Many of us take supplements of one kind or another. Personally, I am very careful about taking them and skeptical about many of the claims made by supplement manufacturers. I do not rely on their advertising claims. I hope you don't either.
Some supplements, high quality fish oil (Omega 3) immediately comes to mind, have unquestionable value. While some others are suspect. A few have even been proved dangerous, such as some of the diet pills that we've all read about.
The Gray Iron advice is to take only those supplements that you have discussed with your physician. Remember that certain substances may interact negatively when combined with prescription or over-the-counter medications you might be taking. Ask a pharmacist for professional advice.
To read more from the National Institutes of Health, go here: Advances in Dietary Supplement Research Highlighted.