Study protocol for a double-blind randomised controlled trial investigating the impact of 12 weeks supplementation with a Fucus vesiculosus extract on cholesterol levels in adults with elevated fasting LDL cholesterol who are overweight or have obesity.

INTRODUCTION: Hyperlipidaemia, hyperglycaemia and chronic inflammation are risk factors for chronic diseases cardiovascular disease and type 2 diabetes. Polyphenols are bioactive compounds found in marine algae with potential antihyperlipidaemic, antihyperglycaemic and anti-inflammatory effects. The modulation of these risk factors using bioactive polyphenols may represent a useful strategy for disease prevention and management; research in humans, however, remains limited. This trial aims to determine the impact of a polyphenol-rich brown seaweed extract on fasting hyperlipidaemia, hyperglycaemia and inflammation. Effects on mood and cognition will also be evaluated.

METHODS AND ANALYSIS: Fifty-eight hypercholesterolaemic participants who are overweight or have obesity will be randomised to receive either a polyphenol-rich brown seaweed extract (2000 mg dose containing 600 mg polyphenols) or placebo (2000 mg rice flour) daily for 12 weeks. Fasting venous blood samples will be taken at baseline, week 6 and week 12 of the intervention to assess serum cholesterol (total, low-density lipoprotein and high-density lipoprotein) and triglyceride concentrations, plasma glucose and insulin concentrations and markers of inflammation. Mood and cognitive function will be evaluated as exploratory outcomes. Independent t-tests or equivalent will be used to determine differences between the two groups in changes from baseline to week 12. Analysis of variance will be used to assess differences between the groups across the three time points (baseline, week 6 and week 12).

ETHICS AND DISSEMINATION: Ethics approval has been granted by the Monash University Human Research Ethics Committee (2017-8689-10379). Results from this trial will be disseminated through publication in peer-reviewed journals, national and international presentations, and a PhD thesis. These results are essential to inform the use of polyphenol-rich brown seaweeds as a functional food or nutritional supplement ingredients for health promotion and disease prevention and management in humans.

TRIAL REGISTRATION NUMBER: ACTRN12617001039370; Pre-results.