Dietary Fatty Acid Composition Research Articles

Site‐specific regulation of adult neurogenesis by dietary fatty acid content, vitamin E and flight exercise in European starlings

Exercise is known to have a strong effect on neuroproliferation in mammals ranging from rodents to humans. Recent studies have also shown that fatty acids and other dietary supplements can cause an upregulation of neurogenesis. It is not known, however, how exercise and diet interact in their effects on adult neurogenesis. We examined neuronal recruitment in multiple telencephalic sites in adult male European starlings (Sturnus vulgaris) exposed to a factorial combination of flight exercise, dietary fatty acids and antioxidants. Experimental birds were flown in a wind tunnel following a training regime that mimicked the bird's natural flight behaviour. In addition to flight exercise, we manipulated the composition of dietary fatty acids and the level of enrichment with vitamin E, an antioxidant reported to enhance neuronal recruitment. We found that all three factors - flight exercise, fatty acid composition and vitamin E enrichment - regulate neuronal recruitment in a site-specific manner. We also found a robust interaction between flight training and vitamin E enrichment at multiple sites of neuronal recruitment. Specifically, flight training was found to enhance neuronal recruitment across the telencephalon, but only in birds fed a diet with a low level of vitamin E. Conversely, dietary enrichment with vitamin E upregulated neuronal recruitment, but only in birds not flown in the wind tunnel. These findings indicate conserved modulation of adult neurogenesis by exercise and diet across vertebrate taxa and indicate possible therapeutic interventions in disorders characterized by reduced adult neurogenesis.

Serum alpha-linolenic and linoleic acids are inversely associated with depressive symptoms in adults

Summary Background & aims Fatty acid composition in diet and serum has been linked to depression, but the evidence on this issue is limited among Japanese, who consume large amounts of fish rich in n-3 polyunsaturated fatty acids. We examined the association between fatty acid composition in serum and depressive symptoms in Japanese men and women. Methods The subjects were 496 participants aged 21–67 years in a cross-sectional study. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Free, cholesterol ester, and phospholipid fatty acids in serum were measured by gas–liquid chromatography. Multiple logistic regression was used to assess the association between serum fatty acid and depressive symptoms. Results A higher free alpha-linolenic acid level was marginally significantly associated with a decreased prevalence of depressive symptoms (CES-D ≥ 16) (P for trend = 0.07). When a cut-off of CES-D ≥ 19 was used, the association was strengthened; the multivariable-adjusted odds ratios (95% confidence interval) of depressive symptoms for the lowest through highest tertile of alpha-linolenic acid levels were 1.00 (reference), 0.49 (0.29–0.84), and 0.47 (0.26–0.83), respectively (P for trend = 0.007). A higher n-6 PUFA in cholesterol esters and free linoleic acid were also significantly associated with a decreased prevalence of depressive symptoms (CES-D ≥ 19) (P for trend = 0.03 and 0.048, respectively). The other polyunsaturated fatty acids including marine-derived n-3 PUFA were not associated with depressive symptoms. Conclusions Fatty acid composition with high levels of serum alpha-linolenic and linoleic acids might be protectively associated with depressive symptoms in Japanese adults.

Effect of dietary fatty acid composition on substrate utilization and body weight maintenance in humans

Dietary fat content is a primary factor associated with the increase in global obesity rates. There is a delay in achieving fat balance following exposure to a high-fat (HF) diet (≥ 40% of total energy from fat) and fat balance is closely linked to energy balance. Exercise has been shown to improve this rate of adaptation to a HF diet. Recently, however, the role of dietary fatty acid composition on energy and macronutrient balance has come into question. We chose studies that compared monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA). We have reviewed studies that measured diet-induced thermogenesis (DIT), energy expenditure (EE), or fat oxidation (FOx) in response to a HF meal challenge, or long-term dietary intervention comparing these fatty acids. While single-meal studies show that SFA induce lower DIT and FOx compared to unsaturated fats, the effect of the degree of unsaturation (MUFA vs. PUFA) appears to yet be determined. Long-term dietary interventions also support the notion that unsaturated fats induce greater EE, DIT, and/or FOx versus SFA and that a high MUFA diet induces more weight loss compared to a high SFA diet. Sex and BMI status also affect the metabolic responses to different fatty acids; however, more research in these areas is warranted. SFA are likely more obesigenic than MUFA, and PUFA. The unsaturated fats appear to be more metabolically beneficial, specifically MUFA ≥ PUFA > SFA, as evidenced by the higher DIT and FOx following HF meals or diets.

