Dietary diversity contributes to microbiome associations in autism

Abstract

Research exploring the links between the microbiome and autism has inadequately considered the contribution of diet diversity. Recently in Cell, Yap et al. addressed the contribution of restrictive dietary patterns to microbiome diversity in autism and found that decreased dietary diversity shapes the microbiome more than previously appreciated.

The complex relationships between brain development, dietary intake, and microbiome diversity in neurotypical development are still poorly understood, making alterations in these pathways that contribute to the development of ASD nearly impossible to identify without consideration and careful concurrent measurement of these potential influential factors. The first 5 years of life are characterized by rapid brain growth and underlying cellular neurodevelopmental processes. During the same period dietary exposures change from exclusive diets of breastmilk and/or formula to the introduction of complementary foods and the development of independent food choices. These changes in diet have also been linked with variation in microbiome composition with a transition from a Bifidobacterium-dominant community to a more adult-like composition corresponding with intake diverse dietary fibers (Roswall et al., 2021). Yap et al. propose a model where autism spectrum disorder is upstream of the development of restrictive eating traits and sensory preferences that result in lowered dietary diversity and ultimately lead to a reduction in taxonomic diversity and changes in stool consistency. According to this model optimal ASD interventions may benefit from strategies to increase diet diversity to improve GI symptoms. Although this approach may successfully alleviate GI discomfort, it is unclear from this work whether it would also improve the core behavioral phenotypes, or when such strategies should be implemented (i.e., during infancy) to prevent severe symptoms.