Standardization is another important issue. Although this seems to be a logical solution, it is not an easy one. This is particularly relevant in the case of those herbs where the active ingredients are not identical or in those where several components work together to produce the desired effect. Standardizing to a key component in a given preparation would likely improve uniformity and consistency among products. Without FDA guidelines and enforced standardization, consumers can't be certain that sufficient active ingredients are present in a product to have at least a chance at being therapeutically useful.
Some examples illustrate the point.
Feverfew contains parthenolide, believed to be the active component responsible for its anti-migraine activity. A recent study in the U.S. revealed that many products containing feverfew had no detectable levels of this active component. Another key issue concerns consistency of active ingredients. Without standardizing to a known reference component in an herbal preparation, wide variations will occur from batch to batch and between manufacturers. This could result from variation in plant-growing conditions, as well as from differences in extraction procedures and stability of the active components.