n-6 PUFA, especially linoleic acid (LA) but also arachidonic acid (AA), have been inversely associated with CHD. However, mechanisms underlying these associations are not fully known. We investigated the associations of the serum concentrations of total n-6 PUFA, LA, AA, γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA), with the odds of myocardial ischaemia during exercise, a predictor of future cardiac events. A total of 1871 men without a history of CHD from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) aged 42–60 years were included. All participants performed a maximal symptom-limited exercise stress test, using an electrically braked bicycle ergometer. Multivariable-adjusted logistic regression was used to assess the OR for exercise-induced myocardial ischaemia in quartiles of the serum n-6 PUFA concentrations. After multivariable adjustment, men in the highest v. the lowest serum AA concentration had 50 % lower odds for exercise-induced myocardial ischaemia (OR 0·50, 95 % CI 0·34, 0·76; P-trend across quartiles < 0·001). For the other PUFA, the OR (95 % CI) were 1·00 (0·69, 1·46; P-trend = 0·89) for LA, 1·07 (0·75, 1·53; P-trend = 0·40) for GLA and 0·74 (0·51, 1·07; P-trend = 0·16) for DGLA. Among the n-6 PUFA, higher serum concentration of AA was associated with lower odds for myocardial ischaemia during an exercise test in middle-aged and older men. This may provide one mechanism for the previously observed possible cardioprotective properties of AA. Our findings also suggest that n-6 PUFA should not be considered as one homogenous group.

The associations between circulating PUFA and cardiovascular risk factors and events in healthy Asian populations have been less examined robustly compared with Western populations. This systematic review aimed to summarise current evidence on the associations between n-3 and n-6 PUFA biomarkers and cardiovascular risk factors and events in healthy Asian populations. Four databases were searched for observational studies from 2010 until 2024. Twenty-three studies were eligible, which covered six Asian countries and included events (n 7), traditional risk factors such as blood pressure and lipids (n 4), physical signs such as arterial stiffness (n 4), non-traditional lipid markers (n 1), markers of inflammation (n 4), markers of thrombosis (n 2) and non-invasive imaging-based markers (n 5). Biological sample types included plasma (n 6), serum (n 14) and erythrocyte (n 3). Higher circulating total n-3 PUFA appeared to be associated with lower hypertension risk and specifically EPA and DHA to be associated with lower myocardial infarction risk, reduction in TAG and inflammation. Higher circulating linoleic acid was associated with improved lipid profiles and lower inflammation. Limited evidence led to inconclusive associations between circulating n-6 PUFA biomarkers and CVD events and blood pressure. No consistent associations with arterial stiffness, obesity, thrombosis and imaging-based biomarkers were observed for circulating PUFA biomarkers in Asian populations. Limited studies exist for each outcome; hence, results should be interpreted with caution. More high-quality and prospective studies in Asian populations are warranted. Several recommendations such as sample size justification and reporting of non-respondents rate are proposed for future studies.

Low intake or tissue concentrations of the n-6 PUFA, especially to the major n-6 PUFA linoleic acid (LA), and low exercise cardiac power (ECP) are both associated with CVD risk. However, associations of the n-6 PUFA with ECP are unknown. The aim of the present study was to explore cross-sectional associations of the serum total n-6 PUFA, LA, arachidonic acid (AA), γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA) concentrations with ECP and its components. In total, 1685 men aged 42–60 years from the Kuopio Ischaemic Heart Disease Risk Factor Study and free of CVD were included. ANCOVA was used to examine the mean values of ECP (maximal oxygen uptake (VO2max)/maximal systolic blood pressure (SBP)) and its components in quartiles of the serum total and individual n-6 PUFA concentrations. After multivariable adjustments, higher serum total n-6 PUFA concentration was associated with higher ECP and VO2max (for ECP, the extreme-quartile difference was 0·77 ml/mmHg (95 % CI 0·38, 1·16, P for trend across quartiles < 0·001) and for VO2max 157 ml/min (95 % CI 85, 230, P for trend < 0·001), but not with maximal SBP. Similar associations were observed with serum LA concentration. Higher serum AA concentration was associated with higher ECP but not with VO2max or maximal SBP. The minor serum n-6 PUFA GLA and DGLA were associated with higher maximal SBP during exercise test and DGLA also with higher VO2max but neither with ECP. In conclusion, especially LA concentration was associated with higher ECP. This may provide one mechanism for the cardioprotective properties of, especially, LA.

