🔎 Fads in Blue  A new health fad is circulating on TikTok among so-called biohackers—individuals who try to optimize their own wellness through behavioral changes, supplements and sometimes experimental tactics or treatments. Some claim that methylene blue, a synthetic dye, boosts cognition and slows aging. It also turns your tongue blue. What the science says: The substance has been around a long time (it was used to treat malaria in the late 19th century), but recent research is lacking. The idea that the blue dye can boost brainpower comes from preliminary studies on methylene blue as a treatment for Alzheimer’s disease; this research is based on the theory that the dye might combine with the tau proteins that are implicated in that disease. But most of that work is in animals, and the few studies of people are very small and show only tiny effects. What the experts say: “There are no compelling human clinical trials that have shown any benefit,” says Joe Schwarcz, professor of ...