by John P. Thomas
Health Impact News
“The ancient texts all seem to agree on the many therapeutic properties of clove – it is a stimulant and has stomachic, expectorant, sedative, carminative, antispasmodic and digestive qualities. It helps flatulence, stimulates digestion and restores appetite, so is good for convalescence. It is a general tonic for both physical and intellectual weakness; and for those suffering from frigidity.
Its principal therapeutic value, though, is antiseptic because of the high proportion of eugenol. This is used for intestinal parasites, and for prevention of virus infections. It is good for the immune system, and particularly effective in mouth and tooth infections.” (quoted from “Clove essential oil,” Daniele Ryman, Aromatherapy Bible )
Here is a review of some of scientific studies published around the world regarding the healing properties of clove essential oil.
Clove Oil and Dentistry
[From India] Eugenol, the major constituent of clove oil, has been widely used for its anesthetic and analgesic action in dentistry. Eugenol exhibits pharmacological effects on almost all systems in the body. Eugenol possesses significant antioxidant and anti-inflammatory properties, in addition to having analgesic and local anesthetic activity. 
[From Argentina] Clove essential oil, used as an antiseptic in oral infections, inhibits Gram-negative and Gram-positive bacteria as well as yeast. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were the microorganisms tested. The clove oil was diluted to 0.4% and 0.2%. The results showed that the 0.4% dilution rate was more effective than the lower dilution. They concluded that the essential oil of clove can be considered as an antimicrobial agent for oral infections. 
Clove Oil and Skin Cancer
[From India]Spices and flavoring agents are now receiving increasing attention as many of them have been shown to have anticarcinogenic properties. Cloves are the sun-dried unopened flower buds from the clove tree (Syzygium aromaticum L.). Cloves are commonly used as a spice and food flavor. The present study was designed to investigate the chemopreventive action of an aqueous infusion of cloves on induced skin cancer in Swiss mice. They found that there was a protective effect gained from the clove. It delayed the formation of papilloma (skin cancer), but it also reduced the incidence of papilloma as well as the cumulative number of papillomas per mouse. The researchers believe that there could be a promising role for cloves for restricting the carcinogenesis process. 
Clove Oil and Diabetes
[From Scotland] High blood sugar in people with diabetes mellitus results in oxidative stress and inflammatory changes which contribute to vascular complications and peripheral neuropathy (nerve damage in hands and feet, which causes weakness, numbness and pain). This study examined whether treatment with eugenol (the major component of clove oil), which has antioxidant and anti-inflammatory properties, could improve vascular and nerve function in diabetic rats. Intervention treatment was given for 2 weeks following 6 weeks of untreated diabetes. The diabetes had reduced sciatic nerve endoneurial blood flow by 49% and this was completely corrected by treatment with 200 mg/kg of eugenol. The level of gastric fundus (lower stomach) nerve-mediated relaxation was 44% of normal, and eugenol treatment corrected this deficit by 69%. For renal artery rings, the maximum endothelium-dependent relaxation to acetylcholine was 51% of normal. Treatment corrected this deficit by 60%. In summary, some aspects of vascular and neurological complications in experimental diabetes were improved by the use of eugenol from clove oil. This could have therapeutic implications for diabetic neuropathy and vasculopathy in humans with diabetes. 
Clove Oil to Treat Menstrual Pain
[From Egypt] Painful menstrual periods (dysmenorrhea) are a common cause of sickness and absenteeism from normal activities by women in their childbearing years. This study investigated the effect of aromatherapy massage on a group of nursing students who suffered from primary dysmenorrhea. A randomized blind clinical trial of crossover design was used.
A group of 48 women received aromatherapy by abdominal massage once daily for seven days prior to menstruation using the essential oils (cinnamon, clove, rose, and lavender in a base of almond oil). Group 2 (n = 47) received the same intervention but with placebo oil (almond oil). The level and duration of pain, and the amount of menstrual bleeding were evaluated at the baseline and after each treatment phase. The level and duration of menstrual pain and the amount of menstrual bleeding were significantly lower in the aromatherapy group than in the placebo group. These results suggest that the use of essential oils in abdominal massage can be effective in alleviating menstrual pain, shortening its duration, and limiting excessive menstrual bleeding. 
