International cooperative study on the relationship between dietary factors and blood pressure: a report from the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study.

To investigate the epidemiological relationship of dietary factors to blood pressure (BP) and major cardiovascular diseases, we carried out the International Cooperative Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study, which so far involves 45 centers in 20 countries. From each population, 100 men and 100 women aged 50-54 years were randomly selected for BP measurement, 24-h urine collection, and blood test. Various biological markers of diets from urine and blood were analyzed centrally in the Izumo CARDIAC center. In within-center multiple regression analyses, body mass index (BMI) was strongly positively and independently associated with BP. Urine magnesium (Mg) excretion was negatively and independently associated with BP. In cross-center simple regression analyses, systolic and diastolic BP showed significant correlations with BMI (p less than 0.01) and 24-h urinary sodium (Na) excretion (p less than 0.005) in men and significant inverse correlations with urinary 3-methylhistidine (3-MH) divided by creatinine (p less than 0.01 and p less than 0.005, respectively) in men, and were inversely correlated with urinary Mg in women (p less than 0.05). Therefore, Na and BMI adversely affect BP, whereas animal protein and Mg intakes may have beneficial influence on BP.