I get almost 3 mg of manganese just from the oat bran I put in my protein shake. I assume I get at least 5 mg from my diet. I also have 2 bottles of manganese. The first I bought was 10 mg capsules, but then I decided it was too much and it's kind of a hassle to empty out part of the capsule because they're so tiny. Then I bought a bottle of 15 mg tablets which I was planning to cut in 1/2 or 1/4. Even though it would be convenient to have b vitamins, mangnesium, malic acid, and manganese all in one capsule especially since I'm taking all of those supplements already I can't justify the expense. I also have a bottle of malic acid and some citrulline malate so I don't need any more malic acid either. And I just ordered some magnesium glycinate and krebs chelates magnesium. Plus, I also have nearly full bottles of P5P and R5P. At most, I might just take 3.75 mg manganese from now on. With my dietary manganese that would put me around 10 mg total. I thought maybe manganese might help with excitotoxicity (although that's not why I originally bought it), but that's only if I'm deficient in manganese and if my excitotoxicity if from glutamate. I'm not sure of either of those things right now. I don't eat nearly as many nuts or seeds as I used to, but I'm eating more grains so I'm probably not deficient. There were also periods in the past where I supplemented with manganese after suspecting a copper toxicity (which again I'm not sure of either).