Research Using Clove Oil for Depression
[From India] This study investigated the effect of clove oil on depression and locomotion in animals. Small doses of clove oil were injected through the peritoneal membrane that encloses the organs of the abdominal cavity for 3 weeks. They then did a series of test such as a forced swim test and the tail suspension test to assess depression. Other tests were used to evaluate locomotor activity. Researchers concluded that pretreatment with clove oil decreased depression and enhanced locomotor activity (improved muscle coordination) similar to that exhibited by psychostimulant drugs. 
Research Using Clove Oil on a Microscopic Parasitic Infection that can Cause Death
Researchers have been examining whether clove oil could be used to treat visceral leishmaniasis, which is also called kala-azar, black fever, and Dumdum fever.  Leishmaniasis is a disease caused by protozoan parasites. It is the second-largest parasitic killer in the world (after malaria), responsible for an estimated 500,000 infections each year worldwide. 
Chemotherapy drugs are the standard treatment for leishmaniasis. These drugs are expensive and associated with multiple adverse side effects. This parasitic disease is endemic in 47 countries with approximately 200 million people at risk of infection. The parasite is spread to humans through the bite of infected female sand flies. It attacks the immune system, and is almost always fatal if not treated. There are between 200,000 and 400,000 new cases a year, about 90 percent of which are in India, Bangladesh, Nepal, Sudan and Brazil. 
Researchers in India found that the essential oil of clove possesses significant activity against this parasite when tested with mice. The parasites attack the macrophages of the immune system. Clove oil did not have cytotoxic effects against healthy macrophage cells. The study authenticated the promising antileishmanial activity of clove oil, which could be useful for the treatment of this disease in humans. 
Research Using Clove Oil for Treating Lung Damage from Breathing Polluted Air
[From Brazil] The inhalation of diesel particles from polluted air can cause pulmonary inflammation and can impair the mechanical functioning of the lungs. Eugenol, a component of clove oil has been shown to have anti-inflammatory and antioxidant properties in experiments with tissue samples. This experiment used mice to examine the possible protective role of eugenol against lung injuries induced by diesel particles. Mice were exposed to diesel particles for an hour and then some were exposed to eugenol (one of the primary ingredients in clove oil). After 24 hours, a variety of pulmonary function measures were assessed. They found that the mice that received eugenol avoided changes in lung mechanics, pulmonary inflammation, and alveolar collapse that had been caused by exposure to diesel particles. 
Clove Oil Kills and Keeps Away Red Fire Ants
[From Taiwan] Researchers tested clove as an insecticide and repellant for red fire ants. They evaluated clove powder, eugenol, eugenol acetate, and beta-caryophyllene against red fire ant workers (Solenopsis invicta Buren). Clove powder applied at 3 and 12 mg/cm2 provided 100% ant mortality within 6 hours, and repelled 99% within 3 hours. Eugenol (active ingredient in the essential oil of clove) was the fastest acting compound. The level of ant repellency did not increase when the amount of clove was increased. The increase in the ant repellant effect improved over time. Eugenol, eugenol acetate, as well as beta-caryophyllene and clove oil may provide another tool for red fire ant integrated pest management. 
Clove Oil Kills Household Dust Mites
[From Thailand] The search for more eco-friendly pesticides for killing house dust mites on mattresses has prompted testing of medicinal plants. This study examined the killing power of clove extract on dust mites as well as on common bacteria and fungi. There was a significant clearance for all the bacteria and fungi. Spraying was 99% and 81% effective on killing dust mites depending on the method used. They concluded that clove oil is a promising agent for killing dust mites on mattresses. The effect of clove oil on mattresses begins to diminish after 3 months. 
Clove Oil Kills Pathogenic Yeast
[From France] The antifungal activity of clove essential oil was evaluated against 53 human pathogenic yeasts in laboratory experiments. Clove oil exhibited a very strong radical scavenging activity. It is clear that clove oil shows powerful antifungal activity against human pathogenic yeasts; and it can be used as a source of natural antioxidants. 
How is Clove Oil Produced?
The following information was taken from the online version of the Aromatherapy Bible produced by Daniele Ryman . I have abbreviated her entry for clove essential oil for inclusion here.
