The probiotics and prebiotics of yogurt and fiber consumption is associated with decreased risk of lung cancer—especially when combined at the greatest dietary amounts, according to a new study.
The men and women who consumed the most fiber and yogurt combined showed a greater than 30% reduced risk of lung cancer than the group that ate the least, according to results published in JAMA Oncology.
“Dietary fiber and yogurt consumption was associated with reduced risk of lung cancer after adjusting for known risk factors and among never smokers,” concluded the study authors. “Our findings suggest a potential protective role of prebiotics and probiotics against lung carcinogenesis.”
The meta-analysis focused on 10 prospective cohort studies involving more than 1.44 million adults from the United States, Europe, and Asia. The observations came from the National Institutes of Health’s AARP Diet and Health Study, the Nurses’ Health Study, the European Prospective Investigation into Cancer and Nutrition (EPIC), among others.
Excluded from inclusion were patients with cancer history, according to the study.
A majority of the subjects were female (n = 817,862; median age, 54.8 years), while men (n = 627,988) were slightly older (median age, 57.9 years).
The cancer risk was calculated by hazard ratios to a 95% confidence interval (CI). Risk factors like smoking status and pack-years were adjusted, and a Cox regression model was employed. The data was pooled using random-effects meta-analysis tools, the study authors explained.
The median follow-up period was 8.6 years. During the observation, 18,822 lung cancer cases were diagnosed.
Food frequency questionnaires and other data determined lifestyle patterns. For instance, the median intake of fiber was 18.4 grams per day for the whole group.
Both fiber and yogurt intakes were inversely associated with lung cancer risk after adjustment for status and pack-years of smoking and other lung cancer risk factor (HR, 0.83; 95% CI, 0.76-0.91) for the highest vs lowest quintile of fiber intake and for high vs no yogurt consumption (HR, 0.81; 95% CI, 0.76-0.87).
The biggest statistical effect was found to be those combining the most fiber and yogurt consumption—suggesting “potential synergism,” the study authors wrote. The most yogurt consumption with the highest quintile of fiber intake correlated with a better than 30% reduced risk of lung cancer than the lowest consumers of yogurt and fiber (HR, 0.67; 95% CI, 0.61-0.73) in total study populations and in never smokers (HR, 0.69; 95% CI, 0.54-0.89).
The exact biological reason for the overall linkage remains unclear.
“The health benefits of fiber and yogurt may be rooted in their prebiotic and probiotic properties, through which they independently or synergistically modulate gut microbiota,” the study authors wrote. “Dietary fiber is nondigestible by humans but can be fermentable by gut microbiota to generate short-chain fatty acids. Emerging evidence has suggested that the beneficial effects of short-chain fatty acids on host immune and metabolism are not restricted to the gut but reach various organs, including the lungs.”
Yang J, Yu D, Xiang Y, et al. Association of Dietary Fiber and Yogurt Consumption With Lung Cancer Risk. JAMA Oncol. doi:10.1001/jamaoncol.2019.4107.