The Science of Food

Absinthe seems to come to us out of the mists, the alleyways and the side streets of Belle Epoque Paris. The verdant symbol of bohemian excess, absinthe speaks to us of the heyday of the Montmartre. A time when bars like the Moulin Rouge and Le Rat Mort¹ provided the chaotic playgrounds for those from all levels of French society with a taste for excess. Places where tortured artists and threadbare writers would bump shoulders with the workers, the prostitutes, the musicians, the cancan dancers and the slumming rich. Absinthe was La Fée Verte, the green fairy. The intoxicant, the aphrodisiac, the muse and the destroyer of men and women that fuelled this riotous nightlife. Eventually, a victim of its own notoriety, absinthe was banned by those who saw nothing but societal ruin in its cloudy depths. This only deepened its mystique and it became a symbol. A symbol of a different, more exciting world. A world forever shattered by the guns of August 1914².

All this is hindsight though. At the time absinthe wasn’t the symbol of a lost age. Absinthe meant something different. And it meant different things to different people. To artists and writers absinthe was more than just 120 proof alcohol. Absinthe was seen, much like LSD would come to be seen, as a way of opening the mind to inspiration. Those seeking a muse believed they found one in the dream-like state that was reputed to accompany absinthe consumption. Those who were opposed to absinthe opposed it for very much the same reasons. Inexpensive, absinthe was within the reach of everyone in French society and some worried that the hallucinogenic properties would cause the ruination of society. Nothing good could come from the common workers having their minds opened for them.

It was all a myth of course. Absinthe, real absinthe, did not, and still doesn’t, cause hallucinations. But the myth of absinthe’s mind-altering properties was useful to both sides, though they used it for different reasons. The artists and revellers in Montmartre enjoyed the notoriety, the street cred, that they gained as absinthe drinkers. They probably also enjoyed getting very, very drunk for not a lot of money. The reformers, on their part, could point to the extreme effects and use absinthe as an easy target. With absinthe they could gain a tactical victory in the wider war against alcohol. With so many different parts of society promoting the myth it is no surprise that to this day absinthe retains an air of notoriety and even danger.

These myths about absinthe centred around one of its main ingredients: the perennial herb wormwood. Though absinthe was a relatively new drink in the 19th century, wormwood had a long history of use as a herbal remedy, mostly to treat intestinal worms (which I wrote a post about here). It was first mentioned in Egypt, in the Ebers Papyrus, around 1500BC³, it shows up in the Old Testament and woman in the Middle Ages daubed wormwood on their nipples to discourage weaning youngsters⁴. Absinthe wasn’t even the first drink to be made from wormwood. Purl, a drink made with warm ale and wormwood, was popular in Tudor England. Significantly, despite mankind’s extensive history with wormwood, and our uncanny ability for uncovering mind altering substances, it does not seem to have ever been used as a hallucinogenic.

It was, however, wormwood’s putative medicinal properties that led to the creation of absinthe. The French physician Pierre Ordinaire, a refugee of the French Revolution, created absinthe while living in Couvet in western Switzerland. Ordinaire was not trying to create a muse for struggling artists. He wanted to create a distillation of wormwood that would mitigate its natural bitterness while retaining some of the health benefits. Despite being a medicine, his highly alcoholic green tonic became very popular in surrounding areas and when he died his recipe made its way into the hands of Henri-Louis Pernod⁵ who, with his father-in-law, started the first commercial absinthe distillery in 1797.

At first business was a bit slow, production was only around 16L a day when the business first opened, most of it consumed locally. But fate had a bigger role planned for absinthe than a regional health tonic and events elsewhere laid the groundwork for absinthe’s future notoriety. A key event was when the French army began supplying absinthe to the troops during the conquest of Algiers, between 1830 and 1847. Intended as an anti-malarial and anthelmintic, the soldiers developed a taste for it and, like British soldiers who drank gin and tonic in India, brought that taste home with them.

Then, beginning in 1863, the phylloxera crisis almost destroyed the entire French wine industry. The crisis, caused by a New World insect that had made its way to Europe and destroyed wine stocks, increased the price of wine and decreased the cost of absinthe as manufacturers shifted to cheaper grain alcohols. The combination of a growing customer base, a shortage of wine and the relative low cost of absinthe caused a massive boom in absinthe consumption. The party had begun.

