I routinely supplement with:
Magnesium
Zinc
Vitamin D
Vitamin C
Collagen
Additional (whey) protein when my regular eating doesn’t afford me enough
Over many (30+) years of exercising (endurance / weights / team sports) I’ve settled on these as the ones where I have noticed over time a correlative benefit,
It’s only personal experience though so I fully accept there could be placebo at work and / or other variables I’m unaware of that impact my perception of efficacy.
I’ve also over time come to better understand my own body and what foods work well for me and those that undermine my performance or health.
Drastically reducing how much alcohol I consume has made one of the biggest positive differences - in particular in terms of recovery after hard exercise.
Similar benefits from changing my mindset in ‘diet’ and instead of seeking to follow a super strict regime; I’ve just come to accept I need to exercise a greater degree of self discipline with regard to high calorie foods that may taste great but don’t help me achieve my goals in the long run.
Also, making a subtle but consistent and embedded shift away from processed food. Upping my vegetable intake and trimming off the processed meat (including sausages and bacon etc) has made a massive difference to how I feel over time.
I’m not vegan as I like fish and (sometimes) chicken too much to give it up; but I now only really eat red meat (a nice fillet steak) once in a blue moon. In terms of recovery I’ve definitely noticed upping my protein over a sustained period had led to improvements in how quickly I feel able to return to exercise.
I’m very far from either the fittest or healthiest person for my age (47) but I do feel much better now than I did 10 years ago and attribute a fair proportion of that improvement to the slow but consistent refinements I’ve made to my diet and supplementation over the last decade.
Or … it could all be coincidence as I have no ‘evidence’ other than how I feel 