Adaptations of Skeletal Muscle Mitochondria to Obesity,Exercise, and Polyunsaturated Fatty Acids

Mitochondria intricately modulate their energy production through the control of mitochondrial adaptation (mitochondrial biogenesis, fusion, and/or fission) to meet energy demands. Nutrient overload may result in dysregulated mitochondrial biogenesis, morphology toward mitochondrial fragmentation, and oxidative stress in the skeletal muscle. In addition, physical activity and diet components influence mitochondrial function. Exercise may stimulate mitochondrial biogenesis and promote mitochondrial fusion/fission in the skeletal muscle. Moreover, some dietary fatty acids, such as n‐3 polyunsaturated fatty acids and conjugated linoleic acid, have been identified to positively regulate mitochondrial adaptation in the skeletal muscle. This review discusses the association of mitochondrial impairments and obesity, and presents an overview of various mechanisms of which exercise training and mitochondrial nutrients promote mitochondrial function in the skeletal muscle.     

Dietary Supplementation of Calcium may Counteract Obesity in Mice Mediated by Changes in Plasma Fatty Acids

The scope of this study was to assess the impact of calcium and conjugated linoleic acid (CLA) supplementation on plasma fatty acid profiles and to evaluate potential synergistic effects of both compounds against dietary obesity. Mice separated into five experimental groups were followed: control (C), high-fat diet (HF), HF with calcium (Ca), HF plus CLA and HF with both Ca and CLA. Plasma metabolites and fatty acids were determined by commercial kits and gas chromatography, respectively. Both dietary calcium and CLA supplementation contributed to lower body fat gain under a HF diet. Maximum efficacy was seen with calcium; no additional effect was associated with the combined treatment with CLA. Plasma leptin, adiponectin and HOMA index were in accordance with an altered glucose/insulin homeostasis in the HF and HF + CLA groups, whereas control levels were attained under Ca-enriched diets. Plasma fatty acids showed minor changes associated to CLA treatment, but a high impact on PUFA was observed under Ca-enriched diets. Our results show that the mechanism underlying the anti-obesity effects of calcium supplementation is mediated mainly by changes in PUFA plasma profile. In addition, the lack of synergy on body weight reduction in combination with associated lipid profiles of calcium and CLA suggests that calcium may interfere with absorption and/or bioactivity of CLA, which can be of relevance when using CLA-fortified dairy products against human obesity.     

Natural Rumen‐Derived trans Fatty Acids Are Associated with Metabolic Markers of Cardiac Health

Evidence suggests that industrial trans fatty acids (iTFA) impair lipid profiles while ruminant trans fatty acids (rTFA) may lower insulin resistance and blood pressure. The objective of this article was to determine if the plasma phospholipid percentage of rTFA is associated with a favorable cardiometabolic profile. We collected fasting blood samples from 200 individuals from Quebec city (QC, Canada) aged from 18 to 55 years old, including 100 obese (BMI ≥ 30 kg m^?2) and 100 non‐obese (BMI < 30 kg m^?2) men and women. Fatty acid levels in plasma phospholipids were determined using gas chromatography. After separating the subjects into two groups, according to the median percentage of rTFA in plasma phospholipids, participants in the group with higher percentages of rTFA (0.86 ± 0.24 %) had higher adiponectin levels (p = 0.01) and a lower blood pressure (systolic, p = 0.005; diastolic, p = 0.04). In contrast, concentrations in plasma phospholipids of elaidic acid, a major iTFA, are positively correlated with glycemia in non‐obese subjects (p = 0.01) and with both triacylglycerol (TAG) (p = 0.0007) and total cholesterol (TC) (p = 0.009) in obese subjects. These data suggest that rTFA may have beneficial effects on cardiometabolic risk factors conversely to their counterpart iTFA. Dietary sources of TFA should be taken into account in future cardiometabolic studies.     

