The impact of pasture-fed versus total mixed ration derived whole milk powder (WMP) on circulating fatty acid concentrations and cardiometabolic health in healthy adults: Results from a randomized controlled crossover trial

• Whole milk powder (WMP) is a key food ingredient globally. • Herd diet can affect fatty acid (FA) composition of dairy foods, including WMP. • Chronic consumption of WMP at a high dose had neutral effects on cardiometabolic health. Whole milk powder (WMP) produced from pasture-fed dairy herds has been shown to have increased concentrations of unsaturated fatty acids (FA), including, but not limited to, ALA (C18:3 n-3) and oleic acid (C18:1 cis -9), compared to WMP derived from indoor herds consuming total mixed ration (TMR). Dairy products have been shown to have neutral or beneficial effects on cardiometabolic health, however, evidence on WMP in this area is lacking. Given the global market for WMP as a food ingredient, an investigation into the effect of TMR vs pasture -fed WMP on human health is warranted. To test the effect of WMP derived from TMR and pasture-fed herds on circulating FA concentrations and other markers of cardiometabolic health in adults. Healthy subjects were randomised to receive up to 200g WMP/day as part of a 6-week crossover trial, with a 4-week washout period. WMP was produced from milks of TMR and pasture-fed cows. WMP were isocaloric and macro-nutrient matched. The primary outcome was differences in circulating FA between weeks 0-6 changes in cholesterol concentrations, glycaemic control, blood pressure, anthropometry were secondary outcomes. Dietary intake was also analysed. A total of n 29 participants, 58.6% male, with a mean ± SE age of 39.8 ± 2.3 years and BMI of 26.12 ± 1.39 kg/m 2 completed the study protocol. No time × treatment interactions were observed for cholesterol concentrations, markers of glycaemic control, blood pressure or anthropometry. There was no time × treatment interaction for classes of FA, however, the very long-chain saturated FA, lignoceric acid (C24:0), decreased in response to pasture-fed WMP consumption (-0.05 ± 0.04 %TFA) with no change observed in response to the TMR WMP consumption (0.00 ± 0.04 %TFA, P=0.041), although this was not significant after Bonferroni correction for Type 2 error. Chronic, high-dose consumption of TMR and pasture-fed WMP had no effect on cardiometabolic health in healthy adults, despite different fatty acid composition. Comparison of foods with a proven dairy matrix effect, e.g., cheese made from TMR and pasture-fed milks, may have more promising effects on human health. This trial was registered as ISRCTN10490434 (https://doi.org/10.1186/ISRCTN10490434).