Fatty Acids in Natural Ecosystems and Human Nutrition

Abstract

Fatty acids (FAs), including polyunsaturated fatty acids (PUFAs) of the omega-3 family, have been the focus of attention of biochemists, physiologists, and ecologists in recent decades. On the one hand, fatty acids, especially long-chain PUFAs, are of great physiological importance for animals, including humans, as i) biochemical precursors of signaling molecules, e.g., oxylipins; ii) structural components of the cell membranes of neural tissues; and iii) "pacemakers" for the metabolism of animal cells, i.e., activators of membrane-bound enzymes. For humans, the consumption of PUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is recommended by the World Health Organization to prevent cardiovascular diseases and neural disorders. On the other hand, FAs are considered the most reliable biomarkers in tracing fluxes of matter and energy in trophic webs of natural ecosystems and, thereby, to evaluate their structure and functions. Among the natural ecosystems, water bodies were found to play a peculiar role concerning long-chain PUFAs. Indeed, vascular plants, the main primary producers in terrestrial ecosystems, do not synthesize EPA and DHA. By contrast, some taxa of microalgae produce substantial amounts of EPA and DHA. Once synthesized by microalgae, PUFAs are transferred through trophic webs to organisms of higher trophic levels, i.e., invertebrates and fish. Thus, aquatic ecosystems are the main source of physiologically important EPA and DHA for many animals, including some omnivorous terrestrial animals and humans. At present, the ability of aquatic ecosystems to produce long-chain PUFAs, including those for human nutrition, is threatened by numerous anthropogenic factors, such as pollution, eutrophication and climate change, and biological invasions. Thus, the evaluation of fatty acids in natural ecosystems are of considerable importance for pure and applied sciences.