LETTER TO THE EDITOR Intake of oxidised fish oil does not affect circulating levels of oxidised LDL or inflammatory markers in healthy subjects Use of n-3 supplements reduces the risk of CHD [1e3]. Long chained n-3 fatty acids (FA) are easily oxidised, and concern has been raised regarding regular consumption of oxidised marine oils [4,5]. It is uncertain whether circu- lating level of oxidised LDL and inflammatory markers are influenced by intake of oxidised lipids. We have previously demonstrated that oxidised fish oil consumption does not affect a variety of markers of oxidative stress or plasma level of n-3 FA differently when compared to non-oxidised fish oil in healthy humans [6]. The aim of the present study was to investigate the effect of oxidised fish oil consumption on the circulating level of oxidised LDL and inflammatory markers. In a seven-week randomised, controlled, double-blinded, parallel designed study 52 healthy subjects (18e50 years) were randomly assigned into one of three intervention groups receiving capsules containing 8 g/d of either: oxi- dised fish oil (peroxide value (PV) 18 mEq/kg; anisidine value (AV) 9), non-oxidised fish oil (PV 4 mEq/kg; AV 3), or high- oleic sunflower oil (PV 4 mEq/kg; AV 3). Both fish oil groups received 1.6 g/d n-3 EPA þ DHA. Detailed description of the study protocol and ethical approval have been described in detail elsewhere [6]. The concentration of serum oxidised LDL and plasma soluble intracellular adhesion molecule (sICAM)-1, vascular cell adhesion molecule (sVCAM)-1, and interleukin (IL)-6 were measured by ELISA from Mercodia (Uppsala, Sweden) and R&D Systems (Minneapolis, MN, USA), respectively, after overnight fast (12 h) and according the manufacturer’s instructions. No effects on circulating oxidised LDL or inflammatory markers (sICAM-1, sVCAM-1 or IL-6) were found after three or seven weeks of intervention with oxidised fish oil (Table 1). These results are in line with our previous findings [6], and may suggest that short-term consumption of oxidised fish oil have no pro or anti-inflammatory effect. Since n-3 FA easily oxidise generating lipid oxidation products, it has been speculated whether this could lead to different properties of oxidised vs. non-oxidised oil [7]. The present study does not indicate that the discrepancy in the literature regarding effect on circulating inflammatory markers in n-3 interven- tion studies [8e10] is influenced by differences in oxidative status of the oil. However, larger studies with longer duration need to be conducted to clarify this. Whether oxidised fish oil is associated with negative health effects in a long term perspective or affecting other populations differently (healthy vs. patients) needs also to be elucidated. In conclusion, oxidised fish oil consumption did not change circulating levels of oxidised LDL, sICAM-1, sVCAM-1 or IL-6 after three or seven weeks in healthy humans. Financial support This study was supported by The Throne Holst Foundation, Oslo and Akershus University College of Applied Sciences, Table 1 Plasma inflammatory markers and serum oxidised LDL at baseline, and after three and seven weeks intervention (n Z 52). Variables Fish oil (n Z 16) Oxidised fish oil (n Z 18) High-oleic sunflower oil (n Z 18) P a P b P c Baseline 3 wk 7 wk Baseline 3 wk 7 wk Baseline 3 wk 7 wk ICAM-1 (ng/ml) 319  76 307  65 283  66 279  44 291  47 284  65 309  73 284  81 303  73 0.21 0.12 0.06 VCAM-1 (ng/ml) 416  85 423  90 383  70 414  90 421  80 411  94 426  87 423  110 433  96 0.90 0.62 0.12 IL-6 (pg/ml) 1.1  1.1 1.5  2.0 0.8  0.3 1.5  0.5 1.5  2.8 1.0  0.5 1.0  0.9 1.4  1.3 1.0  0.5 0.52 0.70 0.37 Oxidised LDL (U/l) 49.4  17.0 51.0  16.3 48.3  17.0 53.6  18.1 53.3  16.1 55.8  16.1 51.2  11.7 50.6  11.7 52.9  12.3 0.75 0.87 0.37 Values are presented as mean  SD, and differences within or between the groups were calculated using one-way ANOVA, with ln transformed data of ICAM-1 and IL-6. a Between groups at baseline. b Between groups after 3 weeks (change from baseline). c Between groups after 7 weeks (change from baseline). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/nmcd Nutrition, Metabolism & Cardiovascular Diseases (2013) 23, e3ee4 0939-4753/$ - see front matter ª 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.numecd.2012.08.009