Alzheimer's disease affects more than 50 million people worldwide and currently has no definitive cure. Existing antibody‑based therapies that target amyloid‑β—the sticky protein that accumulates in the brains of Alzheimer's patients—offer limited real‑world benefits, come with high costs, and carry side effects including dangerous brain swelling. Researchers have long sought safer, more affordable alternatives.

Kindai University's team found one in an unexpected place: arginine, a clinically approved amino acid that the body produces naturally and that is also widely available as a dietary supplement. The research team, led by graduate student Kanako Fujii and Professor Yoshitaka Nagai from the Department of Neurology at Kindai University Faculty of Medicine in Osaka, tested arginine across multiple experimental stages.

In laboratory settings, arginine slowed the formation of amyloid‑β aggregates in a dose‑dependent way. In fruit fly models carrying Alzheimer's‑related mutations, it reduced toxic protein accumulation. In the most significant tests—mice engineered to develop Alzheimer's‑like brain pathology—oral arginine supplementation produced striking results. Plaque deposits decreased, markers of neuroinflammation fell, and the animals showed measurable improvements in cognitive behaviour.

The researchers emphasised that arginine functions as a "chemical chaperone"—a molecule that physically prevents proteins from misfolding and clumping together. This is a fundamentally different mechanism from the antibody therapies currently available, which attempt to clear amyloid after it has already formed.

Associate Professor Toshihide Takeuchi, also from Kindai University, was part of the research team. The group noted that while arginine is available over the counter, the dosage and administration protocol used in their experiments was specifically optimised for research and does not correspond to commercially available supplements. Self‑medicating with standard arginine supplements would not replicate these results.

The findings, published in Neurochemistry International, have generated significant excitement in the Alzheimer's research community. Arginine's established safety profile, low cost, and wide availability make it an attractive candidate for rapid therapeutic development—provided human clinical trials confirm the animal model results.