Effect of sweet fennel seed extract capsule on knee pain in women with knee osteoarthritis

Knee osteoarthritis is one of the most common types of arthritis. The disease not only has a high disease burden but also reduces the quality of life of patients. The purpose of this research was to study the effect of Foeniculum vulgare Mill. (commonly known as Fennel) seed extract on knee pain in women patients with knee osteoarthritis.In this randomized, double-blind trial, a total of 66 patients were assigned randomly via the blocking method in two groups, fennel and placebo. All patients received four capsules daily of either powdered fennel extract (each capsule contained 200 mg dried fennel extract from 7 g of fennel seeds) or placebo twice a day for two weeks. The patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire and Visual Analog Scale (VAS) for pain intensity measurement before and after the study completion. Data were then analyzed via intention to treat method using the SPSS statistical software package.Two weeks after the trial, a significant decrease was noted between the two groups in terms of pain, disability, total WOMAC score, and VAS variables. After comparing the pre- and post-intervention, the variables mentioned above revealed a significant decline in both groups. The stiffness variable indicated a significant reduction in the fennel group (between baseline and study completion) after two weeks, but this decline was not significant in the placebo group, and was not significant either between the two groups. At the end of the trial, the percentage change was higher in the fennel group than in the placebo group. Also, the effect size was greater in the fennel group especially in pain variable based on WOMAC and VAS than in the placebo group.The results indicated that fennel may be an appropriate alternative for complementary treatment in patients with knee osteoarthritis. This study is the first clinical trial using oral fennel on knee pain in these patients, and the outcomes should be confirmed through additional studies.