Anecdotal evidence suggests that the incorporation of n-6 polyunsaturated fatty acid (n-6 PUFA) containing oilseeds in dairy feeds depletes saturated fatty acids (SFA) in dairy fats such as butter. However, due to the lack of chemical evidence, the current status of n-6 PUFA or SFA in butter is unknown. We hypothesized that n-6 PUFA levels in commercial butter were inversely proportional to its SFA content and directly proportional to the extent of n-6 PUFA-rich oilseed production of its country of origin. We analyzed grass-fed and commercial butters from Australia, Belarus, Canada, China, England, France, Germany, Iceland, India, Israel, Japan, the Netherlands, New Zealand, Russia, and the United States via gas chromatography. Extent of n-6 PUFA containing oilseed production for countries was obtained from the FAOStat 2015 database. Globally, SFA from commercial butters had a strong negative correlation (Spearman r = -0.53, p = 0.025) with its n-6 PUFA content, with U.S. and Canadian butter demonstrating the highest n-6 PUFA as well as n-6/n-3 PUFA ratios. As predicted, we show that countries with >5% of its agricultural land dedicated to n-6 PUFA oilseed production demonstrate a "spillover" increase of n-6 PUFA in their commercial butters (Spearman r = 0.85, p = 0.0054). The overall significance of this study is that it presents novel evidence of the global impact of rising n-6 PUFA production on commercial butter fat composition. We hope these data will lead to inclusion of actual biochemical analyses of dairy fats in future clinical trials. We believe that this inclusion of analyses will better explain the differential health outcomes among different countries for such interventions.
Keywords: PUFA; butter; dairy; linoleic acid; omega-6; saturated fats.