Readers discuss marathoners’ myelin, menopausal chimps and more

Running on myelin

Marathon runners’ myelin levels in the brain temporarily dwindled in the days after a race. The finding suggests that this fatty tissue that insulates nerve cells may be an energy source for the athletes, Meghan Rosen reported in “Brain tissue may help fuel marathoners” (SN: 11/18/23, p. 16).

Reader Julian Young wondered whether myelin levels could also drop in people on a restrictive diet such as the low-carb keto diet or in people who experience low blood sugar levels for long periods.