Abstract / Summary
Abstract Fruit and vegetable intakes have been associated with reduced risk of depressive symptoms in observational studies, potentially due to anti-inflammatory properties, micronutrient content, and effects on the gut-brain axis. Understanding the genetic and environmental influences on these intakes may provide insight into factors influencing dietary behaviour. Participants were 5,789 individual twins (aged 45–90 years, 51.8% female; 2,208 monozygotic; 3,581 dizygotic) drawn from four international community-based cohorts. Consumption of fruit and vegetables was self-reported via food frequency questionnaires and depressive symptoms were measured with validated scales. Structural equation models were used to estimate the proportion of variation in intakes and depressive symptoms contributed by genetic and environmental influences, as well as assess genetic and environmental influences shared by fruit and vegetable intakes and depressive symptoms. Reported intakes and depressive symptoms were generally low (fruit 1.1 serves/day IQR 1.5, vegetables 1.7 serves/day IQR 1.3, depressive symptoms median 18 IQR 4 on a scale of 17–49). Heritability was 25% (95% CI 0.16, 0.34) for fruit intake, 17% for vegetable intake (95% CI 0.09, 0.25) and 29% for depressive symptoms (95% CI 0.19, 0.38). No shared environmental influences were detected. A weak-to-moderate positive genetic correlation was found between fruit and vegetable intakes and weak negative genetic correlations between each intake and depressive symptoms. These findings suggest low-to-moderate heritability of fruit and vegetable intakes and depressive symptoms. Shared genetic influences may exist, but do not imply causality. Longitudinal studies, including co-twin control designs, are needed to clarify the direction and nature of these associations.