Astragalus (Latin name Astragalus membranaceus, Astragalus mongholicus), which is native to China, has been used for centuries in traditional Chinese medicine. Astragalus achieved a certain popularity in the western world in the eighties of the 20th century. There are over 2000 different species of Astragalus, but the two related species Astragalus membranaceus and Astragalus mongholicus are the species primarily used for health purposes. Historically, Astragalus - usually in combination with other medicinal plants - has long been used in traditional Chinese medicine to support and promote the function of the immune system, where it is known as Huang Qi. In China, astragalus is still frequently used for chronic hepatitis and as an adjuvant therapy for cancer. It is also used as a folk remedy for colds and upper respiratory tract infections, as well as for heart disease. Astragalus has also long been used in the oriental system of medicine under the name "Qi tonic" (1). Most astragalus supplements contain Astragalus membranaceus and are advertised as life-prolonging extracts. The root is the only part of the plant that is used medicinally and usually 4 year old plants are used. In herbal medicine, Astragalus is referred to as an adaptogen. The root of the astragalus plant is typically used in the form of soups, teas, extracts or capsules. Generally, astragalus is combined with other medicinal plants such as ginseng, angelica and licorice.
Polysaccharides are the main functional constituents of astragalus. They are responsible for the antimicrobial, antiviral and anti-inflammatory properties of this medicinal plant (2). Astragalus also contains several saponins called astragalosides (I to X), which are known for their ability to lower cholesterol levels and improve immune function (1). Other active constituents include flavonoids, which have antioxidant qualities and can help prevent heart disease and immune system weakness. Other ingredients include amino acids, folic acid and minerals such as selenium, zinc and copper (3).
In the Chinese traditional system of medicine, astragalus is used to treat symptoms of hypofunction of the spleen such as diarrhea, exhaustion, spontaneous sweating and loss of appetite. Other traditional uses include conditions associated with severe weight loss, night sweats, chronic ulcers, numbness and paralysis of the extremities and edema (4). Astragalus is also traditionally used as a remedy for diarrhea, as a laxative and to treat colds (2).
Astragalus may be helpful in the treatment and prevention of heart disease In two studies, intravenous astragalus injections significantly improved heart function in 134 patients with congestive heart failure (5, 6). In another study, Astragalus injections (astragaloside IV) reduced symptoms such as chest tightness and shortness of breath in 15 of 19 patients with congestive heart failure. In addition, a significant improvement in cardiac function was observed (7, 1).
92 patients with ischemic heart disease treated with astragalus experienced significant relief from angina (chest pain) and an improvement in heart rate. In another study, improved heart function was observed in 20 patients with angina pectoris after two weeks of treatment with astragalus (7). Astragalus (A. membranaceus injection) appeared to improve the treatment of viral myocarditis in combination with conventional therapy in 6 studies. However, the authors pointed out limitations such as a small number of subjects, a limited number of trials and a high risk of bias (8). Administration of Astragalus in the form of A. mongholicus to rats with high blood lipid levels resulted in a significant reduction in total cholesterol and triglyceride levels, as well as an increase in HDL cholesterol levels in the blood (9).
In obese rats, scientists observed that astragalus may have the potential to improve cardiovascular function (10).
There is evidence that astragalus may stimulate the function of the immune system by increasing the production of white blood cells. These are the cells of the immune system that are important for preventing disease (89, 90). In one study, daily administration of 8 grams of astragalus over a two-month period significantly stimulated white blood cell production in 14 healthy volunteers. In another study, the administration of an Astragalus extract for 20 days increased Igm, IgE and cAMP blood levels in healthy adults (11).
In a human study, a herbal Astragalus tincture stimulated the CD4 and CD8 T cells of the immune system and led to the production of DC69 (12). In patients with myocarditis, increased T3 and T4 cell concentrations and an improved T4/T3 ratio were observed after oral administration of an oral astragalus extract, indicating an increased immune response (7). A Chinese study also found that Astragalus was able to reduce overactive immune function in people suffering from systemic lupus erythematosus - an autoimmune disease (13). Astragalus polysaccharides activated B cells and macrophages (scavenger cells of the immune system) in human tumor cell cultures (14). Initial clinical studies have also shown that Astragalus can support the function of the immune system by stimulating the activity of macrophages and killer cells of the immune system (16). Although the scope of studies is limited, astragalus may also help fight viral infections in humans, including the common cold and liver infections (91, 92, 93). Summary: Astragalus may help improve immune system function and fight bacterial and viral infections, including the common cold. However, further human studies are needed to confirm this.
Astragalus may support kidney health by improving blood flow and other laboratory markers of kidney function, such as the amount of protein in the urine. Proteinuria is a condition in which abnormally high amounts of protein are found in the urine, which is a sign that the kidneys may be damaged or not functioning normally (28). Astragalus has been shown in several studies to improve proteinuria in subjects with kidney disease (94). Astragalus may also help prevent infections in people with reduced kidney function (95). In one study, daily administration of 7.5 to 15 grams of astragalus over a three-month period reduced the risk of infection by 38% in people with kidney disease. However, further studies are needed to confirm this effect (95). Summary: Some studies suggest that astragalus may help improve kidney function in people with kidney disease and reduce the risk of infection.
