New research published this week found that regularly eating at least two servings of yogurt per week was tied to lower rates of proximal colorectal cancer (developing in the right side of the colon) that tested positive for the bacterial species Bifidobacterium. Bifidobacterium is a type of bacteria commonly found in yogurt that may have cancer-suppressing properties, according to study authors — but the exact mechanism behind these properties is still unclear.
“The takeaway message is that yogurt is good for your health,” says study coauthor Shuji Ogino, MD, PhD, the chief of molecular pathological epidemiology in the pathology department at Brigham and Women’s Hospital in Boston.
“The evidence is strong, as results are based on details about dietary intake from more than 130,000 people over 40 years,” Dr. Ogino says.
Certain Colorectal Cancers Are Especially Dangerous
Proximal (right-sided) colorectal cancer in particular leads to significantly worse outcomes compared to distal (left-sided) colorectal cancer.
A Healthier Gut May Help Fight Colorectal Cancer
For the analysis, Ogino and colleagues followed more than 132,000 health professionals over four decades. They collected dietary information, including details on yogurt intake, nearly every four years via questionnaire. Over the course of the study, the scientists identified 3,079 cases of colorectal cancer.
Overall, the study authors did not observe a significant link between regular yogurt consumption and colorectal cancer incidence. When looking at specific bacteria, however, they did find an association with yogurt consumption and Bifidobacterium-positive tumors. Information on Bifidobacterium content was available in 1,121 colorectal cancer cases — nearly one-third of which tested positive for the bacterium, while the remainder tested negative.
Those who ate two or more servings of yogurt a week were about 20 percent less likely to have Bifidobacterium-positive proximal colorectal cancer.
Ogino says that more research is needed to understand why this association exists, but the results suggested that yogurt may be linked to a protective effect by positively changing the gut microbiome (the ecosystem of microbes that live in your intestines).
“Yogurt may promote microbiome diversity, which may help improve immune function,” says Ogino, adding that a stronger immune system can help fight cancer.
While the study did not distinguish outcomes according to types of yogurt consumed, Ogino noted that plain yogurt was more likely to have a positive influence than products with sugar added.
The Link Between Diet and Cancer Risk
“Multiple large studies have shown that yogurt can decrease the risk of colon cancer,” says Arun Swaminath, MD, chief of the gastroenterology division at Lenox Hill Hospital in New York City and a spokesperson for the American Gastroenterological Association. “This study goes a step further to show its relationship to a specific bacteria and tumor subtype.”
The results did not show that yogurt caused a lower rate of cancer, merely an association between yogurt consumption and a possible protective effect, notes Ogino. He also points out that the study was limited in that it was based on preexisting data, and not clinical trials that closely monitored patients, their habits, and food intake.
An Overall Healthy Diet May Lower Cancer Risk
Dr. Swaminath suggests that it would be helpful to see additional data on participant diet and lifestyle “People who eat lots of yogurt may have a healthier diet overall, and it’s not clear that it’s only the yogurt that has this effect,” he says. “Maybe people who eat yogurt frequently eat lots of fermented food that has been shown to be supportive of a more broad-based microbiome.”
He stresses that an active lifestyle, avoiding obesity, and eating a broad-based diet of unprocessed foods will serve almost everybody in decreasing their risk of developing colorectal cancer.