Polyphenols are a diverse group of naturally occurring compounds found in plants, with notable examples including flavonoids, phenolic acids, and stilbenes. They are present in foods such as berries, tea, coffee, red wine, and cocoa. Interest in their use for Alzheimer's Disease (AD) stems from their antioxidant and anti-inflammatory properties, as oxidative stress and neuroinflammation are key contributors to AD pathology.

Preclinical studies in cell and animal models have demonstrated that various polyphenols may reduce amyloid-beta aggregation, modulate signaling pathways, and improve synaptic function. For example, resveratrol (a stilbene from grapes) and epigallocatechin gallate (EGCG, a flavonoid from green tea) have shown neuroprotective effects in laboratory settings. However, human clinical trials are limited and have produced mixed results. Systematic reviews and meta-analyses (e.g., Pan et al., 2023, Frontiers in Aging Neuroscience) indicate some potential cognitive benefits, but overall evidence is inconsistent, with issues related to bioavailability, dosing, and study design.

In summary, while there is scientific rationale and some early evidence for the use of mixed polyphenols in Alzheimer's Disease, the clinical data remain insufficient for strong recommendations. The evidence base is growing but currently rates as weak to moderate (2/5).