The seasonal nutritional value of red (Jania rubens, Laurencia papillosa, Spyridia filamentosa and Dasya rigidula) and brown macroalgae (Padina pavonia and Stypopodium schimperi) was evaluated as a dietary supplement for human and animal nutrition based on proximate and fatty acid profiles. The protein content varied from 0.80% (L. papillosa) to 3.41% (J. rubens) of wet weight with the highest values in winter. The highest lipid levels were recorded in S. schimperi (2.03% in spring, 2.16% in summer), the lowest in S. filamentosa (0.08% in spring). The ash content of J. rubens (46.11-51.63%) was significantly higher than that of the other species (2.28-16.57%). Analysis of the fatty acid composition showed that these seaweed species are very rich in n-3 fatty acids.