The researchers looked at diets and the subsequent development of different types of the growths, or adenomas, in almost 90,000 male and female subjects.
Compared with men who didn’t eat yogurt, those who ate two or more servings a week were less likely to develop adenomas that were highly likely to become cancerous.
The observed associations were strongest for adenomas that will probably become cancerous, and for those located in the colon rather than in the rectum, the findings indicate.
Previously published research has suggested that eating a lot of yogurt might lower the risk of bowel cancer by changing the type and volume of bacteria in the gut.
But it’s not been clear whether yogurt intake might also be associated with a lower risk of pre-cancerous growths, known as adenomas.
All the study participants had had a lower bowel endoscopy between 1986 and 2012. Every four years they provided detailed information on lifestyle and diet, including how much yogurt they ate.
Compared with men who didn’t eat yogurt, those who ate two or more servings a week were 19% less likely to develop a conventional adenoma.
This lower risk was even greater—to the tune of 26%—for adenomas that were highly likely to become cancerous, and for those located in the colon rather than in the rectum.
While no obvious association was seen for men with the potentially more dangerous serrated adenoma, a trend towards reduced risk was seen for those measuring 1cm or more, which is considered to be large.
No such associations between yogurt intake and the development of adenomas were evident among the women.
As an observational study, its findings can’t establish cause. Further research would be needed to confirm the findings and uncover the biology involved, emphasised the researchers.
But the large number of people studied and the regular updates on diet and lifestyle factors add heft to the findings, they suggest.
By way of a possible explanation for what they found, the researchers point out that Lactobacillus bulgaricus and Streptococcus thermophilus, two bacteria commonly found in live yogurt, may lower the number of cancer-causing chemicals in the gut.
And the stronger link seen for adenomas growing in the colon may partly be due to the lower acidity in that part of the gut, making it a more hospitable environment for these bacteria, the researchers added.
Alternatively, yogurt may have anti-inflammatory properties and may reduce the “leakiness” of the gut as adenomas are associated with increased gut permeability, the findings suggested.
“Yogurt consumption and risk of conventional and serrated precursors of colorectal cancer”
Authors: Xiaobin Zheng, et al.