We evaluated the association between dietary estimates of fatty acid (FA) consumption and type 2 diabetes (T2D) risk in the French E3N (Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale) cohort. In total, 71 334 women without diabetes at baseline were followed up from 1993 to 2011. Diabetes was identified using questionnaires and drug-reimbursement claims, and incident cases were validated. FA consumption in 1993 was estimated from a validated dietary questionnaire. Cox regression estimated hazard ratios (HR) and 95 % CI of diabetes risk, comparing the upper tertile group with the lowest. High n-3 PUFA consumption was associated with T2D even after adjustment for confounders, including other FA and BMI (HR 1·26; 95 % CI 1·13, 1·41; upper tertile compared with lowest). Upon stratification by overweight (BMI≥25 kg/m2)/non-overweight, a positive association between total PUFA consumption and T2D was observed, but it was restricted to non-overweight women (HR 1·22; 95 % CI 1·05, 1·42), whereas n-3 PUFA consumption was associated with increased T2D risk in both BMI strata (BMI<25 kg/m2: HR 1·19; 95 % CI 1·01, 1·40 and BMI≥25 kg/m2: HR 1·38; 95 % CI 1·20, 1·59). Within the n-3 PUFA, high DPA (HR 1·41; 95 % CI 1·23, 1·63) and α-linolenic acid (ALA) intakes were associated with increased T2D risk, but the effects of ALA were restricted to overweight women (HR 1·17; 95 % CI 1·01, 1·36). Within the n-6 PUFA, only arachidonic acid (AA) intake was associated with T2D risk (HR 1·49; 95 % CI 1·33, 1·66). The associations with DPA and AA persisted even after adjustment of their principal source in this cohort, the consumption of meat. The effects of PUFA are heterogeneous within the FA group. Intake of DPA and AA may contribute to T2D development.

Demand for organic meat is partially driven by consumer perceptions that organic foods are more nutritious than non-organic foods. However, there have been no systematic reviews comparing specifically the nutrient content of organic and conventionally produced meat. In this study, we report results of a meta-analysis based on sixty-seven published studies comparing the composition of organic and non-organic meat products. For many nutritionally relevant compounds (e.g. minerals, antioxidants and most individual fatty acids (FA)), the evidence base was too weak for meaningful meta-analyses. However, significant differences in FA profiles were detected when data from all livestock species were pooled. Concentrations of SFA and MUFA were similar or slightly lower, respectively, in organic compared with conventional meat. Larger differences were detected for total PUFA and n-3 PUFA, which were an estimated 23 (95 % CI 11, 35) % and 47 (95 % CI 10, 84) % higher in organic meat, respectively. However, for these and many other composition parameters, for which meta-analyses found significant differences, heterogeneity was high, and this could be explained by differences between animal species/meat types. Evidence from controlled experimental studies indicates that the high grazing/forage-based diets prescribed under organic farming standards may be the main reason for differences in FA profiles. Further studies are required to enable meta-analyses for a wider range of parameters (e.g. antioxidant, vitamin and mineral concentrations) and to improve both precision and consistency of results for FA profiles for all species. Potential impacts of composition differences on human health are discussed.