Postnatal dietary fatty acid composition permanently affects the structure of hypothalamic pathways controlling energy balance in mice

We previously reported that dietary lipid quality during early life can have long-lasting effects on metabolic health and adiposity. Exposure to a postnatal diet with low dietary omega-6 (n-6) or high omega-3 (n-3) fatty acid (FA) content resulted in reduced body fat accumulation when challenged with a moderate Western-style diet (WSD) beginning in adolescence. We determined whether this programming effect is accompanied by changes in hypothalamic neural projections or modifications in the postnatal leptin surge, which would indicate the altered development of hypothalamic circuits that control energy balance. Neonatal mice were subjected to a control diet (CTR) or experimental diet with altered relative n-6 and n-3 FA contents [ie, a diet with a relative reduction in n-6 fatty acid (LOW n-6) or a diet with a relative increase in n-3 fatty acid (HIGH n-3) compared with the CTR from postnatal day (PN) 2 to 42]. Compared with CTR mice, mice fed a LOW n-6 or HIGH n-3 during postnatal life showed significant reductions in the density of both orexigenic and anorexigenic neural projections to the paraventricular nucleus of the hypothalamus at PN 28. These impairments persisted into adulthood and were still apparent after the WSD challenge between PNs 42 and 98. However, the neuroanatomical changes were not associated with changes in the postnatal leptin surge. Although the exact mechanism remains to be elucidated, our data indicate that the quality of dietary FA during postnatal life affects the development of the central regulatory circuits that control energy balance and may do so through a leptin-independent mechanism.

Manifestations of Fasting-Induced Fatty Liver and Rapid Recovery from Steatosis in Voles Fed Lard or Flaxseed Oil Lipids

Long-chain n-3 polyunsaturated fatty acids (PUFA) can have beneficial effects against fat deposition, cardiovascular diseases, and liver steatosis. We investigated how diets based on lard (predominantly saturated and monounsaturated fatty acids) or flaxseed oil (rich in 18:3n-3) affect liver fat-% and fatty acid profiles of tundra voles (Microtus oeconomus). We also studied potential participation of hyaluronan (HA) in the pathology of fatty liver and whether the development and recovery of fasting-induced steatosis are influenced by n-3 PUFA. The dietary fatty acid composition was manifested in the liver fatty acid signatures. Fasting for 18 h induced macrovesicular steatosis and the liver fat-% increased to 22% independent of the preceding diet. Fasting-induced steatosis did not involve inflammation or connective tissue activation indicated by the absence of both leukocyte accumulation and increased HA. Food deprivation modified the liver fatty acid signatures to resemble more closely the diets. Fasting reduced the proportions of long-chain n-3 PUFA in both dietary regimes and n-3/n-6 PUFA ratios in the lard-fed voles. Decreases in long-chain n-3 PUFA may promote lipid accumulation by modulating the expression of lipid-metabolizing genes. Dietary 18:3n-3 did not prevent the development or attenuate the manifestation of steatosis in the fasted voles or promote the recovery.

Effect of dietary fatty acids on metabolic rate and nonshivering thermogenesis in golden hamsters

Hibernating rodents prior to winter tend to select food rich in polyunsaturated fatty acids (PUFA). Several studies found that such diet may positively affect their winter energy budget by enhancing torpor episodes. However, the effect of composition of dietary fatty acids (FA) on metabolism of normothermic heterotherms is poorly understood. Thus we tested whether diets different in FA composition affect metabolic rate (MR) and the capacity for nonshivering thermogenesis (NST) in normothermic golden hamsters (Mesocricetus auratus). Animals were housed in outdoor enclosures from May 2010 to April 2011 and fed a diet enriched with PUFA (i.e., standard food supplemented weekly with sunflower and flax seeds) or with saturated and monounsaturated fatty acids (SFA/MUFA, standard food supplemented with mealworms). Since diet rich in PUFA results in lower MR in hibernating animals, we predicted that PUFA-rich diet would have similar effect on MR of normothermic hamsters, that is, normothermic hamsters on the PUFA diet would have lower metabolic rate in cold and higher NST capacity than hamsters supplemented with SFA/MUFA. Indeed, in winter resting metabolic rate (RMR) below the lower critical temperature was higher and NST capacity was lower in SFA/MUFA-supplemented animals than in PUFA-supplemented ones. These results suggest that the increased capacity for NST in PUFA-supplemented hamsters enables them lower RMR below the lower critical temperature of the thermoneural zone.

