Eating yogurt may offer protection against hard-to-detect colon cancer

BOSTON — For years, experts have praised yogurt’s potential benefits for digestive health, but that’s not the only punch it packs. New research suggests its cancer-fighting properties might be more nuanced than previously thought. A new study reveals that yogurt consumption may help prevent certain types of colorectal cancer, specifically those containing higher levels of beneficial bacteria called Bifidobacterium.

Colorectal cancer ranks as the third most common cancer worldwide, affecting both men and women. Prevention strategies have become increasingly important as rates rise, particularly among younger adults. While regular screening through colonoscopy remains the gold standard for early detection, researchers continue searching for dietary and lifestyle factors that might reduce cancer risk.

Research teams from Mass General Brigham and Harvard Medical School analyzed data from over 132,000 health professionals spanning multiple decades. Research published in Gut Microbes reveals a surprising link between yogurt consumption patterns and subsequent colorectal cancer diagnoses.

“Our study provides unique evidence about the potential benefit of yogurt,” says Dr. Shuji Ogino, chief of the Program in Molecular Pathological Epidemiology at Brigham and Women’s Hospital, in a statement. “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.”

Through two major studies, the Nurses’ Health Study and the Health Professionals Follow-up Study, researchers tracked more than 100,000 female nurses since 1976 and 51,000 male health professionals since 1986. Every two years, participants answered detailed questions about their health, lifestyle, and medical history. Every four years, they provided specific information about their diets, including how much plain and flavored yogurt they consumed.

This long-term tracking allowed researchers to understand not just occasional yogurt consumption but established eating patterns over decades. When participants developed colorectal cancer, researchers analyzed tumor samples for the presence of Bifidobacterium, a type of beneficial bacteria naturally present in the human gut and commonly added to yogurt products.

Among 3,079 documented colorectal cancer cases, researchers examined 1,121 for Bifidobacterium content. The findings revealed that this beneficial bacteria was quite common. Thirty-one percent of cases were Bifidobacterium-positive, while 69% were negative. For participants who ate two or more servings of yogurt per week, researchers observed a 20% lower rate of Bifidobacterium-positive tumors compared to those who ate yogurt less than once per month.

Most notably, this protective effect appeared strongest in the proximal colon, also known as the right side of the colon. Located near where the small intestine connects to the large intestine, the proximal colon poses unique challenges for cancer detection and treatment. Cancers in this area often grow with fewer obvious symptoms and are harder to spot during routine colonoscopy procedures. Research has shown that patients with proximal colon cancer typically face worse survival outcomes than those with cancers in other parts of the colon.

“It has long been believed that yogurt and other fermented milk products are beneficial for gastrointestinal health,” says co-senior author Dr. Tomotaka Ugai. “Our new findings suggest that this protective effect may be specific for Bifidobacterium-positive tumors.”

Bifidobacterium, a beneficial gut bacterium often found in yogurt, plays a role in digesting dietary fiber, maintaining gut barrier integrity, and regulating immune responses—all factors linked to colorectal cancer risk. The study’s authors hypothesize that yogurt consumption may contribute to a healthier gut microbiome, which in turn could influence cancer risk, particularly in the proximal colon.

However, because different yogurt products contain varying levels and strains of probiotics, more research is needed to determine whether specific types of yogurt provide greater protective benefits than others. Future studies may explore how dietary patterns interact with individual gut microbiomes to influence cancer risk, potentially leading to more personalized dietary recommendations for colorectal cancer prevention, though this remains an emerging area of research.

Regular yogurt consumers in the study demonstrated other healthy habits as well. They typically exercised more, smoked less, and maintained better overall dietary patterns than those who rarely ate yogurt. However, even after accounting for these factors, the association between yogurt consumption and reduced risk of Bifidobacterium-positive proximal colon cancer remained significant.

“This paper adds to the growing evidence that illustrates the connection between diet, the gut microbiome, and risk of colorectal cancer,” says Dr. Andrew Chan, chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital.

Beyond the general recommendation to consume yogurt, this research raises questions about which products might offer the most benefit. Not all yogurts contain the same bacterial strains or concentrations. While many products include Bifidobacterium, the amounts can vary significantly. Future research may help determine whether certain formulations provide better protection against colorectal cancer.

Different subtypes of colorectal cancer may respond differently to preventive measures, suggesting that a one-size-fits-all approach to prevention might not be optimal. This understanding could eventually lead to more personalized prevention strategies based on individual risk factors and gut bacterial composition.

The research team continues to investigate how dietary choices influence the gut microbiome and cancer risk. While these findings suggest yogurt consumption might help prevent certain types of colorectal cancer, they emphasize that it should be part of a broader approach to cancer prevention that includes regular screening, maintaining a healthy weight, staying physically active, and following an overall healthy diet.