Increased intake of vegetable oils rich in n-6 PUFA, including soyabean oil, has been associated with an increase in allergic disease. The present study aimed to determine the effect of an increasing dose of dietary vegetable oil on allergic outcomes in mice. To study this, mice received a 7 v. 10 % soyabean oil diet before and during oral sensitisation with whey or whey hyperimmune serum transfer. Another group of mice received partial whey hydrolysate (pWH) while being fed the diets before oral sensitisation. The acute allergic skin response, serum Ig level, mouse mast cell protease-1 (mMCP-1) concentration and/or splenic T-cell percentages were determined upon whey challenge. When the diets were provided before and during oral sensitisation, the acute allergic skin response was increased in mice fed the 10 % soyabean oil diet compared with the 7 % soyabean oil diet. Whey IgE and IgG1 levels remained unaltered, whereas mMCP-1 levels increased in mice fed the 10 % soyabean oil diet. Furthermore, allergic symptoms were increased in naive mice fed the 10 % soyabean oil diet and sensitised with whey hyperimmune serum. In addition to enhancing the mast cell response, the 10 % soyabean oil diet increased the percentage of activated Th1 and Th2 cells as well as increased the ratios of Th2:regulatory T cells and Th2:Th1 when compared with the 7 % soyabean oil diet. Oral tolerance induction by pWH was abrogated in mice fed the 10 % soyabean oil diet compared with those fed the 7 % soyabean oil diet during pretreatment with pWH. In conclusion, increased intake of soyabean oil rich in n-6 PUFA suppresses tolerance induction by pWH and enhances the severity of the allergic effector response in whey-allergic mice. Dietary vegetable oils rich in n-6 PUFA may enhance the susceptibility to develop or sustain food allergy.

Increasing dietary n-3 PUFA decreases the risk of CHD. Since n-6 PUFA compete with n-3 PUFA for common metabolic enzymes, the n-6:n-3 ratio intake rather than the n-3 PUFA intake levels per se may be critical. We aimed to examine whether altering the n-6:n-3 ratio affects cardiovascular risk factors in hypercholesterolaemic patients on lipid management with statins. Adhering to a randomised, crossover study design, patients on statins (n 11) were placed on one of two dietary interventions (Diet high-ratio (HR) – n-6:n-3 = 30:1 or Diet low-ratio (LR) – n-6:n-3 = 1·7:1) for 4 weeks followed after an 8-week washout period by the alternate diet. Foods enriched with n-3 or n-6 PUFA were delivered to each patient, who were given clear guidance on consumption expectations for the study. Measures of lipid profile, blood pressure and vascular function were determined. Diet LR significantly reduced body weight, LDL-cholesterol, high-sensitivity C-reactive protein, blood pressure and the apoA-1:apoB ratio. While Diet HR trended towards a similar cardioprotective profile, most of the parameters examined did not reach statistical significance. A direct comparison between diets demonstrated no significant superiority of Diet LR over Diet HR. These results suggest that a dietary intervention focused on n-6 and n-3 fatty acids may improve cardiovascular risk factors in patients over and above standard lipid management, but there is no significant advantage of a low n-6:n-3 ratio diet when compared to a high-ratio diet.

n-6 PUFA are well known for their critical role in many physiological functions and seem to reduce risks of CHD. However, some argue that excessive consumption of n-6 PUFA may lead to adverse effects on health and therefore recommend reducing dietary n-6 PUFA intake or fixing an upper limit. In this context, the present work aimed to review evidence on the link between n-6 PUFA and risks of CVD. Epidemiological studies show that n-6 PUFA dietary intake significantly lowers blood LDL-cholesterol levels. In addition, n-6 PUFA intake does not increase several CVD risk factors such as blood pressure, inflammatory markers, haemostatic parameters and obesity. Data from prospective cohort and interventional studies converge towards a specific protective role of dietary n-6 PUFA intake, in particular linoleic acid, against CVD. n-6 PUFA benefits are even increased when SFA intake is also reduced. In regards to studies examined in this narrative review, recommendation for n-6 PUFA intake above 5 %, and ideally about 10 %, of total energy appears justified.

Rats were fed from weaning on chow supplemented with suet or sunflower oil (10 % (w/w) each). The appearance of receptors for tumour necrosis factor-α on perinodal adipocytes from the popliteal depot following a subcutaneous injection of bacterial lipopolysaccharide was examined. In rats fed on sunflower oil-supplemented chow receptors appeared at a time similar to that described in rats fed unsupplemented chow, but in rats fed on chow supplemented with suet receptor appearance was significantly delayed. The popliteal adipocytes were found to contain different proportions of fatty acids as assessed by GLC. These preliminary results suggest that the fatty acid component of the diet can, by influencing the triacylglycerol-fatty acids within adipocytes, directly alter the time course of an early inflammatory immune response.