Clove (Syzygium aromaticum)

Clove (Syzygium aromaticum) is the dried unopened flower bud of a tropical evergreen tree in the Myrtaceae family, native to the Maluku Islands, the Spice Islands of eastern Indonesia. The bud is hand-picked before it opens, sun-dried until it turns dark brown, and shipped worldwide as one of the most aromatic spices in the global trade. The signature bioactive is eugenol, which makes up around seventy to ninety percent of the essential oil; eugenyl acetate and beta-caryophyllene are the next major components. The same chemistry that gives clove its warm, sweet, intense aroma also gives it the tongue-numbing quality that European herbalists noticed centuries ago.

The European Medicines Agency Committee on Herbal Medicinal Products (EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC)) adopted a traditional-use monograph for clove oil, Caryophylli floris aetheroleum, for relief of minor inflammations of the oral mucosa and for minor toothache. For the bud itself, Caryophylli flos, the HMPC issued a public statement rather than a monograph, while the German Commission E published a positive monograph on the bud covering inflammation of the mouth and pharynx and dental analgesia. Named modern work includes Alqareer and colleagues 2006, who reported that a clove gel was comparable to twenty percent benzocaine for topical dental anaesthesia, and Shan and colleagues 2005, who ranked clove highest of twenty-six common spices on the ORAC in-vitro antioxidant assay. ORAC is a laboratory measurement, not a clinical outcome, and EFSA does not recognise it as a basis for antioxidant health claims. For Christianes Naturkraft, clove is one of the warming spices in our Klassik Sirup, anchored in the European Weihnachts-Tradition of Glühwein and Lebkuchen.

Clove has one of the longest and most colourful biographies of any spice. Chinese court records from the third century before the common era describe officials chewing clove buds before addressing the emperor, to freshen the breath. Arab and Indian traders carried clove westward along the spice routes for more than a thousand years. The botanical origin, the Maluku Islands in eastern Indonesia, stayed a closely guarded secret of the trading houses; when Portuguese and then Dutch ships reached the Moluccas in the sixteenth century, clove became one of the central commodities of European colonial expansion, with the Dutch East India Company maintaining a deliberate monopoly through the seventeenth and eighteenth centuries. The English word clove and the German Nelke both trace back to Latin clavus, nail, a description of the bud shape.

In the Austrian and broader German-speaking tradition, clove is first and foremost a Christmas spice. Whole cloves stuck into oranges make the classic Weihnachts-Pomander. Glühwein on the Christkindlmarkt is unthinkable without clove, cinnamon, and orange peel. Lebkuchen, Magenbrot, and the wider Weihnachtsbäckerei rely on ground clove for the deep, warm note that signals winter. The Apothekentradition runs in parallel: Nelkenöl as a topical Zahnschmerzen remedy is a classic of European household medicine, and the EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) traditional-use monograph for clove oil (Caryophylli floris aetheroleum) formally recognises the traditional use for minor oral mucosa inflammation and minor toothache, with the bud (Caryophylli flos) covered by the German Commission E positive monograph. The plant therefore arrives in Austria along two routes that share the same chemistry: the culinary one through the Glühwein pot and the Lebkuchen tin, and the medicinal one through the pharmacy shelf.

Eugenol is the chemical signature of clove. Around seventy to ninety percent of the essential oil is eugenol, with eugenyl acetate and beta-caryophyllene as the other major components. Eugenol acts on the TRPV1 receptor, the same receptor that responds to capsaicin and to heat, and this interaction explains the local-anaesthetic, tongue-numbing quality of a chewed clove or a drop of clove oil on the gum. The same molecule has been shown in laboratory studies to inhibit COX-2 and NF-kB signalling pathways, which is the mechanistic basis for the anti-inflammatory line of research summarised by Barboza and colleagues 2018.

Two other mechanism stories run alongside eugenol. Beta-caryophyllene is a partial agonist of the CB2 cannabinoid receptor, an emerging line of pharmacological interest; it is present in small amounts in clove and in many culinary spices and is not unique to clove. Eugenol also has mild antiplatelet activity in laboratory studies, the documented basis for the anticoagulant interaction caution in the safety section. The clinical translation of either mechanism at culinary doses is uncertain; both are research-level observations rather than dosing rules. The mechanism story most relevant to the Weihnachts-Tradition is therefore the simplest: clove is a warming aromatic that the European bitter-and-aromatic digestive tradition has used for centuries, with a chemistry that is consistent with that role.

