Impact of Dairy Consumption on Hypertension: a Clinical Study
Condition: Hypertension; Cardiovascular Diseases
MeSH terms: Hypertension; Cardiovascular Diseases
Study type: Interventional

Summary: 
      Hypertension and endothelial dysfunction are being increasingly recognized as key etiological
      factors in the development of atherosclerosis and subsequent cardiovascular disease (CVD). A
      substantial body of evidence indicates that treating patients with elevated blood pressure
      (BP) leads to marked reduction in the risk of stroke, myocardial infarction, heart failure,
      and renal failure. There is also accumulating evidence associating endothelial dysfunction,
      which is defined as incapacity of the arteries to vasodilate when required, to elevated BP
      and an increased risk of CVD.

      While there are more and more studies on how diet affects BP in healthy subjects, the impact
      of dairy consumption per se on both endothelial function and ambulatory BP has not been well
      characterized in patients with established essential hypertension. Therefore, the general
      objective of the study is to investigate in a single-blind randomized controlled study the
      impact of dairy consumption on ambulatory BP and endothelial function in subjects with mild
      to moderate essential hypertension.
    

Detailed description: 
      The proposed research will be undertaken as a single-center randomized cross-over controlled
      study. A total of 80 men and women with mild to moderate essential hypertension but otherwise
      healthy will consume two 4-week diets, one rich in dairy and one without dairy, while
      consuming a diet low in saturated fat (<10% energy), in trans fat (<1% energy) and in
      cholesterol (<200 mg/day). During the DAIRY diet, subjects will be asked to incorporate 3
      servings of dairy (milk, yogurt, cheese) into their every day diet. During the CONTROL arm of
      the study, participants will be asked to consume energy equivalent replacement products. The
      primary analysis consists in comparing mean daytime ambulatory BP values and endothelial
      function between the two treatments.

      A 2-week stabilization run-in period will precede the randomization of participants. During
      this run-in period, participants will be asked and instructed to adapt their diet to a
      prudent dietary pattern low in saturated fat (<10% energy), in trans fat (<1% energy) and in
      cholesterol (<200 mg/day). The total amount of fat in the diet will not be restricted, with
      recommendations ranging from 25-35% of energy. However, substitution of saturated for
      unsaturated fat will be advocated. Sodium intake <2300 mg/d will also be recommended.
      Recommendations will also include advice on how to restrict the consumption of processed and
      energy dense foods. This 2-week run-in period will allow participants to familiarize
      themselves with the dietary recommendations used during the intervention per se. The two
      diets will be separated by a 4-week wash out period and will also consist to the prudent
      dietary pattern recommended. It must be stressed that foods will not be provided during the
      run-in and wash-out periods. These periods are imposed to minimize the inter- and
      intra-individual variability before and between the experimental phases.
    

Intervention name(s): Dairy diet; Control diet
Intervention type(s): Other; Other
Intervention description(s): During the DAIRY diet, subjects will be asked to incorporate 3 servings of dairy: 375 ml of reduced fat milk (1% fat), 175 g of low fat yogurt (1.5% fat) and 30g of regular cheese (34% fat) into their every day diet.; During the CONTROL diet of the study, participants will be asked to consume energy equivalent replacement products (290 ml of fruit juice, 156 ml of vegetable juice, 1 homemade cookie, 20g of cashew).
Other intervention name(s): Dairy products; Milk; Yogourt; Cheese
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention
Keywords: Endothelial function; Dairy