**9. Conclusions on Trends and Challenges for the Sector**

The term "functional food" can be defined as foods claiming to have additional function(s) by incorporating new ingredients or greater amounts of the existing ones. Such ingredients, called "functional ingredients" have specific health benefits, including immunomodulation, and reduction of the risk of certain diseases, among others. Seaweeds that can be consumed by humans appear as innovative resources with an interesting potential to be used as functional ingredients. Some of them contain high insoluble dietary fiber. In particular, the high content of non-digestible polysaccharides converts marine algae in a rich source of prebiotics or prebiotic candidates. Further investigations about prebiotic properties both in vitro and in vivo are still necessary to incorporate such ingredients in the formulation of functional foods. On the other hand, certain secondary metabolites from marine algae, including antioxidants, are able to decelerate or prevent oxidation processes, thus being favorable health related compounds. Therefore, there is a need to solve problems such as the determination of the identity of the harvests as fresh materials for functional foods, and the regularization of the products, because seaweeds from different locations can produce different levels of active compounds.

In addition of being a source of novel, beneficial, and natural products, algae and their cultivation offer advantages on a larger scale, since aquaculture is an environmentally friendly process and favors the production of compounds rich in biomass and proteins that could supply or mitigate industries with many more toxic waste. Furthermore, the implementation of this technique in developing countries could entail great financial advantages. However, to do so, it would be first necessary to solve problems, such as the lack of marine spaces, where to carry it out, or the initial economic support. For the development of the aquatic plants cultivation industry (i.e., algae), the transfer of technological improvements (i.e., creation of sea beds not requiring coastal areas) to tropical areas would be very convenient. This way, the problems of lack of cultivable surfaces would be overcome.

In conclusion, governments shRedondelaould become part of this booming industry, supporting sustainable development through investments in infrastructure, personnel, materials, and projects aimed at research, development and innovation, thus committing to a green future for our planet.

**Author Contributions:** All authors (A.G.-Z., M.A.P.L., C.J.-L., J.S.-G., and J.C.M.) contributed equally to the conceptualization, methodology, validation, formal analysis, investigation, writing—original draft preparation, writing—review and editing, visualization, supervision, and project administration.

**Funding:** The authors thank CYTED (Ibero-American Program of Science and Technology for Development) for the funds obtained to grant AQUA-CIBUS network (Strengthening aquaculture in Ibero-America: quality, competitiveness and sustainability; Ref. 318RT0549). To MICINN for the financial support for the Ramón and Cajal researcher of M.A. Prieto Lage. To the University of Vigo for the financial support for the pre-doctoral researcher C. Jiménez López. To Xunta de Galicia for the financial support by the Axudas Conecta Peme of the NeuroFood Project (IN852A 2018/58). To the Argentinean Agency for the Promotion of Science and Technology (PICT startup (2016)/4808 and PICT (2017)/1344. A.G.-Z is member of the research career from the Argentinean Research Council (CONICET). The authors are also grateful to the Interreg España-Portugal for financial support through the project 0377\_Iberphenol\_6\_E.

**Acknowledgments:** This review article is an emotional and well-deserved tribute to Prof Isabel Ferreira (CIMO, IPB) for her scientific career of excellence in a line of research that received a great boost with her research group, the recovery of bioactive ingredients from natural products. We wish her and her group all the best personally and professionally.

**Conflicts of Interest:** The authors declare no conflicts of interest.
