SEASONAL-VARIATION IN HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL

We investigated the seasonal variation in high density lipoprotein cho lesterol (HDL) in 142 dyslipidemic (non-HDL-cholesterol greater-than-o r-equal-to 5.2 mmol/1) middle-aged men in the placebo group of the Hel sinki Heart Study over the 5-year trial period. A seasonal pattern was found in HDL fluctuation, with a 4.5% drop during mid-winter (5-year mean 1.192 +/- 0.265 mmol/1) compared with a stable level (5-year mean 1.248 +/- 0.281 mmol/l) during the rest of the year (P < 0.001). A le ss pronounced seasonal variation in HDL was observed in 85 subjects re ceiving gemfibrozil. Although affecting pretrial HDL level in cross-se ctional analyses, age, alcohol consumption, dietary adherence, physica l activity and serum triglycerides had no influence on the seasonality of HDL variation. Smoking had a slight attenuating effect on the vari ation pattern. Pretrial HDL was influenced by relative weight, but the re was also an inverse relationship between HDL and body weight variat ions, i.e. the annual drop in HDL coincided with the annual peak in bo dy weight. However, seasonal HDL variation was not directly reflected in the annual variation in CHD incidence.