What is the best running supplement for your needs depends on your running goals. One product can be wholeheartedly recommended for all types of runners: protein powder. The best protein powders can aid recovery, and given their convenient powder form, protein shakes are easily digestible and can get into your bloodstream faster. Put protein powder and water/milk/milk substitute in a protein shake blender and have a shake within half an hour after you're done with your run for the best results.