In a recent paper (http://www.ncbi.nlm.nih.gov/pubmed/24184513), Ikuyo Ichi and coworkers focus on Mead Acid.
In mammals, 5,8,11-eicosatrienoic acid (Mead acid, 20:3n−9) is synthesized from oleic acid during a state of essential fatty acid deficiency (EFAD). Mead acid is thought to be produced by the same enzymes that synthesize arachidonic acid and eicosapentaenoic acid, but the genes and the pathways involved in the conversion of oleic acid to Mead acid have not been fully elucidated.
The levels of polyunsaturated fatty acids (PUFA) in cultured cells are generally very low compared to those in mammalian tissues. In this study, the authors found that cultured cells, such as NIH3T3 and Hepa1–6 cells, have significant levels of Mead acid, indicating that cells in culture are in an EFAD state under normal culture conditions.
In general, cultured cells acquire EFAs from serum added to the culture medium. Because EFAs are much less abundant in FBS than in in-vivo plasma and tissues, the level of EFAs is low in cells cultured in FBS-containing medium. In other words, cells in culture are most often in an EFA-deficient state.
EFA-deficient state means membranes are less fluid, and many bio-physical properties are altered for this reason. Therefore, keep calm and keep an eye on Mead Acid!