Polyunsaturated fats, membrane lipids and animal longevity

Fatty acids are essential for life because they are essential components of cellular membranes. Lower animals can synthesize all four classes of fatty acids from non-lipid sources, but both omega-6 and omega-3 cannot be synthesized de novo by 'higher' animals and are therefore essential components of their diet. The relationship between normal variation in diet fatty acid composition and membrane fatty acid composition is little investigated. Studies in the rat show that, with respect to the general classes of fatty acids (saturated, monounsaturated and polyunsaturated) membrane fatty acid composition is homeostatically regulated despite diet variation. This is not the case for fatty acid composition of storage lipids, which responds to diet variation. Polyunsaturated fatty acids are important determinants of physical and chemical properties of membranes. They are the substrates for lipid peroxidation and it is possible to calculate a peroxidation index (PI) for a particular membrane composition. Membrane PI appears to be homeostatically regulated with respect to diet PI. Membrane fatty acid composition varies among species and membrane PI is inversely correlated to longevity in mammals, birds, bivalve molluscs, honeybees and the nematode Caenorhabditis elegans.

Effects of Different Dietary Lipid Sources on Growth Performance, Fatty Acid Composition, and Antioxidant Enzyme Activity of Juvenile Rockfish, Sebastes schlegeli

AbstractThis study was carried out to investigate and compare the effects of various dietary lipid sources on growth performance, body composition, fatty acid profiles, and hepatic and plasma antioxidant enzyme activities of juvenile rockfish, Sebastes schlegeli. Three replicate groups of fish (initial mean weight, 1.7 ± 0.04 g) were fed four isonitrogenous and isolipidic diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO), or a mixture of SO and LO (SO + LO) for 8 wk. There were no significant differences in survival, weight gain, feed efficiency, and protein efficiency ratios of fish fed the diets containing different lipid sources (P > 0.05). The fatty acids compositions of the liver and muscle tissues reflected the dietary fatty acid compositions. Liver and muscle of fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid. Liver and muscle of fish fed the FO diet had significantly (P < 0.05) higher levels of eicosapentaenoic acid and docosahexaenoic acid than those of fish fed the SO and LO diets. Dietary lipid source had no significant effect on the hepatic and plasma enzyme activities of superoxide dismutase and glutathione peroxidase. The results of this study suggest that SO and LO can be used as a replacement for FO in the diets of juvenile rockfish without incurring any negative effects on growth, feed utilization, and antioxidant enzyme activity, when the dietary essential fatty acid requirements are satisfied for rockfish.

Microarray Analysis of Hepatic Gene Expression in Juvenile Japanese Flounder Paralichthys olivaceus Fed Diets Supplemented with Fish or Vegetable Oils

Gene expression profiling was performed in Japanese flounder Paralichthys olivaceus fed diets supplemented with fish oil (FO), linseed oil (LO), or olive oil (OO) for 6weeks. The LO and OO groups showed significantly retarded growth, lower feed intake, lower protein efficiency ratio, and lower hepatosomatic index (P < 0.05). Liver fatty acid composition reflected the dietary fatty acid composition. Microarray analysis revealed that dietary n - 3 highly unsaturated fatty acid (HUFA) deficiency affected 169 transcripts. In the LO group, 57 genes were up-regulated and 38 genes were down-regulated, whereas in the OO group nine genes were up-regulated and 87 genes were down-regulated. Analysis of the functional annotations suggested that dietary n - 3 HUFA affected genes involved in signal transduction (23.2%), cellular processes (21.1%), metabolism (including glucose, lipid, and nucleobase; 15.5%), transport (11.3%), regulation of transcription (10.5%), and immune response (4.2%). Several genes encoding serine/threonine kinases such as protein kinase C and calmodulin-dependent kinase and nuclear hormone receptors such as vitamin D receptor, retinoic acid receptor, and receptors for cytokines (bone morphogenic protein and transforming growth factor β) were affected. Among 169 transcripts, 22 genes were affected in both LO and OO groups. The present study identified several genes involved in n - 3 HUFA deficiency-sensitive pathways, which will be useful for selective breeding of flounder strains able to adapt to n - 3 HUFA deficiency.

