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Common Supplement Reduces Alzheimer’s Protein Clumps in Animal Tests — Promising but Early

Japanese researchers found that oral arginine reduced amyloid-beta plaques and improved behavioural and inflammatory markers in mice engineered to model Alzheimer’s. Complementary experiments in fruit flies and in vitro assays showed arginine can disassemble existing amyloid clumps and inhibit new aggregation. Although arginine is inexpensive and known to cross the blood–brain barrier, the animal doses were high and clinical trials are needed to assess safety and efficacy in humans.

07:39 PM, 11/26/2025Health
Common Supplement Reduces Alzheimer’s Protein Clumps in Animal Tests — Promising but Early

Researchers report that oral arginine, an amino acid already used as a medication for chest pain and high blood pressure, reduced amyloid-beta protein aggregates in animal models of Alzheimer’s disease and improved several related measures of brain health.

What the team did

A collaboration between Kindai University and Japan’s National Institute of Neuroscience tested whether arginine could affect amyloid-beta plaques, sticky protein clumps strongly associated with Alzheimer’s disease. Male mice genetically engineered to develop Alzheimer’s-like amyloid-beta aggregations received arginine in their drinking water. The researchers complemented the mouse studies with experiments in fruit flies and in vitro assays.

Key findings

Arginine treatment produced multiple encouraging effects in the preclinical models:

  • Marked reduction of amyloid-beta accumulation in the brains of treated mice.
  • Improved performance on behavioural tests compared with untreated animals.
  • Lower activity of genes linked to neuroinflammation, suggesting reduced inflammatory stress in the brain.
  • In fruit flies and laboratory assays, arginine appeared to disassemble existing amyloid aggregates and inhibit new clump formation.

How arginine may work

Prior research indicates arginine can act as a chemical chaperone, helping prevent proteins from misfolding and aggregating. Animal data also suggest arginine can cross the blood–brain barrier, an important property for agents intended to act on brain pathology.

“Our study demonstrates that arginine can suppress amyloid-beta aggregation both in vitro and in vivo,” said neuroscientist Yoshitaka Nagai. He noted arginine's established clinical safety and low cost make it an attractive candidate for repurposing.

Important caveats

Despite promising preclinical results, several important limitations remain:

  • The doses of arginine used in the animal experiments were relatively high; safe and potentially effective human doses have not been established.
  • Animal and insect models do not always predict human outcomes, so clinical trials are necessary to determine whether similar benefits occur in people.
  • It remains uncertain whether clearing amyloid-beta plaques alone will meaningfully alter the course of Alzheimer’s disease. While plaques are harmful to neurons, researchers debate whether they drive the disease or reflect other underlying processes.

Overall, these results provide a practical and low-cost avenue for further research into therapies that target protein misfolding and aggregation. The study has been published in the journal Neurochemistry International.

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