Does methylene blue really work for your energy and brain?
Do not take this as a supplement. Methylene blue is a registered medicine and industrial dye, not a food, and not authorised as an EU supplement. For energy or brain function in healthy people there is no evidence, and it can be dangerous: it interacts severely with antidepressants (serotonin syndrome) and is risky with a G6PD deficiency.
Methylene blue is promoted online as a substance for energy and brain function, but that is not based on evidence in healthy people. It is a medicine (among other things for a blood disorder) and an industrial dye, not a nutrient.
As a supplement it is not authorised in the EU. And it is not harmless: methylene blue inhibits the enzyme MAO-A, so that together with antidepressants such as SSRIs it can cause a life-threatening serotonin syndrome, a risk regulators explicitly warn about.
It is also dangerous for people with a G6PD deficiency (it can cause breakdown of red blood cells) and its industrial origin can bring impurities. In short: do not take it yourself; only use it if a doctor prescribes it as a medicine.
Based on the medicine and novel-food status and safety warnings (among others about serotonin syndrome); no evidence for energy or brain in healthy people.