Fish oil source differentially affects rat immune cell alpha-tocopherol concentration.
We have previously reported that both the source of dietary fish oil and the chemical form of vitamin E supplied in the diet affect the vitamin 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 vitamin E status using free alpha-tocopherol (alpha-T) at the AIN recommended level as the sole source of vitamin E. Sixty weanling female rats were fed semipurified, high fat (20 g/100 g) diets containing either tocopherol-stripped lard (LRD), menhaden fish oil (MFO), sardine fish oil (SRD) or cod liver oil (CLO) as the primary lipid source. Endogenous 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 final concentration of alpha-T in the mixed diet of 30 mg/kg. An additional group of rats was fed LRD without supplemental vitamin E (LRD-) as a negative control. After feeding experimental diets for 5 or 10 wk, tissues were collected for alpha-T analysis by HPLC. After 5 wk, plasma and liver alpha-T (micromol alpha-T/g lipid) were significantly lower in SRD- and CLO-fed rats compared with LRD-fed rats. At 10 wk, only plasma alpha-T in CLO-fed rats remained significantly depressed. Plasma and liver alpha-T concentrations (micromol alpha-T/g lipid) were not significantly 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 significantly greater alpha-T content of immune cells. In similar fashion, SRD-fed rats, compared with LRD-fed rats, also had significantly greater alpha-T content in splenocytes at both time points and greater thymocyte alpha-T at 10 wk. In all instances, the alpha-T status of rats fed CLO was indistinguishable from that of rats fed the vitamin E-free diet (LRD-). These data further demonstrate the complexity of the relationship between vitamin E status and dietary (n-3) polyunsaturated fatty acids (PUFA).
McGuire
S O
SO
Graduate Nutritional Sciences Program and Department of Animal Sciences, University of Missouri, Columbia, MO 65211, USA.
Alexander
D W
DW
Fritsche
K L
KL
D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004041:Dietary Fats / Q000494:pharmacology; D005227:Fatty Acids / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005260:Female; D005395:Fish Oils / Q000494:pharmacology*; D007107:Immune System / Q000737:chemistry* / Q000166:cytology*; D008055:Lipids / Q000032:analysis / Q000097:blood; D008099:Liver / Q000033:anatomy & histology / Q000737:chemistry; D009929:Organ Size / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000033:anatomy & histology / Q000737:chemistry / Q000166:cytology; D013950:Thymus Gland / Q000033:anatomy & histology / Q000737:chemistry / Q000166:cytology; D013997:Time Factors; D014810:Vitamin E / Q000032:analysis* / Q000097:blood
D004041:Dietary Fats; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D008055:Lipids; D014810:Vitamin E; C029310:lard