factor in seaweed direct intake is their high mineral concentration, where the ingestion of 5 g/day of dried seaweed biomass is the recommended dosage of some minerals, enough to provide several human health benefits [7; 12]. Furthermore, it is necessary to study the seaweed's nutritional value and the parameters that affect its quality, such as seawater quality and seaweed nutritional variation in different locations where seaweeds are found, in order to evaluate the seaweed's potential to be incorporated as a direct food source [13]. In Portugal, four species exist (Figure 1a-d) and are considered kelps: the native species _Laminaria ochroleuca_, _Saccharina latissima_, and _Sacorhiza polyschides_ and the non-native species _Undaria pinnatifida_[13; 14; 15]. _Laminaria ochroleuca_ grows in extensive populations in deep intertidal pools and relatively sparse patches in the upper subtidal zone in the northern region of Portugal, whereas _Sacorhiza polyschides_ dominates the subtidal zone [16; 17]. Between 1999 and 2007, _Undaria pinnatifida_ was only found in two locations in the north of Portugal; therefore, it was thought to be a recent introduction that has begun to colonize intertidal coastlines [18; 19]. These seaweeds are more localized in the northern area, mainly in the Viana do Castelo region, where _L. ochroleuca_ and _S. latissima_ are considered stable populations [14; 20]. The presence of _S. polyschides_ and the non-native species _U. pinnatifida_ appears to replace the ecological niche of _L. ochroleuca_ and _S. latissima_ in the southern regions, due to their capacity to survive in warmer seawater and better adaptability to environmental changes [13; 14]. Kelps are used mainly as a raw food source or alginate extraction for the food industry [21; 22; 23]. As raw food, _U. pinnatifida_ (known as wakame) is one of the most consumed seaweeds in the world, mainly in the Asiatic cuisine, and is regularly used as a food supplement in several cooked dishes, like _L. ochroleuca_ (known as kombu) and _S. latissima_ (known as sugar kelp) [22; 23; 24]. In the food industry, alginate extracted from these seaweeds is usually applied as a food additive (mainly _L. ochroleuca_ and _S. latissima_) due to its inherent ability to stabilize, emulsify liquids, and to form gels of liquids. Thus, they are normally applied in jams, jellies, ice creams, and water-oil solutions (such as myxonnaise). In this case, they can also be added, in mild acid processed foods, as stabilizers [21]. In current times, the potential of the seaweeds _U. pinnatifida_ and _S. latissima_ is being studied towards the quest of novel ingredients in the food industry, such as fucoidan (polysaccharide), phlorotannin's (phenolic compounds), and fucoxanthin (pigments) [5; 25]. However, the  
Figure 1: Photographic record of (**a**) Laminaria ochroleuca, (**b**) Saccharina latissima, (**c**) Sacorhiza polyschides, and (**d**) Undaria pinnatifida. seaweed _S. polyschides_ is not so much exploited by the food industry but it is the basis of \"Sargaco\" (a natural seaweed mixture used traditionally in agriculture in Portugal [26; 27; 28; 29]). The seaweeds _L. ochroleuca_ and _S. latissima_ have a high biomass productivity due to their large size, and it is possible for them to be cultivated, whereas _S. polyschides_ and _U. pinmatifida_ have a fast growth rate [13; 14; 30; 31]. Despite the information gathered and the studies done with these seaweed species, there is a general lack of the nutritional and mineral profile of these species, which can be a key for global food safety [5]. The goal of this research is to determine the nutritional value of four Portuguese kelps (_L. ochroleuca_, _S. latissima_, _S. polyschides_, and _U.