Background: Dispositional optimism is a psychological trait that has been associated with positive health outcomes such as reduced risk of cardiovascular diseases. However, there is little knowledge on the relationship between optimism and dietary intake in the population. The objective of this cross-sectional study was to assess whether optimism was associated with overall diet quality, food group consumption and snacking. Methods: In 2016, 32,806 adult participants from the NutriNet-Santé study completed the Life-Orientation Test Revised (LOT-R) which assesses dispositional optimism. Overall diet quality (assessed by the mPNNS-Guideline Score) and consumption of 22 food groups were evaluated using at least three self-reported 24-h dietary records. Snacking behavior was evaluated by an ad-hoc question. Logistic and linear regressions were used to analyze the associations between optimism and these dietary behaviors, taking into account socio-demographic, lifestyle and depressive symptomatology characteristics. Results: Optimism was associated with greater overall diet quality (β (95% CI) = 0.07 (0.004-0.11), P < 0.0001) and higher consumption of fruit and vegetables, seafood, whole grains, fats, dairy and meat substitutes, legumes, nonsalted oleaginous fruits, and negatively associated with consumption of meat and poultry, dairy products, milk-based desserts, sugar and confectionery. In addition, optimism was associated with less snacking (OR (95% CI) = 0.89 (0.84, 0.95)). In contrast, optimism was associated with higher consumption of alcoholic beverage (β (95% CI) = 5.71 (2.54-8.88), P = 0.0004) and appetizers (OR (95% CI) = 1.09 (1.04, 1.14)). Finally, no association was observed between optimism and energy intake. Conclusions: Optimism was associated with better overall diet quality and less snacking. It was also associated with consumption of healthy food groups as well as unhealthy food groups typically consumed in social eating occasions. These findings suggest that optimism could be taken into account in the promotion of a healthy eating behavior.

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