Low-fat diets significantly reduce lung cancer risk in older adults

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 (over 55 years). Specifically, they assessed changes in lung cancer hazard ratios as a function of long-term (~8.8 years) intake of various fat components (saturated, unsaturated [mono- and polyunsaturated]). To improve accuracy, associations between fat intake and both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) were further examined.

Results of the study show that following low-fat diets significantly reduces the risk of lung cancer across different cancer subtypes. These results and observed benefits were most significant in participants who continued to smoke. In contrast, consuming high levels of saturated fatty acids 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 in 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 regularly ranks among the two most common cancer subgroups worldwide, and its detrimental impact on human health and public well-being is largely attributed to smoking. However, a growing body of scientific evidence reveals the role of healthy 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 major focus in oncology, with studies from European cohorts highlighting the role of retinol, beer/cider and organ meats in increasing cancer risk. At the same time, fiber, fruit and vitamin C reduce this risk. Dietary fat intake has been suggested to be associated with lung cancer pathology, and low-fat diets (LFD) have been suggested to significantly reduce the risk of lung cancer.

Unfortunately, traditional definitions of LFD—less than 30% of calories from total fat intake—do not take into account actual eating habits and therefore are not ideal representations of typical dietary patterns. Moreover, most previous studies either used small cohort sizes or had insufficient follow-up periods, complicating their results.

In the present study, researchers examined the long-term effects of different fat intake (including 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 coming from fat compared to protein and carbohydrates.

The study cohort was derived from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO), a long-term randomized controlled cohort trial conducted by the US National Cancer Institute (NCI). Participants were included in the study if they had no history of cancer at baseline and provided completed demographic and medical reports. Data collection included baseline health assessments and annual surveys, including the Dietary Historical Questionnaire (DHQ) and the Specific Questionnaire (SQX) adapted for the study.

Of more than 155,000 participants enrolled in the PLCO trial, 98,459 met the inclusion criteria and were included in the present study. Of these, 47.96% were male and 92.65% were from the "white" ethnic group. The LFD assessment showed that adherence to the low-fat diet was greatest among older women and participants from non-white ethnic groups, with educational 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

Results of the study suggest that saturated fatty acids (SFAs) may lead to worse cancer outcomes as their consumption significantly increases 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 smoking history, but the benefits of PFA were also most pronounced in this subgroup.

The present study examined long-term associations between dietary fat intake (LFD score) and lung cancer risk. Findings from a large American cohort show a direct association between increased LFD scores and decreased cancer risk, highlighting that low-fat diets may have a protective effect against this disease. It is important to note that while SFAs were strongly associated with increased cancer risk, MUFAs and PUFAs did not show the same patterns. Encouragingly, although smokers were found to be at greatest risk for cancer, the protective effect of LFD adherence was strongest in this cohort.

"With regard 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 adherence to an LFD and reduced SFA intake as a strategy for lung cancer prevention." "