The Role of Benjakul in Knee Osteoarthritis Treatment: A Perspective Through the Influence of Body Innate Elements

Abstract

Introduction and Objective: Benjakul (BJK), a traditional Thai remedy, shows potential in treating knee osteoarthritis particularly in the elderly due to its anti-inflammatory, analgesic, and circulation-boosting properties. In Thai traditional medicine, disease is believed to result from imbalances among the four Innate Body Elements (IBE): earth, water, wind, and fire, which influence both symptoms and treatment response. However, limited research has explored the link between IBE types and treatment outcomes in osteoarthritis. This study aims to compare the efficacy of BJK in relieving knee pain among osteoarthritis patients, grouped according to their dominant IBE type.

Methods: A multicenter clinical trial was conducted at four Thai hospitals with 170 participants aged 50–80 years diagnosed with knee osteoarthritis (Kellgren and Lawrence grade 1–3) by orthopedists, pain score ≥ 3 and BMI ≤ 32 kg/m². Participants received 100 mg BJK extract capsules three times daily after meals for 28 days, along with omeprazole for gastric protection. The extract was prepared according to the Thai Herbal Pharmacopoeia and contained equal parts Piper retrofractum, Piper sarmentosum, Piper interruptum, Plumbago indica, and Zingiber officinale, extracted with 95% ethanol and encapsulated under quality control. The 500 mg capsules each contain 100 mg of the BJK extract. The results were assessed using the Visual Analogue Scale (VAS), the 40m Fast-Paced Walk Test (40mFPWT), the Timed Up and Go Test (TUG), the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the assessment of global improvement in efficacy. Liver and kidney function tests were also performed for safety testing. Participants were categorized into four IBE types based on their date of birth. Descriptive statistics summarized the characteristics of the sample, while chi-square tests analyzed categorical data. One-way analysis of variance (ANOVA) for normally distributed data was used for between-group comparisons, and paired-samples t-tests were used for within-group comparisons. Statistical significance was defined as p < 0.05.

Results: Of the 151 participants who completed the study, 23.8% were assigned to the element of fire, 33.8% to the element of wind, and 21.2% each to the elements of water and earth. After taking BJK extract capsules for 28 days together with omeprazole, all groups showed a significant reduction in VAS pain scores (p < 0.001). The 40m Fast-Paced Walk Test showed a slight improvement, with significance only in the earth group (p < 0.001). TUG times improved significantly in the fire, wind and earth groups (p < 0.001) and moderately in the water group (p < 0.05). KOOS scores improved in several dimensions: The fire, wind and water groups improved in all domains (p < 0.05), while the earth group improved in daily activities, sports/recreation, and quality of life (p < 0.05). The overall efficacy was 87.5% in the fire, wind and water group and 75% in the earth group, with the wind group showing the highest efficacy. At the end of the study, 43% rated their condition as moderately better, with the water group having the highest mean score (2.69/4), followed by the wind group (2.31/4). No adverse changes in liver or kidney function were observed.

Discussion: Most participants were classified as wind element, followed by fire element. This is consistent with Thai traditional medicine’s view that knee osteoarthritis (Lom-Chap-Pong-Haeng-Khou) is caused by an imbalance of wind (Lom). The warming properties of BJK help to dispel wind, stimulate fire, improve circulation and restore element balance, resulting in reduced pain, inflammation and improved joint function. The mechanism, supported by previous studies, involves the activation of heat-sensitive receptors that desensitise pain pathways while modulating inflammatory responses —­­ particularly effective in people suffering from wind elements. Post-treatment results showed significant improvements in pain, mobility and balance (as indicated by the TUG test and KOOS scores) attributable to BJK’s anti-inflammatory agents, including piperine, 6-gingerol, 6-shogaol and plumbagin. The warming properties of the BJK extract effectively relieved wind-induced blockages in knee osteoarthritis, resulting in pain relief and improved joint function. The earth element group showed a lower response to treatment, possibly due to a higher BMI, which is consistent with the traditional theory that earth element individuals tend to have a larger physique and higher weight factors that contribute to osteoarthritis. BJK was well tolerated and had no adverse effects on liver or kidney function.

          Conclusions and Recommendation: BJK extract (100 mg, three times daily with omeprazole) is effective in relieving the pain of knee osteoarthritis and is safe to use. Although the differences between the IBE groups were minimal, the wind and water groups showed slightly better results than the earth group. The improved efficacy of treatment outcomes may be important information for considering the use of hot herbal medicine formulas for pain relief based on the theory of wind element disease in traditional Thai medicine. Controlling weight and incorporating knee exercises, which are part of the treatment for knee osteoarthritis, may improve treatment efficacy and adherence. Further studies with larger samples and standard drug comparisons are recommended.