About Herbs

Bottom Line: Astragalus has immunostimulant effects, but it has not been shown to treat or prevent cancer.

From the research that has been conducted on astragalus, scientists believe that it works by stimulating several factors of the immune system. In laboratory studies, astragalus extracts augment the activity of monocytes, natural killer cells, and lymphocytes, even when their activity is suppressed by substances such as steroids. In addition, astragalus reversed immune suppression from cyclophosphamide (a common chemotherapy drug) in rats.

Astragalus extracts also protect liver cells from chemical injury in animals and in laboratory studies. Studies conducted in China suggest that astragalus may also protect the kidneys when used in combination with the herb angelica. In studies using senile rats, astragalus increased the ability of their brain cells to respond to stimuli, but it is still unknown if these effects occur in humans. An herbal formula containing astragalus has been shown to reduce fatigue in athletes by increasing uptake and use of oxygen.

End-stage kidney disease:
Thirty-one patients with end-stage kidney disease on hemodialysis were followed to test whether astragalus could improve their immune response. Patients received either intravenous astragalus extract or placebo for two months. Compared to the placebo group, the astragalus group had significantly higher levels of IL-2, a substance that stimulates the growth of immune cells and their response to disease. However, this does not necessarily indicate that astragalus improved immune response in these patients. It would be more helpful to know whether astragalus helped these patients fight off disease or live longer, which this study does not address.

Astragalus is often used in combination with other botanicals in Traditional Chinese Medicine. Clinical trials conducted in China suggest astragalus-based herbal formulas may enhance the efficacy and reduce the side effects of certain chemotherapy.

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Huang chi, huang qi, milk vetch, Radix astragali

Astragalus root is used in Traditional Chinese medicine for its immunestimulating properties. Studies done in China suggest that astragalus, when used with angelica, has renal protective effects ⁽⁶⁾. In addition, astragalus decreases the proteinuria associated with idiopathic membranous nephropathy ⁽⁷⁾ as well as possesses natriuretic action ⁽⁸⁾. Astragalus may also suppress airway hyper reactivity associated with allergic asthma in vivo ⁽⁹⁾. An herbal formula using astragalus as a major ingredient has been shown to reduce fatigue in athletes ⁽¹⁰⁾. Furthermore, astragalus increases M-cholinergic receptor density in senile rats ⁽¹¹⁾, which suggests that it may have a role in combating senility. Astragalus extract may also act as a nerve-growth promoting factor in vitro and in vivo ⁽¹⁷⁾, and alleviate obstructive uropathy in mice in combination Angelica sinensis and standard care ⁽¹⁸⁾.

Astragalus extracts possess cytostatic properties, inhibiting tumor growth ⁽⁵⁾ and were shown to delay chemical-induced hepatocarcinogenesis in rats ⁽⁴⁾. In vitro, animal, and anecdotal human data show that astragalus reduces immune suppression, a side effect of chemotherapy ^{(1) (2)}, and may also enhance the effects of platinum-based chemotherapy ⁽³⁾. Conclusions from a meta-analysis suggest benefits of astragalus-based treatments for hepatocellular cancers, but data need to be evaluated in larger, well designed trials ⁽¹⁶⁾.

Patients taking immunosuppressants (e.g., tacrolimus or cyclosporin) should not take this supplement. Astragalus preparations should be administered only by oral route.

Astragalus works by stimulating several factors of the immune system. The polysaccharides potentiate the immune-mediated antitumor activity of interleukin-2 in vitro ⁽¹³⁾, improve the responses of lymphocytes from normal subjects and cancer patients, enhance the natural killer (NK) cell activity of normal subjects, and potentiate the activity of monocytes ⁽¹⁴⁾, increasing phagocytosis perhaps by regulating tumor necrosis factor (TNF) production ⁽⁵⁾. The saponins potentiate NK cell activity and restore steroid-inhibited NK cell activity in vitro. They also increase phagocytosis and demonstrate hepatoprotective effects on chemically-induced liver injury in vitro ⁽⁶⁾ and in vivo ⁽⁴⁾. Chinese studies suggest that astragalus, when used with angelica, has renal protective effects by mediating gene expression. Astragalus increases M-cholinergic receptor density in senile rats, suggesting that astragalus may have a role in combating brain senility ⁽¹¹⁾. An herbal formula containing astragalus can reduce fatigue in athletes by increasing uptake and utility of oxygen ⁽¹⁰⁾.

No adverse effects have been reported.

Immunosuppresants: Astragalus may antagonize the effects of immunosuppressants such as tacrolimus and cyclosporine.

Aldesleukin: Concomitant treatment with astragalus has resulted in a 10-fold potentiation of tumor-cidal activity with decreased side effects.

Cyclophosphamide: Astragalus may decrease immunosuppression following treatment.
^{(1) (14) (15)}

Most of the clinical trials on astragalus were conducted in China using multiple-herbal formulas that contain astragalus as the major component. The selection of herbs is based on Traditional Chinese Medicine.

Qun L, et al. Effects of astragalus on IL-2 / IL-2R system in patients with maintained hemodialysis (letter). Clin Neph 1999;52:333-4.
Prospective evaluation of 31 patients in end-stage renal disease, on hemodialysis. Participants were randomized to receive either intravenous astragalus or placebo. After 2 months of treatment, the astragalus group had significantly higher levels of IL-2 compared to placebo.

McCulloch M, et al. Astragalus-based Chinese herbs and platinum-based chemotherapy for advanced non-small-cell lung cancer: Meta-analysis of randomized trials. J clin Oncol 2006;24(3):419-430.
This analysis sought to determine whether Chinese herbal medicine containing Astragalus increases the effectiveness of platinum-based chemotherapy for advanced non-small-cell-lung cancer.  Thirty-four randomized studies involving 2,815 patients were analyzed. Results suggest that when used in conjunction with platinum-based chemotherapy, Astragalus-based medicine improved survival, tumor response, performance status, and reduced chemotherapy toxicity when compared with chemotherapy alone.
However, the low quality of the studies analysed is a drawback and the results are therefore, not conclusive. Well-designed studies are warranted.

Taixiang W, et al. Chinese medical herbs for chemotherapy side effects in colorectal cancer patients (Review). The Cochrane Database Syst Rev 2005; (1):CD004540.
Four clinical trials were included in this review to assess the effectiveness of Astragalus (Huangqi) compounds on the quality of life, side effects of chemotherapy, and on adverse effects in colorectal cancer patients. A decoction of Huangqi compounds was used in combination with chemotherapy in three studies, whereas the fourth study compared Huangqi compounds with two other Chinese herbal formulas. Patients who were given Huangqi compounds experienced a reduction in nausea and vomiting along with a decrease in the rate of leucopenia and an increase in CD3, CD4 and CD8 subsets of T-lymphocytes when compared to those treated with chemotherapy alone in the three studies or with other Chinese formulas in the fourth study.
Use of Chinese herbal medicine along with chemotherapy appears promising for patients with colorectal cancer; however, a major limitation of this review is that it includes only four studies and the studies are of poor quality. Further properly designed trials are needed to confirm these observations.