Dietary supplements are in short "stuff you eat in addition to your regular diet". Typically they are in the form of tablets, pills or capsules.
What prompted me to start writing on this topic is the growing interest in CBD in it's many shapes and forms. While there seems to be no lack of interest in these products, I have yet to be presented with any scientific evidence that CBD actually works. This is not to say that THC has no effect, the psychoactive substance procured from some hemp plants, affectionately known as marijuana. The therapeutic effects of this drug are still being explored, but it certainly does relieve pain and alter your state of mind.
In short: Medicine that works is called medicine.
Stop wasting money on supplements.
Diet and exercise works, use it.