My father (I am his caregiver; he has PMR) takes low dose naltrexone (LDN) for fatigue. It's also thought to have an anti-inflammatory effect. It's believed to increase endorphins in the body and modulate glial cells, which when overactive contribute to chronic pain.

It's by prescription from a compounding pharmacy because it's a tiny fraction of the regular dose of naltrexone. At such small doses, it's used off label for chronic pain and chronic fatigue conditions, and some autoimmune conditions. While it's not a supplement as you're considering, my dad and I are both very sensitive to medications and have not experienced side effects. It's very low risk. It used to fly much more under the radar, but now it seems more people are looking into it because of it's potential utility with long covid.

He does take predisone. His PMR was severe and the risk of GCA very high; despite the risks of prednisone I don't believe an anti-inflammatory diet, supplements or NSAIDs (which are contraindicated for him) would have been effective enough. But of course each situation is different and it comes down to personal preference and health needs.