A diet high in fiber and yogurt has been associated with a reduced risk of lung cancer in a major study of over 1.44 million adults around the world.
The study pooled data from 10 prospective cohort studies that recorded dietary information and cases of lung cancer in the USA, Europe and Asia. People taking part in the studies filled in a dietary questionnaire at the start and were followed up for an average of 8 years.
For the analysis, the participants were divided into 5 groups based on the amount of fiber they ate (lowest to highest), and into 3 groups based on their yogurt consumption (none, low, high).
Dietary fiber, yogurt and lung cancer risk
When it came to analyzing the results, the researchers adjusted for a wide range of known risk factors for lung cancer, such as smoking and saturated fat excess, so that differences in these factors didn’t interfere with the results.
People eating the highest amount of fiber were 17% less likely to develop lung cancer than people eating the least. People eating the most yogurt were 19% less likely to develop lung cancer than those who ate none.
People with the highest intakes of both fiber and yogurt in their diet showed the greatest reduction in risk – on average the likelihood of them developing lung cancer was reduced by one-third compared with people who didn’t eat any yogurt and had the lowest intake of fibre.
Could prebiotics and probiotics explain the association?
Fiber is a source of prebiotics, which are non-digestible materials that feed ‘friendly’ bacteria among the gut microbiota. Probiotics are beneficial live bacteria found in foods such as yogurt. Eating prebiotics and probiotics can help to establish a healthy gut microbiota.
The composition of the gut microbiota may help to maintain a healthy immune system, which is important in our defence against cancer.
Recent evidence shows that metabolites produced by the gut microbiota, including short-chain fatty acids, can suppress lung inflammation, which may play a key role in lung cancer development. Prebiotics and probiotics have anti-inflammatory properties, and high intakes of dietary fiber and yogurt have previously been shown to have anti-inflammatory effects, say the authors.
‘Dietary fiber and yogurt consumption was associated with reduced risk of lung cancer after adjusting for known risk factors and among never smokers. Our findings suggest a potential protective role of prebiotics and probiotics against lung carcinogenesis.’ – Yang JJ et al, 2019.