British Journal of Nutrition

Research Article

The effect of feeding structured triacylglycerols enriched in eicosapentaenoic or docosahexaenoic acids on murine splenocyte fatty acid composition and leucocyte phagocytosis

Samantha Kewa1, Edward S. Gibbonsa1, Frank Thiesa1a2, Gerald P. McNeilla3a4, Paul T. Quinlana3a5 and Philip C. Caldera1 c1

a1 Institute of Human Nutrition, University of Southampton, Southampton SO16 7PX, UK

a2 Department of Medicine and Therapeutics, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK

a3 Unilever Research Colworth Laboratory, Sharnbrook, Bedford MK44 1LQ, UK

a4 Loders Croklaan NA, Channahon, IL 60410, USA

a5 Unilever Health Institute, Unilever Research Vlaardingen, 3130 AC Vlaardingen, The Netherlands

Abstract

The effects of altering the type of n-3 polyunsaturated fatty acid (PUFA) in the mouse diet on the ability of monocytes and neutrophils to perform phagocytosis were investigated. Male weanling mice were fed for 7 d on one of nine diets which contained 178 g lipid/kg and which differed in the type of n-3 PUFA and in the position of these in dietary triacylglycerol (TAG). The control diet contained 4·4 g α-linolenic acid/100 g total fatty acids. In the other diets, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) replaced a proportion (50 or 100 %) of the α-linolenic acid, and were in the sn-2 or the sn-1(3) position of dietary TAG. There were significant increases in the content of n-3 PUFA in spleen-cell phospholipids when EPA or DHA was fed. These increases were largely independent of the position of EPA or DHA in dietary TAG except when EPA was fed at the highest level, when the incorporation was greater when it was fed in the sn-2 than in the sn-1(3) position. There was no significant effect of dietary DHA on monocyte or neutrophil phagocytic activity. Dietary EPA dose-dependently decreased the number of monocytes and neutrophils performing phagocytosis. However, when EPA was fed in the sn-2 position, the ability of active monocytes or neutrophils to engulf bacteria was increased in a dose-dependent fashion. This did not occur when EPA was fed in the sn-1(3) position. Thus, there appears to be an influence of the position of EPA, but not of DHA, in dietary TAG on its incorporation into cell phospholipids and on the activity of phagocytic cells.

(Received April 10 2003)

(Revised July 16 2003)

(Accepted August 07 2003)

Correspondence:

c1 *Corresponding author: Professor P. C. Calder, fax +44 23 80595489, email pcc@soton.ac.uk

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