Myth, Reality and Absinthe – The Truth about Thujone
Myth, Reality and Absinthe – The Truth about Thujone
Absinthe has always had an ambivalent history, on one hand it was
praised as âThe Green Museâ by its devotees, and on the other it was
condemned by it detractors as a cause of madness and moral degeneracy.
But is there any scientific or medical basis for either position?
Evidence for mind-altering effects is largely anecdotal and the
frequently quoted first-hand descriptions of its mind-altering effects
have come from artists and poets who may be expected to describe events
in a fanciful manner. Imbibers of alcohol have always described their
favourite tipple in extravagant terms, whether it be Burns on whisky or
Yeats on wine. The case for its harmful effect is largely based on
research on laboratory animals conducted at the behest of the
prohibitionist lobby and assumptions drawn from examinations of mental
patients in the late 19th century.
The origins of absinthe can be traced back to the end of the 18th
century, when Pierre Ordinaire, a French doctor, used wormwood
(Artemisia absinthium) together with anise, fennel, hyssop and various
other herbs distilled in an alcoholic base as a herbal remedy for his
patients. Ordinaireâs recipe eventually found its way into the hands of
Henri-Louis Pernod who established the Pernod fils dynasty when he
opened his first distillery in 1805, and very soon âExtrait dâabsintheâ
stopped being a local curiosity and started on its route to becoming a
national phenomenon in France, and by the end of the 19th century it
had been embraced by the Bourgeoisie and demi-monde alike with over 2
million litres being consumed annually in France.
So what is the
published scientific evidence for the harm or benefits of absinthe?
Wormwood has had a long history in folk medicine dating back as far as
ancient Greece when it was variously prescribed for rheumatism,
jaundice, menstrual pains and as an aid in child birth, but it only
attracted scientific attention in the mid-19th century.
At
this time there was a powerful prohibitionist lobby gaining public
attention throughout France and it should be noted that research was
rarely totally independent and was conducted to support a particular
position, for or against the banning of alcohol. The first published
evidence for absintheâs harmful effects in animals dates from the 1860s
(Magnan V. Epilepsie alcoolique; action spéciale de l’absinthe:
épilepsie absinthique. Comptus Rendu des Seances et Memoires de la
Société de Biologie (Paris) 1869; 5(4th series): 156-61); (Amory R.
Experiments and observations on absinthe and absinthism. Boston Medical
and Surgical Journal 1868; 7: 8:68-71, 83-5). This purportedly shows
that wormwood oil and alcohol produce a synergistic effect which leads
to epileptiform convulsions. Magnan extended his studies to acute
alcoholics and concluded that absinthe produced symptoms in humans that
were distinct from alcoholic delirium tremens and manifest themselves
as epileptic convulsions
However, it is now accepted that
Magnanâs interpretations were oversimplified and alarmist. He not only
concluded that absinthe caused medical and psychological troubles not
associated with the high consumption of alcohol, he argued that
absintheâs deleterious effects were hereditary. Magnan was preoccupied
with the degeneration of the French race, which he blamed on alcohol
and in particular, absinthe. There should be no surprise at the
correlation of absinthe drinking amongst the destitute and alcoholics,
it was the cheapest way of buying strong alcohol. On the other hand,
millions of French people enjoyed the occasional glass of absinthe
after work without any ill effects. At around the same time, it was
becoming generally accepted that thujone, a terpene found in wormwood,
was responsible for absintheâs secondary effects, detrimental or
otherwise. It is often stated that the absinthe produced in the 19th
century had much larger amounts of thujone present than are allowed in
todayâs versions of the drink, which have to comply with EU limits of
10 mg/l. Values as high as 260 mg/l have been quoted by Arnold
(Absinthe, Arnold WN, Scientific American, 1989 Jun, 260(6):112-7).
However analytical techniques available in the 19th century were not
capable of separating thujone from many of the related compounds
present in the essential oils of the plants used to make absinthe and
it is therefore likely that concentrations were grossly overestimated.
Indeed, Bedel gives the amount of dried wormwood used in a typical
recipe as 2.5 kg in 100 l which, based on widely accepted yields of
oil, equates to 87.5 mg/l of oil, of which between 34 and 72% will
comprise thujone, giving a final maximum concentration of thujone in
the predistilled absinthe of 30 to 63 mg/l assuming 100% extraction
(Traite Complet de la Fabrication Des Liqueurs, Bedel, 1899, Paris).
However not all of the thujone will find its way into the distillate,
and the final concentration in the finished absinthe would have been
lower still. This is indeed confirmed when GLC analysis is applied to
samples of absinthes and the results do show much lower thujone levels
than expected. Analyses were performed on a sample of vintage Pernod
fils circa 1900, a sample of absinthe produced by a home distiller and
two modern commercial absinthes produced by traditional methods in
Pontarlier, France by using 19th century protocols. The vintage Pernod
absinthe is shown to have the lowest concentration of total thujone of
any of the samples tested and the highest is found in the Swiss sample,
but even this was lower than the EU limit of 35 mg/l for thujone in
bitters.
Table 1 Analysis of absinthe by GLC
Sample…………………………………………………..Thujone mg/l……………Anethole mg/l
Private distillation……………………………………………..25………………………..956
Vintage Pernod fils circa. 1900……………………………..6……………………….1400
Emile Pernot 45%……………………………………………….8……………………….1053
Un Emile 68%……………………………………………………10………………………..792
Samples
were analysed on a BP10 capillary column with FID. Programmed from 70 C
(held for 10 min) to 120 C at 5 C/min and held isothermally for a
further 10 min.
