PremiumAriana Eunjung ChaWashington Post·13 May, 2026 12:00 AM9 mins to readThe global market for nutritional supplements was estimated at US$517.1 billion in 2025, according to Grand View Research.Just one supplement has been shown in clinical trials to slow cognitive ageing. Here’s what you need to know.

They arrive in cheerful bottles with names that sound like promises – Daily Brain Boost, Brain Drive, Brain guard+. And Americans, in turn, spend billions of dollars each year chasing the