The Effect of Purple Sweet Potato (PSP)-Juice on Liver Enzymes and Blood Pressure

Study design: The study is designed as a randomized, parallel, placebo-controlled, double-blind study.

Study population: 40 healthy adult female and/or male subjects, 40-70 yr old with a BMI 25-35 kg/m2, mildly elevated serum liver enzymes, and high normal blood pressure or mild hypertension.

Intervention: Daily oral intake of 3x 125 ml of PSP-juice or control juice for a period of 8 weeks.

Main study parameters/endpoints: Liver enzymes (GGT, ALAT, ASAT), blood pressure, glucose, insulin, haematology and serum clinical chemical profile

Inclusion criteria

• Healthy as assessed by the: Health and Lifestyle Questionnaire, results of the pre study laboratory tests in blood
• Males/Females aged 40-70 years (boundaries included) at Day 01 of the study
• Body Mass Index (BMI) 25-35 (boundaries included) kg/m2
• Liver enzymes above reference values GGT ≥ 45 IU/L (for males) and ≥ 35 IU/L (for females), and/or ASAT ≥ 45 IU/L (for males and females), and/or ALAT ≥ 50 IU/L (for males) and ≥ 40 IU/L (for females)
• Blood pressure (automated measurements at site): systolic blood pressure 130-159 mm Hg (boundaries included) and/or diastolic blood pressure 85-99 mm Hg (boundaries included)
• Voluntary participation
• Having given written informed consent
• Willing to comply with the study procedures
• Willing to give up blood/plasma donation during the study
• Willing to accept use of all nameless data, including publication, and the confidential use and storage of all data for at least 15 years
• Willing to accept the disclosure of the financial benefit of participation in the study to the authorities concerned.

Exclusion criteria

• Participation in any clinical trial including blood sampling and/or administration of substances up to 90 days before Day 01 of this study
• Participation in any non-invasive clinical trial up to 30 days before Day 01 of this study, including no blood sampling and/or oral, intravenous, inhalatory administration of substances
• Having a history of medical or surgical events that may significantly affect the study outcome
• Any concomitant medication, with the exception of occasional use of a paracetamol tablet, that may influence the outcome of the study (to be judged by the medical investigator)
• Food allergy/intolerance
• Alcohol consumption > 28 units/week for males and > 21 units/week for females
• Smoking > 10 cigarettes per day
• Reported unexplained weight loss or gain of > 2 kg in the month prior to the pre study screening
• Reported slimming or medically prescribed diet
• Participation in night shift work
• Pregnant or lactating or wishing to become pregnant in the period of the study
• Personnel of TNO Quality of Life, their partner and their first and second degree relatives
• Not having a general practitioner
• Not willing to accept information-transfer concerning participation in the study, or information regarding his/her health, like laboratory results, findings at anamnesis or physical examination and eventual adverse events to and from his general practitioner.