Maternal Diet and the Microbiome: How Dietary Patterns May Influence Child Neurodevelopment

A new review paper in Frontiers in Cellular Neuroscience examines how a mother’s diet changes her gut bacteria—and through them may influence her child’s risk of autism spectrum disorder (ASD). The authors go over the “popular culprits”—too much sugar, salt, and fat, alcohol, too little fiber, and ultra-processed foods—and explain the chains of events that these diets trigger in the microbiota and immune system, and then in the developing brain. This isn’t a human experiment, but an analysis of cumulative data (much of it from animal models), so it’s about associations and plausible mechanisms, not direct evidence of causality.

What exactly was dismantled?

• #Sugar, #salt, #fat: such diets deplete microbial diversity, increase intestinal permeability and promote chronic inflammation. In experiments, key bacterial groups change (for example, Lactobacillus/Bifidobacterium falls), short-chain fatty acids (SCFAs) shift, which affects immune regulation.
• #Alcohol: Distorts the composition of the microbiota, increases barrier leaks, and can alter the composition of breast milk—another way it can affect the infant's microbiome.
• #Low fiber: deprives bacteria of “fuel” for synthesizing beneficial fatty acids (acetate, propionate, butyrate), which feed intestinal cells, reduce inflammation and indirectly affect the brain.
• #Ultraprocessed foods (UPF): a combination of refined ingredients and additives is associated with adverse microbiota and metabolite shifts; the authors discuss such a diet as an additional stressor of the gut-brain axis.

How can this reach a child's brain?

The authors draw several “bridges” from the mother’s plate to the fetus’s nervous system:

• Gut-placenta axis and breastfeeding. Maternal microbiota and its metabolites (SCFA, bile acids, etc.) can influence inflammatory signals and barriers, and after birth, they can reach the infant through milk.
• Immune activation. Dysbiosis → leakage of bacterial molecules → systemic inflammation in the mother. Such an environment is associated with the risk of neurodevelopmental disorders in models.
• Neurotransmitters and their precursors. Microbes are involved in the metabolism of tryptophan (serotonin/quinuenine), GABA, and glutamate; imbalance in these pathways is one suspected mechanism.
• Microbial metabolites. Excess/deficiency of SCFA and other compounds can change immune and neuroglial responses, and therefore the “tuning” of developing brain circuits.

What does this mean in practice (with caveats)

The authors formulate their recommendations cautiously: during pregnancy, it is worth relying on diets high in fiber (vegetables, fruits, legumes, whole grains), limiting added sugar, salt, saturated fats and FFAs, and completely eliminating alcohol. Microbiome-targeted approaches (prebiotics/probiotics) are also discussed, but it is emphasized that clinical trials are needed to understand who, when, and what interventions are truly beneficial.

Important "buts"

• This is a review: it has a lot of data from animal models and observational studies in humans. It does not prove cause and effect, but rather summarizes the most plausible associations and mechanisms. Long-term cohort studies and randomized trials of diets/probiotics in pregnant women are needed.
• Autism is a multifactorial condition: genetics, environment, infections, stress, etc. Nutrition and the microbiome are only part of the big picture.