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Farmed and Wild Macroalgae as a Safe Source of Macro and Trace Elements
by
, , , , , and
Tomás Chainho
1,*
,
Rui Cereja
1,2
,
Alícia Pereira
3,
Vera Marques
1,
João C. Silva
4,
Sofia Pessanha
4,
Pedro Reis Costa
1,5
and
António Marques
1,3 1
IPMA, I.P.—Portuguese Institute for the Sea and Atmosphere, I. P., Avenida Doutor Alfredo Magalhães Ramalho, nº 6, 1495-165 Algés, Portugal
2
MARE—Marine and Environmental Sciences Centre, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisbon, Portugal
3
CIIMAR—Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal
4
Laboratory for Instrumentation, Biomedical Engineering and Radiation Physics, LA-REAL.NOVA School of Science and Technology, Campus FCT-UNL, 2829-516 Caparica, Portugal
5
Centre of Marine Sciences (CCMAR/CIMAR LA), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
*
Author to whom correspondence should be addressed.
Biology 2026, 15(11), 820; https://doi.org/10.3390/biology15110820 (registering DOI)
Submission received: 20 April 2026
/
Revised: 12 May 2026
/
Accepted: 18 May 2026
/
Published: 22 May 2026
Simple Summary
Seaweed products are rising within the food industry, but consumers need clear information about their nutritional value and safety. This study examined wild and farmed samples collected from three areas of the Portuguese coast to understand whether species, origin, or season affected their elemental composition and the presence of biotoxins. The results showed that the species factor had the strongest effect on element composition, while farmed and wild samples showed no major differences. All macro and trace elements analyzed were below dietary limits. No regulated marine toxins were detected in any sample. These findings highlight the potential that Portuguese seaweeds represent a safe food resource and support their use in sustainable aquaculture production.
Abstract
The increasing popularity of macroalgae products highlights their potential as a safe source of essential macro and microelements for consumers. This study characterized wild and farmed macroalgae elemental composition and assessed the presence of biotoxins to identify potential health risks. Wild and farmed macroalgae samples were collected throughout 2024–2025, from three aquaculture production sites along the Portuguese coast (Ria de Aveiro, Matosinhos, and Olhão). Samples were freeze-dried, compressed and using a micro-XRF spectrometer, elemental composition was assessed. Macroalgae species factor was the strongest driver of elemental composition, explaining over 80% variation in macro and trace elements. Origin did not showcase statistical significance for elemental composition. Seasonal differences, though relatively small in extent, significantly impacted redox-sensitive elements in macroalgae, namely copper and manganese. All elements stayed below 30% of the recommended dietary recommendations, except iron (ranging from 0.5% to 111.8% of UL%) and Mn (ranging from 0.1% to 101% of UL%). All samples revealed the absence of regulated marine toxins. Only traces of the non-regulated cyclic-imine toxin SPX1 were detected in samples of Fucus vesiculosus. All quantified elements do not represent any risk for human health, strengthening the safety of macroalgae from the Portuguese coast.
Keywords:
seaweeds; food-safety; seasonality; elemental profile; marine biotoxins
