Another good one for mitochondrial health is TMG ( trimethylglycine) or betaine.  

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6171430/

ETA - any of the methyl donors help the electron transport chain.  Just make sure you get folate and not folic acid , methylcobalamin and not cyanocobalimin... helps keep the homocysteine down ...

that looks like it is 50 doses. Thanks, none of the others I looked at had any of those dosing charts.

I will read the study reports again and see how long until improvements were seen to figure out if I should try this.

Just a random FYI - not sure why I'm bothering to mention it at this point:

For the better part of a year now, I have, I think, a touch of Phantosmia.

I smell smells that aren't there. It's almost always the smell of.....ehhh, let's call it roasted animal feed. A really 'dry' smell. I've heard people mention burnt toast. Mine isn't really burnt toast. Mine is more......maybe roasted soybean hulls or something like that. The closest thing I can compare it to is the cheaper animal feeds we buy - they're dry, non-sweet roasted waste grain byproducts, I think, and the smell I catch a whiff of from time to time is like that, but stronger. Like my head was stuck in the feed bag.

*shrug*

I have that. It is fairly common among the post-covid because the receptors got permanently damaged. A smell, real or imagined, gets stuck in your brain and stays there in the background until the next one decides to take over.

The whiff of Febreze or whatever it was the seller sprayed in a package I bought off of e-bay lasted for weeks. The strong mothball/chemical BO of an older lady I trained at work for 2 days before she stopped showing up was stuck in my sinuses for months until I got a whiff of the toasted grain smell (like you mention) when I opened a bag of Koi pellets and it took over residence of my brain...thankfully.

So I'm not crazy and not the only one?

Mine didn't start immediately. I don't think I noticed it at all for the first 2(?) years post-covid. It's only in this last year. Did I have a second undetected infection? Or am I getting worse?

I don't know how to even begin answering those questions.

Part of me thinks it's not a phantom smell, part of me thinks it's like my brain takes what should be a wide range of smells and reduce them down to 'roasted grain feed' smell. Like my nose is a computer sending a picture to the printer (my brain's olfactory center) but it spits it out in B&W instead of color.