham and Women’s Hospital, a founding member of the Mass General Brigham health care system, and the study's corresponding author, in a statement.¹ “My lab’s approach is to try to link long-term diets and other exposures to a possible key difference in tissue, such as the presence or absence of a particular species of bacteria. This kind of detective work can increase the strength of evidence connecting diet to health outcomes.”

The prospective cohort study is published in Gut Microbes.²

This study leveraged data from 2 large, ongoing US prospective cohort studies—the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS)—along with the prospective cohort incident-tumor biobank method.² The NHS enrolled 121,700 female registered nurses in 1976, and the HPFS followed ny enrolling 51,529 male health professionals starting in 1986. Biennial questionnaires collected data on demographics, lifestyle factors, medical history, and disease outcomes.

Dietary intake was assessed using a validated semiquantitative food frequency questionnaire (FFQ) administered at baseline (1980 for NHS, 1986 for HPFS) and approximately every 4 years thereafter. Cumulative average yogurt intake was calculated across all previous cycles to capture long-term dietary patterns. Participants were categorized into 4 yogurt intake groups, and additional dietary factors such as alcohol, folate, vitamin D, processed meat, and red meat intake were also recorded. Lifestyle variables—body weight, physical activity, smoking history, colorectal cancer screening, family history, aspirin use, and postmenopausal hormone use (for women)—were updated through biennial questionnaires.

The final analysis included 87,379 women from the NHS and 44,677 men from the HPFS after excluding individuals with preexisting cancer, polyposis syndrome, inflammatory bowel disease, implausible energy intake, or missing yogurt intake data.

During the follow-up of 132,056 individuals, researchers identified 3079 colorectal cancer cases, including 1121 with available Bifidobacterium data.

The association between long-term yogurt consumption and colorectal cancer incidence varied based on Bifidobacterium abundance (P heterogeneity = .0002). Individuals who consumed 2 or more servings of yogurt per week had an HR of 0.80 (95% CI, 0.50-1.28) for Bifidobacterium-positive tumors compared with those consuming less than one serving per month.

However, no significant association was observed for Bifidobacterium-negative tumors (HR, 1.09; 95% CI, 0.81-1.46). This differential effect was particularly evident in proximal colon cancer cases (P heterogeneity = .018), suggesting that yogurt intake may exert a protective effect specifically against Bifidobacterium-positive proximal colon cancer.

The researchers acknowledged limitations to their findings. First, yogurt intake was self-reported using food frequency questionnaires. Second, potential inaccuracies may have been present in the bacterial assay. Third, the study population consisted primarily of health professionals and non-Hispanic White individuals, limiting generalizability to more diverse populations. Lastly, although the study focused on Bifidobacterium, yogurt contains other probiotic strains, such as Lactobacillus, which may have influenced findings.

Despite these limitations, the researchers believe the study adds to growing evidence linking diet, the microbiome, and cancer risk.

“It has long been believed that yogurt and other fermented milk products are beneficial for gastrointestinal health,” said co-senior author Tomotaka Ugai, MD, PhD, Department of Pathology, Brigham and Women's Hospital, and the Department of Epidemiology at the Harvard TH Chan School of Public Health, in the statement.¹ “Our new findings suggest that this protective effect may be specific for Bifidobacterium-positive tumors.”

References

1. Long-term yogurt consumption ties to decreased incidence of certain types of colorectal cancer. Mass General Brigham. News release. February 12, 2025. Accessed February 24, 2025. https://www.massgeneralbrigham.org/en/about/newsroom/press-releases/long-term-yogurt-intake-lower-colorectal-cancer-rates#:~:text=Using%20data%20from%20studies%20that,bacterial%20species%20found%20in%20yogurt

2. Ugai S, Liu L, Kosumi K, et al. Long-term yogurt intake and colorectal cancer incidence subclassified by Bifidobacterium abundance in tumor. Gut Microbes. 2025;17(1). doi:10.1080/19490976.2025.2452237