Bacosides are the primary active compounds found in Bacopa monnieri, a traditional Ayurvedic herb. There is moderate scientific evidence supporting their role in modulating the nervous system, including effects relevant to the parasympathetic nervous system (PNS). Bacosides have been shown in animal and limited human studies to enhance synaptic activity, increase dendritic branching, and protect neurons from oxidative stress, which are mechanisms consistent with improved cognitive and nervous system function. Some preclinical studies suggest that bacosides modulate neurotransmitters such as acetylcholine, which is crucial for PNS activity, and may support relaxation and stress resilience—functions regulated by the PNS.

Human studies on Bacopa monnieri primarily focus on cognitive enhancement and reduction of anxiety, outcomes indirectly related to PNS support. While these findings provide a scientific rationale for the use of bacosides in supporting nervous system health, specific clinical trials directly measuring parasympathetic activity (such as vagal tone or heart rate variability) in response to bacosides are limited. Therefore, while the use of bacosides to support the parasympathetic nervous system is plausible and has some scientific backing, the evidence is not comprehensive, and further research is needed to fully establish this link.