Skullcap Adulteration Still Plagues Industry

AUSTIN, TexasSkullcap(Scutellaria lateriflora), an herb that has been used for centuries as a mild sedative, is often substituted or adulterated in dietary supplements, according to botanist Steven Foster in an article in the Winter 2012 issue of HerbalGram. This problem has occurred for more than 30 years, Foster said, and unfortunately, it's not getting any better.

In a 2011 study, USDA researchers found of 13 skullcap-containing dietary supplements tested, all of which were purchased through the Internet, only 5 had a measurable amount of true skullcap. Four supplements contained potentially toxic American germander (Teucrium canadense)also sometimes known as wild germander, wood sage and wild basilwhich has been a known adulterant of skullcap products since the 1980s. Three supplements contained very low concentrations of skullcap and one sample contained Chinese skullcap (Scutellaria baicalensis) rather than the American species (S. lateriflora).

A study from 2009 found similar results.

Skullcap received international attention in the 1990s when some herbal products that claimed to contain it were associated with several cases of liver dysfunction. Analyses later revealed the source of toxicity to be European germander (Teucrium chamaedrys), another known skullcap adulterant. In the article, Foster describes a scientific paper from 1992 that first established germander as the source of harm.

There are those who believe that skullcap and germander may look similar, since they are both members of the mint family (Lamiaceae or Labiatae). Foster, and various herbal experts, believe their physical characteristics are distinct enough to warrant an accurate identification with the naked eye, i.e., in the field.

According to an extensive quality control and therapeutic monograph on skullcap ("Skullcap Aerial Parts, Scutellaria lateriflora L.") produced by the nonprofit American Herbal Pharmacopoeia (AHP), the relatively comparable appearances of skullcap and other herbs can lead to accidental adulteration. The AHP monograph states, "Skullcap has historically been adulterated with various species of the potential hepatotoxic germander (Teucrium canadense, T. chamaedrys) due to morphological similarity between S. lateriflora and T. canadense."

Foster recommends using the AHP monograph as a guide for properly identifying skullcap and germander species.

Foster's article is the second in a series of publications to come from the ABC-AHP-NCNPR (National Center of Natural Products Research) Botanical Adulterants Program, a nonprofit educational consortium that includes numerous third-party analytical laboratories and experts on herbs and herbal quality control. The program is preparing a technical laboratory guide to skullcap-germander adulteration, as well as a variety of review and technical publications on the adulteration of other herbs, herbal extracts, and essential oils.

For more on this topic, view the On-Demand video, "How To Ensure Botanical Integrity."