Seaweeds (SW) are a widely available resource, which can be a solution to meet an increasing global consumer’s demand for sustainable and healthy alternative food sources. SW are a rich source of nutrients, as iodine (I), being its consumption advised in the prevention/delay of some diseases. Still, as for others foods, their consumption is subject to a nutritional-toxicological conflict, since some SW may contain potentially dangerous high I and contaminants levels, as arsenic (As). These elements have different health impacts, which need assessment. A realistic risk-benefit assessment (RBA) requires not only knowing a total compound’s level, but also the maximum fraction released from the food into the digestive tract, bioaccessibility (Bioac). Moreover, SW may be eaten fresh, dry, rehydrated or cooked. This may affect compounds’ content, Bioac, and RBA, albeit rarely studied.
This work aimed to study 12 cultivated/wild SW species, green (Rhizoclonium riparium and three Ulva species), red (Pterocladiella capillacea, Osmundea pinnatifida, Asparagopsis armata and A. taxiformis), and brown (Petalonia binghamiae, Halopteris scoparia, Fucus spiralis and Saccorhiza polyschides) consumed and/or produced/caught in Portugal/Europe. Proximate composition, fatty acids (GC), and elements (ICP-MS) were analysed by standard methods. Bioac was simulated by an in vitro model. The RB was assessed by calculation of the probability of exceeding the advised thresholds.
Results showed that SW have a unique nutritional profile. Fat levels were low (< 4 %) and had a specific fatty acids profile. They had high levels of essential elements, particularly I. Non-essential elements (Hg, As, Cd, and Pb) were lower and, for most of the studied species, do not represent a hazard to consumers. Bioac varied across compounds and species. Namely, I Bioac reached 50-75 % in wild S. polyschides and F. spiralis, respectively, but in green SW and S. polyschides cultivated in an Integrated Multi-Trophic system it did not exceed 40 %. This study enabled to set advisable consumption frequency intervals for several seaweed species.