I want to give horse owners a different perspective on whether to feed their horses vitamins. Most discussions on this subject discuss what diseases are prevented by supplementing with which vitamin. I will not repeat this because 1) others have done this, and 2) there needs to be more good science behind their findings. Instead, I will tell you how vitamins work, if supplementation works, and the difference between vitamins from food, food sources, and chemicals like coal tar.  Doing a thought experiment, I asked listeners if giving synthetic vitamins (and amino acids) can cause inflammation. I also ask if processed foods have more benefits to health than whole foods, identifying some unique situations where they may be indicated (soybean meal).