Curious if it could be related to the hormone disruption properties of lavender.
https://www.endocrine.org/news-room/2018/chemicals-in-lavend...
https://www.endocrine.org/news-room/2018/chemicals-in-lavend...
The hypothesis is highly questionable to begin with, simply because the chemicals in lavender that show hormone disruption in vitro (almost all of them terpenes in the latest studies) are ubiquitous in nature, being present in hundreds of other widely consumed foods and herbs, often in high concentrations. Nature has surrounded us with these chemicals, and we've evolved in their presence. It would be really odd for lavender to cause problems, and not any of the other plants that contain the same substances.
The 2007 report (by Henley et al) that kicked off the whole panic over lavender and tea tree oil is a textbook case of poor quality pseudo-research that should never have been published. It had a sample size of three. That's right, three. It was neither blinded nor controlled in any way. It was simply a doctor who thought he noticed a decrease in gynecomastia among three kids after they stopped using some products that might have contained lavender or tea tree oil. If you want to know what's wrong with scientific publishing and reporting nowadays, reading about this case is a great place to start [1].
1 - https://roberttisserand.com/2013/02/lavender-oil-is-not-estr...
Update: OK, weirdly enough, Tisserand seems to be highly involved in the aromatherapy industry per their own website, and the study [0] seems to involve researchers from the "Research Institute for Fragrance Materials" which sounds suspiciously like an industry-related group - is this reputable at all??
[0] http://journals.sagepub.com/doi/abs/10.1177/1091581812472209
> Does the 2013 rebuttal study in that link tell us anything about the safety of ingesting lavender extract?
No, only topical application, albeit in far greater quantities than is seen in typical usage.
> Wouldn't that involve much higher absorption than topical application?
No, not necessarily. Silexan is delivered in 80mg doses. Higher levels of the same chemicals can easily be delivered by common foods. For example, a dish that's well seasoned with thyme or coriander can easily contain far more than 80 mg of linalool, and a few other ingredients would easily provide the same terpenoid profile as found in lavender, just as if you were to eat a large amount of lavender oil. Lavender really isn't anything special.
This might stop some of the people who jump on bandwagons from using it without talking with a doctor first.
https://www.nih.gov/news-events/news-releases/lavender-tea-t...
https://scholar.google.com/scholar?start=20&q=lavender+antia...
but merely smelling it should be a much smaller exposure. Disclaimer: I am not a doctor, I just like to read a lot.
The authors try to bolster their credibility by including some in-vitro evidence of estrogenic activity, which is extra-credit bullshit because there are plenty of common (and natural) substances that can disrupt hormones in a test tube, but show no such ability in actual humans. This is cheap research that the authors sensationalized with three completely uncontrolled and unblinded anecdotes. It blows my mind that this thing got published.
Notice how many other studies in your list cite that the Henley report. Also notice how many more recent studies list the same authors, namely Henley and Korach. Given the poor quality of their work and the overall implausibility of the proposed effect in vivo, I'd recommend taking their reports with a large amount of salt, at least until actual in-vivo effects are demonstrated in a higher quality study.
Case studies are widely used in medicine. But thanks for the downvote.
>Notice how many other studies in your list cite that the Henley report.
Here is a different report (early puberty in a girl):
https://www.pediatricnursing.org/article/S0882-5963(16)00076...
>Given the poor quality of their work and the overall implausibility of the proposed effect in vivo, I'd recommend taking their reports with a large amount of salt, at least until actual in-vivo effects are demonstrated in a higher quality study.
The cautious option is to avoid systemic use of lavender in populations where xenoestrogenic activity may be undesirable. Particularly in light of the fact that the “refutation” you linked was written by someone with an obvious conflict of interest.
Why are you saying I downvoted you? I'm not trying to be adversarial, just trying to provide counterpoints to what I believe is poor-quality reporting. Case studies are indeed often used in research. However in this situation we have an n=3 sampling without even a semblance of scientific control or analysis. They apparently didn't even bother to confirm whether the products that the kids were using actually contained lavender, much less characterize the quantity or composition. This isn't scientific by any stretch of the imagination. It's pure anecdote. It's no better than a facebook rumor.
> Here is a different report (early puberty in a girl)
Okay, another single case report, and again no analysis of the product being used, and no analysis of the "other CAM remedies" that the mother was reportedly using, nor any attempt to isolate other coincident changes in diet, treatment, chemical exposure, etc. Not sure how this helps anything.
> The cautious option is to avoid systemic use of lavender in populations where xenoestrogenic activity may be undesirable.
I disagree. You are of course free to be as cautious as you like, but IMO it's a paranoia that isn't justified by the research we've seen so far.
And as I said, the whole thing doen't really make sense. If we really do have to worry about lavender, then we're pretty fucked, because the chemicals of interest (such as the eight studied in the report you cited) are everywhere. Eucalyptus, basil, coriander, pine oil, mints of all kinds, citrus of all kinds... all of these and many more contain estrogenic terpenes in quantities similar to (or greater than) lavender. Are you going to be cautious of these as well if someone starts a rumor that they can disrupt your hormones?
> Particularly in light of the fact that the “refutation” you linked was written by someone with an obvious conflict of interest.
Tisserand's monetary interest in the industry could well lead to a conflict of interest. I don't know anything about him, but I'll grant that. But be careful about discounting him out of hand; it's easy to cross over into ad-hominem attacks. That he may have a dog in this fight doesn't necessarily make him wrong, and it doesn't make Henley's report more legit. Do you have a specific quarrel with Tisserand's reasoning? Do you have a rebuttal to his rebuttal, so to speak?
Agreed and that's why I said there's a "fear" about it and not a "scientific fact".
The articles say that it doesn't increase serum estrogen levels but I wonder if it might help the skin to achieve more "female" properties.