The Neuroprotective Potential of Spirulina and Chlorella Prebiotics in Neurodegenerative Diseases: A Review of the Gut-Brain Axis

Abstract

This review summarizes the recent scientific knowledges, neuroprotective benefits of Spirulina and Chlorella specific to neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis (ALS) as well as their prebiotic activities on gut-brain axis. With increasing prevalence of these diseases and the gut–brain axis being involved in brain health, other therapy modalities are therefore highly sought. Here, pre-clinical and clinical studies are reviewed to evaluate the modulatory capacity of these microalgae. The review is centered on its effect on gut microbiota composition, neuroinflammation, and oxidative stress. There is abundant preclinical evidence in support of this concept but very few clinical data with only three small randomized controlled trials to date. This differentiation is crucial for interpretation of the manuscript’s findings. A broad search (2010-2025) of scientific databases for relevant literature was performed and all identified literature was checked for relevance to the findings related to the mechanistic pathways. These findings suggest that Spirulina and Chlorella may have the potential to regulate the gut microbiota community by promoting beneficial flora as well as SCFA production. These shifts are linked to the improvement of gut integrity, decrease in systemic inflammation and suppression of neuroinflammatory circuits. In addition, all these microalgae appear to activate antioxidant defense systems, which would prevent neurons from oxidative damage. There should be a disclaimer to indicate an apparent discrepancy over the abundance of preclinical versus clinical data. Thus, although the prebiotic factors in Spirulina and Chlorella may represent a novel adjunctive strategy for neurodegenerative diseases, their therapeutic potential remains to be demonstrated. Additional prospective and large controlled trials are needed to confirm these early results and their benefit as a therapeutic option.