Effects of Blackberry-derived Polyphenols on Cardiovascular Risk in Adults
Condition: Hypertension
MeSH terms: Hypertension
Study type: Interventional

Summary: 
      Cardiovascular disease (CVD) is the most common cause of death in Ireland, accounting for 33%
      of all deaths. Hypertension or elevated blood pressure, is also a significant health problem,
      however, it is one of the major controllable risk factors associated with CVD. While
      increased consumption of fruit and vegetables is associated with reduced risk of CVD,
      evidence is accumulating that consumption of berry fruits in particular, may promote
      cardiovascular health. Blackberries have a favourable nutritional profile, in that they are
      rich in dietary fibre, vitamins C, K and folate but low in dietary fat and kilocalories. In
      addition, blackberries are a rich source of antioxidants, and contain numerous phytochemicals
      including polyphenols. The aim of this study is to investigate the potential beneficial
      effects of blackberry consumption on cardiovascular health, in particular, effects on blood
      pressure.
    

Detailed description: 
      Dietary factors play a significant role in the prevention and/or treatment of hypertension
      and significant efforts are being put in to the development of functional foods with
      antihypertensive activity. Blackberries and their intrinsic polyphenols, consumed as part of
      a healthy diet, may be of functional interest in both the treatment and prevention of
      hypertension and dyslipidaemia. The Cardio-Rubus study presents healthy adults with an
      opportunity to participate in a human nutrition study that will assist in identifying
      biological effects of blackberry-derived components establishing further the value of berries
      as a nutritious, health conducive food.

      It is proposed to carry out a crossover, randomized double-blind 18-week supplementation
      study in 100 men and women aged 45-70 years with a systolic blood pressure of 130-149 mmHg
      but who are otherwise in good health. The proposed sample size is based on systolic blood
      pressure data derived from baseline values of 700 adults who participated in RCTs that we
      have conducted at UCC over the last 6-7 years. The calculation for sample size is based on
      observational data of systolic blood pressure in older pre-hypertensive adults, which showed
      a mean (SD) SBP of 135 (3) mmHg. The proposed study is powered to detect a mean drop of 2
      mmHg systolic blood pressure at 85% power and with a significance level of 5%. The
      calculations support the recruitment of 100 participants in total (n = 41 per group, rounded
      up to 50 to account for a 20% attrition rate).

      Potential study participants will be recruited by researchers at the School of Food &
      Nutritional Sciences and all study visits will take place at the Human Nutrition Studies
      Unit, UCC. In addition to the provision of written information, the study protocol will be
      clearly and comprehensively discussed with each potential participant prior to enrollment and
      their provision of informed written consent. Participants will initially complete a 2-week
      run in period which involves refraining from the consumption of specified foods items
      (predominantly berries and other fruits) until the end of the study. Each participant will be
      randomly assigned to receive one of two beverages (either a high dose or low dose blackberry
      polyphenol enriched beverage) for a period of 6-weeks (study phase 1) and then after a 2-week
      wash-out, the participant will receive the opposite treatment to that which was provided
      during study phase 1 for the next 6-weeks (study phase 2). After completion of study phase 2
      there will be a 2-week wash-out followed by a final visit to UCC. Thus, after screening and
      enrolment on to the study, there will be a further 5 visits to UCC (at the baseline and
      endpoint of each study phase and at the end of the final washout phase). All 5 visits will be
      fasting morning visits where the nurse will take a small blood sample which will be analysed
      for blood lipids, fasting glucose and biomarkers of endothelial function. Brachial and
      central blood pressure will be measured as well as an assessment of arterial stiffness by
      pulse wave velocity analysis. Body weight, BMI and waist circumference will also be measured.
      Each participant's body composition (% body fat & lean mass) will be assessed by DXA scan.

      All information collected is strictly confidential. Samples and questionnaires will be
      labelled with a unique identifying code, and participant's names will not be used at any
      stage during data collection, database construction or data analysis. Data will be archived
      by the principal investigator. In any publications or other documents, participants will not
      be identified by name or code numbers. Group summary data will be presented in place of
      individual data, further ensuring confidentiality.
    

Intervention name(s): blackberry polyphenol enriched beverage; blackberry beverage with minimal polyphenol concentrations
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Double-blind intervention study, cross-over design with one 250 mL bottle of high-dose blackberry polyphenol beverage per day or placebo (blackberry beverage with minimal polyphenol) in Phase one followed by cross-over in Phase two.; Double-blind intervention study, cross-over design with one 250 mL bottle of high-dose blackberry polyphenol beverage per day or placebo (blackberry beverage with minimal polyphenol) in Phase one followed by cross-over in Phase two.
Other intervention name(s): Rubus Fructicosus; Rubus Fructicosus
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention