Low Hdl-C In Turks: Genetic/Lifestyle Interactions Modulate Plasma Levels

Objectives: Many studies have shown that extremely low high density lipoprotein cholesterol (HDL-C) levels (mean similar to 36 mg/dl in men; similar to 42 mg/dl in women) constitute a prime coronary heart disease (CHD) risk factor in Turks. We reviewed three separate cohorts of Istanbul residents surveyed over the past 14 years and evaluated trends in risk factors for CHD in men and women during this period.Study design: The study subjects were healthy Turkish residents of Istanbul >= 20 years of age. Subjects recruited in 1996-2000 (n=828) and in 2003 (n=1100) were compared with the original Istanbul cohort (n=2686) of the Turkish Heart Study, recruited in 1990-1993.Results: The mean HDL-C level increased from 45.3 +/- 9.5 mg/dl in 1990-1993 to 49.7 +/- 12.0 mg/dl in 2003 in women (p<0.0001). In 2003, university-educated women had markedly higher mean HDL-C levels than women with a primary school or less education (56 +/- 9 mg/dl versus 48 +/- 12 mg/dl, p<0.0001). Consistent with this difference, highly educated women with higher HDL-C levels had a lower body mass index (mean 25.6 +/- 4.9 kg/m(2) versus 29.7 +/- 5.1 kg/m(2)), smaller waist circumference, smoked less, and exercised more. Among men, the HDL-C distributions were very similar in both the 1990-1993 and 2003 cohorts (38.3 +/- 8.3 mg/dl versus 39.3 +/- 9.8 mg/dl, respectively). There was no significant difference in terms of HDL-C distribution between men with higher and lower levels of education.Conclusion: Data from the three cohorts show that, although genetically determined to a great extent, low HDL-C levels can be modulated by lifestyle factors. Higher levels of education are associated with a 10% to 15% increase in the HDL-C levels of women. However, the lack of an association between educational level and HDL-C in men remains to be explained.