Acute Effect of Orange Juice Mixed With Oat β-Glucan on Bioavailability of Polyphenols in Healthy Individuals

Brief summary Orange juice is the most widely consumed fruit juice, accounting for around a third of the total fruit juice market and is a rich source of vitamin C and bioactive compounds, predominantly flavonoids. Current research into the health effects of fruit juice consumption has presented some conflicting conclusions. Although potential health benefits have been attributed to the anti-inflammatory and anti-oxidant properties of the bioactive components in juice, other studies have suggested that the benefits of consuming orange are outweighed by the negative implications of the high sugar content leading to increases in blood glucose and insulin. At the same time it is well established that supplementation with a mean dose of 5g of β-Glucan, a soluble fibre derived from cereals such as oats or barley, significantly reduces insulin and glucose in healthy subjects and metabolic compromised individuals. Thus, the formulation of an OJ beverage with an added β-Glucan supplement may be a useful strategy to attenuate the detrimental impact of high sugar content. However, while delaying the absorption of glucose brings about favourable effects on post-prandial glycemia, dietary fibre may also reduce the bioavailability of some beneficial compounds, including polyphenols. So far, it remains unclear how addition of β-Glucan impacts bioavailability of orange juice flavanones. Thus, this study aims to determine how the bioavailability of orange juice polyphenols of healthy adults is affected mixing orange juice with 3 g and 6 g of oat β-Glucan.

Eligible participants for this study will be healthy adults aged 18 - 50 years and with a BMI in the normal or overweight to obese range (≥20 kg/m2). Participants will be required to be non-smokers, with a stable weight for the previous 3 months, and not engage in regular strenuous physical activity. Other exclusion criteria will include suffering from any chronic disease, taking any medication, or following a special diet, including being vegetarian and vegan. Before being enrolled in the study, potential participants will attend a health screening session, in which they will complete a health screening and physical activity questionnaire

This study will be a randomised controlled cross-over trial in which each participant will complete two 24-h feeding trials. The experimental trials will be separated by a wash out period of at least 7 days. The order of trials will be randomised for each participant, using a random sequence generator. In the morning of the experimental trial participants will consumed approximately 500ml of OJ (Tropicana 'with bits') without or with Oatwell fibre supplement, providing either 6g or 3 g of β-Glucan. Blood samples and urinary fractions will be collected prior to (baseline) and for 24 hours after consumption of corresponding beverage. Participants will be asked to follow a special polyphenol-free diet and record weighted dietary intake for 2 days preceding each trial and during the day of the experimental trial.