Is essential fatty acid interconversion an important source of PUFA in humans?

Abstract

Humans can obtain preformed long chain polyunsaturated fatty acids (PUFA) from the diet, but are also able to convert essential fatty acids (EFAs) to longer chain PUFA. The metabolic pathway responsible for EFA interconversion involves alternating desaturation and carbon chain elongation reactions, and carbon chain shortening by peroxisomal β-oxidation. Studies using stable isotope tracers or diets supplemented with EFAs show that capacity for PUFA synthesis is limited in humans such that docosahexaenoic acid (22:6n-3) synthesis in men is negligible. PUFA synthesis is greater in women of reproductive age than men. However, the magnitude of the contribution of hepatic PUFA synthesis to whole body PUFA status remains unclear. A number of extra-hepatic tissues have been shown to synthesise PUFA or to express genes for enzymes involved in this pathway. The precise function of extra-hepatic PUFA synthesis is largely unknown, although in T lymphocytes PUFA synthesis is involved in the regulation of cell activation and proliferation. Local PUFA synthesis may also be important for spermatogenesis and fertility. One possible role of extra-hepatic PUFA synthesis is that it may provide PUFA in a timely manner to facilitate specific cell functions. If so, this may suggest novel insights into the effect of dietary PUFA and / or polymorphisms in genes involved in PUFA synthesis on health and tissue function.

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ORCID for Graham Burdge: orcid.org/0000-0002-7665-2967

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