Diet quality and environmental sustainability across vegan, vegetarian and omnivorous adults: A cross-sectional analysis

Dietary habits significantly affect not only individuals’ health but also environmental sustainability indicators such as carbon emissions and water usage. This study aimed to evaluate diet quality and environmental effects in vegan, vegetarian and omnivorous adults. This cross-sectional study included 77 vegans, 28 vegetarians and 72 omnivores. Healthy eating index (HEI) was used to determine the diet quality of individuals. Carbon and water footprint values were calculated. In HEI scores, it was determined that vegans and vegetarians had higher scores than omnivores in whole fruits, total vegetables, greens and beans and seafood and plant protein scores (p < 0.05). Omnivores had highest values ​​in carbon footprint and vegans had lowest values, while omnivores had the highest values in water footprint and vegetarians had the lowest values ​​(p < 0.05). Carbon footprint values ​​had a negative relationship with whole fruits scores, total vegetables scores, greens and beans scores, whole grains scores, seafood and plant protein scores and fatty acids scores; and a positive relationship with dairy scores, total protein scores, refined grains scores, added sugars scores and saturation fats scores (p < 0.05), while water footprint values ​​had a negative relationship with whole fruits scores, total vegetables scores, whole grains scores and saturation fats scores; and a positive relationship with dairy scores, total protein scores, refined grains scores, added sugars scores and saturation fats scores (p < 0.05). These study findings showed that diet quality and diet type are determinants of carbon and water footprint values.