I checked all of the above (plus being a marathoner on an organic plant-based diet) and still experienced a 6-month period of long COVID, lasting from May until mid-September this year (after having a rather mild infection at the end of April). I had brain fog and fatigue for the first two months (needing almost 10-12 hours of sleep daily), but muscle and back pain persisted until recently.

I was taking all sorts of supplements, such as B12, magnesium, vitamin C, etc., and nothing seemed to help.

Then I remembered a book I read a couple of years ago about an ultramarathoner who drank 2 dl of seawater (marine plasma, as some call it) every day to improve his recovery. Since I live very near the coast, this isn't a problem for me. So I tried it, and my symptoms went away within a week.The working hypothesis of this individual is that seawater contains the same trace minerals as our blood plasma, so it nourishes the body completely.Of course, you could argue that it's a placebo effect, but if that were the case, why didn't other pills work when I believed in them equally (if not more)?