Scientific Study

Objectives: Many dietary guidelines encourage nut intake. However, the role of nuts in environmentally sustainable diets has been questioned due to their water-intensive agricultural demands. Nuts are condensed sources of protein and fats, making them a reasonable replacement for protein and fat-rich animal foods, thus potentially influencing a diet’s environmental sustainability. The proposed study aims to assess if self-selected nut-rich diets as a whole in the general population have any environmental advantage compared to diets with low nut intake. This study will further explore sustainable practices based on food-related behaviors. Methods: We are preparing a cross-sectional study among free-living individuals. Building upon a validated, online semi-quantitative food frequency questionnaire, we are developing a novel approach to assess the environmental impacts of food-related practices. The environmental impacts, comprising land use, water consumption, and global warming potential, will be assessed using the food-specific impacts previously determined by our group (Berardy et al., Sustainability, 2020, 12, 10267). Based on established coefficients, we will further adjust those food impacts based on the individual food practices specific to each food group. These include food purchasing preferences (frozen versus fresh, single-serving versus bulk), food waste, and cooking practices, among others. By multivariate linear regression models, we will conduct energy-adjusted comparisons between the diets on different levels of nut intake and account for covariates. We will recruit subjects via email using a recruitment database. The target population is adult California residents with stable body weight and dietary practices. Given the expected differences in the three environmental impacts among diets for a power > 80%, a sample size of 550 subjects is estimated. Results: N/A. Conclusions: The novelty of the described protocol centers on quantifying food intake in a single online survey while simultaneously measuring diet-related sustainable practices. The study is in development and will elucidate the sustainability of self-selected diets high in nuts. If successful in our endeavors, similar methods could be used in the future to assess the sustainability of different diets.