D-limonene is a chemical in the class called terpenes, which is a monoterpene, found in citrus oils from oranges, lemons, mandarins, limes and grapefruit. It has the flavor of lemon and is used as a flavoring in packaged foods, in perfumes and in soaps.
Orange juice contains 100 ppm (parts per million) of D-limonene. In the general population, the daily intake is .27 mg/kg of body weight for a 60 kg. Person, and the average intake being 16.2 mg./day. In an Arizona study, the daily intakes were 20-40 mg./day from citrus juice and 50-90 mg./day from citrus peel, much of which is lost in the urine within 48 hours.
D-limonene has low toxicity, being stored in fatty tissues and breast tissues. A dosage of 15 g/day can cause nausea, vomiting and diarrhea. D-limonene can dissolve cholesterol gallstones.
D-limonene neutralizes stomach acid, increases gastric contractions and is, therefore, of benefit in heartburn and gastroesophageal reflux. In one study, patients were given 1,000 mg./day, or every other day. On the second day of treatment, 32% of patients had significant relief of symptoms and 89% of the patients had complete relief after 14 days of treatment. Symptom relief develops over time and the best results come after 10 doses.
D-limonene has been shown to be chemopreventive against many kinds of cancer. Three patients with colorectal cancer did well for six months on D-limonene. One patient with breast cancer showed a partial response to D-limonene. Animal studies show benefit with liver cancer, pulmonary adenomas and stomach cancer. D-limonene increases apoptosis in gastric cancer.
Epidemiologic studies show that people who don’t have epithelial cell cancer eat “significantly more” citrus peel than people who do have epithelial cell carcinoma.
CONCLUSION: D-limonene of citrus has been shown to be of low toxicity, can be used to dissolve cholesterol gallstones, can relieve heartburn and works against various cancers.
NOTE: Read about d-limonene and the treatment of gastroesophageal reflux disease.
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