Description

Syzygium aromaticum is a tropical evergreen tree belonging to the Myrtaceae (myrtle) family. It grows to a height of 8–12 meters (26–39 feet) with large leaves and crimson flowers arranged in terminal clusters. The aromatic flower buds, which are the primary commercial product, start pale, turn green, and then bright red when ready for harvest, measuring 1.5–2 centimeters (0.6–0.8 inches) long. Each bud consists of a long calyx ending in four sepals and four unopened petals forming a central ball. The tree thrives in tropical climates and is now cultivated in countries like Indonesia (the largest producer), Madagascar, Tanzania, Sri Lanka, Comoros, India, Malaysia, and Brazil. Clove buds are harvested before flowering, typically after the tree is 4 years old, either manually or using phytohormones to induce maturation. The plant’s essential oil, rich in eugenol (72–90%), contributes to its strong aroma and flavor. Other components include acetyl eugenol, beta-caryophyllene, vanillin, tannins, flavonoids (e.g., kaempferol, quercetin), and phenolic acids like gallic acid. Clove is botanically classified as: Kingdom Plantae, Clade Tracheophytes (Angiosperms, Eudicots, Rosids), Order Myrtales, Family Myrtaceae, Genus Syzygium, Species S. aromaticum. It has been historically significant in trade, driving colonial economies, and is used for its preservative, medicinal, and culinary properties.

Other Names

  • English: Clove, Clovetree
  • Spanish: Clavo, Clavo de olor
  • French: Clou de girofle
  • Hindi: Laung (लौंग)
  • Sanskrit: Lavanga (लवङ्ग)
  • Arabic: Qaranful (قرنفل)
  • Mandarin Chinese (中文): Dīngxiāng (丁香)
  • Malay: Cengkih, Bunga cengkih
  • Portuguese: Cravo, Cravo-da-índia
  • German: Gewürznelke, Nelke
  • Tamil: Kirambu (கிராம்பு)
  • Portuguese: Cravo-da-índia 
  • Yoruba: Kanafuru 
  • Hausa: Karanfil 
  • Igbo: Ose oyibo 
  • Swahili: Karafuu 

Health Benefits

Cloves have been used for centuries in various traditional medicine systems, such as Ayurveda and Traditional Chinese Medicine, primarily due to the biological activity of eugenol. Modern research has validated many of these traditional uses.

  1. Dental Analgesic and Antiseptic: This is the most well-known benefit. Eugenol is a natural anesthetic and antibacterial agent. Clove oil or a whole clove is commonly used to relieve toothache, reduce gum inflammation, and fight oral pathogens that cause plaque and gingivitis. It is a common ingredient in toothpaste, mouthwash, and dental cement.
  2. Antioxidant Powerhouse: Cloves have the highest recorded antioxidant capacity of all foods and spices, as measured by the ORAC (Oxygen Radical Absorbance Capacity) score. The antioxidants, including eugenol, help combat oxidative stress, which is linked to chronic diseases like cancer, heart disease, and diabetes.
  3. Anti-inflammatory and Pain Relief: Eugenol possesses significant anti-inflammatory properties. Topical application of clove oil is traditionally used to relieve pain and inflammation associated with arthritis, sore muscles, and minor wounds.
  4. Antimicrobial and Antifungal: Clove essential oil exhibits broad-spectrum activity against bacteria like E. coli and Staphylococcus aureus, as well as fungi like Candida albicans. This supports its use in food preservation and in treating infections.
  5. Aid in Digestion: In traditional medicine, cloves are used to treat digestive ailments. They are carminative, meaning they help relieve gas and bloating. Cloves may also stimulate the production of digestive enzymes.
  6. Potential Blood Sugar Regulation: Some studies suggest that compounds in cloves can help improve insulin sensitivity and lower blood sugar levels, showing potential for managing type 2 diabetes.
  7. Hepato-protective: Cloves may support liver health by improving toxin-induced damage, though high doses could harm the liver.
  8. Anticancer Properties: They exhibit anticancer properties, with eugenol promoting cell death in cancer cells like breast cancer, but more human studies are needed.
  9. Bone Health: They promote bone health through eugenol and manganese, potentially increasing bone mass.
  10. Antiulcer: Cloves reduce stomach ulcers by combating H. pylori and exerting anti-ulcer effects.
  11. Respiratory Relief: Inhalation of clove oil vapors or its use in teas can relieve symptoms of cough, asthma, and bronchitis due to its expectorant and soothing effects. 
  12. Traditional Uses: Traditionally, they relieve nausea, respiratory symptoms, toothache, and joint pain, with evidence supporting analgesic effects for dental pain and alveolar osteitis.

