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Scope: Increased consumption of fish oils rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is associated with improved cardiometabolic health and inflammatory status; however, age-related responses remain poorly described., Methods and Results: In a placebo-controlled study, healthy young and older men consumed five fish oil capsules daily, providing 2.0 g/d EPA and 1.0g/d DHA, for three months. Both young and older men experienced a ∼30% reduction in blood triglycerides with fish oil supplementation. A significant group × time interaction was observed for DHA, with young men experiencing a ∼twofold increase in DHA in serum and RBCs, while older men showed negligible increases. Other fatty acids were differentially regulated between young and older men, most notably osbond acid and several saturates. Small changes were observed in serum oxylipins, with both groups of men responding similarly: 5-HETE was reduced, while PGF2α and 17-HDoHE were increased. Changes in oxylipins occurred independent of changes in whole blood expression of key genes regulating oxylipin production., Conclusion: Our study suggests that both young and older men experience the triglyceride-lowering benefits associated with fish oil supplements, but show differential responses in blood fatty acids. Additionally, fish oil promotes an improved oxylipin profile in both groups of men., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Obesity is associated with numerous health complications; however, a subgroup of obese individuals (termed the metabolically healthy obese or MHO) appear to have lower risk for complications such as type 2 diabetes and cardiovascular disease. Emerging evidence suggests that MHO individuals have reduced inflammation compared to their metabolically unhealthy obese (MUO) counterparts. As it is recognized that fatty acids (FAs) have a strong relationship with inflammation, the current study aimed to uncover if the reduced inflammation observed in MHO individuals is mirrored by a more favourable FA profile., Methods: Fasted serum samples were collected from lean healthy (LH), MHO, and MUO participants (n = 10/group) recruited from the Diabetes Risk Assessment study. A panel of pro- and anti-inflammatory markers were measured by immunoassay. Total serum FA profiling, as well as the FA composition of circulating phospholipids (PL) and triglycerides (TG), was measured by gas chromatography. ANOVA and Mann-Whitney-Wilcoxon tests were used to assess statistical significance between the groups (P<0.05)., Results: MHO and MUO individuals had similar BMI and body fat %; however, lipid parameters in MHO individuals more closely resembled that of LH individuals. MHO individuals had circulating levels of high sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) similar to LH individuals, while levels of platelet derived growth factor-ββ (PDGF-ββ) were intermediate to that of LH and MUO individuals. FA profiling analysis combined with discriminant analysis modelling highlighted a panel of nine FAs (consisting of three saturated, three monounsaturated, and three polyunsaturated FAs) in PL and TG fractions that distinguished the three groups. Specifically, saturated FA (myristic and stearic acids) levels in MHO individuals resembled that of LH individuals., Conclusion: Our results suggest that the reduced inflammatory state of MHO individuals compared to MUO individuals may stem, in part, from a more favourable underlying FA profile.

Background: Although evidence indicates that fatty acids (FA) can affect insulin resistance (IR), not all FA contribute equally to the process. Indeed, monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) are reported to reduce IR, whereas saturated FA (SFA) and trans FA appear to increase IR. However, it is not yet clear how individual FA are associated with markers of IR, and whether these relationships are influenced by ethnicity and/or sex. Therefore, the goal of this study was to examine the ethnic- and sex-specific relationships between plasma FA and markers of IR in a cohort of healthy young Caucasian, East Asian, and South Asian adults. Methods: Gas chromatography was used to quantify fasting plasma FA from young Canadian adults (22.6 ± 0.1 yrs) of Caucasian (n = 461), East Asian (n = 362), or South Asian (n = 104) descent. Linear regression models were used to investigate associations between plasma FA and markers of IR (i.e. fasting insulin, glucose, and HOMA-IR) according to ethnicity and sex. Results: Numerous significant associations (P < 0.05, adjusted for multiple testing) were identified between individual FA and markers of IR, with the majority identified in Caucasians. For SFA, positive associations were found between 14:0 and fasting insulin and HOMA-IR in Caucasian and East Asian populations, and 18:0 and fasting glucose in Caucasians only. Several positive associations were also found for specific MUFA (18:1t11 and 18:1t6-8 with HOMA-IR, and 18:1c9 with fasting glucose) and PUFA (18:2n6 with fasting glucose and 18:2c9t11 with HOMA-IR) in Caucasian adults only. Most of the aforementioned associations were stronger in males compared to females. Interestingly, no significant associations were found between FA and markers of IR in South Asian adults. Conclusions: We report numerous associations between plasma FA and markers of IR in Caucasian and East Asian populations, but not in South Asian individuals. Furthermore, these associations appeared to be more robust in men. This demonstrates the importance of investigating associations between FA and markers of IR in an ethnic- and sex-specific manner in order to better understand the contribution of plasma FA to the development of IR and type-2 diabetes. [ABSTRACT FROM AUTHOR]

The need to better predict the development of insulin resistance (IR) and type 2 diabetes (T2D) is necessary as the prevalence of T2D is projected to increase in Canada and cost Canadians ∼$18 billion by 2030. The International Diabetes Federation currently advises the use of total blood triglycerides (TGs) as a predictor for identifying individuals at risk of developing IR and T2D. However, it has been demonstrated that total TG levels do not reliably reflect IR across multiple ethnicities. This suggests that a more accurate marker of IR is required. Interestingly, recent evidence suggests that distinct fatty acids (FAs) in blood TGs can reflect an individual's IR status more accurately than total TGs. It is therefore reasonable to postulate that an analysis of the FAs within TGs and other blood lipids could lead to the discovery of a more accurate marker of IR. Over the course of 3 studies, the following thesis aimed to demonstrate that distinct FAs within serum lipids are associated with markers of IR more robustly than total TGs or total FAs. First, a large cross-sectional cohort that comprised young adults was used to demonstrate the associations between individual serum FAs and markers of IR (e.g., fasting glucose). Second, a population of Caucasian men that varied in IR-risk was examined to demonstrate that specific serum FAs within TGs associate with markers of IR more strongly than total TG levels. Finally, a cohort of individuals was investigated to demonstrate the improved ability of phospholipid and TG FA profiles (compared with total FAs) to distinguish individuals varying in metabolic health. This thesis demonstrated that circulating FAs associate with markers of IR and that these associations vary between individuals of different sex and ethnicity. Furthermore, the findings of this thesis indicate that compared with total serum TGs, specific FAs within lipid fractions may provide a more accurate means to identify individuals at increased risk of developing IR and T2D. Collectively, this thesis encourages future investigations of FAs within serum lipid fractions to uncover an improved method for identifying individuals at risk of IR and T2D. [ABSTRACT FROM AUTHOR]