Researchers have long suspected that the link between our gut and brain plays a role in Parkinson's disease development. A recent study has identified gut microbes likely involved and linked them to decreased riboflavin (vitamin B2) and biotin (vitamin B7), suggesting a potential treatment: B vitamins.

"Supplementation of riboflavin and/or biotin is likely to be beneficial in a subset of Parkinson's disease patients, in which gut dysbiosis plays pivotal roles," writes Nagoya University medical researcher Hiroshi Nishiwaki and colleagues in their published paper.

The neurodegenerative disease affects almost 10 million people globally, with therapies aimed at slowing and alleviating symptoms being the best hope.

Symptoms often begin with constipation and sleep problems up to 20 years before progressing to dementia and debilitating muscle control loss.

Previous research found people with Parkinson's disease experience changes in their microbiome long before other signs appear. Nishiwaki's team analyzed fecal samples from 94 Parkinson's patients and 73 healthy controls in Japan, comparing their results with data from China, Taiwan, Germany, and the US.

While different bacteria were involved in each country, all influenced pathways that synthesize B vitamins in the body. The researchers found changes in gut bacteria communities were associated with decreased riboflavin and biotin in Parkinson's patients.

Nishiwaki and colleagues also linked this lack of B vitamins to decreased short-chain fatty acids (SCFAs) and polyamines, molecules crucial for a healthy intestinal mucus layer.

"Deficiencies in polyamines and SCFAs could lead to thinning of the intestinal mucus layer, increasing intestinal permeability, both of which have been observed in Parkinson's disease," explains Nishiwaki.

The weakened protective layer may expose the intestinal nervous system to more toxins, including cleaning chemicals, pesticides, and herbicides, which can lead to the overproduction of α-synuclein fibrils and increased nervous system inflammation. These changes eventually result in the motor and dementia symptoms of Parkinson's.

A 2003 study found high doses of riboflavin can help recover some motor functions in patients who eliminated red meat from their diets. High doses of vitamin B may prevent some damage, Nishiwaki and team suggest.

This implies ensuring patients have healthy gut microbiomes may also be protective, as would reducing environmental toxins.

With Parkinson's disease involving a complex chain of events, not all patients experience the same causes. Each individual needs to be assessed.

"We could perform gut microbiota analysis on patients or conduct fecal metabolite analysis," explains Nishiwaki. "Using these findings, we could identify individuals with specific deficiencies and administer oral riboflavin and biotin supplements to those with decreased levels, potentially creating an effective treatment."

This research was published in npj Parkinson's Disease.