Daily Yogurt Habit Could Shield Against Aggressive Colon Cancer

In a finding that could reshape dietary recommendations for cancer prevention, researchers have discovered that eating yogurt regularly may help protect against certain types of colorectal cancer, particularly aggressive forms that develop in the proximal colon. The protective effect appears linked to beneficial bacteria found in both yogurt and tumor tissues.

The large-scale study, published today in Gut Microbes, followed over 132,000 health professionals for decades, documenting their dietary habits and cancer outcomes. The research team from Mass General Brigham found that people who consumed two or more servings of yogurt weekly had a 20% lower risk of developing colorectal cancers that tested positive for Bifidobacterium, a beneficial bacterial species commonly found in yogurt.

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

The research drew from two of the largest ongoing health studies in the United States – the Nurses’ Health Study and the Health Professionals Follow-up Study – which have tracked participants’ health and lifestyle factors since the 1970s and 1980s. During the follow-up period, researchers documented 3,079 cases of colorectal cancer, with detailed bacterial analysis available for 1,121 cases.

The findings were particularly striking for cancers in the proximal colon – the portion of the large intestine closest to the small intestine. This type of cancer typically has worse survival outcomes than cancers in other parts of the colon, making prevention strategies especially valuable.

“It has long been believed that yogurt and other fermented milk products are beneficial for gastrointestinal health,” noted Dr. Tomotaka Ugai, co-senior author from the Department of Pathology at Brigham and Women’s Hospital. “Our new findings suggest that this protective effect may be specific for Bifidobacterium-positive tumors.”

The mechanism behind yogurt’s protective effect may involve its influence on the gut microbiome – the complex community of microorganisms living in our digestive system. Bifidobacterium, found in about 31% of colorectal tumors studied, appears to play a key role in this relationship, though researchers emphasize that more work is needed to fully understand the connection.

Dr. Andrew T. Chan, chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital and study co-author, highlighted the broader implications: “This paper adds to the growing evidence that illustrates the connection between diet, the gut microbiome, and risk of colorectal cancer. It provides an additional avenue for us to investigate the specific role of these factors in the risk of colorectal cancer among young people.”

The research team used advanced molecular techniques to analyze tumor samples, measuring Bifidobacterium DNA levels in cancer tissues. This detailed analysis allowed them to identify specific subtypes of colorectal cancer that might be more responsive to dietary intervention.

While the study shows promise for yogurt as a preventive measure, researchers caution that their findings need to be replicated in other populations, as their study group consisted primarily of health professionals who were mostly non-Hispanic White. Additionally, while the food questionnaires used in the study were validated for accuracy, they relied on self-reporting by participants.

Despite these limitations, the study’s strengths lie in its large scale, long-term follow-up, and sophisticated analysis of bacterial presence in tumor tissues. The findings suggest that something as simple as including yogurt in one’s regular diet might help reduce the risk of developing certain types of colorectal cancer.

The research was conducted as part of the OPTISTIMISTICC team’s work, funded by Cancer Research UK through Cancer Grand Challenges, a research initiative co-founded with the National Cancer Institute in the United States. The team aims to transform understanding of how the microbiome contributes to cancer development and potentially develop new prevention strategies.