Nationwide survey of high-density lipoprotein cholesterol among farmers in Japan.

A total of 2,134 blood samples (788 from men and 1,346 from women), were collected nationwide from adult farmers in Japan (44 regions in 21 prefectures) during the winters of 1978 through 1981. They were analyzed in a single laboratory for high-density lipoprotein cholesterol (HDL) by means of a precipitation method. The serum HDL level was 47.3 +/- 14.2 mg/100 ml (mean +/- SD; n = 788) in men and 47.4 +/- 12.8 mg/100 ml (n = 1,346) in women. Sex and age differences in HDL were not statistically significant (P greater than 0.10). Alcohol consumption was associated with elevated HDL levels in both sexes; the association was statistically significant only in men (P less than 0.05) and was positively correlated with daily alcohol consumption (P less than 0.05). Conversely, smoking habits were negatively (P less than 0.05) associated with HDL in men. The comparison of HDL in the nondrinking and nonsmoking population revealed that HDL in women (47.0 +/- 12.8 mg/100 ml; n = 900) did not differ significantly (P greater than 0.10) from the male values (45.3 +/- 12.5 mg/100 ml; n = 60). When 23 nondrinking and nonsmoking married couples were selected from 348 couples, for whom information on drinking and smoking habits was available, the HDL (+/- SD) was essentially the same in husbands (44.2 +/- 12.8 mg/100 ml) and in wives (43.7 +/- 9.5 mg/100 ml). In the blood samples collected from 535 subjects once in winter and once in summer, HDL concentration was significantly higher in summer than in winter (P less than 0.01 in both men and women); the HDL means (+/- SD) in winter and in summer were 48.1 +/- 14.3 and 50.9 +/- 11.3 mg/100 ml, respectively, for men, and 47.0 +/- 12.0 and 50.3 +/- 11.0 mg/100 ml, respectively, for women. The mean HDL distributed across a fairly wide range depending on the 44 regions studied. Maximum-minimum mean values were 58.3-33.1 mg/100 ml in men and 59.7-37.4 mg/100 ml in women, and the regional difference was statistically significant (P less than 0.01) both in men and women. Furthermore, a significant inverse relation (P less than 0.05) was observed in men between the mean regional HDL values and standardized regional ratios of mortality from coronary heart diseases.