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Low-fat diets significantly reduce the risk of lung cancer in older adults
Last reviewed: 02.07.2025
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In a recent study published in The Journal of Nutrition, Health and Aging, researchers examined the association between dietary habits and lung cancer risk in a large cohort of older Americans (aged 55 years and older). Specifically, they estimated the change in lung cancer hazard ratios based on long-term (~8.8 years) intake of different fat components (saturated, unsaturated [mono- and polyunsaturated]). To improve precision, they further examined the associations between fat intake and both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).
The results of the study show that low-fat diets significantly reduce the risk of lung cancer across different cancer subtypes. These results and the observed benefits were most significant in participants who continued to smoke. In contrast, high saturated fatty acid intake was associated with an increased risk of lung cancer in the cohort studied.
Lung cancer is one of the leading non-communicable causes of death among humans, with the Global Cancer Observatory (GLOBOCAN) estimating 2.2 million new cases and 1.8 million deaths from the disease in 2020 alone. Lung cancer is consistently ranked among the two most common cancer subgroups worldwide, and its detrimental impact on human health and societal well-being is largely attributed to smoking. However, a growing body of scientific evidence is revealing the role of health habits, particularly sleep patterns and dietary habits, in the development and progression of lung cancer.
Research examining the relationship between dietary elements and lung cancer is currently a focus of oncology, with studies of European cohorts highlighting the role of retinol, beer/cider and organ meats in increasing cancer risk. At the same time, fibre, fruit and vitamin C reduce this risk. Dietary fat intake has been suggested to be associated with lung cancer pathology, and low-fat diets (LFDs) are thought to substantially reduce lung cancer risk.
Unfortunately, traditional definitions of LFD—less than 30% of calories from total fat intake—do not account for real-world dietary habits and are therefore not ideal representations of typical dietary patterns. Moreover, most previous studies either used small cohort sizes or had insufficient follow-up periods, which hampers their findings.
In the current study, the researchers examined the long-term effects of different fat intakes (including a modified LFD score) on lung cancer and its subtypes (SCLC and NSCLC) in a large cohort. The new LFD score is based on the percentage of calories from fat compared to protein and carbohydrates.
The study cohort was derived from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening (PLCO) trial, a long-term randomized controlled cohort trial conducted by the U.S. National Cancer Institute (NCI). Participants were included in the study if they had no history of cancer at baseline and provided complete demographic and medical reports. Data collection included baseline health assessments and annual surveys, including the Dietary History Questionnaire (DHQ) and the Special Health Questionnaire (SQX) adapted for the study.
Of the over 155,000 participants enrolled in the PLCO trial, 98,459 met inclusion criteria and were included in the present study. Of these, 47.96% were men and 92.65% were white. Evaluation of the LFD showed that adherence to the low-fat diet was highest in older women and non-white participants, with education level playing a significant role in LFD adherence (direct relationship).
During a follow-up period of 8.83 years, 1,642 patients developed lung cancer (1,408 with NSCLC and 234 with SCLC).
"In the fully multivariable model, participants in the highest quartile had a reduced risk of lung cancer compared with the lowest quartile (HR Q4 vs. Q1 = 0.76, 95% CI: 0.66−0.89, P < 0.001 for trend). Additionally, there was an inverse association between the LFD score and the risk of NSCLC (HR Q4 vs. Q1 = 0.79, 95% CI: 0.67−0.93, P = 0.001 for trend) and SCLC (HR Q4 vs. Q1 = 0.59, 95% CI: 0.38−0.92, P = 0.013 for trend)."
The study results suggest that saturated fatty acids (SFA) may be associated with worse cancer outcomes, as their consumption significantly increased the risk of lung cancer. In contrast, such associations were not observed for monounsaturated (MUFA) or polyunsaturated fatty acids (PUFA). Encouragingly, the highest incidence of lung cancer was observed in subgroups with a current or past history of smoking, but the benefits of PFA were also most pronounced in this subgroup.
The present study examined the long-term associations between dietary fat intake (LFD score) and lung cancer risk. The results of this large US cohort show a direct association between increasing LFD score and decreased cancer risk, highlighting that low-fat diets may have a protective effect against this disease. Importantly, while SFA were strongly associated with increased cancer risk, MUFA and PUFA did not show the same pattern. Encouragingly, although smokers were at highest risk for cancer, the protective effect of LFD adherence was strongest in this cohort.
"With respect to dietary fatty acids, high SFA intake may contribute to an increased risk of lung cancer, with a higher risk observed for SCLC in particular. Therefore, our findings support the potential benefits of adhering to an LFD and reducing SFA intake as a strategy for preventing lung cancer."