Chronic consumption of conventional and saturated-fat reduced dairy products have differential effects on low-density lipoprotein cholesterol levels in adults at moderate cardiovascular disease risk

Abstract

Reducing the intake of dietary saturated fatty acids (SFA) to ≤10 % of total energy intake is a key public health strategy aimed at lowering current cardiovascular disease (CVD) incidence. Consumption of dairy products (including butter) represents approximately 35 % of total dietary SFA intake(1). Supplementation of the bovine diet with oleic acid‐rich plant oil has been reported to depress SFA and increase cis‐monounsaturated fatty acids levels in milk, providing a strategy to lower total dietary SFA intake (2). This human intervention study aimed to investigate whether consumption of SFA‐reduced, compared with conventional dairy products, would impact on the fasting lipid profile, glucose and insulin concentrations of adults at moderate CVD risk. Fifty‐four adults (mean age 53 (SD 13) years, BMI 26 (SD 3) kg/m2), completed a double blind, randomised, controlled 12‐week cross‐over study with an 8‐week washout period between treatment arms. Participants replaced habitual dairy foods/snacks with SFA‐reduced or conventional UHT milk, Cheddar cheese and butter (fatty acid (FA) composition of SFA‐reduced vs. conventional dairy products: total SFA: ‐7·0 g/d, C18:1cis: 3·0 g/d, C18:1trans: 2·4 g/d), achieving an isoenergetic daily dietary exchange (41 g/d total fat). At the beginning and end of each treatment period, fasting blood samples were collected for biochemical analysis. LDL‐C was estimated using the Friedewald formula. The homeostatic model assessment of insulin resistance (HOMA‐IR) was calculated using the glucose and insulin data. Preliminary results using mixed model analyses indicate that from baseline, only LDL‐C concentrations were influenced by the FA composition of the dairy products, with the observed increase in LDL‐C concentrations with Diet B shown to be significantly attenuated following Diet A. These preliminary findings are part of the RESET intervention trial (NCT02089035), which will also investigate the impact of consumption of SFA‐reduced dairy products on inflammatory markers and vascular function.