Effect of Dietary Vegetable Oils on the Growth Performance and Fatty Acid Composition of Fingerlings of Rainbow Trout,Oncorhynchus mykiss

This study evaluated the suitability of canola and flaxseed oils as source of supplemental dietary lipid for fingerlings of rainbow trout. Triplicate groups of the 30 fingerlings were fed twice daily by iso-nitrogenous, and iso-calorific diets for 8 weeks. Experimental diets consisted of 30.2% protein, 18.6 kJ/g energy and 16.6% lipid from fish oil, canola oil, flaxseed oil, 1:1 blends of fish and canola oils, 1:1 blends of fish and flaxseed oils, 1:1 blends of canola and flaxseed oils and 1:1:1 blends of fish, canola and flaxseed oils. Protein and lipid was significantly highest in fish fed the fish and canola oils diet. Condition factor of fingerlings reared on fish oil diet were significantly higher than other treatments. Protein efficiency ratio (PER) was significantly higher in fish fed the flaxseed oil diet and canola and flaxseed oils diet. The results of fatty acid profile revealed that flesh fatty acid composition is effected by dietary fatty acid composition. The highest amounts of HUFA n-3 were detected in fish fed fish oil diet, which was significantly different from other treatments. Present results indicate the fingerlings can be reared on diets in which fish oil has been replaced with canola and flaxseed oils.

Moderate Compared to Low Dietary Intake of trans‐Fatty Acids Impairs Strength of Old and Aerobic Capacity of Young SAMP8 Mice in Both Sexes

The senescence accelerated SAMP8 mouse is a model for sarcopenia and provides an opportunity to study the effects of lifelong dietary composition on the loss of physical function with age. We studied the effects of trans-fatty acids (2 % of total energy, TFA diet) on the loss of strength and aerobic exercise capacity (VO₂peak) with age. SAMP8 mice were studied at two ages (young, 25 weeks; old, 60 weeks) and on two diets (control vs TFA). Body composition, grip strength, VO₂peak, blood metabolites, and biochemical parameters were assessed. Body weight, fat mass, and body fat percentage all increased with age (p < 0.05) but were not significantly impacted by diet. There was a significant age-related decline in total grip strength as well as that normalized to fat-free mass (FFM) (p < 0.05) with a further decrease at old age in these metrics of strength on the TFA diet vs control diet (p < 0.05). Total VO₂peak exhibited no change with age or diet, but when normalized to FFM, VO₂peak exhibited age and TFA-related declines (p < 0.05). Intramuscular triacylglycerol (p < 0.05) and collagen content (p < 0.05) significantly increased with age, while blood triacylglycerol was increased by the TFA diet (p < 0.05). These data further characterize the SAMP8 mouse as a model for sarcopenia and indicate that dietary fatty acid composition can impact the degree of this age-related loss of physical function.

Dietary fatty acids and lipoprotein metabolism

Dyslipidemia is a powerful risk factor for cardiovascular disease (CVD). Dietary fatty acid composition regulates lipids and lipoprotein metabolism and may confer CVD benefit. This review updates understanding of the effect of dietary fatty acids on lipoprotein metabolism in humans. High dietary fish-derived n-3 polyunsaturated fatty acid (PUFA) consumption diminished hepatic triglyceride-rich lipoprotein (TRL) secretion and enhanced TRL to LDL conversion. n-3 PUFA also decreased TRL-apoB-48 concentration by decreasing TRL-apoB-48 secretion. High n-6 PUFA intake decreased liver fat, and plasma proprotein convertase subtilisin/kexin type 9, triglycerides, total-cholesterol and LDL-cholesterol concentrations. Intake of saturated fatty acids with increased palmitic acid at the sn-2 position was associated with decreased postprandial lipemia, which might be due to decreased triglyceride absorption. Replacing carbohydrate with monounsaturated fatty acids increased TRL catabolism. Ruminant trans-fatty acid decreased HDL cholesterol, but the mechanisms are unknown. A new role for APOE genotype in regulating lipid responses was also described. The major advances in understanding the effect of dietary fatty acids on lipoprotein metabolism have focused on n-3 PUFA. This knowledge provides insights into the importance of regulating lipoprotein metabolism as a mode to improve plasma lipids and potential CVD risk. Further studies are required to better understand the cardiometabolic effects of other dietary fatty acids.

