FISH-OIL SOURCE DIFFERENTIALLY AFFECTS RAT IMMUNE CELL ALPHA-TOCOPHEROL CONCENTRATION

We have previously reported that both the source of dietary fish oil a nd the chemical form of vitamin E supplied in the diet affect the vita min E status of immune cells in rats, The purpose of this study was to investigate further the effect of fish oil source on immune cell vita min E status using free alpha-tocopherol (alpha-T) at the AIN recommen ded level as the sole source of vitamin E, Sixty weanling female rats were fed semipurified, high fat (20 g/100 g) diets containing either t ocopherol-stripped lard (LRD), menhaden fish oil (MFO), sardine fish o il (SRD) or cod liver oil (CLO) as the primary lipid source, Endogenou s alpha-T concentration was measured and equalized to 150 mg/kg oil by addition of free RRR-alpha-T to each lipid source, allowing for a fin al concentration of alpha-T in the mixed diet of 30 mg/kg, An addition al group of rats was fed LRD without supplemental vitamin E (LRD-) as a negative control. After feeding experimental diets for 5 or 10 wk, t issues were collected for alpha-T analysis by HPLC, After 5 wk, plasma and liver alpha-T (mu mol alpha-T/g lipid) were significantly lower i n SRD- and CLO-fed rats compared with LRD-fed rats, At 10 wk, only pla sma alpha-T in CLO-fed rats remained significantly depressed, Plasma a nd liver alpha-T concentrations (mu mol alpha-T/g lipid) were not sign ificantly lower in MFO-fed rats than LRD-fed rats at either time point . Compared with LRD, feeding MFO to rats for 5 or 10 wk resulted in si gnificantly greater alpha-T content of immune cells, In similar fashio n, SRD-fed rats, compared with LRD-fed rats, also had significantly gr eater alpha-T content in splenocytes at both time points and greater t hymocyte alpha-T al 10 wk. In all instances, the alpha-T status of rat s fed CLO was indistinguishable from that of rats fed the vitamin E-fr ee diet (LRD-). These data further demonstrate the complexity of the r elationship between vitamin E status and dietary (n-3) polyunsaturated fatty acids (PUFA).