Immunological aspects of the potential role of dietary carbohydrates and lectins in human health.

BACKGROUND: Little is known regarding the immunobiology of dietary carbohydrate intake and its relevance to human health, although foodstuffs contain many simple and complex carbohydrates. SYNOPSIS: Lectins, immunoglobulins, viruses, bacteria and host cells interact with each other forming a delicate equilibrium within the alimentary canal which may be perturbed by saccharide intake. The ways in which these components may interact at different sites within the alimentary canal are discussed, as are the possible influences on mucosal immunity and the induction of oral tolerance. The possible systemic influences of absorbed saccharides at loci remote from the gut are considered in terms of inhibition of dietary and endogenous lectins, inhibition of bacterial attachment, and alteration of leukocyte homing behaviour. Finally, possible means by which dietary carbohydrates might modify various specific diseases are considered.
CONCLUSIONS: It is probable that dietary carbohydrates can alter the equilibria between lectins, secretory IgA and micro-organisms in the alimentary canal, and this consideration could be exploited to promote health. The possible effects of dietary saccharides on allergy/oral tolerance or on recognition events at gut-remote sites warrant further investigation.