Nutritional Benefits of Edible Macroalgae from the Central Portuguese Coast: Inclusion of Low-Calorie ‘Sea Vegetables’ in Human Diet

In this work, major nutrients were determined in edible green (Codium tomentosum, Ulva rigida), red (Gracilaria gracilis, Osmundea pinnatifida, Porphyra sp), and brown macroalgae (Saccorhiza polyschides, Undaria pinnatifida) collected from the central Portuguese coast. The results showed that selected species had the macroelements (Ca+Mg+Na+K+P) ranged from 85 (Porphyra sp) to 226mg g-1 (Codium tomentosum), and the oligoelements (Cu+Fe+Mn+Se+Zn) ranged from 60 (U. pinnatifida) to 655µg g-1 (O. pinnatifida), thus representing a sustainable source of minerals. The low values of Na/K (0.3-3.7) showed that selected species can be of special nutritional interest for patients with hypertension. The highest contents of Fe (552µg g-1) found in O. pinnatifida and Se (30µg g-1) in S. polyschides, suggest the increased proportion of these oligoelements, by the inclusion of macroalgal species in the diet, rather than some traditionally known food. The total content of proteins (15.5-24%), carbohydrates (52-62%), crude fibres (14-32%), and lipids (0.9-4.8%) indicated that the selected macroalgae were relatively low-calorie food. Analyzed red species were characterized by the higher content of proteins (24% in Porphyra sp), whereas brown species showed increased levels of crude fibres (32% in S. polyschides). The caloric values ranged from 172 (S. polyschides) to 256kcal 100g-1 (Porphyra sp) and they were negatively correlated (R = -0.81) with the ash content in studied species. The correlation between calories and ash indicated the influence of (thallus) morphology of species on their mineral and nutritional composition. Based on their particular nutritional profiles, the studied species can be recommended for selective inclusion in the human diet, ensuring high-quality and health-promoting food.