Replacing with whole grains and legumes reduces Lp-PLA₂ activities in plasma and PBMCs in patients with prediabetes or T2D

To determine dietary effects on circulating lipoprotein-associated phospholipase A₂ (Lp-PLA₂) activity and enzyme activity in peripheral blood mononuclear cells (PBMCs), 99 patients with impaired fasting glucose, impaired glucose tolerance, or newly-diagnosed T2D were randomly assigned to either a control group (usual diet with refined rice) or the whole grain and legume group. Substitution of whole grains and legumes for refined rice was associated with the replacement of 7% of energy from carbohydrates with energy from protein (about 4%) and fat. After 12 weeks, the whole grain and legume group showed a significant decrease in fasting glucose, insulin, homeostasis model assessment-insulin resistance, hemoglobin A_1c, malondialdehyde, plasma Lp-PLA₂ activity, and oxidized LDL (ox-LDL), and an increase in LDL particle size. The changes (Δs) in these variables in the whole grain and legume group were significantly different from those in controls after adjustment for the baseline levels. When all subjects were considered, Δ plasma Lp-PLA₂ positively correlated with Δ glucose, Δ PBMC Lp-PLA₂, Δ ox-LDL, and Δ urinary 8-epiprostaglandin F_2α after being adjusted for confounding factors. The Δ PBMC Lp-PLA₂ correlated positively with Δ glucose and Δ ox-LDL, and negatively with Δ LDL particle size and baseline PBMC Lp-PLA₂. The substitution of whole grains and legumes for refined rice resulted in a reduction in Lp-PLA₂ activities in plasma and PBMCs partly through improved glycemic control, increased consumption of protein relative to carbohydrate, and reduced lipid peroxides.