Changes in dietary intake account for seasonal changes in cardiovascular disease risk factors

Objectives: (1) to compare dietary intake in summer and winter time; (2) to measure the change in body mass index (BMI), blood pressure and serum chol esterol between winter and summer; and (3) to determine the relationships b etween seasonal differences in dietary intake and BMI, blood pressure and s erum cholesterol measurements. Subjects and methods: Ninety-four male industrial employees were screened t wice in one year, in their work place, at winter and summer time. Workers w ere recruited from two factories and response rate was 95%. Health-related variables, including dietary intake, blood pressure and serum cholesterol w ere evaluated at each season and were compared. Correlation coefficients be tween seasonal differences in dietary intake and in BMI, blood pressure and serum cholesterol were calculated. Results: From summer to winter the mean values of BMI increase from 26.1 kg /cm(2) to 26.6 (P = 0.038), systolic blood pressure from 119.6 to 121.6 (P = 0.025), diastolic blood pressure from 75.2 to 77.2 mmHg (P = 0.001), tota l cholesterol from 200.8 to 208.6 mg/dL (P = 0.001), LDL cholesterol from 1 25.2 to 134.9 (P = 0.001) and HDL cholesterol from 42.7 to 44.3 (P = 0.0084 ). Triglycerides levels decrease from 174 to 145 in the winter (P = 0.03). Mean dietary intake of fat increases from 99.1 to 106.0 (P = 0.0016), satur ated fat from 43.6 to 46.3 (P = 0.0137), polyunsaturated fat from 25.1 to 2 8.3 (P = 0.0002), cholesterol from 462.0 to 497.9 (P = 0.0313), sodium from 5778.5 to 8208.2 (P = 0.0035), zinc from 11.6 to 12.3 (P = 0.0001), vitami n B-1 from 1.4 to 1.5 (P = 0.002), vitamin D from 4.3 to 4.9 (P = 0.0323) a nd vitamin E from 11.2 to 12.7 (P = 0.0073). Significant correlation was sh own between the seasonal increase in saturated fat and the increase in BMI (r = 0.37), total cholesterol r = 0.21) and LDL cholesterol (r = 0.29). Sea sonal change in dietary cholesterol intake was significantly and positively correlated with serum total cholesterol (r = 0.24) and LDL cholesterol (r = 0.24). Blood pressure was not associated with nutritional intake variable s. Conclusions: Dietary intake in summer and winter is different as well as bl ood pressure, BMI and serum cholesterol. The seasonal increase in fat and c holesterol intake at winter time is associated with changes in BMI and seru m cholesterol.