In his book In Defense of Food, Michael Pollan suggests that we should be the kind of person who takes supplements but then saves his money by not buying them. He argues that clinical studies have not proven the effectiveness of nutritional supplements.
I agree that we should seek to get the nutrients that our bodies need by eating whole foods. However I believe that there is a place for herbal/botanical supplements as we seek to restore or maintain our health. The state of our industrial food system often results in diets that provide an excess of calories while being deficient in essential nutrients. Nutritional supplements provide one option by which we can make up for this nutrient deficiency.
However, in Food Politics, Marion Nestle explores the the way the Nutritional Supplement industry has successfully lobbied to minimize the regulation of nutritional supplements. The result is that supplements can marketed containing ingredients that have not been scientifically proven to be effective and bearing health claims that may or may not be accurate.
Since this regulatory environment gives us "freedom of choice", this places the burden on each of us to carefully choose supplements in a way that minimizes our risk and maximizes the potential benefit to us. To that end we should find a source of supplements that is trustworthy and consult a practitioner with knowledge and experience relevant to our needs.