Pregnant women who develop pre-eclampsia (PE) and/or intra-uterine growth restriction (IUGR) have reduced polyunsaturated fatty acid (PUFA) status compared to healthy pregnancy(1). It is unknown if pregnant women diagnosed with Gestational Diabetes Mellitus (GDM), and their offspring, also have compromised PUFA status. To determine if women with GDM, and their offspring, have altered PUFA status compared to healthy pregnancy. Pregnant women were recruited from Glasgow Scotland, and Brisbane, Australia from antenatal clinics for this cross sectional study. Third trimester maternal blood samples were collected after an overnight fast and cord blood samples were collected at delivery. Plasma fatty acids were analysed using gas chromatography from women with GDM (n = 37) and healthy pregnancies (n = 27) and their respective offspring (n = 31, from women with GDM, and n = 27 from healthy women). T-tests were used to determine significant differences between maternal with GDM and healthy pregnancy, as well as for their offspring and significance was set at p<0.05. Previously, erythrocyte fatty acids were analysed from women with PE (n = 21), IUGR (n = 13) and healthy pregnancies (n = 86)(1). All results were expressed as mol percent of total fatty acids. There were no differences in maternal plasma arachidonic acid (4.51 ± 1.23 vs. 4.72 ± 0.64, p = 0.39) and plasma EPA & DHA (2.33 ± 0.74 vs 2.69 ± 1.04, p = 0.14) in women with GDM and healthy pregnancies, respectively. There were no differences in fetal plasma arachidonic acid (11.58 ± 2.26 vs. 12.63 ± 1.69, p = 0.08) and plasma EPA & DHA (4.44 ± 1.17 vs. 4.44 ± 1.00, p = 0.89) in offspring from women with GDM and healthy pregnancies, respectively. Women with PE and IUGR had approximately 25% lower erythrocyte EPA & DHA and 35% lower erythrocyte arachidonic acid compared to healthy pregnant(1). Offspring from women with PE and IUGR had approximately 25% lower erythrocyte EPA & DHA and 22% lower erythrocyte arachidonic acid compared to healthy pregnancy(1).Women with PE and IUGR had lower PUFA status likely due to reduced PUFA synthesis(1) and offspring from women with PE and IUGR had reduced PUFA status likely due to ectopic fat in placenta tissue(2). Women with GDM do not have compromised PUFA status suggesting there is no reduced synthesis and transport of PUFA. Offspring from women with GDM do not have reduced PUFA status suggesting there is no problem with PUFA transport across the placenta, unlike offspring from women with PE and/or IUGR. Women with GDM, and their offspring, do not have compromised plasma PUFA status compared to healthy pregnancy.

Information on the Omega-3 Index (O3I) in the United Kingdom (UK) is scarce. The UK-Biobank (UKBB) contains data on total plasma n3-PUFA% and DHA% measured by NMR. The aim of our study was to create an equation to estimate the O3I (eO3I) from these data. We first performed an inter-laboratory experiment with 250 random blood samples in which the O3I was measured in erythrocytes by GC, and total n3 % and DHA% were measured in plasma by NMR. The best predictor of eO3I included both DHA% and a derived metric, the total n3 %–DHA%. Together these explained 65 % of the variability (r = 0·832, P < 0·0001). We then estimated the O3I in 117 108 UKBB subjects and correlated it with demographic and lifestyle variables in multivariable-adjusted models. The mean eO3I was 5·58 % (sd 2·35 %) in this UKBB cohort. Several predictors were significantly correlated with eO3I (all P < 0·0001). In general order of impact and with directionality (–, inverse and +, direct): oily-fish consumption (+), fish oil supplement use (+), female sex (+), older age (+), alcohol use (+), smoking (–), higher waist circumference and BMI (–), lower socioeconomic status and less education (–). Only 20·5 % of eO3I variability could be explained by predictors investigated, and oily fish consumption accounted for 7·0 % of that. With the availability of the eO3I in the UKBB cohort, we will be in a position to link risk for a variety of diseases with this commonly used and well-documented marker of n3-PUFA biostatus.

