And in many cases, an herb's beneficial effects depend on all its compounds acting together. The actual amount may be greater. It is important to note that the presence of a specific amount of a certain compound cannot by itself guarantee efficacy. At this point, consumers and retailer alike must rely largely on manufacturer's claims and reputation for integrity, as testing each extract would be prohibitively expensive. European physicians prescribe a standardized herbal extract when a patient needs a precise, rather than guaranteed minimum dose of a particular compound or compounds.
Strength is expressed as a ratio of herb to solvent.
The smaller the second number the stronger the extract. The quality of an extract depends upon the medicinal quality of the source plant, which is affected by genetics, soil, climate, and the skill of the manufacturer. There is greater assurance of potency if you choose a crude extract from a highly reputable brand like Gaia, Zand, Herb Pharm, or Frontier. It is hard to say which of these three forms is superior. Many herbalists prefer liquid alcohol extracts, because their taste and smell may trigger important reactions in the body.