Several studies have found that moderate red wine consumption can favorably impact LDL cholesterol particle size:
A study published in the American Journal of Clinical Nutrition examined the effects of red wine consumption on lipoprotein levels.
They found that red wine reduced LDL cholesterol levels and increased the LDL cholesterol to apolipoprotein B ratio, implying an increase in LDL particle size.
Another study in Nutrition Journal looked at the impact of red wine on patients with carotid arteriosclerosis.
They reported that red wine consumption led to a decrease in the LDL/HDL ratio, which was independent of lifestyle changes. The researchers noted this effect was likely due to an increase in LDL particle size.
A review article in Molecules summarized that while alcohol in red wine appears to be responsible for increasing HDL cholesterol levels, the polyphenolic compounds may play a key role in reducing LDL oxidation
Oxidized LDL is a major contributor to atherosclerosis, so reducing it by increasing LDL particle size is a potential mechanism for red wine's cardioprotective effects.