Cloves are the dried buds from the clove tree. They grow best in tropical regions near the sea. Clove trees are fairly short. They normally grow to 30 feet tall. They are usually kept at a more accessible height — 16 to 20 feet. This helps with picking the flower buds, which contain the highest concentration of clove oil.
The cloves flower buds appear at the end of the rainy season. When these turn pink, just before opening, they are picked by hand or beaten from the tree. The flowers are then dried in the sun or over low heat for a few days until they are the familiar dark brown color of the spice.
The clove tree does not produce the spice until it is about five years old, and can carry on increasing its yield until it is about 20 years old. The yield of a mature tree is generally around 6.6 pounds to 8.8 pounds of fresh buds. When these are dried, the weight reduces down to about 2.2 pounds. The distillation of the dried flowers from one tree produces about 150 ml (5 ounces) of essential oil of clove.
Pliny praised cloves, as did the great Roman doctor, Alexander Trallianus. St Hildegarde, in her book Morborum Causae et Gurae, wrote that cloves were included in treatments for headaches, migraines, deafness after a cold, and dropsy. She advised that cloves would warm people feeling the cold, and cool down those who felt hot. During the Renaissance, pomanders were made with cloves to keep epidemics and plague at bay. 
[From South Africa] Eugenol is a major volatile constituent of clove essential oil obtained through hydrodistillation of mainly Eugenia caryophyllata (=Syzygium aromaticum) buds and leaves. It is a remarkably versatile molecule incorporated as a functional ingredient in numerous products and has found application in the pharmaceutical, agricultural, fragrance, flavor, cosmetic and various other industries. Its vast range of pharmacological activities has been well-researched and includes antimicrobial, anti-inflammatory, analgesic, anti-oxidant and anticancer activities, amongst others. In addition, it is widely used in agricultural applications to protect foods from microorganisms during storage, and as a pesticide and fumigant. As a functional ingredient, it is included in many dental preparations and it has also been shown to enhance skin permeation of various drugs. 
Dangers: Clove oil is often adulterated with a vegetable oil (usually palm) and oil of pimento berries and leaves. Sometimes the adulterant is copaiba, an oil made from the gum resin of a Brazilian balsam tree, Copaifera officinalis. This is a great pity, as the therapeutic values are only present in the absolutely pure essential oil. Because of the eugenol content the oil can corrode metal.
Using Cloves and Clove Oil
Clove Oil has historically been used to numb the pain of a toothache. But there are many other powerful uses that make this essential oil an important part of a home remedy kit.
Daniele Ryman  offers these suggestions:
When I am under physical or mental strain, or simply tired, I suck a clove several times a day. It has an agreeable taste, and acts as a relaxant. Sucking cloves is a particularly good idea for those trying to give up smoking.
The dental value of cloves is well known. They are antiseptic, but have sedative and minor anesthetic properties too (a sucked clove will slightly numb your tongue). If you have a toothache, either suck a clove on the side of the sore tooth, or apply a cotton bud with a drop of the essential oil to the tooth. This will give you relief until you get to the dentist, and also helps to keep the mouth clean because of the antiseptic effect. Never use too much of the oil, and don’t leave it on the tooth (on a piece of cotton wool, say) as your gums could begin to flake. A good mouthwash can be made for halitosis: boil a few cloves in a little water for 5 minutes, let it cool down, then add a few mint leaves and rinse and gargle with the strained liquid.
For rheumatic pains, mix together 1 fluid ounce of castor oil, 5 drops each of juniper and wheatgerm oils, and 5 drops clove oil in a brown bottle. Rub on the affected parts and keep warm.
In popular medicine, an infusion of cloves was given to activate labor after the first pains were felt. This could also ease the pains. 
CLOVE SOUP Serves 4
This ‘soup’ should be taken when minor discomforts start to appear at the beginning of winter – colds, sore throats or snuffles. As soon as any symptoms are felt, make and drink this concoction.
2 and ½ cups beef stock
2 onions, peeled and thinly sliced
1 bay leaf
Salt to taste
Put all the ingredients in a pan, bring to a boil, then simmer for 30 minutes. Remove the cloves and bay leaf, and serve hot.
