GUT INFLAMMATION in Parkinson’s disease (PD) may be improved by branched-chain amino acids (BCAAs), according to new preclinical research investigating the gut–immune axis in neurodegenerative disease.
Parkinson’s Disease and Gut Immune Dysfunction
PD is increasingly recognised as a systemic condition extending beyond motor symptoms. Gastrointestinal complications, particularly constipation, are among the earliest and most common non-motor manifestations, often appearing years before neurological decline becomes evident.
Previous studies have suggested that gut microbiota disruption contributes to immune dysregulation in PD. BCAAs, essential amino acids produced partly through microbial metabolism, have also been implicated in immune homeostasis and T-cell regulation.
However, the relationship between BCAAs, gut inflammation, and constipation symptoms has remained poorly understood.
BCAAs Improved Constipation Symptoms in Parkinson’s Disease
In the new study, researchers used a chronic MPTP-induced mouse model of PD and observed persistent constipation symptoms alongside significant immune imbalance.
Increased infiltration of pro-inflammatory T helper 1 (Th1) and T helper 17 (Th17) cells was identified in the colonic lamina propria, mesenteric lymph nodes, and spleen.
Metagenomic and metabolomic analyses revealed that microbial dysbiosis favoured BCAA degradation rather than biosynthesis, leading to lower circulating BCAA concentrations in serum.
Following BCAA supplementation, constipation symptoms improved significantly.
Researchers also observed marked reductions in inflammatory CD4+ T-cell infiltration across gut-associated immune tissues, suggesting that BCAAs may help restore immune balance within the gastrointestinal tract.
Future Research on BCAAs
While the findings were limited to a mouse model, the study provided further insight into how altered microbial BCAA metabolism and immune dysfunction may contribute to gastrointestinal symptoms in PD.
Future studies will be needed to determine whether similar immune and metabolic alterations are present in patients and whether these changes are associated with gastrointestinal symptom severity.
Further clinical research will also be required to establish whether BCAA supplementation could have a role in managing gastrointestinal symptoms associated with PD.
The findings add to growing research into the role of gut microbiota and immune signalling in PD and other neurodegenerative conditions.
Reference
An K et al. Branched-chain amino acids ameliorate CD4+ T-cell-associated gut immune inflammation in Parkinson’s disease. npj Parkinsons Dis. 2026;DOI:10.1038/s41531-026-01375-y.
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