I have done my best to describe the ingredients and how they are obtained. I am not a licensed medical doctor or health care professional, and don't advise you to take any supplement. I am just providing an overview of a few supplements.
Most supplements are not going to cure any kind of disease, but it is true that they can be good for you if you understand how they work. Many of them work by increasing your natural vitamin A levels. The problem with that is that vitamin A levels are not high by a very large margin and you will need much higher amounts to get the same level of health. Many supplements don't contain sufficient amounts of vitamins A, C, E, and B6. This is a common problem and many people want to take too much. Many supplements can actually interfere with the body's ability to absorb nutrients and this is why they are called "supplements."
Here is a list of some supplements that should be avoided for those who want to get the best possible results. The more supplements you take, the more supplements you are going to consume and the more likely you are to end up with deficiencies.