The n-3 PUFA, EPA and DHA, play an important role in human health. As the intake of EPA and DHA from the diet is often inadequate, supplementation of those fatty acids is recommended. A novel source of n-3 PUFA is Calanus finmarchicus oil (CO) which contains fatty acids mainly bound in wax esters. To date, no data are available on the effects of long-term intake of this marine oil on n-3 PUFA blood levels. Therefore, the aim of this study was to evaluate the effect of CO on the n-3 PUFA blood levels using the omega-3 index (O3I). The data originate from a larger randomised controlled trial. For this analysis, samples from seventy-two participants (59·2 (sd 6·2) years, BMI 27·7 (sd 5·28) kg/m2) were analysed. Of those, thirty-six performed 2×/week exercise and received 2 g of CO, which provided 124 mg stearidonic acid (SDA), 109 mg EPA and 87 mg DHA daily (EXCO group), while the other group performed exercise only (EX group) and served as a control for this analysis. The O3I increased from 6·07 (sd 1·29) % at baseline to 7·37 (sd 1·10) % after 12 weeks within the EXCO group (P < 0·001), while there were no significant changes in the EX group (6·01 (sd 1·26)–6·15 (sd 1·32) %, P = 0·238). These data provide first evidence that wax ester-bound n-3 PUFA from CO can significantly increase the O3I despite relatively low EPA + DHA amounts. Further, the effects of exercise could be excluded.

Non-alcoholic fatty liver disease (NAFLD) is an independent predictor of CVD in otherwise healthy individuals. Low n-3 PUFA intake has been associated with the presence of NAFLD; however, the relationship between a biomarker of n-3 status – the Omega-3 Index – and liver fat is yet to be elucidated. A total of eighty overweight adults (fifty-six men) completed the anthropometric and biochemical measurements, including the Omega-3 Index, and underwent proton magnetic resonance spectroscopy assessment of liver fat. Bivariate correlations and multiple regression analyses were performed with reference to prediction of liver fat percentage. The mean Omega-3 Index was high in both NAFLD (intrahepatic lipid concentration≥5·5 %) and non-NAFLD groups. The Omega-3 Index, BMI, waist circumference, glucose, insulin, TAG, high-sensitive C-reactive protein (hsCRP) and alanine aminotransferase (ALT) were positively correlated, and HDL and erythrocyte n-6:n-3 ratio negatively correlated with liver fat concentration. Regression analysis found that simple anthropometric and demographic variables (waist, age) accounted for 31 % of the variance in liver fat and the addition of traditional cardiometabolic blood markers (TAG, HDL, hsCRP and ALT) increased the predictive power to 43 %. The addition of the novel erythrocyte fatty acid variable (Omega-3 Index) to the model only accounted for a further 3 % of the variance (P=0·049). In conclusion, the Omega-3 Index was associated with liver fat concentration but did not improve the overall capacity of demographic, anthropometric and blood markers to predict NAFLD.

n-3 and Trans fatty acids are considered to be the important modifiable factors of the metabolic syndrome. The purpose of this study was to test the hypothesis that lower Omega-3 fatty acids and/or higher trans fatty acids of erythrocytes (RBC) are associated with the risk of the metabolic syndrome. Forty-four patients with the metabolic syndrome, defined by three or more risk factors of the modified Adult Treatment Panel III criteria, and eighty-eight age- and sex-matched controls with less than three risk factors were recruited for the study. The mean age was 54·5 (sem 0·8) years and 45 % of subjects were female. Trans fatty acids of RBC were higher in patients than controls (0·82 (sem 0·04) v. 0·73 (sem 0·03) %; P = 0·043), while their Omega-3 indexes, the sum of EPA and DHA in RBC, did not significantly differ (11·78 (sem 0·04) v. 12·39 (sem 0·02) %). Multivariable-adjusted regression analysis showed positive association between trans fatty acid and risk of the metabolic syndrome (OR 7·13; 95 % CI 1·53, 33·27; P = 0·013). Fasting serum insulin (7·9 (sem 0·7) v. 4·9 (sem 0·3) μU/ml; P < 0·001) and high sensitivity C-reactive protein (18 (sem 3) v. 11 (sem 17) mg/l; P = 0·042) were also higher in patients than controls. There were significant positive relationships between trans fatty acids and waist circumference, and between trans fatty acids and BMI. The results suggested that RBC trans fatty acids might be a predictor of increased risk for the metabolic syndrome, but n-3 fatty acids were not in this population.