When I was doing long endurance rides in college I did supplements of vitamins E and B 12 and B 6 and B 2. Depletion of the water soluble B vitamins directly interferes with endurance performance. I supplemented B 2 because women use it faster than males and it's important in assisting in the breakdown of carbs and fats. I supplemented vitamin E if I though I was going to have some premenstrual tension.

Because a Professor friend was doing research into choline supplements for endurance athletes I also got a good look through blood/urine tests before and after efforts of how my body was using and depleting it so I used that only in 400km+ brevets or marathons

For long chain carbohydrates I usually used Hammer Nutrition fuels. For fats, fiber and protein from plant sources, I was and still am a vegetarian, I made my own granola bars with things like rolled oatmeal, nuts, chia and sunflower seeds, whey protein, flax seed, acai berry pulp, raisins and dates. I drank lots of water.

After a prolonged endurance effort I always took the next few days easy and use supplements consisting of multiple anti-oxidant free-radical scavengers to help recover in the shortest possible time.

Not doing extended long efforts because of work obligations now I still make my own energy bars and now my own sports drinks with water, sea salt, a crushed calcium magnesium tablet, some fruit juice and for sweetener a small amount of stevia leaf brewed into a base liquid.