Dietary modulation of immune function by β-glucans

The immune response can be modulated by nutrients like β-glucans, which are glucose polymers that are major structural components of the cell wall of yeast, fungi, and bacteria, but also of cereals like oat and barley. There is a lot of structural variation in the β-glucans from these different sources, which may influence their physiological functions. In this review the current status concerning possibilities to modulate immune function by β-glucans is discussed. In vitro as well as in vivo studies in animals and humans show that especially β-glucans derived from fungi and yeast have immune modulating properties. Most frequently evaluated are effects on leukocyte activity, which has been suggested to contribute to the increased resistance against infections observed after β-glucan interventions. Although most studies supply the β-glucans parenteral (e.g. intravenous or subcutaneous), also enteral administrated (dietary) β-glucan influence the immune response. Although more human studies are needed, it is tempting to suggest that dietary β-glucans may be a useful tool to prime the host immune system and increase resistance against invading pathogens.