The other substances to look for are those that have scientific evidence for their efficacy and safety. There is no problem with using synthetic ingredients because they are available in a wide range of formulations. The problem comes when supplements containing questionable ingredients are manufactured. Unfortunately, this does not result to the consumer getting a health supplement with the desired effect.
One example of questionable ingredients includes thistle. This substance has been shown to cause certain liver diseases as well as to interfere with the absorption of other nutrients. Another example is beta-sitosterol. This substance is commonly found in dietary supplements that are intended for weight loss. Although its purpose is weight loss, research shows that some people develop cancerous tumors when they consume it.