The incredible antioxidant capacity of clove oil (Syzigium aromaticum) may tempt some to ingest it. It is however a potential carcinogen. A carcinogen is a cancer causing agent which is responsible for damage to the genetic material or DNA. Most aromatherapy sites that promote the use of essential oils advise that no essential oils should be ingested. The FDA does list some essential oils that are safe to ingest. Clove oil is found in cloves, used in cooking, but the amounts would be minute. Other sites do say a drop of two per day can be ingested. However the quality and purity needs to be assured by purchasing from a accredited source. Under Toxicology safety data at http://physchem.ox.ac.uk/MSDS/CL/clove_oil.html they state, “Not believed to present a serious risk to health”.
However, other researchers note that the eugenol component is a suspected carcinogen. Clove oil is 85 to 95% eugenol. Isoeugenol and methyleugenol make up 5 to 15% of the remaining ingredients. Methyleugenol (ME) is a chemical compound occuring naturally in a variety of spices and herbs, including clove oil, nutmeg, allspice, and walnuts. In both its natural and synthetic forms, it is an FDA-approved additive. It is widely used as a flavoring agent in desserts, condiments, and cigarettes, as an attractant in insecticides, and as a fragrance in perfumes and soaps. However, as it is structurally similar to other flavorants that are known to be carcinogenic (e.g. safrole and estragole), ME has come under suspicion of carcinogenicity (Craigmill, 2000). Research by the National Toxicology Program at the NIEHS, has established that ME causes cancer in laboratory rodents and suggests that it may be a human carcinogen as well. Based on this data, it is better to avoid clove oil as a dietary antioxidant. There may even be a trend towards the eventual elimination of ME from the commercial marketplace.
Clove Oil vs. Eugenol
Clove oil is a mixture of different compounds. The three main active ingredients are eugenol, isoeugenol and methyleugenol. “Clove oil” is 85 to 95% eugenol. Isoeugenol and methyleugenol make up 5 to 15% of the remaining ingredients. Isoeugenol is the compound considered an anaesthetic effect (USDHHS, 2002).
Approval Status of clove oil and derivatives
Clove oil has been affirmed as Generally Recognised as Safe (GRAS) as a substance added directly to human food (21 CFR 184.1257). Eugenol is GRAS in animal feed (21 CFR 582.60) and isoeugenol is cleared for use in human food (21 CFR 172.515). Both compounds are listed as synthetic flavouring substances and adjuvants. Eugenol (not clove oil) is used as a component in dental cement for temporary fillings (21 CFR 872.3275) (USDHHS, 2002).
Human Food Safety
Clove oil and isoeugenol have been used in foods and eugenol has been used in animal feeds. Concern for this class of chemical compounds led to the investigation of eugenol, isoeugenol, and methyleugenol under the National Toxicology Program (NTP). The NTP conducts studies in nominated drugs and chemicals to determine their carcinogenic potential (potential to produce cancer). Studies have been completed for eugenol and methyleugenol, and are planned for isoeugenol. NTP determined that eugenol is an equivocal carcinogen and methyleugenol is carcinogenic to rodents. The contamination of clove oil with methyleugenol or isoeugenol raises the level of concern for human safety (USDHHS, 2002).
You can see the status of toxicology studies conducted on these compounds by going to the NTP website at http://ntp-server.niehs.nih.gov/ . Once there, use the search function. A search for 'eugenol' brings up all the related test results.
Clove oil is derived from a food so may be safe, but its carcinogenic potential needs to be established. As such the idea that a drop of clove in your drinking water or a drop of any edible essential oil in anything you eat, is good for long, healthy living, supplying the daily ORAC dosage quite easily, needs to be put on hold until other factors are established.
Some sites do advocate the ingestion of clove oil - see the Foreverhealthy and http://www.ourverybest.com/ site’s articles on essential oils for example. TWO DROPS OF ESSENTIAL OIL OF CLOVE have the anti-oxidant power of 2.2 kilograms of carrots, 2.5 litres of carrot juice, 10 oranges, 1.1 kilograms of beets, 4 cups of raspberries or 2.5 cups of blueberries. This means a drop of clove in your drinking water or a drop of any edible essential oil in anything you eat, is good for long healthy living, and you don't have to eat a dozen oranges or drink a quart of beet juice every day to achieve it. Other backgrpond infotmation is at