Yarrow may also interfere with the absorption of iron and other minerals. At least one in three Americans use some sort of herb or herbal formulation for health purposes and in many other parts of the world this ratio is even higher. Herbs are advertised for their preventative qualities and effectiveness, such as avoiding memory loss, curbing stress, fighting colds, relieving pain, or even improving the quality of sleep. Roughly 25 percent of pharmaceutical drugs have herbal origins. Though many herbs are not as potent as traditional drugs, they still contain some of the same active ingredients as drugs, plus they often contain other ingredients, some of which may have different functions or may even be toxic.
Herbs are less regulated than drugs.
The U.S. Food and Drug Administration does not exercise control or employ the same rigorous testing for herbal products that it does for foods and drugs. Consumers rely primarily on the company selling the herb for assurances that it is effective and safe to use. Herb quality can vary significantly. Without standards, companies can sell whatever they want. Last year, the Los Angeles Times looked at ten brands of Saint John's Wort - a popular herb for fighting depression.