Among subfractions of low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (SdLDL-C) has been highlighted as the most atherogenic lipoprotein cholesterol. The present study aimed to compare the relationship of SdLDL-C with blood viscosity, a surrogate marker for cardiovascular disease, with that of other lipid fractions with blood viscosity in essential hypertensives (EHTs). In 128 untreated, early-stage EHTs, blood viscosity was measured with a falling-ball microviscometer, and serum levels of lipid fractions were determined. Blood and plasma viscosity was significantly higher in 49 patients with dyslipidemia (fasting serum level of LDL-C > 140 mg dl(-1), triglyceride > 150 mg dl(-1) or high-density lipoprotein cholesterol (HDL-C) < 40 mg dl(-1)) compared with 79 patients without dyslipidemia, although hematocrit and RBC rigidity index 'k' did not differ between the two groups. Together, SdLDL-C, LDL-C, triglyceride and large LDL-C were positively correlated with blood viscosity, but for HDL-C, the correlation was negative. After adjusting for non-lipid variables that correlated with blood viscosity (that is, the age, body mass index, resting diastolic blood pressure, sex, hematocrit, plasma viscosity and homeostasis model of assessment of insulin resistance), SdLDL-C was most strongly associated with blood viscosity among the lipid fractions. These data suggest that SdLDL-C could strongly increase blood viscosity in EHTs.

Background: An increase in plasma low-density lipoprotein (LDL) is a well-known risk factor in the development of atherosclerosis. Dairy consumption may lower the risk of atherosclerosis; however, studies on the effects of milk on cardiovascular risk factors are still scarce. We were interested in investigating whether the intake of milk improves the atherogenic lipoprotein profile. Aims: We investigated the effects of consuming whole or nonfat milk on plasma lipoprotein composition in healthy Japanese subjects as a pilot study. Methods: Normolipidemic subjects consumed 500 ml of whole milk (whole milk group; n = 7) or nonfat milk (nonfat milk group; n = 7) every day for 2 weeks. Results: The consumption of nonfat milk resulted in a lowering of plasma triglyceride (TG) and phospholipid levels and TG level in high-density lipoprotein (HDL) and increased the plasma apolipoprotein (apo) C-III level. In addition, the TG/cholesterol ratios in HDL and LDL were significantly decreased, and LDL particles became larger. In contrast, the only changes observed following whole milk consumption were increases in the plasma levels of apoC-III and apoE. Conclusions: These findings suggest that consumption of nonfat milk, but not whole milk, may result in a less atherogenic lipoprotein profile, and that the constituents of nonfat milk may improve lipid metabolism.