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Some milk thistle with your krill oil, sir?



I like a piping hot mug of mint tea as much as the next person but I wouldn’t say I ride the herbal medicine bandwagon. That’s not to say I don’t think natural medicines can be beneficial, I simply wouldn’t know where to start. If you are the type to put flaxseed in your smoothies or take krill oil before bed here’s something you might want to know.

The ginseng tea you have been sipping to reduce stress may actually be half alfalfa sprouts. Researchers in Ontario, Canada performed genetic analysis on 44 commercially available herbal supplements from 12 companies in North America and found that most contained something other than what was on the label.

The scientists used a process they call “DNA barcoding” which allows them to compare DNA they found in the supplements to a huge database of DNA sequences and the plant species they belong to. DNA barcoding is a relatively young procedure for comparing plant DNA, but the authors of this paper make exciting headway. The procedure relies on comparisons between the sequences of a common gene among plants. The tricky part is finding a gene that all plants have but whose sequence varies enough between species to differentiate them.

The winner? A gene called rbcL that codes for an enzyme nicknamed RuBisCo. RuBisCo is arguably the most important enzyme a plant has because it starts the plant’s metabolic cycle. The sequence of a plant’s RuBisCo gene turns out to be highly conserved within species, but significantly varied between species. This made it an excellent candidate for the DNA barcoding the scientists used in this study.
The scientists, just like we consumers, expected that bottles labeled “Ginkgo” would contain only Ginkgo DNA. However they found that one Ginkgo product was contaminated with walnut DNA and a product labeled St. John’s Wort contained Senna alexandrina which can cause chronic diarrhea. The authors found scores of contaminants and fillers in most of the products they tested, some with nasty sounding side-effects and others that were obviously just used to skimp on production costs. Nine percent of the products tested were actually just ground up rice or wheat to be sold as this, that or the other.

Even though some of the contaminants and fillers sound harmless—people eat walnuts and rice all the time—you can imagine that someone with a nut or gluten allergy would probably be worried about them! The point is not that everyone should avoid herbal supplements at all costs. The misrepresentation of product labels and the lack of industry standards for what constitutes a “pure” supplement are obviously out of whack. Even with the study’s small sample size, the degree of deception is surprising, emphasizing the vigilance we all need to have with regard to what we consume. And we should all be concerned enough about what we put into our bodies to take note of this study.

Sources and further reading
Newmaster, S.G; Grguric, M; Shanmughanandhan, D; Ramalingam, S; Ragupathy, S. (2013) DNA barcoding detects contamination and substitution in North American herbal products. BMC Medicine, 11:222. Accessed here: http://www.biomedcentral.com/content/pdf/1741-7015-11-222.pdf

Newmaster, S.G; Fazekas, A.J; Ragupathy, S. DNA barcoding in land plants: evaluation of rbcL in a multigene tiered approach. (2006) Can. J. Bot. 84, pp 335-341. Accessed here: http://www.nrcresearchpress.com/doi/pdf/10.1139/b06-047

New York Times article: http://www.nytimes.com/2013/11/05/science/herbal-supplements-are-often-not-what-they-seem.html?ref=science

Also check out what a Hendrix college alum, pharma-blogger Derek Lowe had to say about it: http://pipeline.corante.com/archives/2013/11/04/the_herbal_supplement_industry_is_not_a_very_funny_joke.php

Background photo credit: http://www.lmitchellacupuncture.com/services.html

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