[Effects of diet and physical activity factors on blood pressure in nine provinces of China: a longitudinal analysis].

Objective To study the effects of diet and physical activity factors on blood pressure in nine provinces, using the multilevel model. Methods Data was collected in the China Health and Nutrition Survey (CHNS). A total of 6706 men and 7140 women aged above 18 who attended at least one of the surveys in the year of 1997,2000,2004 and 2006 were selected, and a two-level male and female random intercept-slope growth models were applied to estimate the relationship between the intake of daily salt, vegetable, fruit, fat, protein as well as the time spent on the moderate or heavy physical activity and blood pressure. Results After controlling for age,education, BMI, drinks and total energy intake, mean of the daily salt intake per person was positively associated with systolic blood pressure in women ( β= 0.0481, s-x= 0.0178, P＜0.01 ). Mean of the daily vegetable intake per person was negatively associated with systolic blood pressure in men and women, with the regression coefficients as -0.0063,-0.0068 respectively, indicating that if mean of the daily vegetable intake per person increased by 100 g, the systolic blood pressure would decrease by 0.6 mm Hg (1 mm Hg=0.133 kPa) or more. In addition, the daily vegetable intake was also negatively associated with diastolic blood pressure (P＜0.01). Daily fruit intake was negatively associated with systolic blood pressure both in men and women, with regression coefficients as -0.0029 and -0.0031 respectively. Time spent on the moderate or heavy physical activity was also negatively associated with systolic blood pressure in both men and women, and diastolic blood pressure in women (P＜0.05). No relationship was found between daily fat, protein intake and blood pressure. Conclusion Daily salt, vegetable, fruit intake, time spent on the moderate or heavy physical activity were associated with blood pressure in both men and women. Programs on integrated lifestyle modifications including dietary salt reduction, eating more vegetable and fruits, increasing physical activity level, plus weight control were critical for the control of high blood pressure. Key words: Dietary factors; Physical activity; Blood pressure; Multilevel analysis