Even among smokers, people who eat more fibre and yogurt may be
less likely to develop lung
cancer than those who don’t consume much of these foods,
a research review suggests.
Researchers examined pooled data from
10 previous studies that
included a total of almost 1.45 million adults in Asia, Europe, and the United
States. After following people for an average of 8.6 years, 18,822 cases
of lung cancer were documented.
Compared to people who never ate yogurt, those who consumed the
most yogurt were 19 per cent less likely to develop lung cancer, the analysis
found.
People who had the most fibre in their diets, meanwhile, were 17
per cent less likely to develop lung
cancer than those who ate the least fibre.
And individuals with the highest fibre intake and highest yogurt
consumption were 33 per cent less likely than those with the lowest consumption
of both to develop lung cancer, the study team reports in JAMA Oncology.
“Our study suggests a potential novel health benefit of increasing
dietary fibre and yogurt intakes in lung cancer prevention,” senior study
author Xiao-Ou Shu of Vanderbilt University Medical Center in Nashville,
Tennessee, and colleagues write.
While the study wasn’t a controlled experiment designed to prove
yogurt or fibre protects against lung cancer, it’s possible these kinds of
foods might lead to changes in the gut microbiota — the bacteria living in our
digestive tract — that help protect against cancer, the study authors
hypothesize.
It’s also possible fibre and yogurt might help protect against
inflammation, which in turn helps reduce the potential for tumors to develop,
the researchers note.
Fibre-rich foods typically have lots of prebiotics, nondigestable
compounds that can be fermented in the gut and serve as food for beneficial
bacteria, the authors note. Yogurt has lots of those beneficial bacteria, or
probiotics.
Considerable research links the gut microbiota to the immune
system overall. And some recent studies have suggested that the gut microbiota
may play a role in lung inflammation, the study authors point out.
The reduced risk of lung cancer associated with fibre and yogurt
in the study persisted even after researchers accounted for smoking habits.
For people who never smoked, the lung cancer risk reduction
associated with the highest levels of yogurt and fibre consumption was 31 per
cent, while for smokers it was 24 per cent and for former smokers, 34 per cent.
The researchers point out that they didn’t know what type of fibre
people consumed or which types of foods they ate to get their fibre, or the
type or fat content of any yogurt people ate.
They also lacked data on some other risk factors for lung cancer,
including low income or limited education levels as well as any history of
chronic obstructive pulmonary disorder.
Even so, the authors conclude it’s worth considering the potential
protective effect of yogurt and fibre.
“For the first time to our knowledge, a potential synergistic
association between fibre and yogurt intakes on lung cancer risk was observed,”
the study authors write.