I use supplements - but not necessarily for cycling...
Daily multi-vitamin
Krill Oil & Coconut Oil
Norwegian Kelp (high in Iodine - for hypothyroid)
Glucosamine / Chondroitin / MSM - for Joint Health - I have loose / painful joints.
Niacin (Cholesterol). It may seem weird, but I actually like the niacin flush.
Taurine (Brain / ADD)
I know there's more...I just can't remember. Maybe I need more Taurine.