treatment of collagenous colitis,treatment of osteoarthritis of knee--a randomized double blind placebo controlled trial. 
 

Benefit
Gum resin extracts of Boswellia species have been traditionally used in folk medicine for centuries to treat various chronic inflammatory diseases, and experimental data from animal models and studies with human subjects confirm the potential of boswellia extracts as a treatment inflammatory conditions but perhaps cancer.

Anti-inflammatory benefits
Boswellia Serrata is an ancient Ayurvedic herb from India and known among herbalists as a treatment for arthritis. It is also beneficial in helping inflammation and joint health. Extracts of boswellia serrata have natural anti-inflammatory activity at sites where chronic inflammation is present by switching off pro-inflammatory cytokines and mediators, which initiate the process. Analysis of the ingredients of these extracts revealed that the pentacyclic triterpenes boswellic acids possess biological activities and appear to be responsible for the respective pharmacological actions.

Boswellia and asthma
Effects of Boswellia serrata gum resin in patients with bronchial asthma: results of a double-blind, placebo-controlled, 6-week clinical study.
Eur J Med Res. 1998; Gupta I, Gupta V, Gupta S, Lüdtke R, Safayhi H, Ammon HP. Pharmakologie für Naturwissenschaftler, Pharmazeutisches Institut der Universität Tübingen, Tübingen, Germany.
The gum resin of Boswellia serrata, known in Indian Ayurvedic system of medicine as Salai guggal, contains boswellic acids, which have been shown to inhibit leukotriene biosynthesis. In a double-blind, placebo-controlled study forty patients, 23 males and 17 females in the age range of 18 - 75 years having mean duration of illness, bronchial asthma, were treated with a preparation of gum resin of 300 mg thrice daily for a period of 6 weeks. 70% of patients showed improvement of disease as evident by disappearance of physical symptoms and signs such as dyspnea, rhonchi, number of attacks, increase in FEV subset1, FVC and PEFR as well as decrease in eosinophilic count and ESR. In the control group only 27% of patients showed improvement. The data show a definite role of gum resin of Boswellia serrata in the treatment of bronchial asthma.

Collagenous colitis
Boswellia serrata extract for the treatment of collagenous colitis. A double-blind, randomized, placebo-controlled, multicenter trial.
Int J Colorectal Dis. 2007; Madisch A, Miehlke S, Eichele O, Bethke B, Kuhlisch E, Bästlein E, Wilhelms G, Morgner A, Wigginghaus B, Stolte M. Medical Department I, Technical University Hospital, Dresden, Germany. 
 The objective of this study was to investigate the effect of Boswellia serrata extract on symptoms, quality of life, and histology in patients with collagenous colitis. Patients with chronic diarrhea and histologically proven collagenous colitis were randomized to receive either oral Boswellia serrata extract 400 mg three times daily for 6 weeks or placebo. Complete colonoscopy and histology were performed before and after treatment. Our study suggests that Boswellia serrata extract might be clinically effective in patients with collagenous colitis.

Crohn's disease

Boswellia and osteoarthritis
Efficacy and tolerability of Boswellia serrata extract in treatment of osteoarthritis of knee--a randomized double blind placebo controlled trial.
Phytomedicine. 2003; Kimmatkar N, Thawani V, Hingorani L. MS Orthopedics, Indira Gandhi Medical College, Nagpur, India.
Boswellia serrata tree is commonly found in India. The therapeutic value of its gum (guggulu) has been known. It posses good anti-inflammatory, anti-arthritic and analgesic activity. A randomized double blind placebo controlled crossover study was conducted to assess the efficacy, safety and tolerability of Boswellia serrata Extract in 30 patients of osteoarthritis of knee, 15 each receiving active  or placebo for eight weeks. After the first intervention, washout was given and then the groups were crossed over to receive the opposite intervention for eight weeks. All patients receiving the herbal treatment reported decrease in knee pain, increased knee flexion and increased walking distance. The frequency of swelling in the knee joint was decreased. Radiologically there was no change. The observed differences between treated and placebo being statistically significant, are clinically relevant. Boswellia serrata Extract was well tolerated by the subjects except for minor gastrointestinal symptoms. Boswellia serrata Extract is recommended in the patients of osteoarthritis of the knee with possible therapeutic use in other arthritis.

Rheumatoid arthritis

Boswellia serrata review
Frankincense: systematic review.
BMJ. 2008; Ernst E. Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, Exeter, UK. 
All randomised clinical trials of Boswellia serrata extract as a treatment for any human medical condition were included and studies of Boswellia serrata preparations combined with other ingredients were excluded. Of 47 potentially relevant studies, seven met all inclusion criteria (five placebo controlled, two with active controls). The included trials related to asthma, rheumatoid arthritis, Crohn's disease, osteoarthritis, and collagenous colitis. Results of all trials indicated that Boswellia serrata extracts were clinically effective. Three studies were of good methodological quality. No serious safety issues were noted. The evidence for the effectiveness of Boswellia serrata extracts is encouraging but not compelling