Effects of increased wholegrain consumption on immune and inflammatory markers in healthy low habitual wholegrain consumers.

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.

Increased whole grain consumption does not affect blood biochemistry, body composition, or gut microbiology in healthy, low-habitual whole grain consumers.

BACKGROUND: Whole-grain (WG) foods have been suggested to reduce the risk of cardiovascular disease, but studies are inconsistent and effects on cardiovascular risk markers are not clear. OBJECTIVE: The objective of this study was to assess the impact of increasing WG consumption to at least 80 g/d on overall dietary intake, body composition, blood pressure (BP), blood lipids, blood glucose, gastrointestinal microbiology, and gastrointestinal symptoms in healthy, middle-aged adults with habitual WG intake <24 g/d. METHODS: Eligible subjects [12 men, 21 women, aged 40-65 y, body mass index (BMI): 20-35 kg/m(2)] were identified through use of food frequency questionnaires and subsequently completed 3-day food diaries (3DFDs) to confirm habitual WG consumption. Subjects consumed diets high in WG (>80 g/d) or low in WG [<16 g/d, refined-grain (RG) diet] in a crossover study with 6-wk intervention periods separated by a 4-wk washout. Adherence was achieved by specific dietary advice and provision of a range of cereal food products. The 3DFDs, diet compliance diaries, and plasma alkylresorcinols were used to verify compliance. RESULTS: During the WG intervention, consumption increased from 28 g/d to 168 g/d (P < 0.001), accompanied by an increase in plasma alkylresorcinols (P < 0.001) and total fiber intake (P < 0.001), without any effect on energy or other macronutrients. Although there were no effects on studied variables, there were trends toward increased 24-h fecal weight (P = 0.08) and reduction in body weight (P = 0.10) and BMI (P = 0.08) during the WG intervention compared with the RG period. CONCLUSION: A combination of dietary advice and provision of commercially available food items enabled subjects with a low-moderate habitual consumption of WG to substantially increase their WG intake, but there was little effect on blood biochemical markers, body composition, BP, fecal measurements, or gut microbiology. This trial was registered at www.controlled-trials.com as ISRCTN36521837.