October 24, 2019
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Eating more yogurt, dietary fiber may reduce lung cancer risk

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Adults who consumed large amounts of dietary fiber and yogurt demonstrated decreased risk for lung cancer, regardless of several risk factors, according to results of a pooled analysis published in JAMA Oncology.

“Our findings have no immediate clinical impacts on [patients with] lung cancer, but do have a major public health impact on lung cancer prevention,” Xiao-Ou Shu, MD, PhD, researcher in the division of epidemiology in the department of medicine at Vanderbilt University Medical Center, told HemOnc Today. “Those at high risk for lung cancer, such as current and former smokers and patients with [chronic obstructive pulmonary disease], may consider increasing fiber and yogurt consumption to reduce their lung cancer risk.”

Gut microbes are known to play a significant role in host immune regulation and have been associated with lung inflammation. Prebiotics, supplied by fiber-rich foods, and probiotics, commonly included in yogurt, modulate the gut microbiota and have anti-inflammatory and antioxidant properties, according to Shu.

Shu and colleagues assessed possible associations between dietary fiber and yogurt intake and lung cancer risk in a large consortium study of 627,988 men (mean age, 57.9 years) and 817,862 women (mean age, 54.8 years) from the United States, Europe and Asia. The participants, from 10 prospective cohort studies, completed food frequency and dietary questionnaires, which researchers used to calculate dietary fiber intake and yogurt consumption in grams per day. The investigators identified incident cancer cases and deaths through linkage to registries, follow-up surveys and medical records.

During median follow-up of 8.6 years, researchers identified 18,822 cases of incident lung cancer. Median dietary fiber intake was 18.4 g/day and median yogurt consumption — among the 62.2% of participants who reported eating yogurt — was 23.3 g/day.

Researchers estimated risk for lung cancer associated with dietary fiber and yogurt consumption by Cox regression and pooled estimates using random-effects meta-analysis.

Results showed those who consumed the highest amount of fiber had a 17% lower risk for lung cancer compared with the lowest amount of fiber intake (multivariable-adjusted HR [aHR] = 0.83; 95% CI, 0.76-0.91).

Compared with nonconsumers of yogurt, those who consumed a high amount of yogurt had a 19% decreased risk for lung cancer (aHR = 0.81; 95% CI, 0.76-0.87) and those who consumed a low amount had a 15% decreased risk (aHR = 0.85; 95% CI, 0.81-0.9).

Researchers observed significant inverse associations among white men and women in the highest vs. lowest quintile of fiber intake (aHR = 0.83; 95% CI, 0.75-0.92) and for high amounts of yogurt consumption vs. no yogurt consumption (aHR = 0.82; 95% CI, 0.77-0.88). Compared with those aged older than 57 years, the inverse association of fiber was more pronounced among those aged 57 years or younger (HR = 0.87; 95% CI, 0.79-0.96 vs. HR = 0.75; 95% CI, 0.60-0.92; P = .02 for interaction).

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Further, the association between fiber or yogurt intake and lung cancer risk appeared more evident among consumers of alcohol, particularly heavy alcohol consumers (fiber: HR = 0.77; 95% CI, 0.62-0.96; P= .02 for interaction; yogurt: HR = 0.76; 95% CI, 0.68-0.85; P = .01 for interaction).

Compared with those who did not consume yogurt and had the lowest fiber intake, those who reported a high consumption of yogurt and the highest fiber intake had a 33% decreased risk for lung cancer (HR = 0.67; 95% CI, 0.61-0.73).

In analyses stratified by smoking status of those with the highest fiber intake with yogurt consumption vs. the lowest fiber intake without yogurt consumption, researchers observed HRs of 0.74 (95% CI, 0.67-0.83) for current smokers, 0.66 (95% CI, 0.59-0.73) for former smokers and 0.69 (95% CI, 0.54-0.89) for never smokers.

A lack of data on types and food sources of fiber served as the study’s primary limitation.

“A randomized clinical trial in the high-risk population is highly desirable to establish a causal connection between fiber and yogurt intake and lung cancer,” Shu told HemOnc Today. “Research on whether fiber and yogurt can improve lung cancer prognosis is also needed.” – by Jennifer Southall

For more information:

Xiao-Ou Shu, MD, PhD, can be reached at Vanderbilt University Medical Center, 2525 West End Ave., Suite 600, Nashville, TN 37203; email: xiao-ou.shu@vumc.org.

Disclosures: Shu reports grants from the NIH. Please see the study for all other authors’ relevant financial disclosures.