Astragalus - used in traditional Chinese medicine for centuries

The root of astragalus (Astragalus membranaceous or huáng qí) is one of the most well-known Chinese medicinal plants and is used in many products throughout the world. It is one of around 2900 astragalus species used as medicines, food and for other applications by different ethnic and cultural groups worldwide.

It can be used as a tonic for older people or those who feel weak or fatigued, and as an immune modulator in those with chronic inflammatory and autoimmune conditions. Pharmacological actions reported for astragalus or its extracts include as an adaptogen, anti-inflammatory, antioxidant, antitumour, antidiabetic, cardioprotective, hepatoprotective, microbiome modulator, neuroprotective, renoprotective, and immune enhancer and modulator.

Astragalus produces inhibitory and preventive effects on airway inflammation in murine models of asthma, with various accompanying actions on immune mechanisms. Several trials have reported that it both prevents and treats asthma in children and adults. Improvements in lung and immune function were measured in a group of 82 patients with chronic obstructive pulmonary disease, including better forced expiratory volumes and forced vital capacity, and reductions in TNF alpha, IL-8, IL-1 beta and IL-32.

Reduced symptoms and improved quality of life were reported in a Croatian trial involving 48 patients with mild to moderate seasonal allergic rhinitis, following six weeks of astragalus administration.

Cardiovascular side effects of immunotherapy drugs have also revealed interactions between the immune and cardiovascular systems, and the signalling cascades affected by T-cell activation, cytokine release and immune system dysregulation.

Given the above, favourable findings from the use of astragalus for various cardiovascular conditions is unsurprising. Cardioprotective effects are shown by astragalus and many of its constituents. Improved recovery from stroke has been implicated in human trials, with effects associated with modulation of inflammatory pathways.

Diabetes and kidney disease
Astragalus is widely used in China and other Asian countries to treat diabetes and its complications. A meta-analysis of 13 studies involving 1054 participants found astragalus had beneficial effects as an adjuvant treatment for type 2 diabetes. Improvements were reported in both fasting and postprandial plasma glucose for both oral and parenteral astragalus, but only oral treatment reduced fasting insulin and levels of HbA1c.

These findings suggest a contribution of the gut microbiome to diabetes pathology, as astragalus increases gut-microbiota richness and diversity in diabetic mice and induces increased abundance of Lactobacillus and Bifidobacterium. Astragalus flavonoids have also been reported to ameliorate brain impairment in diabetic mice, with modulation of the gut microbiota and gut–brain axis suggested to play a pivotal role.

Kidney disease is a common diabetes complication with a multifactorial pathogenesis, but with the immune response and inflammation being integral to its onset and severity. Systematic reviews have shown that astragalus could enhance creatinine clearance, reduce albuminuria and reduce blood pressure in patients with chronic kidney disease and diabetic kidney disease.

A combination of astragalus with dong quai (Angelica sinensis) produced improvements in diabetes and diabetic nephropathy, and enhanced enalapril’s protection against chronic renal failure in rats.

Residual symptoms and feelings of fatigue occurring for weeks, months or longer after the acute infection period are highly debilitating, but are being experienced by a significant percentage of patients following COVID-19 (caused by SARS-CoV-2).

Just as the so-called “cytokine storm” can cause severe symptoms in acute infections, an ongoing elevation of inflammatory cytokine levels in the central nervous system, and the presence of damaging autoantibodies or ongoing dysregulation of the immune system, may lead to chronic inflammation and damaging effects on the brain, lungs and heart.

Such effects have a close resemblance to classical autoimmune conditions. As such, phytomedicines with immunomodulatory actions can often produce benefits. Imbalance within the gut microbiome is also likely to be involved.

Astragalus is an adaptogenic herb with a strong reputation for alleviating chronic and post-viral fatigue and increasing overall vitality.

Parenteral administration of astragalus polysaccharides reduced fatigue while lowering levels of the inflammatory cytokines IL-1 beta and IL-6 in a trial involving patients with cancer. Reduced fatigue when given to patients following a stroke has also been reported.

Research recently found extracts of astragalus to upregulate a group of microRNAs which can reduce the pathogenesis of COVID-19 and suppress proinflammatory cytokines, including IL-6 or TNF alpha (mediators of the cytokine storm). Several other actions to inhibit SARS-CoV-2 activity, viral entry and replication were also found. Beneficial influences on the dysbiosis seen within the gut microbiome of patients with COVID-19 have also been implicated.

While clinical trials are lacking to date, the body of both scientific and traditional use evidence suggests astragalus can produce many benefits, in both acute and long COVID. 

Possible applications in treating neurological diseases, including Alzheimer disease, are suggested from astragalus’ anti-inflammatory and neuroprotective activities, and inhibitory effects on amyloid aggregation. Subcutaneous injection with an astragalus glycoprotein peptide relieved the inflammation of experimental autoimmune encephalomyelitis in mice.

Several studies have reported administration of astragalus-based traditional Chinese herbal medicines alongside platinum-based chemotherapy to enhance antitumour efficacy and reduce adverse events in patients with cancer.

Improved menopausal symptoms were reported recently from a clinical trial of Korean blackberry (Rubus coreanus) and astragalus when taken by menopausal or perimenopausal women for a 12-week period.