The aetiology of Parkinson s disease PD has been linked to the aggregation and spread of misfolded alpha synuclein via the gut-brain axis. We previously reported the effects of a biological response modifier, beta glucan, produced by the AFO 202 strain of Aureobasidium Pullulans, which improves clinical symptoms and controls gut Enterobacteriaceae associated with curli and amyloid alpha synuclein production. In this study, we report the effects of beta-glucan on PD. Eight patients with PD were recruited, five of whom completed the study. Each participant was administered 3 g of AFO-202 B glucan orally daily for 90 days in addition to their regular prescription drugs. Pre and post study comparison revealed that the mean UPDRS decreased from 43.25 at baseline to 40 post intervention. Improvements in cognition, walking and balance, postural stability, and constipation scales were observed. The mean constipation severity score decreased from 3 to 1.75 post intervention. The serum creatinine kinase levels decreased and the blood glucose and lipid levels normalised. The MRI Parkinson s index MRPI improved in one patient. This safe AFO 202 B glucan produced beneficial diseasemodifying improvements in the UPDRS and MRI that were clinically significant in the short timeframe of 90 days. Further validation in larger, longer-term clinical trials will help confirm the use of beta glucan as a potential adjuvant treatment for PD which may pave way for future evaluations of these beta glucans in other synculeinopathies as well Lewy body related pathogenesis.