Reviewed: Matkovic Z, Zivkovic V, Korica M, et al. Efficacy and safety of Astragalus membranaceus in the treatment of patients with seasonal allergic rhinitis. Phytother Res. June 5, 2009: [Epub ahead of print].

The symptoms of seasonal allergic rhinitis (SAR)* include sneezing, runny nose, nasal passage obstruction, watery eyes, and itchy nose, throat, and eyes. The purpose of this randomized, double-blind, placebo-controlled clinical trial was to assess the efficacy of an “herbal-mineral complex” containing an extract of astragalus (Astragalus membranaceus, Fabaceae) root in the treatment of SAR. Astragalus is used in Traditional Chinese Medicine (TCM), and research has indicated that it stimulates the immune system.^1,2

The trial was conducted from May to October 2007 at the University Hospital Dubrava in Zagreb, Croatia. Patients with histories of moderate to severe SAR and positive skin prick tests to grass or weed pollen were eligible. Patients with positive skin prick tests for tree pollen were excluded. (The reason for this exclusion was not explained but may have been due to possible overlap and confounding with the pollen seasons for grasses and weeds.) The patients provided blood samples and completed the self-administered mini Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ). The mini RQLQ includes 14 questions covering 5 domains: activity limitations, practical problems, nasal symptoms, eye symptoms, and other symptoms. Each item was rated on a 7-point scale from 0 (no impairment) to 6 (severely impaired). The total reflective symptom score (TSS) was also assessed. The TSS includes ratings of the severity of symptoms over the previous 24 hours on a scale of 0 (none) to 3 (severe). Individual symptoms included rhinorrhea (runny nose), nasal congestion, sneezing, and itching or burning eyes.

Forty-eight patients were randomized to take 2 capsules twice daily of either the astragalus complex (n=32) or an identical-appearing placebo containing lactose powder (n=16) for 6 weeks. Astragalus was harvested in the Hunan Province of China and extracted with water and ethanol (final drug-extract ratio: 18:1). The astragalus capsules contained 80 mg of astragalus extract standardized to contain 40% polysaccharides, plus calciumaluminum-silicate.

The patients were evaluated at baseline and after 3 and 6 weeks of treatment. The patients and physicians separately rated the overall severity of signs or symptoms and the response to treatment on a 5-point scale from 1 (worsening) to 5 (significant improvement). A blinded cytologist performed nasal smears in order to assess the eosinophils on a 4-point scale from 0 (none) to 3 (almost all cells on smear eosinophils).

Out of 48 patients who began the study, 7 withdrew early (5 in the astragalus group and 2 in the placebo group). There was no statistically significant difference in the number of drop-outs between the groups. Reasons for withdrawal included severe SAR symptoms (n=3), lost to follow-up (n=2), and poor compliance (n=2). There were no statistically significant demographic or disease differences between the 2 groups at baseline. The patients were studied during their respective allergy seasons: grass pollen (May-June, n=26) and weed pollen (August-October, n=22).

After 3 weeks of the treatment, there was a statistically significant difference in the rhinorrhea score between the 2 groups (P=0.048). Other primary efficacy variables—TSS, mini-RQLQ score, and changes for immunoglobulin (Ig) E and IgG—did not show significant inter-group differences in individual symptom scores.

In contrast, at the end of the study the investigators and patients gave astragalus significantly higher efficacy ratings compared to placebo for the secondary variables (P=0.003 and P=0.025, respectively). In the astragalus group, significant improvements from baseline were observed for the symptoms of rhinorrhea, sneezing, and itching after 3 weeks (P=0.02, P=0.06, and P=0.04, respectively). The changes from baseline in the astragalus group were still significant after 6 weeks of treatment (rhinorrhea: P=0.01, sneezing: P=0.03, itching: P=0.03). There were no significant changes from baseline for individual symptom scores in the placebo group.

(After 6 weeks, the TSS in the astragalus combination and placebo groups significantly improved to baseline levels [p=0.001 and p=0.04, respectively]. An expert peer reviewer for HerbalGram suggests that this may indicate that the duration of the treatment period was too long; the symptoms may have disappeared because of less pollen exposure.)

The researchers also performed a post hoc analysis of the 22 patients with weed pollen allergies. There were significant differences between the placebo and astragalus groups after 3 and 6 weeks of treatment in TSS scores (3 weeks: P=0.037, 6 weeks: P=0.022) and mini RQLQ scores (3 weeks: P=0.017, 6 weeks: P=0.001). The patients and investigators gave significantly higher efficacy ratings to astragalus compared to the placebo (P=0.001 for both). During the study, 10 patients reported a total of 15 mild-to-moderate adverse events, including rhinosinusitis (the main outcome being studied), pharyngitis, enterocolitis (inflammation of the small intestine and colon), and nausea. According to the authors, none were considered to be connected to the study material (astragalus-mineral combination).

The authors conclude that this study provides “a significant number of positive signals” indicating that the herbal-mineral formulation of astragalus used in this study can be therapeutically effective against SAR. Multicenter clinical trials with larger samples of patients are needed to confirm the trends observed in this study.

An expert peer reviewer commented that the fact that astragalus demonstrated immune-stimulating effects should have been discussed in detail in the original study, noting that a 3 to 6 week duration of treatment should have been enough time to show measurable changes in the immune response of subjects, i.e., changes in indicators of immune system activity, such as ECP (Eosinophil Cationic Protein), tryptase (a serine proteinase found in mast cells associated with the immune response), IL (interleukin)-4, IL-5, and IL-13—none of which were measured in this trial—although, as noted, changes in nasal eosinophils were measured.

–Marissa Oppel, MS

* The acronym SAR used here should not be confused with SARS, the acronym for severe acute respiratory syndrome.

References

1. Milot B. Astragalus review—immunostimulant and cardioprotective. HerbClip. October 31, 2003 (No. 060133-243). Austin, TX: American Botanical Council. Review of Anon. Astragalus membranaceus [monograph]. Alternative Medicine Review. 2003;8(1):72-77.
2. Upton R, ed. Astragalus—Astragalus membranaceus. American Herbal Pharmacopoeia and Therapeutic Compendium: Astragalus Root. Scotts Valley, CA: American Herbal Pharmacopoeia; 1999.