Skip to main content

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

Comments

Post a Comment

Popular posts from this blog

Precision murder -- wait, no -- medicine

A non-zero amount of what we call ‘medicine’ could be described as just controlled cell murder.  This was my revelation after researching a new treatment for certain cardiac arrhythmias called Pulsed Electric Field Ablation, which I became interested in when my father-in-law asked me how it worked during our Christmas visit. “How can it kill the heart cells and leave the nerves and blood vessels intact?” I had no idea. I know next-to-nothing about medical treatments for cardiac patients, much less how this Pulsed Field Ablation technique could have fewer side effects than the standard-of-care ablation techniques. A quick Google search piqued my curiosity when I learned that PFA is also sometimes called “high frequency irreversible electroporation”. While less catchy, that name revealed a bit more about the mechanism of action behind PFA - electroporation - which happens to be something I actually do know something about. Electroporation refers to the formation of holes (pores) in c...
Post a Comment
Read more

AlphaFold2 Part 2: The ion channel challenge

Last month I wrote about the wonders and perils of the artificial intelligence program that predicts 3D protein structures, AlphaFold2. As an ion channel enthusiast , I naturally wanted to know how AlphaFold2 performs at predicting the structures of proteins embedded in cell membranes. When I search PubMed for articles that mention both "AlphaFold" and "ion channel" I only get 34 hits. This surprised me, given the hype and the general paranoia around AI replacing humanity. If we use these search results as a proxy for the state of the ion channel protein structure prediction field, I'd say the juice is still in the coconut. I wanted to know how well AF2 would do at predicting an ion channel protein structure, so I asked it to generate the structure of Kv2.1, a voltage-gated potassium ion channel that I studied during graduate school. Kv2.1 is a pretty important protein. It regulates neuron firing throughout the brain and body where it helps us learn new stuff, ...
Post a Comment
Read more

iPSCs, the new model organism?

Induced pluripotent stem cells. The name doesn't exactly roll off the tongue and it certainly doesn't conjure images of mice, fruit flies, monkeys, or any of the other classic model organisms used for basic biomedical research. These so called "model organisms" are just that; animals that help scientists model the way that the most promising human therapeutics in the collective pipeline will behave in humans. And now induced pluripotent stem cells, or iPSCs, are becoming an increasingly popular tool used for developing and testing novel drugs way before we expose any real human patients to them. The upside to using model organisms is pretty obvious -- we minimize exposure of humans to potentially unsafe molecules. The downsides are many, but one big one is that sometimes potential new drug molecules look really promising when they are given to a mouse with a human-like disease, but then that same molecule does nothing (or worse, is toxic!) when it goes into human clin...
Post a Comment
Read more