ISLAMABAD, FEB 17 (ONLINE): Yogurt that contains live bacteria is thought to protect against several diseases, including some forms of cancer.
Experts have not yet found exactly how it does this, but some suggest that it may be due to yogurt’s effect on the gut microbiome.
Now, a study has found that regularly eating ‘live’ yogurt may reduce the likelihood of one form of colorectal cancer.
The researchers found that people who habitually consumed 2 or more servings of yogurt a week had a 20% lower rate of Bifidobacterium-positive bowel tumors.
Colorectal cancer is the third most common cancer worldwide, with the World Health Organization (WHO) reportingTrusted Source that it makes up more than 10% of all cancer diagnoses.
Lifestyle factors, such as being sedentary, smoking, obesity and excessive alcohol consumption, as well as high intake of processed meats and low intake of fruits and vegetables, can all increase a person’s risk of developing colorectal cancer.
Eating a healthy, high-fiber diet, with plenty of fresh fruits and vegetables, whole grains, calcium and dairy products is associated with a lower colorectal cancer risk.
A study led by researchers from Mass General Brigham — and published in the journal Gut Microbes — has now found that yogurt could also decrease the risk of some types of colorectal cancer.
The researchers found that people who ate 2 or more servings of yogurt containing live bacteria each week had a 20% lower risk of developing colorectal tumors that were positive for Bifidobacterium, a strain of bacteria that is common in the gut microbiome.
Gemma Balmer-Kemp, PhD, Head of Research at Cancer Research UK’s Cancer Grand Challenges, one of the funders of the study, told Medical News Today that:
“Endogenous bacterial species are of significant interest for their application in human health. This study provides new evidence about the potential benefit of yogurt (which contains live bacteria) in reducing risk of a certain subtype of colorectal cancer.”
“While this study has shown a correlation between long-term consumption of yogurt and lower rates of proximal colorectal cancer positive for Bifidobacterium, more work is required to understand any causative role of Bifidobacterium and the mechanisms involved if so,” she added.
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“Live” yogurt contains several strains of bacteria. Lactobacillus bulgaricus and Streptococcus thermophiles are commonly used to ferment milk to form yogurt, but many other bacterial strains, or probiotics, may also be added.
Research has suggested that probiotics may boost the immune system, improve gut health, reduce the risk of osteoporosis, type 2 diabetes and cardiovascular disease, and could even reduce the risk of some cancersTrusted Source.
To investigate whether yogurt consumption affects colorectal cancer risk, the researchers in this study used data from the Nurses’ Health Study and the Health Professionals Follow-up StudyTrusted Source, which have followed more than 100,000 female nurses since 1976 and 51,000 male health workers since 1986.
Participants in both studies answer frequent lifestyle, diet and health questionnaires, which include questions about intake of both plain and flavoured yogurts, as well as other dairy products. For those people diagnosed with colorectal cancer, researchers assessed tissue samples for Bifidobacterium DNA.
Of the cohort, 3,079 people developed colorectal cancer and, of these, the researchers could access Bifidobacterium data for 1,121. A total of 775 people had Bifidobacterium negative colorectal cancer, and 346 were Bifidobacterium positive.
Yogurt eaters had fewer colorectal tumors
Although researchers did not see a significant difference between long-term yogurt intake and overall incidence of colorectal cancer, they found a 20% lower rate of incidence of Bifidobacterium-positive tumors in those who ate more yogurt.
Kelsey Costa, MS, RDN, a registered dietitian nutritionist and owner of Impactful Nutrition, not involved in this study, explained for MNT how Bifidobacterium might affect colorectal cancer risk.
“This study does not suggest that yogurt reduces Bifidobacterium in the gut; just the opposite. In fact, it highlights that Bifidobacterium is an important bacterial strain in yogurt that produces short-chain fatty acids (SCFA) in the gut and has anti-cancer properties through antioxidant, anti-inflammatory, and immune-boosting effects,” she pointed out.
According to her: “The research suggests that the Bifidobacterium found in Bifidobacterium-positive tumor tissue could reflect impaired intestinal barrier function. And cited studies show that Bifidobacterium may improve the intestinal barrier by reducing harmful inflammatory proteins like tumor necrosis factor and interleukin 6.”
“Yogurt may help strengthen the gut barrier and support Bifidobacterium‘s beneficial role in suppressing Bifidobacterium-positive tumor growth, rather than suppressing Bifidobacterium itself,” she added.
The current study was observational, so the findings only show an association, not a causative relationship, as Balmer-Kemp explained:
“This study suggests that yogurt consumption over time may protect against this specific type of colorectal cancer, potentially via changes in the gut microbiome. The strain of bacteria identified was Bifidobacterium, a bacterial species found in yogurt and also in the human gut.”
“There are different subtypes of Bifidobacterium in the human gut and different strains have different fun
ctions, including the metabolism of dietary carbohydrates, for example. This study did not explore whether there is a causative role for the microbiome, or Bifidobacterium, or any potential mechanisms involved,” she told MNT.
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