British Journal of Nutrition

Research Article

The effect of dietary n-3 fatty acids on serum concentrations of C-reactive protein: a dose–response study

Trine Madsena1 c1, Jeppe H. Christensena2, Mogens Bloma3 and Erik B. Schmidta1

a1 Department of Cardiology, Aalborg Hospital, Denmark

a2 Department of Nephrology, Aalborg Hospital, Denmark

a3 Department of Clinical Biochemistry, Hjørring/Brønderslev Hospital, Denmark

Abstract

C-reactive protein (CRP) is a sensitive marker for low-grade inflammation. Long-chain n-3 polyunsaturated fatty acids (PUFA) have anti-inflammatory effects. The objective of the present study was to investigate the effect on serum levels of CRP of n-3 PUFA at two different doses. We also investigated correlations between CRP and the cellular contents of PUFA. Sixty healthy volunteers (twenty-five women and thirty-five men) were randomly assigned to three treatment groups in a double-blind design. The subjects received a supplement of either 6·6 g n-3 PUFA/d, 2·0 g n-3 PUFA/d or placebo (olive oil) for 12 weeks. CRP was measured using a highly sensitive assay. The median serum CRP concentration was 0·78 mg/l. No significant correlations were found between CRP and the content of n-3 PUFA in granulocytes or platelets. Subjects receiving n-3 PUFA had a significant (P<0·01) increase in the cellular contents of 20: 5n-3, 22: 5n-3 and 22: 6n-3, with the largest increase occurring in the group receiving 6·6 g PUFA/d. A significant (P<0·01) decrease in cellular content of 18: 2n-6 and 20: 4n-6 was observed simultaneously. Serum CRP concentrations, however, were unaffected by the PUFA-containing supplements. The present study shows that dietary supplementation with PUFA-containing supplements has no effect on serum concentrations of CRP, measured with a highly sensitive assay, in healthy subjects.

(Received May 10 2002)

(Revised November 14 2002)

(Accepted November 26 2002)

Correspondence:

c1 *Corresponding Author: Dr Trine Madsen, fax +45 99322361, email tmadsen@dadlnet.dk