The objective of the present study was to investigate the relationship between plasma n-3 PUFA composition and weight status. A total of 124 adults, stratified by weight status: healthy weight (n 21), overweight (n 40) and obese (n 63) were recruited. Fasting blood samples, anthropometric measures and body composition were collected. Plasma fatty acid composition was determined by GC. BMI, waist circumference and hip circumference were inversely correlated with n-3 PUFA, EPA and DHA (P < 0·05 for all) in the obese group. Obese individuals had significantly lower plasma concentrations of total n-3 PUFA, compared with healthy-weight individuals (4·53 (sd 1·11) v. 5·25 (sd 1·43) %). When subjects were pooled and stratified into quartiles of total n-3 PUFA, a significant inverse trend was found for BMI (P = 0·002), waist circumference and hip circumference (P = 0·01 and P < 0·001 respectively). Higher plasma levels of total n-3 PUFA are associated with a healthier BMI, waist circumference and hip circumference. Our findings suggest that n-3 PUFA may play an important role in weight status and abdominal adiposity.

High sensitivity C-reactive protein (hs-CRP) is a marker of low-grade sustained inflammation. Omega-3 (n-3) fatty acids have anti-inflammatory properties and are associated with reduced cardiovascular disease (CVD) risk. The aim of this study was to investigate whether plasma n-3 fatty acid concentration is related to hs-CRP concentration. A total of 124 free-living adults, were divided into tertiles of plasma hs-CRP (o1.0, 1.0-3.0 and 43.0 mg/l). Body composition and anthropometric measurements were recorded. Hs-CRP was analysed using immunoassays and fatty acids were measured by gas chromatography. Plasma hs-CRP concentration was negatively correlated with total n-3 fatty acids (P ¼ 0.05), eicosapentaenoic acid (EPA; P ¼ 0.002) and docosapentaenoic acid (DPA; P ¼ 0.01). The highest hs-CRP tertile (43.0 mg/l) had significantly lower concentrations of total n-3 fatty acids, EPA and DPA, when compared with the other tertiles (Po0.05). This study provides evidence that in healthy individuals, plasma n-3 fatty acid concentration is inversely related to hs-CRP concentration, a surrogate marker of CVD risk.

Obesity has been linked with low levels of ω-3 fatty acids. Generally, intervention studies have failed to establish benefits of supplementation with ω-3PUFA in reducing body weight or fat mass in humans. The aim of this study was to investigate whether supplementation with LCω-3PUFA alone, then consumed concomitantly with a very low energy diet (VLED), facilitated weight loss, improvements in blood lipids and positive changes to inflammatory mediators. This was a double blind randomised controlled trial with two parallel groups. For 4 weeks of prior supplementation, one group consumed 6 × 1 g capsules per day monounsaturated oil (placebo), the other group consumed 6 × 1 g capsules per day LCω-3PUFA (fish oil) each comprising 70 mg EPA and 270 mg DHA, while consuming their usual diet. Each group continued with their supplements for another 4 weeks while both groups followed a VLED regimen (n = 19 placebo, n = 20 fish oil). Fasting blood samples, anthropometric measurements and 3-day food diaries were collected at baseline, at 4 weeks and at 8 weeks. At 4 weeks levels of EPA and DHA increased two-fold in the fish oil group (P < 0.001), with no significant changes to anthropometric measurements for either group. At 8 weeks a significant 3-way interaction between time, group and gender was observed for percentage reduction in weight, F(1,35) = 5.55, P = 0.024, and BMI, F(1,35) = 5.3, P = 0.027 with a greater percentage decrease for females in FO compared to PB for weight (-7.21% vs.-5.82%) and BMI (-7.43% vs.-5.91%) respectively (P < 0.05 for both). It would appear that supplementation with LCω-3PUFA had a time dependent effect on weight loss in females.

Obesity is associated with elevated levels of inflammation and metabolic abnormalities which are linked to CVD. The aim of the present study was to investigate whether long-chain n-3 PUFA (LCn-3PUFA), combined with a very-low-energy diet (VLED), facilitated weight loss and weight maintenance, and improvements in blood lipids and inflammatory mediators. This was a double-blind, randomised, controlled trial with two parallel groups. For 14 weeks, one group consumed 6 × 1 g capsules/d of monounsaturated oil (placebo group, PB), and the other group consumed 6 × 1 g capsules/d of LCn-3PUFA (fish oil group, FO), each comprising 70 mg EPA and 270 mg DHA. Both groups were on VLED for 4 weeks (n 14 PB, n 18 FO), which was then followed by 10 weeks of weight maintenance (n 12 PB, n 17 FO). Fasting blood samples, anthropometric measurements and 3 d food diaries were collected at baseline, at 4 and 14 weeks. A greater-than-2-fold increase occurred in plasma levels of EPA and DHA in the FO group (P < 0·001). At 4 weeks, the mean weight loss was -6·54 (SD 2·08) kg (-6·9%) for PB and -6·87 (SD 1·83) kg (-7·7%) for FO. At week 14, after the maintenance phase, there was a further mean decrease in weight, -1·57 (SD 3·7) kg (1·85%) for PB and -1·69 (SD 2·32) kg (-1·9%) for FO. Both groups experienced improved metabolic profiles and there was a significant reduction in fat mass for the FO group at week 14 but not for PB. However, it would appear that supplementation with LCn-3PUFA had no significant effect on weight loss or weight maintenance over the 14 weeks.

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