Astragalus root found to counteract exercise-weakened immune response, study finds

20-Aug-2021 - Last updated on 19-Aug-2021 at 10:05 GMT

Astragalus extract may promote normal immunological function, a new study thinks, as researchers identify the root’s role in counteracting the immunosuppression caused by strenuous exercise.

Findings suggest the Astragalus Membranaceus Root (AMR) restores immunological balance towards the Th1 immune response to compensate for the effects of strenuous exercise.

“Our study on AMR intake in athletes demonstrates a beneficial shift of Th1/Th2 balance that is in line with existing articles on the use of this supplement,” the team from the University of Physical Education in Poznań, Poland says.

“The discovered phenomenon provides science-based evidence on the toning effect on the immune system, exceptional for Astragalus among other herbal supplements.

“It seems that the protection against illnesses typical for shifting immunological balance towards Th2, such as Upper Respiratory Tract Infections (URTIs) or eczema, could therefore be attained by the implementation of the AMR extract into athletes’ diet.”

Study details

To test this theory, the researchers enrolled 18 members of the Polish Rowing Team onto the double-blind study.

Ten members of the rowing team were then assigned to the supplemented group with the remaining eight assigned to the placebo group.

The participants then performed a 2000 metre (m) test on a rowing ergometer at the beginning and end of the six-week study period. During this time the supplemented group received 500 milligrams (mg) of AMR.

Blood samples were taken one minute after the exercise completion and 24 hours after the exertion test.

The levels of interleukin 2 (IL2), interleukin 4 (IL4), interleukin 10 (IL10), interferon ɤ (IFN-ɣ), and lactic acid were also determined.

T regulatory lymphocytes [CD4+/CD25+/CD127−] (Treg), cytotoxic lymphocytes [CD8+/TCRαβ+] (CTL), natural killer cells [CD3−/CD16+/CD56+] (NK), and TCRδγ-positive cells (Tδγ) subpopulations were also noted.

Analysis of initial levels pointed towards the immuno-stabilising effect of AMR. This was characterised by the shift of the immunological balance towards Th1 response after the second exertion test.

“Our main observation was that in the supplemented subgroup, long-term training did not cause visible changes in the NK [CD3/CD16+/CD56+] initial percentage,” the team wrote. “This is in contrast to the placebo subgroup, for whom the percentage clearly decreased.”

Furthermore, Tδγ levels increased while the Treg percentage did not change significantly, which consequently decreased the value of the Treg/Tδγ ratio, relative to the control group.

Relative to the control group, the long-term training camp also resulted in a post-recovery (I-R) increase in IL2/IL10 ratio as a consequence of post-exertion (I-E) IL2 decrease.

Six-week results

Further results revealed that after six weeks, an increase in initial levels of IL2, IL10, CTL, and Tδγ with a decrease in IL2/IL10 ratio and IL4 were also observed, suggesting a general activation of the immune system.

Further tests revealed initial CTL [CD8+/TCRαβ+] percentage increased both in the supplemented and the control subgroup.

“This reveals the impact of the long-term intensive training itself on enhancing the number of CTL cells, which was not modifiable by AMR supplementation,” the team adds.

On the other hand, NK decreased in the placebo subgroup, while in the supplemented subgroup, their average level remained at the baseline.

“This could be considered a protective effect of the AMR supplementation on NK levels, preventing their decrease under the impact of Treg and strenuous exercise. Similarly, Tδγ lymphocytes increased in both subgroups supplemented and placebo.”

AMR extract is a non-toxic, bioactive substance with beneficial effects on the immune system, particularly in levelling out imbalances between cellular (Th1) and humoral (Th2) immunological responses.

Along with a beneficial shift in the immunological balance towards Th1, AMR supplementation appears to increase interferon gamma levels and decrease interleukin 4 (IL4) levels in asthmatic children.

Athletes already use AMR in their daily routine as an adaptogenic and anti-fatigue agent for improving endurance performance. However, little work has been carried out on its impact on the immune system.

Source: Journal of the International Society of Sports Nutrition

Published online: doi.org/10.1186/s12970-021-00425-5

“Standardized astragalus extract for attenuation of the immunosuppression induced by strenuous physical exercise: randomized controlled trial.”

Authors: Latour, E. et al.