Effects of Seaweed Extract on Postprandial Response to White Bread

Investigating the Effects of Seaweed Extract on Blood Glucose and Insulin Levels After a Meal in Healthy Subjects

The study is designed to determine whether seaweed extract added to a carbohydrate-rich meal, can lower blood glucose levels after its consumption, and hence lower its glycaemic index, and if this effect is mediated through effects on insulin. It is designed as an acute, randomised, cross-over, controlled, three-arm dietary intervention trial in healthy subjects. Participants will be asked to consume either white bread, white bread with lower dose of seaweed extract or white bread with higher dose of seaweed extract.The effects on plasma glucose levels and levels of insulin will be determined over 3 hours after the consumption.

It has been shown in a large number of in vitro studies that seaweed extracts act as potent inhibitors of enzymes of carbohydrate digestion suggesting their potential to modulate postprandial glycaemic response and prevent the damaging effects of hyperglycaemic state. However, the results from human trials are limited and inconsistent.

The investigators confirmed that the in vitro inhibitory effects of seaweed extracts depend on the type, level and ratio of bioactive compounds, and optimised the composition of the extract to obtain the most potent one, to be tested in the proposed study.

The present study will determine whether the seaweed extract added to a carbohydrate-rich meal, can lower blood glucose levels after its consumption, and hence lower its glycaemic index, and if this effect is mediated through effects on insulin or determined by the individual levels of digestive enzymes.

Healthy volunteers will be asked to consume three different meals: (1) white bread; (2) white bread with the lower dose (LD) of the extract; (3) white bread with the higher dose (HD) of the extract

The levels of glucose and insulin will be measured in plasma isolated from blood samples obtained before and up to 3 hours after the consumption of each meal.

Additional measurements taken at the screening will include blood pressure values and blood lipids levels. All participants will be characterized for the activity of salivary a-amylase.

Inclusion Criteria:

• 18-65 years old
• Healthy

Exclusion Criteria:

• Smoking
• Diagnosis of any chronic illness (including diabetes, hypertension, gastrointestinal diseases etc.)
• On long term prescribed medication (except contraceptives)
• Pregnant or lactating
• On a special diet or dietary regimen (for weight management or if regularly consuming fruit extract supplements)
• Allergy to fruits vegetables or pollen
• Unwillingness to follow dietary recommendations or record the diet during recommended period
• Donated blood 4 weeks before or intend to donate blood during the study or 4 weeks after the last study samples
• Participation in another research project in parallel which also involves dietary intervention (e.g. taking vitamin supplements) or requires sampling of blood