Objectives: A 6-week cross-over study design was used to determine the effect of increased dairy consumption in typically low-dairy consumers (n = 37) with metabolic syndrome (MetS) on systemic inflammation and hepatic enzymes.
Methods: This was a randomized study in which participants consumed low-fat dairy (LFD) (10 oz 1% milk, 6 oz nonfat yogurt, 4 oz 2% cheese) or a carbohydrate-based control (CNT) (1.5 oz granola bar and 12 oz 100% juice) for 6 weeks. After a 4-week washout, they were allocated to the alternate dietary treatment. Inflammatory status was assessed by fasting plasma concentrations of C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), and monocyte chemoattractant -1 (MCP-1). In addition, gene expression of interleukin (IL)-1, IL-6, and TNF-α was evaluated in peripheral blood mononuclear cells isolated from a subset of 17 subjects (13 women, 3 men) at the end of each dietary period. Liver enzymes were also assessed to evaluate whether dairy components would affect hepatic function.
Results: Participants had lower concentrations of both hepatic alanine aminotransferase (p < 0.05) and aspartate aminotransferase (p < 0.005) after the LFD period. No significant changes in any of the plasma inflammatory compounds were found when all data were analyzed together. In contrast, expression of IL-1b and IL-6 were reduced by 46% and 63%, respectively, compared to the control period. When stratified by gender, women had lower TNF-α, (p = 0.028) and MCP-1 (p = 0.001) following LFD consumption compared to CNT. In addition, hepatic steatosis index scores were significantly lower (p < 0.001) during the LFD period.
Conclusions: We conclude that three dairy servings per day improved both liver function and systemic inflammation in subjects with MetS.
Keywords: dairy; hepatic enzymes; inflammation; metabolic syndrome.