Purpose: Wholegrain (WG) consumption is associated with reduced risk of cardiovascular disease, but clinical data on inflammation and immune function is either conflicting or limited. The objective of this study was to assess the impact of increasing WG consumption to at least 80 g/day on markers of inflammation and glucose metabolism and on phenotypic and functional aspects of the immune system, in healthy, middle-aged adults with low habitual WG intake.
Methods: Subjects consumed a diet high in WG (>80 g/day) or low in WG (<16 g/day, refined grain diet) in a crossover study, with 6-week intervention periods, separated by a 4-week washout. Adherence to the dietary regimes was achieved by dietary advice and provision of a range of food products, with compliance verified by analysis of plasma alkylresorcinols (ARs).
Results: On the WG intervention, WG consumption reached 168 g/day (P < 0.001), accompanied by an increase in plasma ARs (P < 0.001) and fibre intake (P < 0.001), without affecting other aspects of dietary intake. On the WG arm, there were trends for lower ex vivo activation of CD4(+) T cells and circulating concentrations of IL-10, C-reactive protein, C-peptide, insulin and plasminogen activator inhibitor-1. The percentage of CD4(+) central memory T cells and circulating levels of adipsin tended to increase during the WG intervention.
Conclusions: Despite the dramatic increase in WG consumption, there were no effects on phenotypic or functional immune parameters, markers of inflammation or metabolic markers.
Keywords: Alkylresorcinols; Fibre; Immune; Inflammation; Wholegrain.