- Huang chi
- Huang qi
- Milk vetch
- Radix astragali
For Patients & Caregivers
Astragalus has immune-stimulating effects and may help to reduce side effects from chemotherapy, but 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 stimulate the immune system
Laboratory studies suggest that astragalus stimulates the immune system.
- 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 fight bacterial infections
There is currently no evidence to support this claim, but one study in humans did suggest that astragalus can induce a viral-type immune response.
- 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 treat diabetes
Although astragalus has not been specifically studied for this purpose, long-term population studies suggest that astragalus is among several herbs used in Chinese medicine that may improve diabetes-related complications. Clinical trials are needed to confirm such effects.
- 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 unknown.
- You are taking immunosuppressants such as tacrolimus and cyclosporine: Astragalus may lessen their effects.
- You have a hormone-sensitive cancer: Because astragalus has demonstrated estrogenic effects, it is unknown how it may affect hormone-sensitive cancers or hormonal chemotherapy.
- You are undergoing cancer treatment: Laboratory studies suggest that certain properties of astragalus might interfere with the effectiveness of some types of cancer treatment.
- You are taking anticoagulants: Lab studies suggest that astragalus may increase bleeding risk.
- You are undergoing surgery: 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 blood pressure medications: Astragalus may increase the blood pressure-lowering effect.
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. Polysaccharides and triterpenoid saponin compounds isolated from astragalus have been used in scientific research.
Astragalus and its constituents have antioxidant (27), anti-inflammatory (28), and antiviral (29) activities. In vitro and animal studies suggest protective effects on the heart (30) (31) (32), kidney (33) (34) (35), bones (36) , and the nervous system (11) (17) (37).
Clinical studies of astragalus in humans showed promising results. A case report suggests it may reduce proteinuria associated with idiopathic membranous nephropathy (7). In small studies of 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). When used as an injection, astragalus appeared to benefit patients with IgA nephropathy (26). Astragalus used in Chinese medicine helped reduce diabetic ketoacidosis (39). In a small study of dialysis patients, an astragalus-based TCM formula significantly preserved residual renal function (40).
Anticancer properties have been observed in vitro with some compounds from astragalus against gastric (41), colon (42) (43) (44) (45), hepatic (46) and ovarian (59) cancers. Astragalus has also been associated with prolonged survival times in acute myeloid leukemia patients (47).
Data also suggest beneficial effects when used with chemotherapy (1) (2). In vitro, concomitant treatment with aldesleukin and astragalus potentiated tumoricidal activity while decreasing side effects (14). It also enhanced platinum-based chemotherapy (3) and protected against oxaliplatin neurotoxicity (48). Astragalus saponins reversed toxicities of fluorouracil (42) (28) and augmented the therapeutic benefit of vinblastine while reducing neutropenic and anemic effects in vivo (44). An injectable form of astragalus with vinorelbine and cisplatin improved quality of life in patients with advanced non-small cell lung cancer (20), but whether orally administered astragalus would exert the same effects is unknown. In another study, an astragalus extract helped to manage cancer-related fatigue (22). Meta-analyses identified astragalus as among the traditional medicines associated with reductions in chemotherapy-induced nausea and vomiting (49), and to have benefits in patients with hepatocellular cancers (16), but larger well-designed trials to confirm these findings are needed.
Although astragalus is generally safe, it may interact with certain drugs. Because this botanical and its constituents have demonstrated antioxidant (27) and estrogenic (23) (50) activities, it may interfere with some chemotherapy drugs and/or affect hormone-sensitive cancers. However, these findings are from in vitro and animal 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.
Clinical studies are needed to determine the circumstances under which astragalus could be useful as an adjuvant therapy to standard cancer treatments.
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).
Benefits to counteract memory disorders were seen with astragalus due to its activity as a nerve-growth promoting factor (17) and by 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), and increase phagocytosis perhaps by regulating tumor necrosis factor production (5). 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.
- Hormonal therapies: Astragalus and its constituents have estrogenic (23) (50) properties and may interfere with their actions.
- 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).