PART 4: Pyrrolizidine Measurements and Limits of Detection

A BO supplier assures us that pyrrolizidine alkaloids "have NEVER been found in borage seed oil"²⁷. The statement implies absence of PAs, non-toxicity, and (therefore) safety for human consumption.

However, several reputable sources express concerns regarding the safety of BO:

1. The Canadian Pharmacy Journal reads:

   "Borage seeds do contain small amounts of the liver toxins called pyrrolizidine alkaloids (PA). However, despite the fact that testing has demonstrated the presence of less than 5 micrograms (ug) per gram of the alkaloid in the seed oil, the consumption of two to four 500mg capsules of borage seed oil could result in an intake of such alkaloids approaching 5 - 10ug per day. In the interests of public safety, borage oil should be PA-free and follow the example set by the German Health Agency, which suggests that no more than 1ug of PA be consumed daily when the herb (sic) is taken as directed."²⁸

   
   
   

2. Herbal Medicines: a Guide for Health-Care Professionals reads:
   

   "In view of the known toxic pyrrolizidine alkaloid constituents, excessive or prolonged ingestion of borage should be avoided."²⁹

   "In view of the documented pyrrolizidine constituents and lack of toxicity data, borage should not be used during pregnancy or lactation."²⁹

   "It is unclear whether borage oil, currently available in food supplements, contains any pyrrolizidine alkaloids."²⁹

   
   
   

3. Regarding borage seed oil, Tyler's Herbs of Choice: the Therapeutic Use of Phytomedicinals states:

   "Borage seeds have been shown to contain small amounts of pyrrolizidine alkaloids, including the known hepatotoxic amibilene. That alkaloid was not detected in samples of seed oil down to levels of 5ug/g. Consumption of 1 to 2g of borage seed oil daily could, nevertheless, result in an intake of toxic unsaturated pyrrolizidines (UPAs) approaching 10ug. As De Smet has pointed out, the German Federal Health Agency now limits internal consumption of such products to not more than 1ug of UPA daily. This means that in the interest of consumer safety, borage seed oil should be certified free of UPAs down to the level of 0,5 to 1ug/g.

   The fact that GLA-rich oils are now available commercially from three different plant sources does not alter the conclusion that the product's efficacy for any condition remains unproven. Likewise, its safety on long-term usage requires additional verification. This is especially important for borage seed oil, which may contain small amounts of UPAs."²⁰

   
   
   

4. In the same book, regarding pyrrolizidines in comfrey and borage, we can read:

   "In 1992, the German Federal Health Agency, in an attempt to balance the popularity of certain herbs containing toxic PAs with a recognized need for their restricted use, established standards for such preparations. These limitations restricted the amount of total PAs with 1,2-unsaturated necine moieties that might be obtained from certain registered preparations to not more than 100ug per day when used externally and 1mcg when taken internally. An exception was made for comfrey tea, which was permitted to provide a maximum internal daily dose of 10ug. In the case of non-registered preparations, the limitations were reduced to 10ug externally and 0.1ug internally daily.

   "It is necessary to point out that these limitations, which apply not only to comfrey but to such other herbs as borage, coltsfoot, life root, and heliptrope, are meaningless in the United States because none of the preparations sold here has been assayed to determine its content of PAs. Further, no adjustment has been made in any of the available dosage forms to assure that safe levels of toxic alkaloids are not exceeded. For this reason, safety requires adherence to the five rules* stated above when dealing with comfrey. Similar precautions should be taken with all herbs containing toxic PAs."²⁰ (emphasis added)
   

   {* The five rules referred to are: "1. The internal use of any species of [comfrey] should be avoided. 2. [Comfrey] root should never be used medicinally. 3. Only the mature leaves of [S. officinale] should be applied externally, and then only to intact skin for limited periods of time. 4. [Comfrey] should never be used by pregnant or lactating women or by young children. 5. Because there are so many other nontoxic yet effective treatments for minor skin ailments that do not present the hazards associated with this herb, [comfrey] has little, if any, place in our modern materia medica."²⁰}

   
   
   
   

5. The same sentiment is expressed in a 1998 comment faxed by Varro E Tyler, PhD, ScD, Dean and Distinguished Professor Emeritus of Purdue University in West Lafayette, IN and a strong ally for the (safe) use of herbs in health care, to the American Botanical Council:

A method for identifying pyrrolizidines in borage oil is described by Mierendorff, but he fails to say whether or not the pyrrolizidines he found in his study were from BO or borage plant material³¹. So, we still don't know.