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Limonene

Limonene is a chemical found in the peel of citrus fruits and other plants. Limonene is used in the manufacture of medicine. Limonene is used to promote weight loss, prevent cancer, treat cancer and treat bronchitis. Limonene is used as a flavoring agent in food, beverages and chewing gum. In pharmaceuticals, limonene is added to help medicinal ointments and creams penetrate the skin. In industrial manufacturing, limonene is used as a fragrance, as a cleaning agent and as an ingredient in anhydrous hand cleaners.

How does limonene work?

Limonene may block cancer-causing chemicals and kill cancer cells in the laboratory. However, further research is needed to determine whether this is also the case in humans.

How effective is limonene?

There is not enough scientific data to say how effective limonene is in treating cancer. One form of limonene (D-limonene) appears to accumulate in tumors in people with advanced cancer when taken orally in 21-day cycles. The high levels of limonene in tumors may slow the progression of cancer, but its effects on survival are not known. There is also a lack of scientific information on the efficacy of limonene in cancer prevention, in promoting weight loss and in the treatment of bronchitis.

Further scientific research is needed to evaluate the effectiveness of limonene in these applications.

Safety and side effects

Limonene is safe and harmless in normal food quantities. Limonene also appears to be safe and harmless for most people when taken orally in medicinal quantities for up to one year.

Precautions and warnings

Pregnancy and breastfeeding: Limonene is safe for pregnant and breastfeeding women at normal dietary levels. However, there is not enough information on whether the larger amounts used as medicine are safe and harmless, so pregnant and breastfeeding women should limit themselves to normal dietary amounts to be on the safe side.

Interactions

Care should be taken when combining limonene with the following medications:

Drugs that are broken down by the liver (cytochrome P450 2C9 (CYP2C9) substrates).

Some drugs are broken down by the liver. Limonene can accelerate the rate at which the liver breaks down certain drugs. Taking limonene in combination with drugs that are broken down by the liver can lead to different effects and side effects. For this reason, you should consult your doctor before taking limonene if you are taking medication that is broken down by the liver.

Drugs that can reduce the breakdown of other drugs by the liver (cytochrome P450 2C19 (CYP2C19) inhibitors, cytochrome P450 2C9 (CYP2C9) inhibitors)

Limonene may be metabolized by the liver. Taking limonene with some drugs that can slow down the breakdown of other drugs by the liver may increase the effects and side effects of limonene.

Drugs that can accelerate the breakdown of other drugs by the liver (cytochrome P450 2C9 (CYP2C9) inducers, cytochrome P450 2C19 (CYP2C19) inducers)

Limonene is broken down by the liver. Taking limonene in combination with drugs that increase the breakdown of limonene in the liver could reduce the effectiveness of limonene.

Dosage

An appropriate dosage of limonene depends on various factors such as age, health status and others. At the present time, there is insufficient scientific data to make a statement about appropriate dosage ranges for limonene. For this reason, you should follow the dosage instructions on the label and/or consult a doctor or pharmacist before use.

References

  1. Crowell PL. Prevention and therapy of cancer by dietary monoterpenes. J Nutr 1999;129:775S-778S.
  2. Duetz WA, Bouwmeester H, van Beilen JB, Witholt B. Biotransformation of limonene by bacteria, fungi, yeasts, and plants. Appl Microbiol Biotechnol 2003;61:269-77.
  3. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid= 786bafc6f6343634fbf79fcdca7061e1&rgn=div5&view= text&node=21:3.0.1.1.13&idno=21
  4. Larsen ST, Hougaard KS, Hammer M, et al. Effects of R-(+)- and S-(-)-limonene on the respiratory tract in mice. Hum Exp Toxicol 2000;19:457-66.
  5. Matura M, Goossens A, Bordalo O, et al. Oxidized citrus oil (R-limonene): a frequent skin sensitizer in Europe. J Am Acad Dermatol 2002;47:709-14.
  6. Miyazawa M, Shindo M, Shimada T. Metabolism of (+)- and (-)-limonenes to respective carveols and perillyl alcohols by CYP2C9 and CYP2C19 in human liver microsomes. Drug Metab Dispos 2002;30:602-7.
  7. Ota Y, Hamada A, Nakano M, Saito H. Evaluation of percutaneous absorption of midazolam by terpenes. Drug Metab Pharmacokinet 2003;18:261-6.
  8. Raphael TJ, Kuttan G. Immunomodulatory activity of naturally occurring monoterpenes carvone, limonene, and perillic acid. Immunopharmacol Immunotoxicol 2003;25:285-94.
  9. Rolseth V, Djurhuus R, Svardal AM. Additive toxicity of limonene and 50% oxygen and the role of glutathione in detoxification in human lung cells. Toxicology 2002;170:75-88.
  10. Topham EJ, Wakelin SH. D-Limonene contact dermatitis from hand cleansers. Contact Dermatitis 2003;49:108-9.
  11. Turner SD, Tinwell H, Piegorsch W, et al.The male rat carcinogens limonene and sodium saccharin are not mutagenic to male Big Blue rats. Mutagenesis 2001;16:329-32.
  12. Vigushin DM, Poon GK, Boddy A, et al. Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee. Cancer Chemother Pharmacol 1998;42:111-7.