Influence of dietary supplementation with long‐chain n−3 or n−6 polyunsaturated fatty acids on blood inflammatory cell populations and functions and on plasma soluble adhesion molecules in healthy adults

Abstract

Greatly increasing the amounts of flaxseed oil [rich in alpha-linolenic acid (ALNA)] or fish oil (FO); [rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in the diet can decrease inflammatory cell functions and so might impair host defense. The objective of this study was to determine the effect of dietary supplementation with moderate levels of ALNA, gamma-linolenic acid (GLA), arachidonic acid (ARA), DHA, or FO on inflammatory cell numbers and functions and on circulating levels of soluble adhesion molecules. Healthy subjects aged 55 to 75 yr consumed nine capsules per day for 12 wk. The capsules contained placebo oil (an 80:20 mix of palm and sunflowerseed oils) or blends of placebo oil with oils rich in ALNA, GLA, ARA, or DHA or FO. Subjects in these groups consumed 2 g ALNA; approximately 700 mg GLA, ARA, or DHA; or 1 g EPA plus DHA (720 mg EPA + 280 mg DHA) daily from the capsules. Total fat intake from the capsules was 4 g per day. None of the treatments affected inflammatory cell numbers in the bloodstream; neutrophil and monocyte phagocytosis or respiratory burst in response to E. coli; production of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 in response to bacterial lipopolysaccharide; or plasma concentrations of soluble intercellular adhesion molecule-1. In contrast, the ALNA and FO treatments decreased the plasma concentrations of soluble vascular cell adhesion molecule-1 (16 and 28% decrease, respectively) and soluble E-selectin (23 and 17% decrease, respectively). It is concluded that, in contrast to previous reports using higher amounts of these fatty acids, a moderate increase in consumption of long-chain n-6 or n-3 polyunsaturated fatty acids does not significantly affect inflammatory cell numbers or neutrophil and monocyte responses in humans and so would not be expected to cause immune impairment. Furthermore, we conclude that moderate levels of ALNA and FO, which could be incorporated into the diet, can decrease some markers of endothelial activation and that this mechanism of action may contribute to the reported health benefits of n-3 fatty acids.

Effects of alpha-linolenic acid versus those of EPA/DHA on cardiovascular risk markers in healthy elderly subjects

“…In combination with the study duration, the intake of ALA might also have been too low to observe effects on sVCAM-1 and sE-selectin within a period of 6 weeks. Even though ALA intake in the study by Thies et al (2001) was lower (2 g/day) than in the present study, the study duration was two times longer. In contrast, the study by Zhao et al (2004) also lasted 6 weeks, but ALA intake was at least twice as high.…”

“…Hence, based on our results, we cannot attribute a beneficial effect to ALA or the marine fatty acids with regard to markers of endothelial integrity in healthy elderly. We do not think that the amount of ingested EPA/DHA in the present study was too low to induce an effect on endothelial markers, as other studies showed beneficial effects after low to moderate intakes of n-3 fish fatty acids Thies et al, 2001;Baro et al, 2003;Berstad et al, 2003;Hjerkinn et al, 2005). Our study duration was however shorter than those of other studies, which may have masked any beneficial effects of EPA/DHA on these endothelial markers.…”

“…In that study, fish oil did not affect sVCAM-1 and increased sE-selectin in young men (o40 years), but significantly decreased sVCAM-1 and tended to lower sE-selectin in the older subjects (455 years). Thies et al (2001) compared the influence of moderate intakes of ALA, DHA and fish oil on plasma-soluble adhesion molecules It was found that, in contrast to DHA alone, both ALA and fish oil supplementation decreased sVCAM-1 and sE-selectin compared to the placebo supplement (an 80:20 mix of palm and sunflowerseed oils). This finding implies that the observed favorable effects are specific for EPA and/or ALA. Zhao et al (2004) also found a decrease in sVCAM-1 and sE-selectin in hypercholesterolemic subjects aged between 36 and 65 years, after consumption of a diet rich in ALA (6.5 En% ALA/d or 13-28 g/day).…”

No effect of fish oil supplementation on serum inflammatory markers and their interrelationships: a randomized controlled trial in healthy, middle-aged individuals

“…Soluble forms of cell adhesion molecule-1 and vascular cell adhesion molecule-1 are found in serum and are elevated during inflammatory conditions (Gearing and Newman, 1993). So far, few studies have addressed the effects of fish oil supplementation on cytokines, in combination with cell adhesion molecules or chemokines, in a healthy, middleaged population, showing conflicting results: some studies showed a decrease in cell adhesion molecules (Thies et al, 2001;Yusof et al, 2008), whereas other studies showed no effect (Murphy et al, 2007;Damsgaard et al, 2008). Therefore, our main aim was to study the effects of fish oil supplementation on a large range of serum inflammatory markers including cytokines, chemokines and cell adhesion molecules, using a multiplex immunoassay in middle-aged individuals.…”

The effects of increased oily fish intake during pregnancy on maternal immune cell subsets – results from the salmon in pregnancy study (SIPS)

“…Studies show that LC PUFAs may affect immune responses and have anti-inflammatory effects (1) . Also, fish oil supplementation during pregnancy alters maternal and offspring immunity in a way that would be consistent with lowered risk of atopy (2) .…”