Brown Seaweeds Effect on Glucose Tolerance and Appetite Response

Effect of Brown Seaweeds on Glycaemia, Gastric Emptying, and Appetite: A Randomized, Controlled Crossover Meal Study

The project is a randomized, 3-way, blinded crossover trial in which 20 healthy, fasted participants consume meals with 30 g of a linear corn starch and 5 g of one of the seaweeds, Laminara digitata or Undaria pinnatifida or a pea protein control. The primary aim is to investigate whether the brown seaweeds affect the postprandial glucose Area Under the Curve (AUC). Stomach emptying, insulin, C-peptide, appetite-regulating hormones (oxyntomodulin, glucagon, GLP-1 and PYY), and specific metabolites from the seaweeds in the urine and plasma as well as subjective satiety are also analyzed.

Brown seaweeds may contain bioactive compounds as they contain secondary plant metabolites, including flavonoids and other phenolic compounds as well as carotenoids. Dietary fibre is the major component of brown seaweeds, mainly composed from laminarans, alginates, fucans and cellulose. Several dietary fibers and secondary plant metabolites have been shown to have an impact on health and more specifically on glycemic control. Therefore, the aim of this study was to investigate whether two selected brown seaweeds have an effect on the postprandial glucose response to a starch load as well as several secondary measures, including appetite responses. In a controlled crossover trial, 20 healthy fasted participants consumed 5 g of either Laminaria digitata (LD) or Undaria pinnatifida (UP) or 1 g of pea protein (CTR). The volunteers concomitantly ingested 200 mL of a drink with corn starch. Blood samples were drawn at baseline, as well as 20, 40, 60, 90, 120 and 180 min after the meal. Differences in glucose, insulin, C-peptide, plasma incretin concentrations, and insulin sensitivity index (ISI) were analyzed and appetite was scored by a visual analogue scale and a subsequent ad libitum test meal.

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence LD-UP-CTR

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence LD-CTR-UP

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence UP-LD-CTR

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence UP-CTR-LD

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence CTR-LD-UP

The meal study was performed with Laminaria digitata (LD), Undaria pinnatifida (UP) or pea protein drink (CTR) in the sequence CTR-UP-LD

Participants ingested 5 g of Laminaria digitata followed by 30 g of corn starch mixed with 200 mL of water.

Participants ingested 5 g of Undaria pinnatifida followed by 30 g of corn starch mixed with 200 mL of water.

The area under the plasma glucose concentration curve was calculated from 0-180 min after 30 g of corn starch was ingested.

Changes in the glucose concentrations determined by a mixed model analysis and subsequently at each time point with time 0 as a co-variate.

Changes in the insulin concentrations determined by a mixed model analysis and subsequently at each time point with time 0 as a co-variate.

Changes in the C-peptide concentrations determined by a mixed model analysis and subsequently at each time point with time 0 as a co-variate.

Changes in the plasma GLP-1 concentrations determined by a mixed model analysis and subsequently at each time point with time 0 as a co-variate

Area Under the Curve (AUC) for all VAS outcomes (satiety, hunger, fullness, prospective food consumption and comfort)

Changes in VAS outcomes (satiety, hunger, fullness, prospective food consumption and comfort), determined by a mixed model analysis and subsequently at each time point with time 0 as a co-variate

Untargeted metabolic profile of urine samples measured in all samples collected before the meal and postprandially from 0-90 min, 90-180 min as well as in samples collected up to 24 hours later. The totality of the profiles is used to explore for changes after baseline as detected by multivariate statistics (PLS-DA) after dividing the data into a training and test set. Contrasts between each of the treatment groups and the placebo group will be assessed using the receiver-operator characteristics (ROC curves) comparing the training and test set.

Untargeted metabolic profile of plasma measured in all samples collected before the meal and postprandially from 0-180 min. The totality of the profile is used to explore for changes after baseline as detected by multivariate statistics (PLS-DA) after dividing the data into a training and test set. Contrasts between each of the treatment groups and the placebo group will be assessed using the receiver-operator characteristics (ROC curves) comparing the training and test set.

Inclusion Criteria: BMI 20-25 kg/m2. Waist circumference < 102 cm. Non-smoking. Like (can tolerate) seaweed, pasta, meat sauce as these foods are part of the test meal. Can tolerate paracetamol (Pinex, Actavis, Denmark). Exclusion Criteria: Systemic infections, psychiatric or metabolic diseases, and any clinical condition, chronic or frequent use of medication (including blood thinners, excluding contraceptives), smoking (throughout the trial and 12 months before the start of the experiment), blood donations during or in the month leading up to the study period, elite athletes (> 10 hours of hard exercise / week, self-reported), high intake of alcohol (defined as a weekly intake of > 7 units for women and > 14 units for men), have or have had a drug addiction, participation in other scientific studies during the study period, lactating, pregnancy or ongoing planning of pregnancy, and vegetarianism or veganism.

Zaharudin N, Tullin M, Pekmez CT, Sloth JJ, Rasmussen RR, Dragsted LO. Effects of brown seaweeds on postprandial glucose, insulin and appetite in humans - A randomized, 3-way, blinded, cross-over meal study. Clin Nutr. 2021 Mar;40(3):830-838. doi: 10.1016/j.clnu.2020.08.027. Epub 2020 Aug 31.