The past 20 years have shown that dietary FA molecules are able to mediate and condition biologic functions in an increasing number of biochemical contexts. Different diet interventions can induce measurable alterations at the ultrastructural level of lipid moieties and circulating FAs. This has many consequences for prevention, for therapy, and, in particular, for the management of chronic degenerative disease. From the earliest stages of life, an adequate availability of the n-6 and n-3 series LCP seems essential to ensure the adequate structural and functional development of the various tissues, especially the central nervous system tissues. Recognition of the numerous steps involved in intermediate FA metabolism should induce us to further our understanding of the manifold possibilities open for intervention on FA profile and balance and stress the need for an interdisciplinary approach.