Lipoprotein(a) lipidome and diet: responses to reducing saturated fat intake in African Americans in a randomized...

Lipoprotein(a) [Lp(a)] is a genetically determined cardiovascular risk factor. Additionally, Lp(a) levels are affected by dietary saturated fat (SFA) reduction. We previously reported an Lp(a) increase in response to SFA reduction in both white and black cohorts. However, less is known whether diets impact Lp(a)'s oxidized phospholipids (OxPL) and lipid components. We assessed responses of Lp(a)-OxPL concentration, Lp(a)-OxPL subspecies abundance, and the Lp(a)-lipidome to SFA reduction [from 16% energy with the average American diet (AAD) to 6% energy with a DASH-type diet] in 166 African-Americans. Responses by variability in Lp(a) levels and apolipoprotein(a) [apo(a)] sizes were tested. Mean age was 35 years; 70% were women; mean BMI was 28 kg/m². Median Lp(a)-OxPL total concentration did not differ although particle concentration of four OxPL subspecies, in particular ALDOPC, decreased from AAD to the DASH-type diet (P = 0.001). Of 440 Lp(a) lipids annotated, 87 species (20%) responded significantly to SFA reduction, with major changes in phosphatidylcholine, sphingomyelin, and alkylphosphatidylcholine classes. A marked Lp(a)-lipidome difference between diets was observed for participants with higher (≥50 mg/dl) but not with lower (<50 mg/dl) Lp(a) levels. The Lp(a)-lipidome response varied across apo(a) sizes; small apo(a) (≤22 Kringles) carriers exhibited a greater decrease (80%) than an increase (20%) in lipids, while the opposite was the case for carriers of apo(a) sizes >22 Kringles. In conclusion, dietary SFA reduction in African-Americans resulted in significant changes in the Lp(a)-lipidome with differences by Lp(a) levels and apo(a) sizes. The findings support a dynamic intraindividual nature of the Lp(a)-lipidome and an impact of metabolic regulation.