Dairy attentuates oxidative and inflammatory stress in metabolic syndrome

Background: Oxidative and inflammatory stress are elevated in obesity and are further augmented in metabolic syndrome. We showed previously that dairy components suppress the adipocyte- and macrophage-mediated generation of reactive oxygen species and inflammatory cytokines and systemic oxidative and inflammatory biomarkers in obesity. Objective: The objective of this study was to determine the early (7 d) and sustained (4 and 12 wk) effects of adequate-dairy (AD) compared with low-dairy (LD) diets in subjects with metabolic syndrome. Design: Forty overweight and obese adults with metabolic syndrome were randomly assigned to receive AD (3.5 daily servings) or LD (<0.5 daily servings) weight-maintenance diets for 12 wk. Oxidative and inflammatory biomarkers were assessed at 0, 1, 4, and 12 wk as primary outcomes; body weight and composition were measured at 0, 4, and 12 wk as secondary outcomes. Results: AD decreased malondialdehyde and oxidized LDL at 7 d (35% and 11%, respectively; P < 0.01), with further decreases by 12 wk. Inflammatory markers were suppressed with intake of AD, with decreases in tumor necrosis factor-alpha at 7 d and further reductions through 12 wk (35%; P < 0.05); decreases in interleukin-6 (21%; P < 0.02) and monocyte chemoattractant protein 1 (14% decrease at 4 wk, 24% decrease at 12 wk; P < 0.05); and a corresponding 55% increase in adiponectin at 12 wk (P < 0.01). LD exerted no effect on oxidative or inflammatory markers. Diet had no effect on body weight; however, AD significantly reduced waist circumference and trunk fat (P < 0.01 for both), and LD exerted no effect. Conclusion: An increase in dairy intake attenuates oxidative and inflammatory stress in metabolic syndrome. This trial was registered at clinicaltrials.gov as NCT01266330. Am J Clin Nutr 2011;94:422-30.