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24.07.2025

Astragalus maintains immunity during prolonged periods of physical exertion

Supplementing with Astragalus membranaceus keeps your immune system in good shape if you've been pushing yourself for weeks on end. According to a small Polish trial, a daily dose of one gram of extract is enough to protect elite athletes from viral infections like the flu, colds, and Covid-19.

Study
In 2021, researchers at the University of Physical Education in Poznan published a trial involving 18 elite rowers.

The study is more complex in design than we describe here, but essentially, the researchers divided the rowers into two groups. During a six-week training camp, the athletes in one group took two capsules daily containing no active ingredients, while the athletes in the other group took two capsules daily, each containing 500 milligrams of extract from the Chinese plant Astragalus membranaceus.

The extract was taken from the roots of the plant. You can see below what the roots look like in dried form. The extract was standardized to contain 0.5 percent 3-hydroxy-7-methoxyisoflavonoids. [Antioxidants (Basel). 2021 Nov 22;10(11):1852.]

Just before and just after the training camp, the researchers took a small amount of blood from the rowers and measured their immune system activity. The athletes were resting at the time the blood samples were taken.

Results
During prolonged periods of strenuous physical exertion, immune system activity decreases. The activity of regulatory T cells [T-reg cells, as immunologists prefer to call them] increases, while the activity of Natural Killer cells decreases.

T-reg cells moderate immune system activity. Natural Killer cells are part of the immune system's first line of defense. They kill cells that misbehave because, for example, they have been infected by viruses.

In the blood of the athletes who received a placebo, the researchers observed exactly what you would expect. But in the athletes who received supplements containing Astragalus membranaceus, the immune system remained intact.

Delta-Gamma T cells are a different story. These are immune cells that occupy an intermediate position between the first line of the immune system and the other lines. Delta-Gamma T cells also quickly spring into action when cells exhibit abnormal behavior.

Unlike NK cells, the activity of Delta-Gamma T cells actually increases with exercise. But as you can see in the table above, the activity of this category of cells increases even more with Astragalus supplementation.

Bioactive phytochemicals
Based on their trial, the researchers cannot specify the exact active ingredients in Astragalus membranaceus, but they refer to in vitro and animal studies in which Astragalus polysaccharides increase the activity of Natural Killer cells and Gamma-Delta T cells. [Process Biochemistry. 2020 Oct;97;140-8.]

In addition, Astragalus also contains immunomodulatory flavonoids and triterpenoids such as astragaloside IV. [Molecules. 2023 Aug 18;28(16):6118.] The chemical structure of astragaloside IV is shown below.

Source:
J Int Soc Sports Nutr. 2021 Jul 16;18(1):57.

More:
Astragalus membranaceus reduces hay fever 09.08.2018
Astragalus for more Leydig cells (and therefore also more testosterone) 11.01.2017
Combine Astragalus with Ginseng to boost the effect of creatine 01.05.2014

Archives:
Astragalus membranaceus
Immune System

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