Can your diet help you live longer? New research reveals that sticking to France’s national nutrition guidelines lowers the risk of early death—except in an unexpected twist for lung cancer.
Study: Adherence to French dietary guidelines is associated with a reduced risk of mortality in the E3N French prospective cohort. Image Credit: ONYXprj / Shutterstock
In a recent study published in the Nutrition Journal, researchers examined the relationship between adherence to the 2017 French dietary guidelines and mortality risk among participants in the Etude Epidémiologique auprès de femmes de l'Éducation Nationale (E3N) French prospective cohort.
Background
Can your diet determine how long you live? Non-communicable diseases (NCDs) cause over 74% of global deaths, according to the World Health Organization. While diet is a key risk factor, NCDs result from multiple influences, including genetics, physical activity, and environmental exposures. In France, nine of the top ten causes of death are linked to NCDs, like cardiovascular disease, cancer, and diabetes. Diet is one of the most powerful tools for disease prevention, yet many struggle to follow national dietary guidelines.
The 2017 French dietary guidelines promote whole foods like fruits, vegetables, whole grains, and lean proteins while limiting processed foods, red meat, and added sugars. However, their actual impact on longevity remains unclear. If these guidelines truly enhance survival, should governments and communities do more to encourage adherence?
Despite strong evidence linking diet to health, gaps remain in understanding how different levels of adherence impact specific types of mortality, particularly cause-specific cancer deaths. Further research is needed to refine dietary recommendations, identify factors influencing these associations, and assess the sustainability of these guidelines across diverse populations.
About the Study
The present study was conducted using data from the E3N French prospective cohort, which initially enrolled 98,995 women in 1990. From this cohort, 72,585 women who completed a food frequency questionnaire in 1993 were selected for analysis.
These participants provided self-reported dietary intake data, which was assessed using a validated semi-quantitative questionnaire containing 208 food items. The adherence to the 2017 French dietary guidelines was evaluated using the simplified Programme National Nutrition Santé-Guidelines Score 2 (sPNNS-GS2), which ranged from -20.4 to 12.6.
Mortality data were obtained from the French Epidemiology Center on Medical Causes of Death (Inserm-CépiDc). Cox proportional hazard models were used to estimate the association between sPNNS-GS2 and all-cause as well as cause-specific mortality. Models were adjusted for confounding factors, including age, birth cohort, body mass index, physical activity, smoking status, education level, menopausal status, and total energy intake.
To account for potential exposure to dietary chemical contaminants, sensitivity analyses were conducted by adjusting the models for dietary exposure to mixtures of food contaminants. These analyses confirmed that the observed associations remained robust. Statistical analyses were performed using SAS 9.4 and R 4.1.2, with significance set at p < 0.05.
Study Results
During an average follow-up period of 19 years, 6,441 deaths were recorded among the study participants. The mean sPNNS-GS2 score was 3.8 (Standard Deviation (SD) 3.0). Higher adherence to the French dietary guidelines was associated with a lower mortality risk from various causes.
The relationship between sPNNS-GS2 and mortality was found to be non-linear. Significant associations were observed up to the 65th percentile of the score, beyond which the benefit stabilized or, in some cases, reversed.
For individuals, these findings suggest that consistently making healthier food choices can significantly extend lifespan. Those who followed the guidelines closely had a lower risk of death from cardiovascular diseases and certain cancers, such as breast cancer.
However, for lung cancer, the risk reduction was observed up to the 65th percentile of adherence, after which the trend reversed. This reversal was described in the study as a statistical non-linearity, though the underlying reasons remain uncertain.
For all-cause mortality, a higher sPNNS-GS2 score was linked to a decreased risk, stabilizing beyond the median value. A similar trend was observed for all-cancer mortality, but at high adherence levels, the protective effect diminished, consistent with the study’s findings of non-linearity rather than an external confounding factor.
Breast cancer mortality followed a pattern of risk reduction up to the median adherence score, while lung cancer mortality exhibited a complex non-linear trend beyond high adherence levels rather than a clear confounding effect.
Conversely, cardiovascular disease mortality demonstrated a linear inverse relationship with sPNNS-GS2, indicating a consistent decrease in risk with higher adherence (hazard ratio per SD increase: 0.86 [95% CI: 0.76-0.97]).
No significant association was found between adherence to the dietary guidelines and colorectal cancer mortality.
Sensitivity analyses confirmed that adjusting for dietary exposure to chemical contaminants did not significantly alter these findings, reinforcing the robustness of the observed associations. Further subgroup analyses confirmed that adherence to dietary guidelines was protective across different population groups, though the study did not emphasize lifestyle factors such as smoking and physical activity as primary effect modifiers.
Conclusions
To summarize, higher adherence to the 2017 French dietary guidelines was associated with a reduced risk of mortality from all causes, cardiovascular diseases, and specific cancers such as breast and lung cancer.
However, for lung cancer mortality, the association reversed at high adherence levels, which the study attributes to statistical non-linearity rather than a confounding effect.
These findings underscore the crucial role of nutrition in public health. On an individual level, they highlight the importance of making informed dietary choices to improve longevity. For communities, they emphasize the need for better education and access to nutritious food. Globally, they serve as a call to action for policymakers to promote dietary guidelines through public health initiatives.