Seaweed as a sustainable protein source: nutrient bioavailability, safety, gastrointestinal tolerance, and sensory impacts in healthy adults
Year: 2026
Type: article
Study designs: Randomized Controlled Trial, Clinical Trial
Abstract: Seaweed, a nutrient-dense and sustainable food source, holds promise for helping to meet growing global dietary protein demands. However, its complex cellular structure embeds protein within membranes and walls, making extraction challenging and limiting protein yields (1) . Seaweed has traditionally been consumed with minimal processing in relatively small quantities, such as 5-10 g daily in Asian diets (2,3) . The volume required for seaweed to serve as a meaningful protein source is relatively high, raising concerns about safety, digestibility, gastrointestinal tolerance, and sensory acceptability. The effects of large servings of minimally processed seaweed have not been examined in human studies. This study evaluated the impact of a minimally processed seaweed meal (SWM, containing ~150 g of seaweed) on postprandial plasma amino acid response, micronutrient bioavailability, safety, tolerance, and sensory acceptability in healthy adults. The hypothesis was that protein in the SWM would increase amino acid concentrations in the peripheral circulation compared to the control (CON) meal. In this single-blinded, randomized cross-over trial, 20 healthy adults (12 females, 8 males; aged 18-60 years, BMI 18-30 kg/m2) consumed either the SWM or a CON meal on separate days. Blood samples and questionnaires were collected at fasting and regular intervals for 4 hours, while urine was collected up to 24 hours post-consumption. Both meals were dumplings with identical ingredients, except seaweed was added to the SWM. It contained more protein (+3.75 g), carbohydrate (+10 g), fat (+2.35 g), energy (~318 kJ), and essential amino acids (EAAs) (+1.56 g). There was no difference between SWM and CON for plasma pooled essential amino acids (EAAs) peak concentration (1036.6± 144.0 vs. 1053.0± 160.5 µmol L −1 ; p=0.66) or incremental area under the curve (iAUC; p=0.65). However, SWM resulted in lower peak plasma concentrations of asparagine (p=0.02) and glutamine (p=0.03), and reduced iAUC for alanine (p=0.02), proline (p=0.01), and tyrosine (p=0.02). Plasma glucose, insulin, and triglyceride responses were similar between meals. Serum iodine concentration was higher following SWM (p=0.02). Urinary iodine peaked 2-4 hours after the SWM meal, declined by 24 hours, but stayed above baseline and was higher than CON (p<0.001). Urinary arsenic was higher at 24 hours in SWM vs. CON (p=0.05) but remained below safety limits. Gastrointestinal symptoms, including abdominal distension and belching, were more pronounced after SWM (treatment×time interaction: p=0.03 and p<0.001, respectively). Appetite-related responses, including hunger and satiation, were less favourable for SWM (main treatment effect: p<0.001), although no treatment×time interaction was observed. Intake of the SWM did not lead to differences in overall bioavailability of EAAs compared to CON, although some individual amino acid responses varied. The SWM resulted in less favourable gastrointestinal symptoms and satiety outcomes, which therefore suggests that meals containing a high proportion of minimally processed seaweed require further optimisation.
Language: English
Subfield: Aquatic Science
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W7170054544