Effects of dietary fatty acid composition from a high fat meal on satiety

The composition of fats within a high-fat (HF) meal may differentially affect hunger and satiety. Purpose: Compare HF meals rich in either monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), or saturated fatty acids (SFAs) on the satiety hormone, peptide YY (PYY), and subjective feelings of hunger and fullness. Methods: Fifteen normal weight women (18–45year) were randomized in a crossover design to complete three study visits. The three treatments (three visits) were HF meals (70% of energy from fat) rich in MUFAs (42% of total energy), PUFAs (42% of total energy), or SFAs (45% of total energy). At each visit, subjects consumed a HF meal and eight blood draws were collected over a 5h period. A visual analog scale (VAS) was completed at the same time as each blood draw for subjective feelings of hunger and fullness. Results: The postprandial PYY response (area under the curve) was significantly lower (p<0.05) for the MUFA-rich meal (MUFA: 534.5±27.2pg/mL/5h) vs. the SFA-rich or PUFA-rich meals (SFA: 607.3±51.6pg/mL/5h, PUFA: 633.1±35.8pg/mL/5h). The SFA-rich meal elicited greater subjective feelings of fullness compared to MUFA- and PUFA-rich meals (288.1±9.6 vs. 236.8±7.9 and 220.9±7.4mm/5h; p=0.04, for 5h AUC for SFA, MUFA, and PUFA, respectively). The only significant correlations between PYY levels and VAS measures were found with the SFA-rich meal. Conclusion: Our data shows that liquid meals rich in MUFAs may elicit a weaker satiety response based on PYY levels compared to liquid meals rich in PUFAs or SFAs in normal weight women.

Two Δ6-desaturase-like genes in common carp (Cyprinus carpio var. Jian): Structure characterization, mRNA expression, temperature and nutritional regulation

Δ6-Desaturase is the rate-limiting enzyme involved in highly unsaturated fatty acid (HUFA) biosynthesis. There is very little information on the evolution and functional characterization of Δ6Fad-a and Δ6Fad-b in common carp (Cyprinus carpio var. Jian). In the present study, the genomic sequences and structures of two putative Δ6-desaturase-like genes in common carp genome were obtained. We investigated the mRNA expression patterns of Δ6Fad-a and Δ6Fad-b in tissue, hatching carp embryos, larvae by temperature shock and juveniles under nutritional regulation. Our results showed that the two Δ6Fad genes had identical coding exon structures, being comprised of 12 coding exons, and with introns of distinct size and sequence composition. They were not allelic variants of a single gene. Both Δ6Fad genes were highly expressed in liver, intestine (pyloric caeca) and brain. The Δ6Fad-a and Δ6Fad-b mRNAs showed an increase in expression from newly hatched to 25days after hatching. The expression levels of Δ6Fad-a were obviously regulated by temperature, whereas Δ6Fad-b was not affected by temperature. The regulation of Δ6Fad-a and Δ6Fad-b in response to dietary fatty acid composition was determined in liver, brain and intestine (pyloric caeca) of common carp fed with diets: diet1with fish oil (FO) rich in n−3 HUFA, diet2 with corn oil (CO, 18:2n−6) and diet3 with linseed oil (LO, 18:3n−3). The differential expression of Δ6Fad-a and Δ6Fad-b genes in liver, brain and intestine in common carps was fed with different oil sources, respectively. Further work is in progress to determine the mechanism of differential expression of the Δ6Fad-a and Δ6Fad-b genes in different tissues and the roles of transcription factors in regulating HUFA synthesis.

