Long-standing concerns about certain isolated components of the spice tarragon have broadened into questions about the safety of even the leaves themselves.
Maxim Fetissenko, PhD, and Laurie-Marie Pisciotta for their keynote help.
Decades ago, concern was raised about some of the components of the spice tarragon, so much so the European Union's Health & Consumer Protection Scientific Committee on Food eventually concluded that one of the constituents may damage DNA, cause cancer, and so we should reduce and restrict its use. But they were talking about an isolated chemical from tarragon being used as a flavoring agent in alcoholic beverages, canned fish, and fats and oils. As recently as 2011, reviews concluded that consumption of the tarragon leaves itself should present little or no risk, but that was based on studies done on rats. A 2012 study made me feel better, suggesting that while the isolated tarragon chemical was toxic to human liver cells, full extracts of the leaves were not, suggesting that the whole food may contain compounds that counteract the toxic effects. And so I was going to leave it at that and not even do a video about it, since tarragon seemed to be cleared, but a 2013 study on human white blood cells reopened the question, finding that whole leaf tarragon extracts may have DNA damaging properties after all—remember the comet test? They conclude that tarragon does indeed appear to be mutagenic to at least a certain extent. However, the current data is not comprehensive enough to draw definitive conclusions regarding its potential risk to human health with sustained use, nor comprehensive enough to establish a safe dose or quantify the risk. Nevertheless, future use of tarragon in both diet or herbal medicine should be undertaken with an awareness of it's potential toxicity. So what have I taken away from all this? Well my family eats tarragon so rarely that it's probably not going to change our intake at all, but if you're a tarragon fanatic, I'd suggest moderating your intake and substituting another herb like a dash of fennel or anise-seed, or chervil, all of which have a similar licorishy tarragon taste. The only caveat I could find is that you probably shouldn't pick chervil wild, as it bears a resemblance to an herb known all too well to Socrates, poison hemlock.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Jonathan Hodgson.
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For those scratching their heads over the significance of that red smudge, see my explanation of the comet tail test in Cancer, Interrupted: Garlic & Flavonoids.
This new tarragon finding reminds me a bit about the in vitro data raising questions about the safety of avocados (Are Avocados Bad for You?) that thankfully appeared to not translate out into population studies. I'll keep an eye out for new data and post to the NutritionFacts.org Facebook page if I find anything. In the meanwhile, there are a bunch of other reasons to avoid canned fish:
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