• Nasal polyposis quality of life questionnaire [ Time Frame: Visits 2, 3,4,5 ] [ Designated as safety issue: No ]
• Nasal patency as assessed by use of the Clement-Clarke peak nasal inspiratory flow meter (PNIF) [ Time Frame: Daily ] [ Designated as safety issue: No ]

• Nasal patency will be measured with a peak nasal inspiratory flow meter (PNIF). Study participants will measure their PNIF twice a day and will record their results on a diary throughout the study.
• Subject's Quality of Life assessment will be made at baseline (prior to randomization), after 4 weeks of treatment, after 4 weeks of washout, and

• Nasal lavage eosinophils. [ Time Frame: Visits 1,2,3,4,5 ] [ Designated as safety issue: No ]
• Peripheral blood eosinophils [ Time Frame: Visits 2,3,4,5 ] [ Designated as safety issue: No ]
• Diary symptom scores. [ Time Frame: Daily ] [ Designated as safety issue: No ]
• Nasal polyp size on visual inspection. [ Time Frame: Visits 1,2,3,4,5 ] [ Designated as safety issue: No ]
• Subjects Global Assessment of symptoms [ Time Frame: Visits 3 and 5 ] [ Designated as safety issue: No ]

• Nasal eosinophils will be collected at screening, baseline, after 4 weeks of treatment, after 4 weeks of washout, and after 4 weeks of crossover treatment.
• Peripheral blood eosinophils will be collected at baseline,after 4 weeks of treatment, after 4 weeks of washout, and again after 4 weeks of crossover treatment.
• Diary symptom scores will be recorded twice daily by the subject.
• Nasal polyp size on visual inspection will be assessed by study physician at screening, baseline, after 4 weeks of treatment, after 4 weeks of wash-out, and again after 4 weeks of crossover treatment.
• Subjects will complete their Global Assessment of symptoms, describing their perception of the change in their nasal polyp symptoms over the course of the study. This assessment will be completed at the end of each treatment period.

The purpose of this study is to evaluate the safety and efficacy of a new treatment for nasal polyps as compared to placebo (an inactive substance). The treatment involved is mint tea high in rosmarinic acid. Rosmarinic acid is a polyphenol, or a chemical substance found in certain plants such as oregano, rosemary, and the mints. It is the active ingredient in spearmint. The placebo used in this study will be mint tea low in rosmarininc acid. In this trial the amount of rosmarinic acid in the high rosmarinic acid tea, or study tea, will be 150mg. The placebo, or low rosmarinic acid tea, will contain 10mg of rosmarinic acid.

Nasal polyps are clear, glistening, grape-like structures that occur in two percent of adults and contain a large number of activated eosinophils - about 20% of the constituents of nasal polyp tissue.

The standard treatment for nasal polyp patients is intranasal steroids which, in troublesome cases, may follow a short course of oral steroids. Surgery is reserved for extremely large polyps and those who fail medical treatment. However, many patients tire of using nasal sprays or are troubled by side effects such as nasal irritation or bleeding. So, while all treatments offer some benefit, there is no gold standard.

Rosmarinic acid is categorized as a polyphenolia phytochemical, or a 'plant phenol' and is found in a variety of plants including the herbs oregano and rosemary, as well as the mints. Peppermint is one of the most widely used single ingredient in herbal teas. It has been found in vitro to have significant antimicrobial and antiviral properties, strong antioxidant and antitumor actions, and some antiallergenic ability. Human based research is limited.

A mint tea high in rosmarinic acid has recently been produced. Anecdotal evidence suggests that it may be beneficial for allergic rhinitis if taken prior to allergen exposure (personal communication). Other anecdotal evidence found a blunting of the sputum eosinophils following allergen challenge in allergic asthmatics (personal communication). This trial aims to study the effects of this mint tea high in rosmarinic acid in adults with bilateral nasal polyps, a condition characterized by chronic eosinophilic inflammation. The control treatment will be a mint tea low in rosmarinic acid.

• Other: Mint tea high in rosmarinic acid
• Other: Mint tea low in rosmarinic acid

• Placebo Comparator: Arm 2 receives 4 weeks of placebo mint tea (consumed twice a day) followed by 4 weeks of washout and then a further 4 weeks of treatment with study mint tea (consumed twice a day).
• Placebo Comparator: Arm 1 receives 4 weeks of treatment with mint tea high in rosmarinic acid, consumed twice a day. Treatment is followed by a 4 week wash-out phase. Subjects then enter a 4 week phase of placebo mint tea (low in rosmarinic acid), to be consumed twice a day.

• Finotto S, Dolovich J, Denburg JA, Jordana M, Marshall JS. Functional heterogeneity of mast cells isolated from different microenvironments within nasal polyp tissue. Clin Exp Immunol. 1994 Feb;95(2):343-50.
• McKay DL, Blumberg JB. A review of the bioactivity and potential health benefits of peppermint tea (Mentha piperita L.). Phytother Res. 2006 Aug;20(8):619-33. Review.
• Takano H, Osakabe N, Sanbongi C, Yanagisawa R, Inoue K, Yasuda A, Natsume M, Baba S, Ichiishi E, Yoshikawa T. Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans. Exp Biol Med (Maywood). 2004 Mar;229(3):247-54.
• Powell KR, Shorr R, Cherry JD, Hendley JO. Improved method for collection of nasal mucus. J Infect Dis. 1977 Jul;136(1):109-11.

Inclusion Criteria:

1. Subjects who are male or female aged 18 years or older.
2. Subjects who have signed an informed consent agreement.
3. Subjects with a history of nasal polyp symptoms during the previous 12 months.

Exclusion Criteria:

1. Subjects with severe nasal polyps requiring immediate surgery.
2. Subjects presenting with unilateral polyps.
3. Subjects who have undergone surgery to treat their nasal polyps (nasal polypectomy) within one year prior to visit one.
4. Subjects who have a known fungal infection of the nose and/or paranasal sinuses, nasal candidiasis, acute or chronic infectious sinusitis of viral or bacterial nature.
5. Subjects who have had an upper respiratory tract infection within two weeks prior to Visit one or any time between Visit 1 and Visit 2.
6. Subjects having cystic fibrosis, Young's syndrome, primary ciliary dyskinesia, known HIV infection or alcohol abuse.
7. Subjects with clinically significant, uncontrolled evidence of cardiovascular, neurological, hepatic, renal, respiratory, or any other medical condition that may interfere with the study.
8. Subjects with a recent history (within six months) of a clinically significant psychiatric disorder other than mild depression.
9. Subjects who have any clinically relevant deviation from normal in the general physical examination.
10. Subjects who have received any depot, systemic or oral corticosteroid in the previous three months prior to the start of the study.
11. Subjects who are unable to cease treatment with intranasal steroids four weeks prior to Visit one.
12. Subjects with a known hypersensitivity to mint.
13. Females who are pregnant or lactating or are likely to become pregnant during the study or are less than 8 weeks postpartum. Women of childbearing age may be included if in the opinion of the investigator, they are taking adequate contraceptive measures.
14. Subjects who are unable to follow the instructions within this protocol or known inability to attend all clinic visits within the intervals stated.
15. Subjects who have participated in a clinical trial involving an investigational or marketed drug within four weeks of visit one.
16. Subjects who are allergy skin test positive to a seasonal allergen which will be present when performing the trial, that has caused, within the past 2 years, a clinically significant deterioration in nasal symptoms.