The convulsive ED50 of thujone in rats is
35.5 mg/kg/day po, and the âno effectâ level is 12.5 mg/kg/day po
(Margaria, R. (1963) Acute and sub-acute toxicity study on thujone.
Unpublished report of Istito di Fisiologia, Università di Milano). No
toxicity studies have been conducted in humans but the FDAs accepts a
safe level for food additives as a highly conservative 100 times less
than the no effect level in animals. Thus a safe (no effect) dose of
thujone could be extrapolated as 8.75 mg/day for a 70 kg human and it
can be seen that even at the highest concentrations found in any of the
samples tested, the effects of the alcohol would far outweigh those of
the thujone.
What is more likely to have caused harm to regular
absinthe drinkers is the adulterants used in the cheaper varieties.
Absinthe existed in a quality pyramid much as wine does today, for each
quality brand there were many more indifferent and positively harmful
versions being sold cheaply to those who could not afford to buy a
reputable brand. Common adulterants were cupric acetate (to provide the
valued green colour) and antimony trichloride (which provided a
cloudiness when water was added in imitation of the milky appearance of
diluted absinthe). The purity of the base alcohol used for lesser
brands would also have been questionable, and toxic levels of methanol
from poor rectification would have been a real possibility. An
additional aggravating factor is that as the cheaper brands were lower
in alcohol than the quality brands, around 45% abv for âabsinthe
demi-fineâ compared to 68 or 72% for âabsinthe superiorâ, someone
drinking the cheaper version and seeking to obtain the same effect from
the alcohol would have needed to consume more of the absinthe and hence
more adulterants.
On the other hand the base alcohol used in
quality absinthe was rectified wine alcohol at 85% which was free from
congeners, and although bottled at 68% (to preserve the natural green
colour of the chlorophyll) the final strength when diluted was no more
than a glass of wine. Interest in absinthe naturally waned after the
ban in Switzerland and France, and scientific interest faded until a
paper was published in 1975 (Castillo et al; Nature, 1975, 253:365-356)
which suggested similarities between the reported effects of absinthe
and those of marijuana (Cannabis sativa) and attempted to explain these
by highlighting similarities in the molecular geometry of thujone and
tetrahydrocannabinol. This reignited the controversy surrounding
absinthe but no further evidence to support these findings and in 1999
Meschler and Howlett determined that thujone had no activity at the
cannabinoid receptor. (Meschler and Howlett, Pharmacol Biochem Behav,
1999, 62(3): 473-80) and current research points to it being a GABA-A
modulator (Mold et al, PNAS, 1999, 97(8), 3826). Thujoneâs GABA
modulating activity explains its convulsant effects at high doses and
smaller doses may produce stimulant action (there is anecdotal evidence
that drinking absinthe produces a clarity of thought that is not
usually associated with alcoholic drinks).
So
if the case for the harmful effects of absinthe is flimsy, does it have
any beneficial ones? Ordinaire first prescribed it as a general tonic
but it is doubtful whether he performed any objective research into
whether it was improving the condition of his patients, they kept
coming back for more so it must be doing them good. The producers
unashamedly sold absinthe on the basis of its health giving properties,
especially in the years leading up to the ban. In 1844 absinthe was
issued to French legionnaires fighting in Algeria as it was believed to
prevent fever and kill bacteria in water. Although there were no
studies to support this at the time, in 1975 researchers found that
dilute oil of wormwood did inhibit the growth of 4 out of 7 types of
bacteria. (Kaul VK; Nigam SS; Dhar KL. Antimicrobial activities of the
essential oils of Artemisia absinthium linn, Artemisia vestita wall’
and Artemisia vulgaris Linn, Indian Journal of Pharmacy, 1976, 38(1),
21-22).
Wormwood
has also been shown to be a hepatoprotective. Gilani and Janbaz found
that an extract of Artemisia absinthium protected against acetaminophen
and carbon tetrachloride-induced hepatotoxicity in mice. The presence
of antioxidants and calcium-channel blockers in wormwood also probably
contributes to its hepatoprotective effects. (Gilani AH; Janbaz KH.,
Preventative and curative effects of Artemisia absinthium on
acetaminophen and CCl4-induced hepatotoxicity, Gen. Pharmacol, 1995,
26(2):309-315; Gilani AH. Search for new calcium channel blocking drugs
from indigenous plants, International Congress on Natural Products
Research, 1994, August 1-5, Halifax 0:29). Recent studies have
demonstrated that extracts of wormwood (and other plants used in
absinthe) have CNS cholinergic receptor binding activity and therefore
contrary to accepted wisdom, absinthe may actually improve cognitive
function (Wake et al, J Ethnopharmacol, 2000 Feb;69(2):105-14.
In
conclusion, there is no evidence that absinthe ever contained the high
concentrations of thujone that would have led to detrimental effects or
that it has hallucinogenic or mind altering properties. The health
problems experienced by chronic users were likely to have been caused
by adulterants in inferior brands and by the high levels of alcohol
present. Claims for beneficial effects must also be treated with some
scepticism as again, the detrimental effects of the alcohol would
presumably outweigh any benefits. It seems likely that the phenomenal
success of absinthe during the 19th century was due to one factor, the
French love of aniseed drinks. The modern equivalent of absinthe,
pastis, is by far the most popular distilled spirit in France with 125
million litres being consumed annually. Perhaps the reason that so much
absinthe was consumed, and absintheurs waxed so lyrically about it was
simply because it tasted good.
This article by Ian Hutton first appeared in Current Drug Discovery, September, 2002; click here to view a facsimile of the original article.