Other Benefits

Culinary Uses/Spice:

  • Cloves are a fundamental spice in cuisines worldwide. They are used whole or ground in both sweet and savory dishes, including curries, meats, marinades, pickles, baked goods (like pumpkin pie), and beverages (like mulled wine and chai tea).
  • They preserve food by inhibiting mold and bacterial growth.

Industrial Uses:

  • Clove essential oil is used in toothpaste, soaps, cosmetics, and as a wood preservative in cultural heritage conservation, outperforming boron-based options.
  • Cloves enhance aroma in betel quids and are key in Indonesian kretek cigarettes (now classified as cigars in the US).
  • Perfumery and Cosmetics: The warm, spicy scent of clove oil makes it a popular middle note in perfumes, soaps, and lotions.

Agricultural Uses:

  • Clove production supports economies in producing countries, with Indonesia leading global output. The spice’s historical trade value spurred colonial expansions and economic development in Asia.
  • Clove extracts have insecticidal properties, making them useful in organic pest control. 

Traditional Uses:

  • In some cultures, clove cigarettes (kreteks) are smoked, though this practice is highly discouraged due to severe health risks.
  • The essential oil is used to relieve stress, improve mental clarity, and enhance mood (Aroma therapy). 

How it is Used

  • Whole Cloves: Used to flavor stews, rice dishes, and broths, and then removed before eating. A single clove can be placed near a painful tooth for temporary relief.
  • Ground Clove: A powder used in baking, spice rubs, and curry powders.
  • Clove Essential Oil (Extracted through steam distillation of the buds). It is used in:
  • Aromatherapy: Diffused for its warming scent. Aromatherapy employs the oil for relaxation.
  • Topical Application: Must be diluted with a carrier oil (like coconut or olive oil) before applying to the skin for pain relief or as an antiseptic.
  • Oral Hygiene: A drop can be added to toothpaste or a glass of water for use as a mouthwash (ensure it is properly diluted and not swallowed). Clove oil can also be applied topically for toothache (diluted on a cotton ball), or used in mouthwashes for oral health and pneumonia prevention in hospitals
  • Digestive Disorders: A few drops of clove oil or a small amount of powdered clove may be added to warm water or tea. 
  • Respiratory Conditions: Clove tea or inhalation of steam infused with clove oil helps relieve congestion. 
  • Clove Tea: A few cloves can be steeped in hot water to make a soothing herbal tea.
  • Traditional Uses: In traditional medicine (Ayurvedic, Chinese), buds, leaves, and stems treat indigestion, pain, infections, and respiratory issues; eugenol provides analgesic effects.
  • Industrial: It’s incorporated into cigarettes, preservatives, and products like soaps.

Side Effects / Caution

While generally recognized as safe when used in culinary amounts, concentrated forms like clove oil require caution.

  1. Skin and Mucous Membrane Irritation: Undiluted clove oil is very potent and can cause skin, gum, or mouth irritation, burns, and contact dermatitis. Always dilute it with a carrier oil.
  2. Toxicity in High Doses: Ingesting large amounts of clove oil can be toxic, leading to symptoms such as sore throat, vomiting, dizziness, difficulty breathing, and even liver damage. The lethal dose for children can be as low as 5-10 mL.
  3. Blood Thinning Effect: Eugenol can slow blood clotting. People with bleeding disorders or those taking anticoagulant (blood-thinning) medication like warfarin should avoid medicinal doses of cloves.
  4. Surgery: Due to its effect on blood clotting, clove consumption should be stopped at least two weeks before a scheduled surgery.
  5. Pregnancy and Breastfeeding: While using cloves as a spice in food is likely safe, there isn’t enough reliable information to confirm the safety of medicinal amounts during pregnancy or breastfeeding. It is best to avoid therapeutic doses.
  6. Hypoglycemia: Because cloves may lower blood sugar, people with hypoglycemia or those on diabetes medication should monitor their blood sugar closely.
  7. Liver: It affects liver-processed drugs (CYP1A2, 2C9, 2D6, 3A4 substrates). High eugenol doses are toxic (50–100 mg/L), is potentially prooxidant and genotoxic in some cells. Those with liver disease, immune disorders, or allergies may experience adverse effects.

References  

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