The effects of conjugated linoleic acid supplementation on immune function in healthy volunteers

Abstract

Objective: To assess the effects of dietary supplementation using two isomeric blends of conjugated linoleic acid (CLA) on immune function in healthy human volunteers. Design: Double-blind, randomised, placebo-controlled intervention trial. Subjects and intervention: A total of 55 healthy volunteers (n ¼ 20 males, n ¼ 35 females) were randomised into one of three study groups who received 3 g/day of a fatty acid blend containing a 50:50 cis-9, trans-11: trans-10, cis-12 CLA isomer blend (2 g CLA), and 80:20 cis-9, trans-11: trans-10, cis-12 (80:20) CLA isomer blend (1.76 g CLA) or linoleic acid (control, 2 g linoleic acid) for 8 weeks.Results: Supplementation with the 80:20 CLA isomer blend significantly (Pr0.05) enhanced PHA-induced lymphocyte proliferation. CLA decreased basal interleukin (IL)-2 secretion (Pr0.01) and increased PHA-induced IL-2 and tumor necrosis factor a (TNFa) production (Pr0.01). However, these effects were not solely attributable to CLA as similar results were observed with linoleic acid. CLA supplementation had no significant effect on peripheral blood mononuclear cells IL-4 production, or on serum-soluble intercellular adhesion molecule-1 (sICAM-1) or plasma prostaglandin E 2 (PGE 2 ) or leukotreine B 4 (LTB 4 ) concentrations.Conclusions: This study shows that CLA supplementation had a minimal effect on the markers of human immune function. Furthermore, supplementation with CLA had no immunological benefit compared with linoleic acid. Sponsorship: CLA supplements were provided by Loders Croklaan.

Effects of dietary conjugated linoleic acids on cellular immune response of piglets after cyclosporin A injection

“…However, dietary CLA increased the IL-2 production of peripheral blood lymphocytes and alleviated the inhibitory effect of CsA injection on IL-2 inductive activity (P < 0.01). Several studies in humans, poultry and rats have shown that dietary CLA increased IL-2 activity induced by Con A (Wong et al, 1997;Nugent et al, 2005;Takahashi et al, 2007). IL-2 messenger RNA expression levels in the CLA diet group were significantly higher than in the control group in a pig model of PCV2-induced immunosuppression (Lee et al, 1994).…”

Mechanisms of body fat modulation by conjugated linoleic acid (CLA)

“…It has been shown that both the cis-9,trans-11 and the trans-10,cis-12 isomers reduce TNF-a levels in macrophage cell line and in mice (Akahoshi et al, 2002;Bhattacharya et al, 2005;Pariza et al, 2000;Park et al, 2003;Sugano et al, 2001;. Effects of CLA on TNF-a levels in human studies, however, were less consistent (Albers et al, 2003;Nugent et al, 2005;Smedman, Basu, Jovinge, Fredrikson, & Vessby, 2005;Song et al, 2005). Recently, it was reported that cis-9,trans-11 and trans-10,cis-12 isomers cause different inflammatory responses and these results suggest a possible link to modified inflammatory responses by CLA and insulin resistance as well (Poirier, Shapiro, Kim, & Lazar, 2006;Ramakers, Plat, Sebedio, & Mensink, 2005).…”

Human health effects of conjugated linoleic acid from milk and supplements

“…However, the sample size was small, at seventeen. In a larger study, with fifty-five subjects, Nugent et al (138) found that either a 50:50 CLA mixture or an 80:20 CLA mixture at about 2 g/d had minimal effects on lymphocytes and cytokines, and had no additional benefit on immune function compared with linoleic acid. CLA supplementation has also been linked to reduced symptoms of birch pollen allergy (104) and improved airway hyper-responsiveness in asthmatics (132) .…”