title: Inverse relationship between urinary markers of animal protein intake and blood pressure in Chinese: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study.
abstract: BACKGROUND
  This issue of the relationship between animal protein intake and blood pressure (BP) is unsolved. We examined the associations between urinary 3-methylhistidine (3MH) excretion (a biological marker of animal protein intake) and BP in 11 Chinese population samples (Urumqi, Altai, Lhasa, Tulufan, Hetian, Guiyang, Guangzhou, Shanghai, Beijing, Shijiazhuang and Taipei).
  
  
  METHODS
  This was a multi-centre cross-sectional study. In each centre, 100 men and 100 women aged 48-56 years were selected randomly from the general population. 3-methylhistidine in 24-hour (24-h) urine collections was measured by an Amino Acid Analyzer (Hitachi 835, Ibaragi, Japan). The total study sample included 966 men and 1025 women. Subjects who failed to collect complete 24-h urine samples were excluded in data analyses regarding associations between 3MH and BP.
  
  
  RESULTS
  The results showed that: (1) for within-centre analyses of individuals, the 3MH and 3MH to creatinine ratios (3MH:cre) were significantly and negatively associated with BP and hypertension. These associations remained significant after adjustment for age, sex, sodium to potassium ratio, body mass index, calcium and magnesium. The pooled regression coefficients (SE) of systolic blood pressure (SBP) and diastolic blood pressure (DBP) on 3MH were -0.020 (0.01) and -0.018 (0.01), and of SBP and DBP on 3MH:cre were -0.022 (0.01) and -0.016 (0.01), respectively. Subjects with lower 3MH excretion had higher relative risks of hypertension than those who had higher 3MH excretion. (2) In cross-centre analyses, mean SBP and DBP were significantly and negatively associated with the mean 3MH:cre across the 11 population samples (R(2) = 0.56, P < 0.01).
  
  
  CONCLUSIONS
  The results provide strong evidence that animal protein intake is associated inversely with BP in Chinese populations.
authors.affiliation: Otsuka Department of International Preventive Nutritional Medicine, WHO Collaborating Center for Research on Primary Prevention of Cardiovascular Diseases, Kyoto University, Sakyo-Ku, Japan. liulongjian@yahoo.com
authors.forename: Longjian
authors.initials: L
authors.lastname: Liu
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ikeda
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamori
mesh_terms: D044466:Asian People; D001794:Blood Pressure / Q000502:physiology*; D003430:Cross-Sectional Studies; D004044:Dietary Proteins; D004435:Eating; D005260:Female; D006801:Humans; D008297:Male; D008762:Methylhistidines / Q000652:urine*; D008875:Middle Aged
chemical_list: D004044:Dietary Proteins; D008762:Methylhistidines; C028118:3-methylhistidine