By the mid 1860s absinthe had become more popular than air fryers are now⁶. Absinthe was so popular that the hour between 5 and 6 PM was known as “l’heure verte“, the green hour. The hour when Parisians flocked to bars and cafes to take in an absinthe or two. Although we sometimes think of absinthe as an illicit drink, consumed by the risk-taking fringes of society, the truth is that absinthe was the national drink of France. Between 1896-1913 absinthe consumption increased by fifteen times, at its height it was estimated that 60L of absinthe was consumed for each and every person in France⁷. To put that in perspective, the 2024 per capita consumption of whiskey in the USA was only 1.4L.

It’s not hard to see why absinthe was so popular. It was inexpensive, had a pleasant taste of anise and fennel, at least when diluted, and, with an alcohol content running between 60-80%, it gave you some bang for your buck. But absinthe also provided a ritual. If you were transported back to 1895 Paris and ordered an absinthe you would be provided a glass of absinthe, a slotted teaspoon with sugar in it and a carafe of water. The idea was to slowly drip water through the sugar, into the absinthe, and then consume the sweetened, and watered down, cocktail. Apart from softening the bitterness and decreasing the incredibly high alcohol content, drinkers were also on the lookout for a phenomenon that was called “la louche“, the transformation of the absinthe from a bright green colour to a uniform cloudy light green⁸.

The louching of the absinthe, apart from being a quaint ritual, actually served a couple of other purposes. Proper absinthe is made by distilling a mixture of alcohol and macerated herbs, generally wormwood, anise and fennel. This process ensured that oils and other hydrophobic compounds from the herbs dissolve in the alcohol and contribute to the flavour of the finished product. When you add water to absinthe the alcohol concentration drops and it can no longer keep the oils in solution. The oils clump together and to form a cloudy emulsion. The same thing occurs in Ouzo, which is basically made the same way. This process, by increasing both the surface area of the oils and their volatility, makes tasting them a lot easier. So much so that one could say that their flavours are released by adding the water.

The other advantage of “la louche” was that it told you that you were drinking proper absinthe. People being people, once absinthe started to increase in popularity the market was flooded with absinthe made by those with less interest in the product and more in cutting corners and increasing profits, just like modern internet platforms. During distillation it is common to discard the start and the finish of the distillate, the parts that often contain undesirable molecules, like methanol. One common method was to take these headings and leavings from a reputable manufacturer and make your crappy absinthe from these. Also common, as it is today, was to not do any distilling at all and just mix flavourings and colourings that approximated absinthe.

These products would not louche when water was added because they didn’t contain the oils isolated from the herbs during the distilling process. If your absinthe did not produce a well distributed cloudy emulsion, you were, as you would be today, not drinking a proper absinthe. Absinthe grifters were aware of this and so they would add things like salts of antimony, which would produced a louche-like effect when water was added, and copper sulphate, to get the green colour of proper absinthe. Methanol was also a common contaminant in poorly made absinthe. All of these compounds are highly toxic, antimony, for example, is a heavy metal that causes vomiting, diarrhoea, severe abdominal pain and damage to the kidney and liver. Methanol causes blindness and death.

These adulterants not only made drinking a cheap absinthe a bit of a risky proposition in the 19th century but they may have also contributed to absinthe’s reputed hallucinatory effects. As I mentioned above a lot of people subscribed to this myth, for different reasons, but chief among the detractors was a doctor called Valentin Magnan. He was an outspoken critic of absinthe and believed that the effects of absinthe went beyond that of simple alcoholic intoxication. Magnan was so sure of this that he created a pathology, distinct from alcoholism, called “absinthism”.

According to Magnan, someone suffering from absinthism would experience seizures, speech impairment, sleep disorder, mental prostration, auditory and visual hallucinations and finally death. Magnan focused on a constituent of wormwood called thujone as the cause of absinthism. Thujone is a member of a family of chemicals called terpenoids (defined as molecules composed of isoprene units and functional side chains if you want to sound clever). There are about 80,000 terpenoids in the plant world, making up an significant component of what is often referred to as essential oils. Menthol, capsaicin, eugenol and delta-9-tetrahydrocannabinol (THC), the active ingredient of marijuana, are all terpenoids.

