Just two servings of yogurt a week may protect the bowels from specific types of cancer, according to a new long-term study conducted in the United States. For years, scientists have suspected that yogurt and its living bacteria have benefits for gastrointestinal health. However, not all research aligns on what those benefits are and when they are reaped.

This new analysis helps explain some of the confusion. Overall, epidemiologists did not find a significant association between yogurt and the overall incidence of colorectal cancer – the third most common cancer worldwide and the second leading cause of cancer-related deaths. However, when researchers split colorectal cancer cases into subtypes, they did find a significant result.

The findings align with several other observational studies which suggest yogurt intake may have anti-tumor properties. “Our study provides unique evidence about the potential benefit of yogurt,” says epidemiologist Shuji Ogino from Brigham and Women’s Hospital and Harvard University. “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.”

While the results are only observational, they cover the health and self-reported lifestyles of 87,000 females and close to 45,000 males, tracked for three decades or more. Ogino and his colleagues’ dataset encompasses a combined total of over 3 million years of individual follow-up data.

Individuals diagnosed with colorectal cancer who consumed two or more servings of yogurt a week were 20 percent less likely to have a Bifidobacterium-positive tumor compared to those who consumed less than one serving of yogurt a month. This was especially true for proximal tumors in the upper part of the intestinal tract.

Bifidobacterium are microbes that are ubiquitous in the human intestine and in the average bowl of yogurt. In about 30 percent of colorectal cancer cases, this bacterium is incorporated into tumor tissue, where it is commonly associated with a particularly aggressive form of the cancer.

Bifidobacterium seems to thrive in the low-oxygen tumor microenvironment, and its presence within certain colon tumors suggests it is leaking past the intestinal barrier into colon tissue at a higher rate than typical. Perhaps counterintuitively, eating more Bifidobacterium could help prevent this leakage in the long run.

Initial studies suggest the bacterium may have antioxidant, anti-inflammatory, and immune activation effects, possibly impacting the integrity of the gut microbiome and the intestine’s semipermeable barrier. Whether or not yogurt can deliver these benefits will require further research, but observational evidence is mounting.

“Our finding suggests that yogurt intake might have a cancer-preventive effect for colorectal cancer with disrupted intestinal barrier,” the authors of the current analysis explain. “Further studies are warranted to elucidate the potential mechanisms for the effects of long-term yogurt intake on colorectal carcinogenesis.”

Compared to distal colon cancer, which results in tumors further down the intestinal tract, proximal colon cancer has a lower survival rate. These types of cancers are also on the rise. The idea that food could work as preventative medicine is worth exploring further. A randomized trial in 2021 from Stanford University found that fermented foods like yogurt can influence the microbiome and immune system in healthy adults.

Epidemiologist Andrew Chan from Massachusetts General Hospital, who was part of the recent analysis, says their 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 study was published in Gut Microbes.

Fresh Insights and Analysis

The study’s findings are particularly relevant in the context of the increasing prevalence of colorectal cancer in the United States. According to the American Cancer Society, colorectal cancer is the third most common cancer diagnosed in both men and women in the U.S. The study’s focus on the role of yogurt in preventing specific subtypes of colorectal cancer offers a promising avenue for further research and potential dietary interventions.

One of the key takeaways from the study is the potential of yogurt to influence the gut microbiome, which plays a crucial role in overall health. The gut microbiome is a complex ecosystem of microorganisms that reside in the digestive system. Recent research has shown that a healthy gut microbiome can help prevent various diseases, including colorectal cancer. The presence of Bifidobacterium in yogurt and its potential to enhance gut health is a significant finding that warrants further investigation.

In addition to the health benefits of yogurt, the study highlights the importance of long-term dietary habits. The dataset used in the study, which encompasses over 3 million years of individual follow-up data, provides robust evidence for the long-term benefits of yogurt consumption. This emphasizes the need for sustained dietary practices that promote gut health.

The study’s findings also raise questions about the potential mechanisms by which yogurt might exert its protective effects. While the study suggests that yogurt intake may have anti-tumor properties, the exact mechanisms remain unclear. Future research should focus on elucidating these mechanisms, which could involve the interaction between yogurt’s living bacteria and the gut microbiome.

One potential counterargument to the study’s findings is the variability in yogurt products available in the market. Not all yogurts are created equal, and the benefits observed in the study may not be applicable to all types of yogurt. For instance, flavored yogurts often contain added sugars, which can negate the health benefits. Consumers should opt for plain, unsweetened yogurt to maximize the potential health benefits.

Another critical consideration is the role of individual dietary habits and lifestyle factors. While yogurt consumption may offer protective effects, it is essential to consider the broader context of a person’s diet and lifestyle. A balanced diet rich in fruits, vegetables, and whole grains, combined with regular exercise and a healthy lifestyle, is crucial for overall health and cancer prevention.

In conclusion, the study’s findings provide valuable insights into the potential benefits of yogurt consumption in preventing specific subtypes of colorectal cancer. While further research is needed to elucidate the exact mechanisms and potential limitations, the observational evidence is compelling. Incorporating yogurt into a balanced diet may offer a simple and effective way to promote gut health and potentially reduce the risk of colorectal cancer.