INTERMAP: International Population Study on Macronutrients and BP
Condition: Cardiovascular Diseases; Heart Diseases; Hypertension
MeSH terms: Cardiovascular Diseases; Heart Diseases
Study type: Observational

Summary: 
      To investigate the relationship between dietary factors, especially macronutrients, and blood
      pressure in an international, multicenter observational study. A particular focus is to help
      elucidate the role of these dietary factors in accounting for the even more adverse blood
      pressure patterns of less educated population strata, especially in the United States, in
      both less educated Blacks and whites.
    

Detailed description: 
      BACKGROUND:

      Overall study findings are to be used to estimate favorable impact on blood pressure of
      multiple improvements in nutrition by populations. The investigators state that this should
      aid in making additional dietary recommendations toward the goal of primary prevention of
      hypertension and shifting blood pressure distributions downward to avoid excess risk
      associated with present levels generally above optimal.

      DESIGN NARRATIVE:

      INTERMAP's cross-sectional design is patterned after the tested INTERSALT model: a large
      sample size of 4,680 persons, half men and half women, ages 40-59 from 17 population samples
      of varied ethnicity, socioeconomic status (SES) and dietary habits in four countries (China,
      Japan, United Kingdom and the United States). There were eight United States INTERMAP
      centers. Specific aims involve elucidating influences on blood pressure of the amount and
      type of protein, lipids, carbohydrates, and also amino acids, calcium, magnesium,
      antioxidants, fiber, and caffeine. Primary hypotheses tested, with control for body mass
      index (BMI), intake of alcohol, age, sex, and other confounders are as follow: dietary
      protein is inversely related to blood pressure; inverse relations between education and blood
      pressure are significantly accounted for by education-related differences in dietary protein
      intake; there is a direct relation to blood pressure of dietary saturated fatty acids,
      cholesterol, Keys score, starch; there is an inverse relation of polyunsaturated fatty acids
      and polyunsaturated/saturated fatty acids. Randomly selected participants provide one timed
      24-hr. urine collection for assessment of sodium, potassium, creatine, and urea, and complete
      four 24-hr. dietary recalls. Blood pressure was measured eight times at each of four clinic
      visits, with standardization and strict quality control of all procedures.

      The study is coordinated by two Coordinating Centers--Northwestern University, Chicago and
      London School of Hygiene & Tropical Medicine. Urinary determinations are made at a Central
      Laboratory in Leuven, Belgium. Twenty-four hour dietary recalls are converted into nutrients
      with use of the Nutrition Data System of the University of Minnesota's Nutrition Coordinating
      Center. Data analyses to test hypotheses are done at the London Coordinating Center.

      Recruitment and data collection began in July, 1996 through January, 1997. The main
      statistical analytic method is multivariate regression analysis. The study was renewed in FY
      2000 and in FY 2004 to continue analysis of the data through August, 2009.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        The INTERMAP study population includes 4,680 men and women ages 40-59 who were recruited
        from 17 population samples of diverse ethnicity/ SES/ eating practices in four countries
        (China, Japan, UK, USA).
      
Biospecimen description: 
      24 hour urine collection among all participants