Thujone is actually a psychoactive compound, that is a molecule the acts on the central nervous system, but not all psychoactive compounds cause hallucinations. In fact, most don’t. Thujone acts on the CNS by acting as an antagonist⁹ of the gamma-aminobutyric acid (GABA) receptor. GABA is one of the most important inhibitory neurotransmitters in the brain and thujone, as an antagonist of its receptors, stops GABA inhibition, making neurons more likely to fire. Its major affect, in large enough doses, is to act as a convulsant. While it can be hard to determine what a drug does to someones state of mind at high doses, because scientists can’t go around poisoning people, one recent, and extremely rare, case of thujone poisoning reported no hallucinatory effects. Thujone also does not produce effects similar to THC, as some have suggested.

Yet, over the course of several years, Magnan conducted a series of experiments that he believed connected absinthism, and its hallucinations, with the thujone that was found in absinthe. There is not enough space here to do a full evaluation of his work, apart to say that it was probably what we would call shoddy research today. He never used absinthe but oils extracted from wormwood, he relied on massive dosages of wormwood oil to elicit symptoms from laboratory animals and he completely ignored alcohol toxicity in his theories. He was also relying on an overestimation of how much thujone was actually in absinthe.

It was thought that 19th century absinthe contained a lot more thujone than what you find in absinthe today. But work analysing surviving pre-WW1 absinthe and also absinthe produced according to recipes at the time both show that there probably was roughly the same amount of thujone in the absinthe from then as you find in absinthe today (for a comprehensive review of the topic you can see here). A level nowhere near the level that could conceivably cause hallucinations or any real observable affect at all. The consensus today is that the so-called effects of absinthism were actually the result of chronic or acute alcoholism, other drugs, poor mental health and the affects of adulterants and contaminants. This was not a particularly healthy era for some members of society.

Regardless of the truth, Magnan’s theories were seized upon by those who wanted to ban absinthe. Absinthism became the bête noire of anti-absinthe activists, blamed for moral decay and the cause of violent crime. Infamously, a French labourer called Jean Lanfray, working in Switzerland, killed his wife and children after his wife had refused to polish his shoes. Anti-absinthe activists were able to frame the murders as a result of Lanfray having consumed absinthe before the murders, sparking a public panic and a consequent ban on absinthe in Switzerland in 1906. Other countries followed suit shortly after. The fact that the police had determined that Lanfray consumed, that day, seven glasses of wine, six glasses of cognac, two coffees laced with brandy, two crème de menthes in addition to two glasses of absinthe got kind of lost in the uproar. The party was over.

Today absinthe is having a bit of a revival. Mostly tied to it’s mystique and a curiosity about the drink that fuelled the artists and writers of the Belle Epoque. Not to mention its dangerous reputation. To me, at least, it all seems a bit empty. Just another example of the mass tourism of the modern age that reduces many things to a selfie and a social media post. The world has moved on from the Montmartre and the Belle Epoque, it’s a different world and it is unlikely that absinthe will be fuelling any new cultural revolutions. Having said that it does taste pretty good so maybe some enterprising group of artists will take up absinthe and make it cool again. After all, after a few absinthes, anything seems possible.

Footnotes

1. The Dead Rat. ↩︎
2. Guns that were no doubt ordered into firing by the very same people who so feared absinthe. ↩︎
3. Though it is thought to be a copy of older texts, potentially as going back as far as 3500BC. ↩︎
4. A practice that Shakespeare mentions in Romeo and Juliet. He has a nursemaid describes how she got Juliet to stop breastfeeding using wormwood:
   “When it did taste the wormwood on the nipple / Of my dug and felt it bitter, pretty fool, / To see it tetchy and fall out with the dug!” Romeo and Juliet; Act 1, Scene 3. ↩︎
5. Pernod named his absinthe ‘Pernod Fils’ and after the absinthe ban the company released a wormwood free aniseed pastis that it still popular today. ↩︎
6. And a lot more fun than air-fryers. ↩︎
7. I’ve referenced a paper that references the Time of London. You can see the original article at their archive but I couldn’t access it. If you have a subscription you should be able to read the article. ↩︎
8. The other ritual you might see is the use of sugar and flame, this was invented in Prague bars in the 1990s because some Bohemian absinthes don’t louche. Bohemian absinthes don’t include anise, or small amounts, and fennel so they don’t louche. Because they lack the other herbs they tend to be more bitter and medicinal in flavour than French style absinthes. They are also often compounded and not distilled (see here for more on this). ↩︎
9. An antagonist is a molecule that inhibits the normal activity of a cell receptor (I discuss this more here and here). ↩︎