Plasma fatty acid responses to a calorie-restricted, DASH-style diet with lean beef

Abstract

BackgroundPlasma fatty acid (FA) levels are used as biomarkers of health outcomes and nutritional intake. MethodsThis was an exploratory analysis of the plasma FA profile from a parallel-designed, controlled-feeding study in older, obese adults (females, n = 17; males, n = 11) consuming a DASH-based diet with two levels of lean beef (3oz and 6oz per day). Plasma FA levels (as percent composition) were measured by gas chromatography from five timepoints over the 12-week intervention. The primary plasma FA change patterns modeled were sustained (initial change to ‘new normal’) or homeostatic (initial change, then return toward original baseline). ResultsThe study diet was low in fat (< 60 g/d), especially polyunsaturated FAs (PUFAs; < 5 g/d), compared to the average American diet of obese individuals as described by a nationally representative sample. Participants lost ∼6% of body mass and lowered plasma fasting triglyceride levels by ∼9% over the course of the study. With strong to very strong strength of evidence, the individual FAs displaying a sustained response were C16:1n7t, C18:1n9, C20:1n9, and C18:2n6, and homeostatic response, C18:0, 24:0, C24:1n9, C18:3n6, C20:4n6, and C22:6n3 (Ps < 0.0021, Bonferroni-adjusted). The data suggested that systematic changes in both the PUFA and de novo lipogenesis pathways occurred. ConclusionsDiet can affect plasma FA changes both due to nutritional composition and by affecting metabolic processes.