Journal Title (Medline/Pubmed accepted abbreviation): Appl. Physiol. Nutr. Metab .
Page numbers: 755-762
doi (if applicable): 10.1139/H10-070
Summary of Background and Research Design
Background: Intense physical activity can depress the immune system. Pleuran (Imunoglukan®) is an insoluble β-glucan that is present in edible mushrooms. β-glucans are available in different varieties; some have been shown to improve the immune system in athletes while others have shown no effect.
Hypothesis/Research Question:Does intake of Pleuran β-glucan for 2 mos. affect the number of peripheral blood cells, lymphocytes, and natural killer (NK) cells after exhausting exercise in elite athletes?
Subjects: 20 winter sport athletes [9 long distance cross-country skiers, 6 figure skaters, 7 sledge (sled) sport athletes] completed the study
Experimental design:Independent groups, random assignment to groups
Treatments and protocol:
Treatment: 1 capsule Imunoglukan every morning on an empty stomach for 2 mos. Each capsule consisted of 100 mg Pleuran β-glucan and 100 mg vitamin C. The placebo contained 100 mg fructose and 100 mg vitamin C.
To determine the individuals’ maximal oxygen uptake, participants cycled at 80 rpm with a 5 min warm-up at 100 W in 7 probands, at 150 W in 3 probands, and 250 W in 10 probands. The load was subsequently increased by 50 W every 2 min until volitional exhaustion. Venous blood samples were collected once at the start of the study and once at the end. During the 2 mos., athletes exercised at least 3 times per week at ≤60% of their maximal oxygen uptake for at least 1 hr.
For experimental measures, blood was acquired before and after 2 mo. supplementation, immediately after, and 1 hr after 20 min of exhaustive cycling.
Summary of research findings:
Due to hydration during exercise, all blood cell components [erythrocytes/red blood cells, leukocytes/white blood cells, hematocrit (% of solids in the blood), and hemoglobin] increased in concentration but there was no treatment effect on these trends. Lymphocyte count was higher 1 hr after exercise for the β-glucan group (1.86 ± 0.16 x 109/L) compared to the control group (1.81 ± 0.14 x 109/L). 1 hr post-exercise, the natural killer cell activity (NKCA) dropped below baseline in the control group but not the β-glucan group. The authors suggest that the NKCA observation is positive; that the β-glucan prevents the exercise-induced immunosuppression that could lead to a chronically low immune system and therefore more susceptibility to disease.
Interpretation of findings/Key practice applications:
Regular supplementation of Pleuran β-glucan may counteract the exercise-induced reduction of NKCA in elite athletes. Further studies are needed to support this preliminary finding.
This study only evaluated potential biomarkers of immune system activity. It is not known if the change in NKCA observed would actually translate to a reduction in illnesses associated with suppression of immunity. In addition, the decrease in NKCA in the placebo group was the only statistically significant treatment effect noted-none of the other blood cells were affected. Thus, it is possible that this finding represented a chance observation, as opposed to a true treatment effect.