Effect of Different Types of Dietary Fatty Acids on Subclinical Inflammation in Humans

Replacing SAFAs (saturated fatty acids) for vegetable PUFAs (polyunsaturated fatty acids) has a well documented positive effect on the lipoprotein pattern while the direct effect of dietary fatty acids composition on systemic inflammation remains to be proven. In well controlled randomised cross-over study with 15 overweight/obese postmenopausal women, the effect of dietary switch on systemic inflammation was investigated. A two 3 weeks dietary period either with predominant animal fat (SAFA, 29 caloric % SAFA) or vegetable fat (PUFA 25 % caloric % PUFA) were interrupted by wash-out period. The expected increasing effect on SAFA diet to LDL-C (low density cholesterol) and opposite effect of PUFA diet was documented following changes in fatty acid spectrum in VLDL (very low density cholesterol) particles. The switch from SAFA diet to PUFA diet produced a significant change of CRP (C-reactive protein) concentration (p<0.01) whereas similar trend of IL-18 did not reach statistical significance. In this study, previous in vitro results of different SAFA and PUFA proinflammatory effects with well documented molecular mechanisms were first proven in a clinical study. It could be stated that the substantial change of dietary fatty acid composition might influence proinflammatory effect in addition to traditional cardiovascular risk factors.

Effects of Trans-Fatty Acids on Liver Lipid Metabolism in Mice Fed on Diets Showing Different Fatty Acid Composition

Aim: Our aim was to investigate the effects of trans-fatty acids (TFA) on liver lipid metabolism in mice fed on experimental diets rich in either oleic or linoleic acid. Methods: Twenty-two male CF1 mice (22.0 ± 0.1 g) were fed with diets rich in corn oil or olive oil, supplemented or not with TFA (0.75 g TFA/100 g diet), for 4 weeks. Changes in triacylglycerol content, the activity and expression of enzymes involved in lipogenesis and fatty acid oxidation were measured. Results: Supplementation of an olive oil-rich diet with TFA increased liver triacylglycerols, the activity and expression of lipogenic enzymes and sterol regulatory element-binding protein SREBP-1a expression. By contrast, when TFA were added to a corn oil-rich diet, they did not modify these parameters. No significant differences were observed among the experimental groups in the activity and expression of carnitine palmitoyltransferase-Ia, body and liver weights or serum triacylglycerol concentrations. Conclusions: The effect of TFA on liver fat accumulation depends on the dietary fatty acid composition. Steatosis induced by TFA when included in an olive oil diet (but not in a corn oil diet) was associated with an increased lipogenesis but not with a decreased fatty acid oxidation in animals fed on the olive oil diet. This metabolic change is mediated by SREBP-1a but not by SREBP-1c, and seems to be independent of insulin.

High fat intake with monounsaturated fatty acids, but not n6 polyunsaturated fatty acid, increases activity of key mitochondrial oxidative enzymes in the heart

Evidence suggests that a high fat intake may be beneficial for cardiovascular health, though optimal dietary fatty acid composition is unclear. In this study, we compare the effects of a standard low fat diet (STD, 15% energy from fat) to high fat diets (40% energy from fat) comprised of monounsaturated fat (MUFA, oleate (18:1)), n6 polyunsaturated fat (PUFA, linoleic acid (18:2n6)), or saturated fat (SAT, palmitate and stearate (16:0 and 18:0)). Male rats (n=13–14/group) were fed the STD diet until 16 weeks of age and then assigned to dietary treatment for 15 weeks. Cardiac function was assessed by echocardiography and left ventricle (LV) pressure measurements and was unaffected by diet. Mitochondria were isolated from the LV and show no impact of dietary treatment on mitochondrial yield or respiration with lipid and nonlipid substrates. Mitochondrial oxidative enzyme activity in whole tissue dramatically increased with MUFA compared to STD. Citrate synthase activity increased from 105±15 μmol/g/min in STD to 157±14 in MUFA (P&lt;0.05 vs STD and PUFA), with no significant effect in PUFA (107±9) or SAT (130±11). Similar changes occurred with aconitase and long chain acyl‐CoA dehydrogenase activities. In summary, a high fat diet did not adversely impact cardiac function, increased activity of mitochondrial oxidative enzymes of the TCA cycle and fatty acid oxidation, and did not affect mitochondrial function.

