Trends of diet and blood pressure in Guangzhou, South China.

As part of the International Cooperative Cardiovascular Diseases and Alimentary Comparison (CAR-DIAC) Study surveys to determine the relationship of dietary factors to blood pressure were carried out in 1985 (pilot study) and 1989 (core study). Thirteen men and 16 women, and 102 men and 115 women aged 50-54 in the rural population of Panyu county in Guangzhou were randomly selected for the pilot and core studies, respectively. Blood pressure was measured by an automatic system and 24-h urine collection by aliquot cups. All urinary specimens were analyzed in the WHO Collaborating Center (Izumo, Japan). Seven hypertensive cases and 17 borderline cases of hypertension were found in 1989 but none in 1985. Mean systolic blood pressure (SBP) and diastolic blood pressures (DBP) were increased, and the intake of dietary sodium (Na), sodium chloride (NaCl), and the ratio of sodium to potassium (Na/K) were increased markedly. The intake of magnesium (Mg) was decreased in 1989. Correlation analyses showed that body mass index was positively related to SBP and DBP (p less than 0.05), Na and NaCl were positively related only to DBP (p less than 0.05), and Mg was inversely related to SBP but with no statistical significance. These results indicate that trends of rise of prevalence rate of hypertension and mean values of SBP and DBP in association with increased dietary Na and decreased Mg intake may be due to rapid changes in dietary habits, changes in lifestyle, and the differing socioeconomic status in the area and may highlight the importance of dietary factors in the prevention of hypertension.