The strongest clinical research on clove sits in the topical dental space. Alqareer and colleagues in 2006 ran a split-mouth randomised study in seventy-three adult volunteers, comparing a clove gel, twenty percent benzocaine, and placebo for needle-stick pain at the injection site; the clove gel performed comparably to benzocaine and significantly better than placebo. This is the use the EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) traditional-use monograph for clove oil (Caryophylli floris aetheroleum) recognises, with the bud (Caryophylli flos) covered by the German Commission E positive monograph, and it is the use Austrian Apothekentradition has carried for centuries. It is also a topical, dental application, and not a use Christianes Naturkraft describes; for any active toothache the right step is to see a dentist, not to rely on clove.

For the warming, digestive, and culinary uses of clove that anchor it in the Weihnachts-Tradition, the evidence is primarily traditional and mechanistic. Shan and colleagues in 2005 ranked clove highest among twenty-six spices on the ORAC antioxidant assay; ORAC is an in-vitro chemical measurement and EFSA does not recognise it as a basis for antioxidant claims in humans. Chaieb and colleagues 2007 reviewed a wide laboratory literature on the broad-spectrum antimicrobial activity of eugenol; the bench data is consistent, the translation to oral bioavailability in everyday culinary doses is not established. Barboza and colleagues 2018 reviewed mechanistic evidence that eugenol inhibits COX-2 and other inflammatory pathways in laboratory models. The honest reading: clove carries more documented pharmacology than most kitchen spices, with most of it sitting at the mechanistic-and-traditional end of the evidence axis.

Forms and preparation

For culinary use, whole cloves are the standard form. Two to four cloves go into a litre of mulled wine or Glühwein together with cinnamon, orange peel, and star anise, simmered gently for ten to twenty minutes and strained before serving. One or two cloves can be added to a chai or to a pot of black tea. Ground cloves are the form most often used in Lebkuchen, Spekulatius, and the broader Weihnachtsbäckerei spice mix; a quarter to half a teaspoon per batch is a typical bakery dose. For a traditional clove tea, one or two crushed cloves steeped in a cup of freshly boiled water for five to ten minutes is the household preparation. For the EMA HMPC traditional indication of minor mouth or throat irritation, a single chewed clove or a clove-bud mouthwash made by infusing one or two cloves in warm water and gargling is the classical Apothekentradition form. Clove essential oil is the most concentrated form and must be handled with care. A drop or two diluted into a carrier oil, such as olive oil, can be applied topically to the affected area; the essential oil is never to be used neat on mucous membranes, and never internally. For an active toothache the right step is to see a dentist; clove is a household first-line comfort measure, not a treatment.

Dosage

For culinary use, one to five whole cloves per dish or per pot of mulled wine is the traditional range; for ground clove, a quarter to half a teaspoon per recipe. For a clove tea, one or two crushed cloves per cup, up to two or three cups per day. For clove essential oil, only diluted topical use is appropriate; a one to five percent dilution in a carrier oil for short-term external application to the affected area. The essential oil is not to be used internally and not to be applied neat. Start at the lower end. Clove is an intensely flavoured spice, and a single bud or a pinch of ground clove is enough to carry a whole pot. If you are using a clove preparation in the EMA HMPC traditional sense for minor oral or dental complaints, treat it as a short-term household measure, not a daily long-term regime; for any complaint that persists more than a day or two, see a dentist or doctor. If you take anticoagulant medication, see the warnings below before using concentrated clove preparations.

1. Alqareer et al.. Alqareer et al. 2006. 2006. PMID:16530911
2. Shan et al.. Shan et al. 2005. 2005. PMID:15713023
3. Chaieb et al.. Chaieb et al. 2007. 2007. PMID:17380552
4. Barboza et al.. Barboza et al. 2018. 2018. PMID:29655293