Eating yoghurt could reduce the risk of pre-cancerous growths, called adenomas, that precede the development of bowel cancer in men, according to a new study published on 17 June in the journal Gut (1).
The researchers from the Univerity of Washington in the US looked at the diets and whether men and women developed different types of adenoma — data on 32,606 men who were part of the Health Professionals Follow Up Study and 55,743 women who were part of the Nurses Health Study.
All patients underwent bowel endoscopies between 1986 and 2012. The procedure allows the surgeon to look inside the gut. And among the patients, 5811 adenomas in men and 8116 adenomas in women were found. Data also included detailed information on lifestyle and diet, including yoghurt consumption.
But interestingly, the researchers discovered that men who consumed more than 2 servings per week had a lower risk of adenoma. More specifically, 19% less likely and even higher(26%) for adenomas most likely to become cancerous. No clear correlation was found in men with the potentially more dangerous type of adenoma, known as serrated, except in the case of large adenomas, 1 cm or larger.
It is important to note that the study is observational and therefore, it is not possible to determine a cause for the association. More research is still needed to confirm the findings and to elucidate underlying biological mechanisms that may lead to differences between genders and the anatomical location in the gut. Although the large size of the study and the amount of data involved do add some weight to the findings, the authors suggest.
Eating yoghurt is known to alter the bacteria in the gut in a positive way, both the type microbes and volume and might even lower the risk of bowel cancer, according to previous studies. Furthermore, the researchers add that two of the bacteria commonly found in live yoghurt — Lactobacillus bulgaricus and Streptococcus thermophilus — may lower the number of cancer-causing chemicals in the intestines.
The findings suggest the association may be strongest for so-called adenomas located in the colon rather than in the rectum. This might be because this part of the gut has a lower pH (more acidic), which creates a more hospitable environment for these bacteria. The researchers also add that yoghurt, which potentially has anti-inflammatory properties, could reduce the increased gut permeability associated with adenomas.
So, can eating two or more weekly servings of yoghurt prevent bowel cancer? Possibly not. And too much of a good thing can have negative effects, too. Another recent study showed that probiotics ― “good bacteria” ― including those found in yoghurt can become ineffective, or even harmful, in the human gut. Nonetheless, findings, like these and others, highlight the importance of diet on our overall health.
(1) Zheng, X. et al. Yogurt consumption and risk of conventional and serrated precursors of colorectal cancer. Gut (2019). DOI: 10.1136/gutjnl-2019-318374