N-3 Polyunsaturated Fatty Acids: Relationship to Inflammation in Healthy Adults and Adults Exhibiting Features of Metabolic Syndrome

Individuals with metabolic syndrome (MetS) have a higher risk of type 2 diabetes and cardiovascular disease, therefore, research has been directed at reducing various components that contribute to MetS and associated metabolic impairments, including chronic low-grade inflammation. Epidemiological, human, animal and cell culture studies provide evidence that dietary n-3 polyunsaturated fatty acids (n-3 PUFA), including alpha-linolenic acid (18:3n-3, ALA), eicosapentaenoic acid (20:5n-3, EPA) and/or docosahexaenoic acid (22:6n-3, DHA) may improve some of the components associated with MetS. The current review will discuss recent evidence from human observational and intervention studies that focused on the effects of ALA, EPA or DHA on inflammatory markers in healthy adults and those with one or more features of MetS. Observational studies in healthy adults support the recommendation that a diet rich in n-3 fatty acids may play a role in preventing and reducing inflammation, whereas intervention studies in healthy adults have yielded inconsistent results. The majority of intervention studies in adults with features of MetS have reported a benefit for some inflammatory measures; however, other studies using high n-3 fatty acid doses and long supplementation periods have reported no effect. Overall, the data reviewed herein support recommendations for regular fatty fish consumption and point toward health benefits in terms of lowering inflammation in adults with one or more features of MetS.     

Polyunsaturated Fatty Acids and Modulation of Cholesterol Homeostasis in THP-1 Macrophage-Derived Foam Cells

Transformation of macrophages to foam cells is determined by the rates of cholesterol uptake and efflux. This study uses a real time RT-PCR technique to investigate the role of conjugated linoleic acid (CLA), α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) in the regulation of the ATP-binding cassette A1 (ABCA1) and liver X receptor α (LXR) genes, which are involved in cholesterol homeostasis. Accordingly, these fatty acids significantly reduced the total, free and esterified cholesterols within the foam cells. While the expression of the ABCA1 and LXRα genes was increased in the presence of the pharmacological LXRα ligand, T0901317, their mRNA expression was not significantly affected by CLA, ALA and EPA. These results suggest that although polyunsaturated fatty acids have an effect on cholesterol homeostasis, they cannot change the expression of the ABCA1 and LXRα genes. Alternatively, several other genes and proteins may be involved.     

Distribution of Glycolipid and Unsaturated Fatty Acids in Human Hair

It has been recognized that human hair lipids play crucial roles in the integrity of cells and matrices, while the details of distribution and structure of the minor lipids are hardly known. Here we investigated the lipids at the hair surface, at the interface between cuticle and cortex and in the interior of hair (cortex, medulla and melanin granules). Hair lipids and fatty acids and their metabolites were detected and characterized by using infrared spectroscopy and several mass spectrometry techniques (FTIR, ToF–SIMS, GCMS, and ESI–MS). As a result, it was found that unsaturated fatty acids were present more in the cortex of hair than at the hair surface. At the interface between cuticle and cortex, it is suggested that steryl glycoside‐like lipids containing N‐acetylglucosamine were present, and contributing to the adhesion between the cuticle and cortex of hair. Oxidative metabolites derived from integral fatty acids such as linoleic and alpha‐linolenic acids were found in the hair bulb and melanin granules. Especially the oxidative metabolites of alpha‐linolenic acid were integrated into the lipids non‐covalently and tightly bound to melanin granules (namely, melanin lipids) and suggested as being involved in the biosynthetic processes of melanosome.     

Enzymatic Modification of Anhydrous Milkfat with n-3 and n-6 Fatty Acids for Potential Use in Infant Formula: Comparison of Methods

A structured lipid (SL) with a high amount of sn‐2 palmitic acid was synthesized from anhydrous milkfat and was then enriched with docosahexaenoic (DHA) and arachidonic (ARA) acids using an immobilized lipase. Three different methods were compared including physical blending, enzymatic interesterification, and enzymatic acidolysis. Products were compared with respect to differences in fatty acid profiles, reaction times, antioxidant contents, oxidative stability, melting and crystallization profiles, and reaction yields. The acidolysis method was the least suitable for the synthesis of desired product because of a low reaction yield, low incorporation of DHA, low oxidative stability, and the extra processing steps required. The physical blending and interesterification methods were suitable, but the interesterification product (IE‐SL) had higher amounts of ARA at the sn‐2 position. The IE‐SL contained total ARA and DHA of 0.63 and 0.50 mol%, and 0.55 and 0.46 mol% at the sn‐2 position, respectively. The IE‐SL also contained 44.97 mol% sn‐2 palmitic acid. The reaction yield for the IE‐SL was 91.84 %, and its melting completion and crystallization onset temperatures were 43.1 and 27.1 °C, respectively. This SL might be totally or partially used in commercial fat blends for infant formula.