Unraveling the Mechanistic Insights of Asparagus Bioactives to Promote Cognitive Health: Insights from the Gut–Brain Axis

Asparagus racemosus, popularly known as Shatavari, is a well-acclaimed medicinal herb for the rejuvenation of reproductive and cognitive health. The therapeutic potential of the herb is primarily due to its famed bioactive compound, Shatavarin IV, which is a steroidal saponin with a close structural resemblance to the female reproductive hormone estrogen. Over the last few decades, independent studies have shown that the steroidal saponins, flavonoids, alkaloids, and polyphenols from the plant can neutralize oxidative stress, arrest neuroinflammation, prevent apoptosis, regulate serotonergic and dopaminergic neurotransmission, and promote synaptic plasticity for holistic cognitive homeostasis. A critical finding in delineating the secret of a healthy brain has been its intricate linkage with a happy gut. Intestinal microbes play a significant role in modulating the synthesis of key neurotransmitters through the diverse plethora of their secreted metabolites, such as short-chain fatty acids. The gut–brain axis, primarily the vagus nerve, acts as a specialized access point for these molecules into the brain. In addition, gut microbes play key roles in ensuring the optimal function of the hypothalamic–pituitary–adrenal axis, the central mechanism for the management and mitigation of physical and emotional stress. Fructooligosaccharide residues, found in abundance in Shatavari, serve as excellent prebiotics for the gut microbial population. This review presents an extensive analysis of the key mechanistic insights obtained thus far on the crossroads of Shatavari with the cells of the nervous system and the microbial community involved therein, including findings from our own laboratory, which could provide long-term solutions in addressing cognitive health.