Impact of Oranges on Cardiovascular Health
Condition: Blood Pressure; Endothelial Dysfunction; Cardiovascular Disease Risk Reduction
MeSH terms: Cardiovascular Diseases
Study type: Interventional
Phase: Phase 1/Phase 2

Summary: 
      Cardiovascular disease (CVD) is the leading cause of deaths in the Western world. Established
      risk factors include high LDL cholesterol, high blood pressure and diabetes. Poor blood
      vessel health is considered a predictor of future CVD risk, but can be reversed. Several
      different measurements can be used to determine blood vessel health; such as blood pressure
      (BP), and newer techniques which measure blood flow through the arteries after a blood
      pressure cuff restricts blood flow for a few minutes in one arm.

      Flavonoids are compounds found in plant-based foods, and are associated with a reduced risk
      of CVD. From the previous studies, there is strong evidence that orange juice and citrus
      foods which have higher amount of specific citrus flavonoids improved cardiovascular risk
      factors such as BP and blood vessel health. Absorption of citrus flavonoids occurs in the
      colon after bacteria breakdown the forms found in food. After the flavonoids are absorbed
      into the blood they are modification by liver enzymes before they are excreted in the urine.
      A large range of citrus flavonoid have been found excreted in the urinary, ranging anywhere
      from 0-57% of the dose. Variation in the potential health effect may reflect the level of the
      citrus flavonoid absorbed, and this is not often considered in human studies.

      This study is a 4-week double-blinded, randomized, cross-over intervention trial using a
      commercially-available orange juice supplement and a placebo control. The aims of the study
      are to determine whether orange juice supplements reduce blood pressure and improve blood
      vessel health after 4 weeks. Furthermore, to determine if there is a relationship between
      absorption of flavonoids (as measured by urinary excretion) and changes in blood pressure or
      blood vessel health.

      The participants will need to attend 4 sessions on 4 separate study days, every 4 weeks for
      12 weeks. On each study day they will have their weight, height, waist circumference, and
      blood pressure measured. A finger-prick blood sample, using a single-use lancet (Accu-Chek
      Safe T Pro Plus), will be taken to check the fasting blood glucose level. Blood flow in
      fingertips will be monitored before and after reducing blood flow in your forearm using a
      blood pressure cuff (called an EndoPAT). Participants will be asked to collect urine for 24
      hr on each of the study days, and to consume the supplements provided daily for two sets of 4
      weeks (there will be 4 weeks in the middle without any supplements).

      An improvement in blood pressure and/or blood flow will provide evidence that blood vessel
      health has improved through short-term (4 week) use of a citrus flavonoid supplement
    


Intervention name(s): Citrus supplement; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Flavanones; Bioavailability; Blood vessel health; Blood glucose