The effect of fish protein hydrolysate on hepatic and white adipose tissue fatty acid composition. hTNFα transgenic mice were given a 15% (w/w) fish protein hydrolysate (FPH) diet for two weeks, fasted over night, and fatty acid composition (wt%) was determined in liver and white adipose tissue (WAT), and gene expression was determined in liver. Elongase activity was calculated as an indirect index based on the n-3 PUFAs C20:3n-6/C18:3n-6 (a). The omega-3 index was based on the sum of EPA (C20:5n-3) and DHA (C22:6n-3) (b). An indirect index of ∆5 desaturase activity based on n-3 PUFAs was calculated as C20:5n-3/C20:4n-3 (c). An indirect index of ∆6 desaturase activity based on n-3 PUFAs was calculated as C18:4n-3/C18:3n-3 (d). Hepatic gene expression of D6 desaturase (Fads2) (e). Hepatic gene expression of D5 desaturase (Fads1) (f). Data are means ± SD (n = 5) of control (white bars) and FPH (grey bars). Values significantly different from control are indicated (*P < 0.05, **P < 0.01, ***P < 0.001).