I am reporting back with an update on manganese.
I used to take half a tab of 25mg manganese chelate 2-3x a week and I didn't feel any different. I wasn't totally sure if I was deficient so eventually I stopped due to fear of taking too much. I started using maple syrup liberally in my tea, coffee, and desserts in hopes that the naturally occurring manganese will be safer.
I got sick at Christmas and then got totally wiped out in early January from the flu. I got through it quickly this time (only 1 week) but just couldn't fully recover. My digestion became extra sluggish and I was constipated for 2 weeks. I also gradually returned to work after being off for a year for illness and I found it unbearably tiring, like I was literally nodding off and falling asleep during a mere 4 hour shift. I initially blamed it on anxiety that caused insomnia, but when it was still happening after getting a decent amount of sleep, I was very worried that this was going to be the rest of my life and I desperately starting looking for answers.
I spent the next night staying up and doing a ton of reading and decided that I should give manganese a try again. I took a 25mg tab and went to bed at 6am and woke up at 10am. Instead of being deathly tired, I experienced incredible mental clarity. Apparently it's a cofactor for thiamine, which I was taking pretty high doses of, but got lazy during the weeks where I was sick. I immediately went back to 200mg of Thiamine HCl TID and 80mg benfotiamine BID while continuing the manganese 25mg once daily along with my usual supplements. I've been running on 4-5h of sleep and have never felt so awake, wow! I spent my life wondering if I had a learning disability but now I can read and comprehend without my mind drifting off.
I also added some zinc and alpha lipoic acid a few days ago and haven't experienced any adverse effects yet. Hopefully the zinc will help my digestion further (I have started to feel hungry these last 2 days and the fullness in my stomach seems to have moved along) and ALA to further support the thiamine.
Hope this helps