- Huang chi
- Huang qi
- Milk vetch
- Radix astragali
For Patients & Caregivers
How It Works
Astragalus has immune-stimulating effects and may help to reduce side effects from chemotherapy. It has not been shown to treat or prevent cancer.
Astragalus root belongs to a group of medicinal plants from the legume family. It has a long history of use in traditional Chinese medicine for a variety of conditions, and as a tonic to increase stamina.
Astragalus works by stimulating several factors of the immune system. However, this property may also reduce the intended effects of certain drugs used to suppress the immune function. In addition, a compound in astragalus may have hormonal effects, and it is unknown whether this characteristic may change the effectiveness of some cancer treatments. So even though lab and population studies suggest astragalus might reduce chemotherapy-associated side effects, this has not been studied well enough. Clinical trials are needed to determine the circumstances under which astragalus can safely be used along with standard cancer treatments.
- To prevent and treat heart disease Lab and animal studies suggest astragalus and its compounds have heart-protective properties as well as blood-thinning effects.
- To reduce severity of chemotherapy side effects, including immune suppression Studies in animals show that astragalus reverses immune suppression caused by cyclophosphamide and stimulates certain cells of the immune system. Astragalus may also reduce the side effects of other types of chemotherapy such as nausea, vomiting, and fatigue. In addition, it may enhance the effectiveness of some types of chemotherapies, but these observations need to be confirmed in well-designed human studies.
- To treat diabetes Although astragalus has not been specifically studied for this purpose, long-term population studies suggest that it is among several herbs used in Chinese medicine that may improve diabetes-related complications. Clinical trials are needed to confirm such effects.
- To stimulate the immune system Laboratory studies suggest that astragalus stimulates the immune system.
- To increase strength and stamina An herbal formula containing astragalus reduced fatigue in athletes by increasing uptake and use of oxygen. Another small study showed that a purified astragalus extract infusion may also help manage cancer-related fatigue, but whether an oral formula would work the same way is not known.
Do Not Take If
- You are taking immunosuppressants such as tacrolimus and cyclosporine: Theoretically, astragalus may lessen their effects. Clinical relevance is not known.
- You have hormone-sensitive cancer: Because astragalus has demonstrated estrogenic effects, it is unknown how it may affect hormone-sensitive cancers or hormonal chemotherapy.
- You are taking anticoagulants: Lab studies suggest that astragalus may increase bleeding risk.
- You are taking diuretic medications: A small study suggests that astragalus may increase their effects.
- You are taking antihypertensive medications: Astragalus extract can lower both systolic and diastolic blood pressure and may have additive effects with other antihypertensive drugs.
- You are taking P-glycoprotein substrates: Astragalus polysaccharides can inhibit P-glycoprotein function, which may increase the cytotoxicity of chemotherapy drugs, including doxorubicin, etoposide, and vincristine. Clinical relevance is not known.
- You are taking Gemcitabine: Pretreatment with an astragalus extract was found to affect pharmacokinetics of gemcitabine in mice. Clinical relevance is not known.
For Healthcare Professionals
Astragalus belongs to a group of medicinal plants from the Leguminosae family. The root of A. membranaceus has a long history of use in traditional Chinese medicine (TCM), and is often used along with other herbs as a tonic to increase stamina, strength, and vitality. Extracts of astragalus are sold as dietary supplements to improve immune function and to decrease fatigue. Beneficial effects of astragalus are attributed to its polysaccharides and triterpenoid saponin compounds. In vitro and animal studies indicate that astragalus and its constituents have antioxidant (27), anti-inflammatory (28), and antiviral (29) activities, along with exerting protective effects on heart (30) (31) (32), kidney (33) (34) (35), bones (36) , and the nervous system (11) (17) (37).
In small studies involving healthy individuals, astragalus exhibited sodium-excreting properties (8) and produced a viral-type immune response (38). A formula containing astragalus as a major ingredient reduced fatigue in athletes (10); and as an adjuvant therapy, it helped manage fatigue in stroke patients (64). In the injectable form, astragalus may benefit patients with IgA nephropathy (26), and when used in Chinese medicine, it helped reduce diabetic ketoacidosis (39). In addition, an astragalus-based TCM formula was shown to preserve residual renal function dialysis patients (40); a case report suggests that it may reduce proteinuria associated with idiopathic membranous nephropathy (7); and a systematic review concluded that adjunctive use of astragalus in addition to conventional therapies may be effective for short-term reductions of albuminuria, proteinuria, and serum creatinine in patients with diabetic kidney disease (60). But further research is needed to determine long-term safety and efficacy (65).
Preclinical studies showed anticancer properties of astragalus against gastric (41), colon (42) (43) (44) (45), hepatic (46) and ovarian (59) cancers, and concomitant treatment with aldesleukin potentiated tumoricidal activity while decreasing side effects (14). Astragalus also enhanced platinum-based chemotherapy (3) and protected against oxaliplatin neurotoxicity (48). Its saponins were shown to reverse toxicities of fluorouracil (42) (28) and augmented the therapeutic benefit of vinblastine while reducing neutropenic and anemic effects (44).
Clinical data are limited. Astragalus has been associated with prolonged survival times in acute myeloid leukemia patients (47), and data suggest beneficial effects when used with chemotherapy (1) (2). Also, injectable forms of astragalus may alleviate cancer symptoms and improve quality of life in patients with advanced (20) and metastatic cancers (66), but whether orally administered astragalus exert similar effects is not known. In another study, an astragalus extract helped to manage cancer-related fatigue (22). Meta-analyses suggest astragalus to be associated with reductions in chemotherapy-induced nausea and vomiting (49), and to have benefits in patients with hepatocellular cancers (16). Larger well-designed trials are needed to confirm these findings.
