Findings from the trial showed that the combination could improve the immune system by stimulating the NK cell activity and increasing the expression of IL-10.
Published in the Journal of Functional Foods, the trial – which was the first of its kind – was conducted by the Daejeon University, Chungnam National University, and the Korea Research Institute of Bioscience and Biotechnology.
Existing literature shows that both sword bean (canavalia gladiata) and burdock (arctium lappa) have anti-inflammatory benefits.
Rich in carbohydrates, proteins, vitamins, and minerals, sword bean has been used to treat nausea, vomiting, abdominal discomfort, and asthma in Korean medicine.
In vitro and in vivo studies also exhibited its anti-allergic, anti-inflammatory, and immunomodulatory effects.
Burdock, on the other hand, contains fructo-oligosaccharides, inulin, pectin and has been used for headaches, sore throat, common cold, cough in Korean medicine.
Study design
A total of 100 subjects completed the trial between March and August last year at the Daejeon Korean Medicine Hospital.
Randomised into the intervention and placebo group, the former took a tablet containing 600mg extract of sword bean and burdock per day.
Sword bean and burdock were mixed in the ratio of 1:4 in the tablet.
Results
The researchers found that the extract enhanced immune function by stimulating the NK cell activity.
For instance, in the intervention group, their NK cell activity had grown by 24.12% from the baseline to the eighth week of the study when the effector-to-target ratio was 50:1. The change in NK cell activity from the baseline level was a significant one where p=0.0009.
In the placebo group, the NK cell activity dipped 0.08% from the start to the eighth week of the study.
NK cell activity is a key parameter since they are innate immune cells that show strong cytolytic function against physiologically stressed cells, such as virus-infected cells and tumour cells.
NK cells modulate the immune system by directly killing aberrant cells or producing a variety of cytokines, including IFN‐γ and TNF.
On the other hand, there was a significant difference (p=0.0396) in the level of IL-10 expression between the intervention and placebo group.
The IL-10 levels increased by 43.61% in the intervention but dropped by 4.35% in the placebo during the last week of the study.
An immunomodulatory cytokine, IL-10 is expressed by both the innate and adaptive immune cells.
The extract, however, did not significantly improve the other immune-related variables, including phagocytosis, IFN-γ, IL-2, IL-12, and WBC count, T cell, B cell, and NK cell populations, as well as IgA and cortisol.
Nonetheless, the researchers said the extract could serve as a functional food for stimulating the immune system.
“Our findings demonstrate that CAEC is safe and enhances immune function by stimulating NK cell activity through IL-10 expression,” they said.
Safety results
There were two adverse events observed in the intervention group and nine from the placebo group.
The most common side effect observed was the common flu.
However, there were no severe adverse events reported and no participants were dropped from the study due to the adverse events.
“All reported adverse events were determined as ‘mild’ and ‘probably not related to product’ by investigators,” the researchers said.
Future studies
The researchers suggested that future studies should focus on larger sample size to verify the immunomodulatory effects of the two ingredients combined.
“Further studies are required to reveal more precise mechanisms of CAEC effects, with clinical trials evaluating the immunity-enhancing efficacy of CAEC.
“Together with our study results, CAEC has the potential to be developed as a functional food for stimulating immunity,” the researchers said.
Till date, several dietary supplements have been developed and approved by the Ministry of Food and Drug Safety (Republic of Korea) for their immune-enhancing functions.
They include the germanium yeast, the phellinus linteus mushroom extracts, angelicae gigantis radix extract, L-glutamine, lentinus edodes mycelium extract, spirulina, chlorella, cordyceps militaris, and yeast beta-glucan.
Source: Journal of Functional Foods
Efficacy and safety of CAEC (Canavalia gladiata arctium lappa extract complex) on immune function enhancement: An 8 week, randomised, double-blind, placebo-controlled clinical trial
https://doi.org/10.1016/j.jff.2020.104259
Authors: Yee Ran Lyu, et al