Could there be a run on Yoplait and Chobani following a new health study about yogurt?
Mass General Brigham researchers have found that eating yogurt over time can help protect against colorectal cancer through changes in the gut microbiome.
The researchers discovered that long-term consumption of two or more servings per week of yogurt was tied to lower rates of proximal colorectal cancer positive for Bifidobacterium — a bacterial species found in yogurt.
The study showed that the bacterial species was quite common: About 30% of patients with colorectal cancer had detectable Bifidobacterium in their tumor tissue.
“Our study provides unique evidence about the potential benefit of yogurt,” said corresponding author Shuji Ogino, of the Department of Pathology at Brigham and Women’s Hospital.
“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,” added Ogino, who’s also a professor at Harvard T.H. Chan School of Public Health. “This kind of detective work can increase the strength of evidence connecting diet to health outcomes.”
Ogino’s team is trying to identify the risk factors and environmental exposures that are behind the rise of early-onset colorectal cancer.
To conduct their study, the researchers used data from two U.S.-wide prospective cohort studies known as the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). The studies have followed more than 100,000 female registered nurses and 51,000 male health professionals.
Participants have been tracked since 1976 for NHS and 1986 for HFPS, answering repeated questionnaires about lifestyle factors and disease outcomes — including questions about average daily intake of plain and flavored yogurt, as well as other dairy products.
The researchers also checked tissue samples for participants with confirmed cases of colorectal cancer, measuring the amount of Bifidobacterium DNA in tumor tissue.
The scientists found 3,079 documented cases of colorectal cancer in the two study groups. Information on Bifidobacterium content was available in 1,121 colorectal cancer cases. Among those, 346 cases (31%) were Bifidobacterium-positive, and 775 cases (69%) were Bifidobacterium-negative.
The researchers did not see a significant connection between long-term yogurt intake and overall colorectal cancer incidence, but they did see an association in Bifidobacterium-positive tumors — with a 20% lower rate of incidence for people who consumed two or more servings of yogurt a week.
This lower rate was driven by lower incidence of Bifidobacterium-positive proximal colon cancer — a type of colorectal cancer that occurs in the right side of the colon. Studies have found that patients with proximal colon cancer have worse survival outcomes than patients with distal cancers.
“It has long been believed that yogurt and other fermented milk products are beneficial for gastrointestinal health,” said co-senior author Tomotaka Ugai, of the Department of Pathology at the Brigham, and the Department of Epidemiology at the Harvard T.H. Chan School of Public Health. “Our new findings suggest that this protective effect may be specific for Bifidobacterium-positive tumors.”
The researchers believe that long-term yogurt intake may reduce the risk of proximal colon cancer by changing the gut microbiome, including Bifidobacterium.
However, they note that further research that brings together basic science and population health studies is needed to draw a definitive conclusion.
“This paper adds to the growing evidence that illustrates the connection between diet, the gut microbiome, and risk of colorectal cancer,” said co-author Andrew Chan, of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital. “It provides an additional avenue for us to investigate the specific role of these factors in the risk of colorectal cancer among young people.”
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