The results of this short-term study suggest that DPA may act as a reservoir of the major long-chain n-3 fatty acids (LC n-3 PUFA) in humans.

In contrast to the well-characterized effects of specialized proresolving lipid mediators (SPMs) derived from eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), little is known about the metabolic fate of the intermediary long-chain (LC) n-3 polyunsaturated fatty acid (PUFA) docosapentaenoic acid (DPA). In this double blind crossover study, shifts in circulating levels of n-3 and n-6 PUFA-derived bioactive lipid mediators were quantified by an unbiased liquid chromatography-tandem mass spectrometry lipidomic approach. Plasma was obtained from human subjects before and after 7 d of supplementation with pure n-3 DPA, n-3 EPA or placebo (olive oil). DPA supplementation increased the SPM resolvin D5 (RvD5) and maresin (MaR)-1, the DHA vicinal diol 19,20-dihydroxy-DPA and n-6 PUFA derived 15-keto-PG E (15-keto-PGE). EPA supplementation had no effect on any plasma DPA or DHA derived mediators, but markedly elevated monohydroxy-eicosapentaenoic acids (HEPEs), including the e-series resolvin (RvE) precursor 18-HEPE; effects not observed with DPA supplementation. These data show that dietary n-3 DPA and EPA have highly divergent effects on human lipid mediator profile, with no overlap in PUFA metabolites formed. The recently uncovered biologic activity of n-3 DPA docosanoids and their marked modulation by dietary DPA intake reveals a unique and specific role of n-3 DPA in human physiology.-Markworth, J. F., Kaur, G., Miller, E. G., Larsen, A. E., Sinclair, A. J., Maddipati, K. R., Cameron-Smith, D. Divergent shifts in lipid mediator profile following supplementation with n-3 docosapentaenoic acid and eicosapentaenoic acid.

Aim To determine the effect of whey protein plus vitamin D supplementation combined with progressive resistance training (PRT) on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle‐aged and older adults with type 2 diabetes (T2D). Materials and Methods In this 24‐week, randomized controlled trial, 198 overweight/obese adults (aged 50–75 years) with T2D undertook PRT (2‐3 days/week) with random allocation to whey protein (20 g each morning plus 20 g postexercise) plus vitamin D3 (2000 IU/day) (PRT + ProD, n = 98) or no supplementation (PRT, n = 100). Primary outcomes were HbA1c and homeostatic model assessment‐2 of insulin resistance (HOMA2‐IR). Secondary endpoints included fasting plasma glucose (FPG), body composition, muscle strength, physical function, blood pressure, blood lipids and inflammatory markers. Results At 24 weeks, supplementation did not enhance the effects of PRT on HbA1c (mean absolute change: PRT + ProD −0.10% [95% CI, −0.24%, 0.05%] vs. PRT −0.17% [95% CI, −0.32%, −0.03%], p = .322) or HOMA2‐IR (PRT + ProD −0.12 [95% CI, −0.27, 0.03] vs. PRT −0.03 [95% CI, −0.14, 0.09], p = .370). There were also no significant between‐group differences for the mean changes in the secondary outcomes, except that FPG improved in PRT versus PRT + ProD (net difference, 0.6 mmol/L [95% CI, 0.1, 1.0], P = .018), while interleukin IL‐10 (61% [95% CI 31%, 92%], P < .001), tumour necrosis factor‐α (16% [95% CI, 3%, 29%], p = .015) and 30‐s sit‐to‐stand performance (number, 1.0 [95% CI, −0.05, 1.5], p = .047) increased in PRT + ProD versus PRT. Conclusions In older overweight/obese adults with T2D, daily whey protein plus vitamin D supplementation did not augment the effects of PRT on measures of glycaemic control, body composition, muscle strength or cardiometabolic risk factors.

BackgroundWhile physical activity, energy restriction and weight loss are the cornerstone of type 2 diabetes management, less emphasis is placed on optimizing skeletal muscle mass. As muscle is the largest mass of insulin-sensitive tissue and the predominant reservoir for glucose disposal, there is a need to develop safe and effective evidence-based, lifestyle management strategies that optimize muscle mass as well as improve glycaemic control and cardiometabolic risk factors in people with this disease, particularly older adults who experience accelerated muscle loss.Methods/DesignUsing a two-arm randomized controlled trial, this 6-month study builds upon the community-based progressive resistance training (PRT) programme Lift for Life® to evaluate whether ingestion of a whey-protein drink combined with vitamin D supplementation can enhance the effects of PRT on glycaemic control, body composition and cardiometabolic health in older adults with type 2 diabetes. Approximately 200 adults aged 50 to 75 years with type 2 diabetes, treated with either diet alone or oral hypoglycaemic agents (not insulin), will be recruited. All participants will be asked to participate in a structured, supervised PRT programme based on the Lift for Life® programme structure, and randomly allocated to receive a whey-protein drink (20 g daily of whey-protein plus 20 g after each PRT session) plus vitamin D supplements (2000 IU/day), or no additional powder and supplements. The primary outcome measures to be collected at baseline, 3 and 6 months will be glycated haemoglobin (HbA1c) and insulin sensitivity (homeostatic model assessment). Secondary outcomes will include changes in: muscle mass, size and intramuscular fat; fat mass; muscle strength and function; blood pressure; levels of lipids, adipokines and inflammatory markers, serum insulin-like growth factor-1 and 25-hydroxyvitamin D; renal function; diabetes medication; health-related quality of life, and cognitive function.DiscussionThe findings from this study will provide new evidence on whether increased dietary protein achieved through the ingestion of a whey-protein drink combined with vitamin D supplementation can enhance the effects of PRT on glycaemic control, muscle mass and size, and cardiometabolic risk factors in older adults with type 2 diabetes.Trial registrationAustralian New Zealand Clinical Trials ACTRN12613000592741.Electronic supplementary materialThe online version of this article (doi:10.1186/1745-6215-15-431) contains supplementary material, which is available to authorized users.

Long-term participation in PRT, independent of change in weight, can result in some improvements in certain inflammatory markers in older overweight adults with type 2 diabetes.