Abstract
Beta Glucan, a polysaccharide derived from yeast, oat and barely has been applied as a nutritional supplement for lowering blood cholesterol and enhancing the immune system. While beta glucan is the key factor in the cholesterol lowering effect of wheat-bran, its therapeutic efficacy as an immunomodulator is less well-defined. Data from in vitro and in vivo (injectable and/or oral route) experiments have demonstrated beta glucan derived from yeast is capable of (i) enhanced killing of tumors, (ii) reduction of tumor cell metastasis (iii) stimulation of hematopoiesis following chemotherapy /radiation, (iv) enhanced oxidative burst and bacterial killing in blood leukocytes and (v) mitigation of some immunosuppressive affects of dexamethosone.
A pilot study was conducted to assess the immunomodulating potential of this supplement in killer whales. Immune parameters examined included analysis of leukocyte subpopulations, lymphocyte function and kinetics of neutrophil phagocytosis. Ten principles and three controls were employed in the study; two dosages of Imprime WGPTM (20 and 40mg/kg; Biothera, Eagan, MN) were administered orally to each of 5 animals residing in 3 different marine parks over a 5 week period. Each park contributed one control animal to the study. Samples were collected at 3 time points; the day of supplement administration (T0) and at 2 and 5 weeks into treatment. An additional leukocyte subpopulation analysis was performed 5 weeks following supplement withdrawal from the diet (T10 weeks).
No significant differences were found in the mean values of either leukocyte subpopulations or neutrophil phagocytosis when comparing the three dose groups at Week 0, indicating that confounding factors were not present at the beginning of the study. The only significant change identified was in monocytes (both % and absolute numbers; p <0.05) and only at a single time-point (2 weeks following initial supplementation). Animals receiving 40 mg/kg doses of beta glucan were significantly more likely to have higher monocyte counts at Week 2 compared to animals receiving 0 mg/kg or 20 mg/kg doses. Statistical evaluation of changes in lymphocyte function has not yet been performed.
The transient elevation in monocytes in animals receiving the highest dose of beta glucan could be attributed to its purported hematopoetic properties; larger sample size would be required to confirm this observation. This minimal evidence of immunomodulation might be attributable to inadequate dosage for this species, lack of adsorption of therapeutic concentrations of beta glucan and/or lack of a deleterious event which would allow detection of immunomodulation. The latter possibility would be supported by previous studies that suggest beta glucan primes cells of the immune system such that a more vigorous immune response is elicited at the time of an insult.