In China, astragalus is the most popular medicinal plant to support diabetes treatment (22, 23). According to a meta-analysis of 13 studies involving 1054 subjects, oral or intravenous administration of astragalus can lower blood glucose levels when astragalus is combined with standard treatment. Oral administration of astragalus also reduced hemoglobin A1c levels, which is a marker for long-term blood glucose levels (24). However, the authors emphasized the limited quality of the studies reviewed and recommended further research. In another study, astragalus was found to lower blood glucose levels, reduce free radical levels and promote antioxidant activity in 84 pregnant women with gestational diabetes (25).
In studies conducted with animals, scientists investigated the potential of the polysaccharides contained in Astragalus to reduce insulin resistance induced by a high glucose intake (26). Among other things, it was observed that astragalus appears to improve both blood glucose levels and kidney function in diabetic rats (20). In mice with type 1 diabetes, astragalus also increased the mass of beta cells responsible for insulin production (27).
Note: Astragalus can neither prevent nor cure cancer, but can only be used as an adjunctive approach to medically supervised cancer treatment. According to a meta-analysis of 34 studies involving 2,815 cancer patients, Astragalus-based Chinese herbal medicine in combination with chemotherapy increased patient survival, improved tumor response to treatment and reduced chemotherapy toxicity. However, the authors emphasized the low quality of the studies reviewed and recommended further research (16). In another study, astragalus supplementation in combination with chemotherapy improved quality of life and reduced symptoms in 136 patients with advanced lung cancer (28). In another study of 120 patients, adjunctive use of Astragalus in combination with chemotherapy inhibited tumor development, reduced the side effects and toxicity of chemotherapy, improved immune function and increased the quality of life of patients (29). Astragalus polysaccharides have been shown to promote the production and maturation of cancer-fighting immune cells in leukemia patients (30).
In mice, Astragalus saponins suppressed the growth of colon cancer as effectively as chemotherapy, but with fewer side effects (31). Furthermore, inhibitory effects on liver cancer and gastric cancer cells were observed in the test tube, but this does not necessarily indicate a corresponding effect in living organisms (32, 33).
Astragalus may be helpful in the treatment of anemia and other blood disorders Astragalus therapy was safe and effective in 57 children suffering from beta-thalassemia. It improved hemoglobin levels and increased red blood cell counts without causing major side effects (34). Astragalus injections improved treatment efficacy and stimulated red blood component production in 60 patients with chronic aplastic anemia (35). In another study, Astragalus as part of a Chinese herbal medicine also reduced the severity of aplastic anemia, but this study lacked a control group (36). In another study of 115 patients, astragalus was found to be effective in treating leukopenia (a reduction in white blood cell count), but this study also lacked a control group, making conclusions about its effect difficult (37). Astragalus has also been shown to have the potential to stimulate bone marrow cells in anemic mice (38).
For the possible health benefits briefly mentioned in this section, there is a lack of conclusive clinical studies to date. As these effects have primarily been observed in animal or test tube studies, it is still too early to say whether astragalus could have similar effects in humans.
Astragalus is considered safe and harmless for most adults (80). However, studies have reported minor side effects such as reddening of the skin, itching, runny nose, nausea and diarrhea (80, 97). When administered intravenously, more serious side effects such as irregular heartbeat have been observed (98). Although astragalus is safe and harmless for most people, the following groups of people should avoid astragalus:
One should be aware that some astragalus species not usually found in dietary supplements may be toxic. For example, some species contain the neurotoxin swainsonine, which has been known to cause poisoning in animals. Other Astragalus species contain potentially toxic amounts of selenium.
Astragalus may interact with drugs that suppress the function of the immune system, including corticosteroids and drugs used in organ transplants. Since astragalus can affect blood sugar levels and blood pressure, there is a possibility of interaction with diabetes and blood pressure medications.
According to preliminary studies, astragalus may have diuretic effects. In theory, this effect could reduce the excretion of lithium and increase its levels in the body (82).
Astragalus is available in many different forms, ranging from capsules to liquid extracts. In addition, the root can also be ground into powder, which can be infused as a tea. Although there is no official consensus on the most effective form or optimal dosage, the typical dosage ranges from 9 to 30 grams and correspondingly lower for extracts (100). In addition, the following dosages have been used in scientific studies:
Based on scientific research, oral doses of up to 60 grams per day for up to four months appear to be safe and harmless for most people. However, there are no studies that have examined the safety of long-term use of higher doses. Chinese herbal medicine textbooks recommend the use of 9 to 15 grams in the form of an infusion. Such an infusion is made by boiling the root in water for a few minutes and then brewing a tea (106).
According to preliminary research, astragalus may produce better results when combined with the following plants:
However, the safety and efficacy of these combinations have not yet been demonstrated in meaningful clinical trials.
Astragalus may improve the function of the immune system and relieve chronic fatigue and seasonal allergies. It may also help people with certain heart conditions, kidney disease and type 2 diabetes.
Although no official dosage recommendations exist, up to 60 grams per day for up to four months appears to be safe for most people.