A Lipidomics Analysis of the Relationship Between Dietary Fatty Acid Composition and Insulin Sensitivity in Young Adults

Relative to diets enriched in palmitic acid (PA), diets rich in oleic acid (OA) are associated with reduced risk of type 2 diabetes. To gain insight into mechanisms underlying these observations, we applied comprehensive lipidomic profiling to specimens collected from healthy adults enrolled in a randomized, crossover trial comparing a high-PA diet to a low-PA/high-OA (HOA) diet. Effects on insulin sensitivity (SI) and disposition index (DI) were assessed by intravenous glucose tolerance testing. In women, but not men, SI and DI were higher during HOA. The effect of HOA on SI correlated positively with physical fitness upon enrollment. Principal components analysis of either fasted or fed-state metabolites identified one factor affected by diet and heavily weighted by the PA/OA ratio of serum and muscle lipids. In women, this factor correlated inversely with SI in the fasted and fed states. Medium-chain acylcarnitines emerged as strong negative correlates of SI, and the HOA diet was accompanied by lower serum and muscle ceramide concentrations and reductions in molecular biomarkers of inflammatory and oxidative stress. This study provides evidence that the dietary PA/OA ratio impacts diabetes risk in women.

Detailed dimethylacetal and fatty acid composition of rumen content from lambs fed lucerne or concentrate supplemented with soybean oil.

Lipid metabolism in the rumen is responsible for the complex fatty acid profile of rumen outflow compared with the dietary fatty acid composition, contributing to the lipid profile of ruminant products. A method for the detailed dimethylacetal and fatty acid analysis of rumen contents was developed and applied to rumen content collected from lambs fed lucerne or concentrate based diets supplemented with soybean oil. The methodological approach developed consisted on a basic/acid direct transesterification followed by thin-layer chromatography to isolate fatty acid methyl esters from dimethylacetal, oxo- fatty acid and fatty acid dimethylesters. The dimethylacetal composition was quite similar to the fatty acid composition, presenting even-, odd- and branched-chain structures. Total and individual odd- and branched-chain dimethylacetals were mostly affected by basal diet. The presence of 18∶1 dimethylacetals indicates that biohydrogenation intermediates might be incorporated in structural microbial lipids. Moreover, medium-chain fatty acid dimethylesters were identified for the first time in the rumen content despite their concentration being relatively low. The fatty acids containing 18 carbon-chain lengths comprise the majority of the fatty acids present in the rumen content, most of them being biohydrogenation intermediates of 18∶2n−6 and 18∶3n−3. Additionally, three oxo- fatty acids were identified in rumen samples, and 16-O-18∶0 might be produced during biohydrogenation of the 18∶3n−3.

Measurement of Palmitoylethanolamide and Other N-Acylethanolamines During Physiological and Pathological Conditions

Palmitoylethanolamide (PEA) belongs to the N-acyl ethanolamines (NAEs), a group of endogenous compounds involved in a variety of physiological processes, including energy homeostasis and inflammation. This review focuses on the analysis of PEA in plasma and tissues and discusses effects of diet and some pathological processes on PEA levels. Originally isolated from egg yolk, PEA has been detected in a variety of tissues and plasma of different species. The compound is present at relatively high levels compared to other NAEs and now mostly analysed using liquid chromatography coupled to mass spectrometry. PEA plasma concentrations show marked fluctuations during the day. However, concentrations in tissues are likely to be more relevant than those in plasma. Most studies suggest that compared to other NAEs, tissue PEA tissue levels are not influenced by changes in dietary fatty acid composition. Effects of inflammation and disease on PEA tissue levels show differences between different models and studies. Therefore, more research is needed on the endogenous role and tissue kinetics of PEA during disease. The rediscovery of the therapeutic potential of PEA has fuelled research and the development of new pharmaceutical formulations. With regard to this there is a need for better kinetic data and models, preferably also on its tissue disposition. Moreover, it is important to learn more about effects of exogenous PEA on the kinetics of other NAEs (and endocannabinoids) and effects of inhibiting its breakdown using inhibitors of the degrading enzymes fatty acid amide hydrolase or N-acylethanolamine-hydrolyzing acid amidase.