Better than Moth Balls
Another classic way to use cloves is to stick them into an orange for a pomander to sweeten the wardrobe and keep moths away. This is an interpretation of the anti-plague properties utilized in the Middle Ages. 
 Pramod K1, Ansari SH, Ali J.; “Eugenol: a natural compound with versatile pharmacological actions,” Nat Prod Commun. 2010 Dec, PMID: 21299140.
 Nuñez L1, Aquino MD.; “Microbicide activity of clove essential oil (Eugenia caryophyllata),” Braz J Microbiol. 2012 Oct, PMID: 24031950.
 Banerjee S1, Das S.; “Anticarcinogenic effects of an aqueous infusion of cloves on skin carcinogenesis,” Asian Pac J Cancer Prev. 2005 Jul-Sep, PMID: 16235990.
 Nangle MR1, Gibson TM, Cotter MA, Cameron NE.; “Effects of eugenol on nerve and vascular dysfunction in streptozotocin-diabetic rats,” Planta Med. 2006 May, PMID: 16773532.
 Marzouk TM1, El-Nemer AM, Baraka HN.; “The effect of aromatherapy abdominal massage on alleviating menstrual pain in nursing students: a prospective randomized cross-over study,” Evid Based Complement Alternat Med. 2013, PMID: 23662151.
 Mehta AK1, Halder S, Khanna N, Tandon OP, Sharma KK.; “The effect of the essential oil of Eugenia caryophyllata in animal models of depression and locomotor activity,” Nutr Neurosci. 2013 Sep, PMID: 23462195.
 James, William D.; Berger, Timothy G.; et al. (2006), Andrews’ Diseases of the Skin: clinical Dermatology, Saunders Elsevier. ISBN 0-7216-2921-0, p 426.
 Desjeux P.; “The increase of risk factors for leishmaniasis worldwide”. Transactions of the Royal Society of Tropical Medicine and Hygiene 1995 (3), Trans R Soc Trop Med Hyg. 2001 May-Jun, PMID 11490989.
 “Kala Azar (Leishmaniasis),” MSF USA, Retrieved 8/6/14. http://www.doctorswithoutborders.org/our-work/medical-issues/kala-azar-leishmaniasis 
 Islamuddin M1, Sahal D, Afrin F.; “Apoptosis-like death in Leishmania donovani promastigotes induced by eugenol-rich oil of Syzygium aromaticum., J Med Microbiol. 2014 Jan, PMID: 24161990.
 Zin WA1, Silva AG, Magalhães CB, Carvalho GM, Riva DR, Lima CC, Leal-Cardoso JH, Takiya CM, Valença SS, Saldiva PH, Faffe DS.; “Eugenol attenuates pulmonary damage induced by diesel exhaust particles,” J Appl Physiol (1985). 2012 Mar, PMID: 22194320.
 Kafle L1, Shih CJ.; “Toxicity and repellency of compounds from clove (Syzygium aromaticum) to red imported fire ants Solenopsis invicta (Hymenoptera: Formicidae),” J Econ Entomol. 2013 Feb, PMID: 3448024.
 Mahakittikun V1, Soonthornchareonnon N, Foongladda S, Boitano JJ, Wangapai T, Ninsanit P.; “A preliminary study of the acaricidal activity of clove oil, Eugenia caryophyllus,” Asian Pac J Allergy Immunol. 2014 Mar, PMID: 24641290.
 Chaieb K1, Zmantar T, Ksouri R, Hajlaoui H, Mahdouani K, Abdelly C, Bakhrouf A.; “Antioxidant properties of the essential oil of Eugenia caryophyllata and its antifungal activity against a large number of clinical Candida species,” Mycoses. 2007 Sep, PMID: 17714361.
 “Clove essential oil,” Daniele Ryman, Aromatherapy Bible, Retrieved 8/6/2014. http://www.aromatherapybible.com/clove.html 
 Kamatou GP1, Vermaak I, Viljoen AM.; “Eugenol–from the remote Maluku Islands to the international market place: a review of a remarkable and versatile molecule,” Molecules. 2012 Jun 6, PMID: 22728369.
 “Clove essential oil,” Daniele Ryman, Aromatherapy Bible, Retrieved 8/6/2014. http://www.aromatherapybible.com/clove.html