The Effect of Sweet Orange and Pomegranate Extract Supplementation on Exercise Capacity in Middle-aged Adults

Background of the study: Polyphenols have been studied for their protective effect against the development of ROS-related diseases like cancers, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. The combined supplementation of pomegranate and sweet orange polyphenols could be an effective strategy to improve exercise performance, due to their antioxidant character and ability to stimulate NO production, to stimulate mitochondrial biogenesis and to accelerate muscle repair and decrease muscle tissue damage. The study aims to assess the effect of a combined supplementation of pomegranate and sweet orange extract on exercise capacity, physical activity, muscle strength and quality of life in healthy adults.

Objective of the study: The aim of the present study is to investigate the effect of 12-week long daily administration of a sweet orange and pomegranate extract on exercise capacity in healthy adults (40 - 65 y).

Study design: Randomized, double-blind, placebo-controlled parallel trial

Study population: Healthy, overweight, sedentary adults between 40 and 65 years old.

Intervention: 12-week supplementation with 650 mg sweet orange and pomegranate extract (2 capsules per day) compared to placebo (760 mg maltodextrin).

Primary outcome of the study: Change in aerobic capacity (VO2max), assessed with an Ekblom-Bak submaximal cycling test.

Secondary study parameters/outcome of the study:

• Daily physical activity as determined by accelerometer
• Dietary intake as measured by a 3-day food record
• Handgrip strength
• Muscle cell proliferation and differentiation and mitochondrial biogenesis assessed in skeletal muscle biopsies
• Quality of Life as measured by the WHO-QOL-100 questionnaire
• General health as measured by SF-36 questionnaire
• Vitality as measured by the Dutch Vitality Questionnaire (Vita-16)
• Cardiometabolic health biomarkers, cortisol, C-reactive protein determined with ELISA
• Antioxidative capacity measured with a Trolox equivalent antioxidant capacity (TEAC) assay

Inclusion criteria

• Healthy male/female (based on medical history provided during a general health questionnaire)
• Age between 40 - 65 yrs
• Overweight (BMI ≥25 to ≤29.9 kg/m2)
• Sedentary subjects (Low Level [<600 MET-minutes/week] as assessed by the Physical Activity Questionnaire (IPAQ))

Exclusion criteria

• Allergy to test product/control or citrus fruits and pomegranate
• Medical conditions that might interfere with endpoints or compromise participant safety during testing (e.g. Cardiovascular diseases, cancer, Parkinson's disease, Gastrointestinal diseases or abdominal surgery) to be decided by the principal investigator
• Use of medication that might interfere with endpoints (i.e.: β-blockers, antioxidant, antidepressants)
• High fasting blood glucose (FBG ≥100 mg/dL)
• Recent skeletal muscle injury in less than one month before the start of the study
• Use of antibiotics within 3 months prior to Visit 2
• Use of probiotics or supplements containing vitamins, minerals or antioxidants four weeks prior to Visit 2
• Regular smoking (including use of e-cigarettes)
• Inability to correctly perform the PA test during screening/familiarization
• Abuse of alcohol (alcohol consumption >20 units/week) and/or drugs
• Plans to change diet or medication for the duration of the study
• Treatment with an investigational drug (phase 1-3) 180 days before the start of the study
• Inability to understand study information and/or communicate with staff