A healthy diet may positively affect the gut microbiome of patients with Parkinson’s disease, according to research published in Nature earlier this year.
The gut microbiome, consisting of bacteria in the gut, may play a role in the development and progression of Parkinson’s through the microbiome’s influence on inflammatory pathways, with resultant alpha-synuclein aggregation in neurons of the enteric nervous system. 1 The “gut-brain” axis, is described as a communication channel implicated in the accumulation of misfolded alpha-synuclein protein (Lewy bodies) in the brain, within dopaminergic neurons of the substantia nigra, which is the pathological hallmark of PD.2
To explore the relationship between diet, the microbiome, and Parkinson’s, researchers assessed fecal samples and diet quality in a subset of 85 patients with Parkinson’s from the Parkinson’s Environment and Gene (PEG) study. Dietary information for the previous month was collected using the Diet History Questionnaire II (DHQ II), which was then used to calculate the Healthy Eating Index (HEI) (score ranges from 0=worst to 100=best). The analysis focused on diet quality and fiber and sugar intake. Fecal samples were assessed using 16S rRNA gene sequencing for microbial diversity.
Mean age at the time of fecal sample collection was 74 years and participants had a mean duration of Parkinson’s of 9.7 years. The study population was mostly male (67%) and of European descent (81%).
The dietary analysis showed that HEI score, fiber intake, and added sugar intake were each associated with beta (between-subject) microbiome diversity (P-trend=0.025, P-trend=0.011, and P-trend=0.044, respectively), supporting the theory that diet affects the microbiome in patients with Parkinson’s. None of these dietary factors were associated with alpha (intra-subject) microbiome diversity.
Higher HEI scores and higher levels of fiber intake were associated with higher levels of short-chain fatty acid (SCFA)-producing bacteria, which are thought to reduce inflammation in the nervous system. Higher sugar intake, however, was associated with lower levels of these bacteria. Higher sugar intake was also associated with higher levels of the pro-inflammatory amyloid-producing bacteria, Klebsiella, which has been shown to increase alpha-synuclein levels in animal models.
Additional sensitivity analyses of patients stratified by constipation status and by Parkinson’s duration (<10 years vs ≥10 years) suggest a weaker association between diet and the microbiome in constipated subjects, and that diet may be more likely to affect the microbiome in early vs later Parkinson’s.
“Overall, our analysis suggests that maintaining a healthy diet may benefit PD patients, with the potential of reducing both motor and non-motor symptoms and slowing disease progression.”
References:
- Wallen, Z.D., Demirkan, A., Twa, G. et al. Metagenomics of Parkinson’s disease implicates the gut microbiome in multiple disease mechanisms. Nat Commun 13, 6958 (2022). https://doi.org/10.1038/s41467-022-34667-x
- Klann EM, Dissanayake U, Gurrala A, Farrer M, Shukla AW, Ramirez-Zamora A, Mai V and Vedam-Mai V (2022) The Gut–Brain Axis and Its Relation to Parkinson’s Disease: A Review. Front. Aging Neurosci. 13:782082. doi: 10.3389/fnagi.2021.782082
