Dr Des Corrigan looks at the crossover between food and beverage and medicinal use of a variety of plants

As I was cocooning, the prospect of a continental holiday faded into distant memories of past trips to France and the Italian lakes. Some images of those visits still linger and continue to intrigue me. Ever since I was a teenager, I have wondered about the contents of various bottles I spotted in French and Italian bars. Names such as Campari, Aperol and Fernet-Branca simply oozed sophistication to me. My parents, for some unknown reason, did have a bottle of Fernet-Branca in their rarely-used drinks cupboard, but all I recall of it is its vile, bitter taste.

I have since realised that the bitter taste is the whole point of the exercise, so I was not surprised to read that the herbal committee at the EMA is in the process of developing a monograph with the Latin title of Species amarae dealing with herbal combinations of bitter plants traditionally used in the therapeutic area of ‘loss of appetite’. As with many traditionally-used herbals, there is a crossover between food/beverage usage and medicinal use of a variety of plants such as gentian, wormwood, centaury, chicory, artichoke and bogbean.

‘Hipster’ essentials

I find it remarkable that what were somewhat neglected drinks suddenly reinvented themselves as ‘hipster’ essentials. I am thinking of course of Aperol Spritz, that trendy mix of Aperol, prosecco and soda water, which seems to be ubiquitous as a summer drink. Personally, I prefer prosecco (preferably from Conegliano-Valdobbiadene) without add-ons, but each to his or her own. According to Wikipedia, Aperol includes gentian, rhubarb and cinchona among its ingredients and gentian is the component most frequently found in a number of what the Italians call amaro, including Campari and Angostura. The latter also contains other herbs in a formula that is still a closely-guarded secret, and similar secrecy surrounds the ingredients of Fernet-Branca. 

Gentian is an alpine plant, the roots of which are used medicinally. The Community Herbal Monograph (CHM) prepared by the EMA describes two indications for gentian (and for the other bitter herbs). Firstly, it is a traditional herbal medicinal product (THMP) for temporary loss of appetite, and secondly, it is a THMP for mild dyspeptic/gastrointestinal disorders. The bitter compounds in both gentian and centaury are secoiridoids, mainly gentiopicroside in gentian and swertiamarin in centaury. Gentian also has a tiny amount of amarogentin, which is the most bitter substance known, as it has a bitter value of 58 million, compared to 12,000 for gentiopicroside. Gentian has long been known to increase gastric secretion in a variety of animal models. This gave rise to a general belief that bitter compounds stimulate the gustatory nerves in the mouth, leading to an increase in gastric juice and bile secretion, thus enhancing appetite and digestion. Clinical studies from the 1960s and 1980s show that secretion of saliva and gastric fluid increased after oral doses of gentian extract. The most recent human study dates back to 1997, but it was an open, non-interventional study in 205 patients with mild gastrointestinal complaints. After 15 days’ treatment with a gentian extract, excellent elimination of symptoms such as mild heartburn, vomiting, loss of appetite and flatulence was observed in 31 per cent of participants. Good results were noted in 55 per cent and moderate-to-poor response in the remaining 14 per cent.

A concern with a number of these plants is the fact that botanically, they belong to the family Asteraceae, which used to be the Compositae. Such plants are notorious for causing allergic reactions due to the sesquiterpene lactones that are characteristic of chrysanthemums, asters, etc…

The other major bitter is Artemisia absinthium, the essential oil of which is the basis of absinthe. It is known in English as wormwood and in German as Wermutkraut, from which the term ‘vermouth’ is derived. According to the European Pharmacopoeia, it has a bitterness value of 10,000 due to its content of sesquiterpene lactones. Some chemical varieties may contain thujone in the volatile oil, which is a concern because it is believed to be neurotoxic and carcinogenic at high doses. Exposure should be limited to less than 6mg per day, according to a Public Statement on Thujone issued by the EMA.

Bile secretion

Significant increases in the secretion of bile, gastric juice and free HCl are reported from studies in dogs given extracts. Studies in healthy humans show that wormwood herb gave a 100 per cent increase of saliva amounts. A study in 15 patients with liver disease showed that the volume of duodenal secretion, bilirubin, cholesterol, lipase and a-amylase levels were all significantly increased after ingestion of an extract. A randomised, placebo-controlled trial in 20 patients with Crohn’s disease treated with 2.25g of powdered wormwood daily for six weeks showed that 80 per cent of those given the herb had achieved clinical remission (defined as Crohn’s disease activity below 170), compared to 20 per cent of the placebo group. 

A concern with a number of these plants is the fact that botanically, they belong to the family Asteraceae, which used to be the Compositae. Such plants are notorious for causing allergic reactions due to the sesquiterpene lactones that are characteristic of chrysanthemums, asters, etc. The CHM from the EMA lists a contraindication in those with known hypersensitivity to other plants of the Asteraceae. This contraindication applies also to centaury and chicory. The latter is better known for its bitter-tasting leaves used in salads than as a medicinal plant. Chicory roots are baked and powdered for use as an additive in coffee or as a substitute for it. It is the roots with their content of sesquiterpene lactones that are used as a THMP. According to the CHM, preclinical studies show cholesterol-lowering and antidiabetic effects at high doses. The observed increase in bile flow (choleretic effect) is consistent, says the EMA, with the plant’s use in digestive disorders. 

Bogbean and chinotto are other bitter plants. Chinotto is the bark of a croton species that is also known as Cascarilla, but not to be confused with cascara bark. It is a major ingredient of Campari. The bitter principles are diterpenes, chiefly cascarillin, first isolated in pure form in 1845. Like the other bitter herbs, it too induces gastric acid secretion in animal studies, thus supporting the use of the bark extracts in preparations aimed at improving digestion. Bogbean, or menyanthes, has a herbal reputation as a bitter and a diuretic due to the presence of iridoids that give it a bitter value up to 10,000, compared to the value of 30,000 attributed to gentian and a CHM is currently under development.

I wonder did the use of gentian in Aperol, for example, arise from a traditional reputation as an appetite stimulant, or did the herbal use arise from the long-standing use of the beverage? I suspect that both went hand-in-hand, though I have no doubt that the owners of the various trademarked drinks will claim otherwise. If you self-identify as a hipster, may you continue to enjoy your summer spritz or your Campari and soda or Negroni, and may your digestion be the better for it.