The association between obesity and cancer is well-documented, sparking additional interest in understanding whether cancer risk is also influenced by diet. While smoking’s connection to lung cancer has been thoroughly established for many years, other lifestyle elements, such as diet, have not garnered the same level of attention.

One significant observational study focusing on older Americans found that individuals on a low-fat diet had a reduced risk of lung cancer, while those consuming high-fat diets—in particular, smokers—faced a heightened risk. This suggests a potential protective role of a low-fat diet against lung cancer in this demographic.

A team of researchers from China analyzed data from over 98,000 participants in the U.S.-based cancer study. Their analysis revealed a 24% lower risk of developing lung cancer among individuals with the lowest fat consumption. These effects were even more striking in smokers, who experienced a 29% reduction in risk when following a low-fat diet. The research, highlighted in *The Journal of Nutrition, Health and Aging*, further indicated that high saturated fat intake was linked with a 35% increased risk of lung cancer and a twofold increase in small-cell lung cancer risk.

This data came from the Prostate, Lung, Colorectal, and Ovarian Cancer Survey—a large-scale cohort study. Participation spanned from late 1993 through mid-2001, with cancer-related data, including incidence and mortality rates, being monitored up until 2018. Participants provided comprehensive medical information, alongside detailed dietary surveys outlining their intake of calories, macronutrients, and various food groups, such as fruits, vegetables, meat, and dairy products.

The study cohort had a mean age of 65 and predominantly consisted of white participants, with close to 48% being male. Upon examining lung cancer rates, the researchers accounted for potential confounding factors such as physical activity, age, education level, BMI, smoking status, and even aspirin use.

Analysis of the data revealed that individuals in the top quartile for low-fat diet adherence were older, predominantly female, and typically possessed higher levels of education. Moreover, these individuals were more active, had lower BMIs, and consumed lower amounts of sodium and cholesterol. Those adhering to higher-fat diets were more likely to be white and male, and exhibited less healthy lifestyle behaviors such as lower physical activity levels.

Interestingly, the data demonstrated a consistent, linear correlation between low-fat diets and reduced lung cancer risk. This trend was particularly apparent among smokers, with high-fat diets showing a pronounced connection to elevated risks in small-cell lung cancer.

‘A noteworthy discovery related to lung cancer’: The research team emphasized that these findings align with other studies that associate low-fat diets with reduced cancer risk. They highlighted parallel evidence from a UK Biobank study, which found that red and processed meats are similarly linked to increased lung cancer incidence.

However, their study is the first to explore the specific impact of low-fat diets on lung cancer risk, they claimed. Commenting on this, Dr. Nilesh Vora, a hematologist and oncologist from MemorialCare Todd Cancer Institute, who wasn’t involved in the research, told Medical News Today that he found these findings notable:

“It is intriguing to see such a clear relationship specifically with lung cancer. While we’ve known about high-fat diets and obesity being linked to breast cancer recurrence, I haven’t seen this kind of data concerning lung cancer before.”

The study didn’t elaborate on why the low-fat-diet effect appeared more pronounced in smokers. Vora suggested that various hypotheses could be formulated, speculating that smoking may trigger mutations and inflammation within cells, potentially exacerbated by fat consumption.

Why might low-fat diets reduce lung cancer risk? Historically, lung cancer has been stigmatized—largely because of its strong association with smoking and the perception that it’s a preventable disease. This study is a novel step toward understanding how dietary fats could influence lung cancer risk. The authors propose that these findings may lead to dietary recommendations geared toward smokers, with particular emphasis on avoiding saturated fats, which are correlated with increased lung cancer risk. Notably, polyunsaturated and monounsaturated fats didn’t show the same harmful association.

Catherine Rall, a registered dietitian based in Denver, CO, who was not involved in the research, proposed an explanation: “Saturated fats might play a key role here, as they can trigger inflammation—an underlying factor in many cancers. It seems plausible that reducing both overall fat intake and specifically saturated fats would lower the risk of cancer, including lung cancer. Especially among smokers, dietary choices could be a significant determinant in their potential cancer development.”

Rachelle Caves, another dietitian and fitness consultant from Massachusetts, agreed with Rall’s assessment. She added, “Given the inflammatory potential of high-saturated-fat foods, it’s no surprise to see that they are linked to increased cancer risk. Conversely, foods low in saturated fats, such as beans, fruits, lentils, and vegetables, are typically seen as protective when it comes to cancer prevention.”

Finally, while Dr. Vora finds the study compelling, he also cautioned against drawing definitive conclusions without further research: “The next logical step would be exploring the idea through a randomized control trial—something that wasn’t part of this prospective observational study, which can inherently present challenges in data collection. Nevertheless, the results are certainly thought-provoking.”