Although astragalus is generally safe, due to its antioxidant (27) and estrogenic (23) (50) activities, it may interfere with some chemotherapy drugs and/or affect hormone-sensitive cancers. However, these findings are based on preclinical studies and cannot be extrapolated to clinical recommendations. The physiological concentration used in these studies is unlikely to be achieved in humans, which makes it difficult to predict the downstream effects/interactions.
Mechanism of Action
Polysaccharides, triterpenoid saponins, and flavonoids are the main constituents of astragalus with immunomodulating, antioxidant, anti-inflammatory, and anticancer effects (27) (51). In vitro studies suggest the saponin astragaloside I promotes osteoblastic differentiation by regulating the Wnt/beta-catenin signaling pathway (36). Cardioprotective effects from astragaloside IV may occur via the notch1/hes1 signaling pathway (30). In addition, it augments fibrinolytic potential via increases in tissue-type plasminogen activator (t-PA) synthesis and downregulation of PA inhibitor type 1 (PAI-1) (21). Other anticoagulant activities are attributed to upregulation of KLF2 mRNA expression and inhibition of NF-kB signaling pathway (52).
Polysaccharides isolated from astragalus produce immunomodulating effects via activation of toll-like receptor 4 (TLR4)-related mitogen-activated protein kinase (MAPK) activities (53). In murine models, they reduced colitis via inhibition of NOD-like receptor protein 3 inflammasome, which decreases inflammatory factors such as interleukin (IL)-18 and IL-1beta (54), and reduced multiorgan iron overload via upregulated hepcidin and IL-6 expression and enhanced p38 MAPK phosphorylation (55). Cardioprotective effects with this constituent were attributed to anti-inflammatory properties and improved balance between reactive oxygen species (ROS) and NO (32). In a diabetic rat model, astragalus polysaccharides exerted effects on glucose and lipid metabolism and insulin resistance (37). Astragalus was also found to reduce the secretion of inflammatory cytokines via increasing levels of CD4+ CD25+ Foxp3+ T cells and by inhibiting the activation of NF-κB (61).
Benefits to counteract memory disorders were seen with astragalus due to its activity as a nerve-growth promoting factor (17) and due to its ability to increase M-cholinergic receptor density in senile rats (11).
In dialysis patients, an astragalus-based TCM formula enhanced NO production and transforming growth factor beta suppression (40). In IgA nephropathy patients, an astragalus injection decreased Core I β3-Gal-T-specific molecular chaperone (Cosmc) gene expression and increased IgA1 O-glycosylation levels (26). In healthy individuals, a sublingual/ingested astragalus root extract produced increases in monocytes, neutrophils, lymphocytes, and platelets, as well as circulating cytokines levels, and self-reported symptoms similar to viral type immune responses such as fatigue, malaise, and headache (38). In another study, a formula containing astragalus reduced fatigue in athletes by increasing the uptake and utility of oxygen (10).
Mechanisms by which astragalus and its constituents may exert anticancer effects have also been examined. In human colorectal cancers cell lines, astragalus suppressed chromosome organization, histone modification, and regulation of macromolecule metabolism, as well as several cancer signaling pathways (56). Saponins induced S phase and G2/M arrest and suppressed p21 expression and cyclin-dependent kinase activity (42). Modulation of mTOR signaling and COX2 downregulation also occurred, which in turn can reduce VEGF levels to suppress angiogenesis (43). In gastric adenocarcinoma cells, caspase 3 activation, G2/M phase cell cycle arrest, cyclin B1, p21 and c-myc regulation, and downregulation of vascular endothelial growth factor (VEGF) and metalloproteinase (MMP)-2 and MMP-9 occurred (41). Combined with vinblastine, saponins boosted downregulation of proangiogenic and proliferative factors while attenuating neutropenia and anemia seen with this chemotherapy (44). In combination with calpain inhibitors, these saponins may also exert more pronounced apoptotic effects (45). Polysaccharides potentiate immune-mediated antitumor activity of interleukin-2 in vitro (13), improve lymphocyte responses, enhance natural killer cell activity, potentiate monocyte activity (14), increase phagocytosis perhaps by regulating tumor necrosis factor production (5), and activate macrophages to release nitric oxie and tumor necrosis factor-alpha, which directly blocks growth of breast cancer cells (62). Apoptotic effects by polysaccharides in hepatocellular carcimona cells were attributed to decreased Notch1 expression (46).
Formononetin derived from astragalus was shown to have estrogen-receptor-modulating effects (50). Angiogenic effects of astragaloside IV appear to be synergized when combined with ferulic acid from Angelica sinsensis (57).
- Immunosuppressants: Theoretically, astragalus may antagonize the effects of immunosuppressants such as tacrolimus and cyclosporine. Clinical significance is not known.
- Hormonal therapies: Astragalus and its constituents have estrogenic (23) (50) properties and may interfere with their actions. Clinical relevance is not known.
- Anticoagulants: In vitro studies suggest that astragalus and its constituents have anticoagulant properties (52), which may increase bleeding risk when used with these drugs.
- Diuretics: In a small study, astragalus was shown to have natriuretic effects (8) and may therefore have additive effects with these medications.
- Antihypertensive drugs: Astragalus extract can lower both systolic and diastolic blood pressure and may have additive effects with other antihypertensive drugs (38).
- P-glycoprotein substrates: Astragalus polysaccharides can inhibit P-glycoprotein efflux pump function. This may increase the cytotoxicity of chemotherapy drugs, including doxorubicin, etoposide, and vincristine (58). Clinical relevance is not known.
- Gemcitabine: Pretreatment with an astragalus extract was found to affect pharmacokinetics of gemcitabine in a murine model. Clinical relevance is not known (63).