Measuring oral fatty acid thresholds, fat perception, fatty food liking, and papillae density in humans

Oral chemoreception of fatty acids and the association with diet and fatty food preferences may enable the identification of mechanisms involved with the development of obesity and why dietary changes may be difficult for many individuals.

Oral fatty acid sensitivity and dietary fat consumption

Lisa investigated the taste of fat and its influence on excess fat consumption and obesity. This research established that taste sensitivity to fat can be modulated by fat intake and may be used as an obesity prevention tool in the future.

Characterisation of lipase fatty acid selectivity using novel omega-3 pNP-acyl esters

 Lipases have applications for the industrial processing of lipids, including concentrating and/or modifying fish oil derived omega-3 fatty acids, widely used as nutritional supplement and functional food ingredients. A range of para-nitrophenol (pNP) acyl esters were synthesised as a means to rapidly screen lipases for fatty acid selectivity using spectrophotometric detection. The chosen esters were based primarily on the most abundant fatty acids present in anchovy and tuna oils. pNP derivatives of C16:1 n-7, C18:1 n-9 (OA), C18:2 n-6 (LA), C18:3 n-3 (ALA), C20:5 n-3 (EPA) and C22:6 n-3 (DHA) were synthesised. Storage stability of these pNP derivatives was shown to be at least 6 months and all pNP derivatives, including those of EPA and DHA, were shown to be stable throughout the conditions of the assay. We applied the new assay substrates for the determination of fatty acid selectivity of five widely utilised lipases. Results showed that the lipase from Candida rugosa was the most selective in terms of omega-3 specificity, preferentially hydrolysing all other medium– long chain substrates. Lipases from Rhizomucor miehei and Thermomyces lanuginosa also showed selectivity, with a significant preference for saturated fatty acids. Candida Antarctica lipase B and Aspergillus niger lipase were the least selective.

Identification of fatty acid translocase on human skeletal muscle mitochondrial membranes: essential role in fatty acid oxidation

Fatty acid translocase (FAT/CD36) is a transport protein with a high affinity for long-chain fatty acids (LCFA). It was recently identified on rat skeletal muscle mitochondrial membranes and found to be required for palmitate uptake and oxidation. Our aim was to identify the presence and elucidate the role of FAT/CD36 on human skeletal muscle mitochondrial membranes. We demonstrate that FAT/CD36 is present in highly purified human skeletal mitochondria. Blocking of human muscle mitochondrial FAT/CD36 with the specific inhibitor sulfo-N-succimidyl-oleate (SSO) decreased palmitate oxidation in a dose-dependent manner. At maximal SSO concentrations (200 μM) palmitate oxidation was decreased by 95% (P < 0.01), suggesting an important role for FAT/CD36 in LCFA transport across the mitochondrial membranes. SSO treatment of mitochondria did not affect mitochondrial octanoate oxidation and had no effect on maximal and submaximal carnitine palmitoyltransferase I (CPT I) activity. However, SSO treatment did inhibit palmitoylcarnitine oxidation by 92% (P < 0.001), suggesting that FAT/CD36 may be playing a role downstream of CPT I activity, possibly in the transfer of palmitoylcarnitine from CPT I to carnitine-acylcarnitine translocase. These data provide new insight regarding human skeletal muscle mitochondrial fatty acid (FA) transport, and suggest that FAT/CD36 could be involved in the cellular and mitochondrial adaptations resulting in improved and/or impaired states of FA oxidation.

Rapid discrimination and determination of polyunsaturated fatty acid composition in marine oils by FTIR Spectroscopy and Multivariate Data Analysis

A rapid analytical approach for discrimination and quantitative determination of polyunsaturated fatty acid (PUFA) contents, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in a range of oils extracted from marine resources has been developed by using attenuated total reflection Fourier transform infrared spectroscopy and multivariate data analysis. The spectral data were collected without any sample preparation; thus, no chemical preparation was involved, but data were rather processed directly using the developed spectral analysis platform, making it fast, very cost effective, and suitable for routine use in various biotechnological and food research and related industries. Unsupervised pattern recognition techniques, including principal component analysis and unsupervised hierarchical cluster analysis, discriminated the marine oils into groups by correlating similarities and differences in their fatty acid (FA) compositions that corresponded well to the FA profiles obtained from traditional lipid analysis based on gas chromatography (GC). Furthermore, quantitative determination of unsaturated fatty acids, PUFAs, EPA and DHA, by partial least square regression analysis through which calibration models were optimized specifically for each targeted FA, was performed in both known marine oils and totally independent unknown n - 3 oil samples obtained from an actual commercial product in order to provide prospective testing of the developed models towards actual applications. The resultant predicted FAs were achieved at a good accuracy compared to their reference GC values as evidenced through (1) low root mean square error of prediction, (2) good coefficient of determination close to 1 (i.e., R 2≥ 0.96), and (3) the residual predictive deviation values that indicated the predictive power at good and higher levels for all the target FAs. © 2014 Springer Science+Business Media New York.

Hydroxyoctadecadienoic acids regulate apoptosis in human THP-1 cells in a PPARγ-dependent manner

Macrophage apoptosis, a key process in atherogenesis, is regulated by oxidation products, including hydroxyoctadecadienoic acids (HODEs). These stable oxidation products of linoleic acid (LA) are abundant in atherosclerotic plaque and activate PPARγ and GPR132. We investigated the mechanisms through which HODEs regulate apoptosis. The effect of HODEs on THP-1 monocytes and adherent THP-1 cells were compared with other C18 fatty acids, LA and α-linolenic acid (ALA). The number of cells was reduced within 24 hours following treatment with 9-HODE (p < 0.01, 30 μM) and 13 HODE (p < 0.01, 30 μM), and the equivalent cell viability was also decreased (p < 0.001). Both 9-HODE and 13-HODE (but not LA or ALA) markedly increased caspase-3/7 activity (p < 0.001) in both monocytes and adherent THP-1 cells, with 9-HODE the more potent. In addition, 9-HODE and 13-HODE both increased Annexin-V labelling of cells (p < 0.001). There was no effect of LA, ALA, or the PPARγ agonist rosiglitazone (1μM), but the effect of HODEs was replicated with apoptosis-inducer camptothecin (10μM). Only 9-HODE increased DNA fragmentation. The pro-apoptotic effect of HODEs was blocked by the caspase inhibitor DEVD-CHO. The PPARγ antagonist T0070907 further increased apoptosis, suggestive of the PPARγ-regulated apoptotic effects induced by 9-HODE. The use of siRNA for GPR132 showed no evidence that the effect of HODEs was mediated through this receptor. 9-HODE and 13-HODE are potent—and specific—regulators of apoptosis in THP-1 cells. Their action is PPARγ-dependent and independent of GPR132. Further studies to identify the signalling pathways through which HODEs increase apoptosis in macrophages may reveal novel therapeutic targets for atherosclerosis.

Is fat the sixth taste primary? Evidence and implications

Taste is the chemical sense responsible for the detection of non-volatile chemicals in potential foods. For fat to be considered as one of the taste primaries in humans, certain criteria must be met including: class of affective stimuli; receptors specific for the class of stimuli on taste bud cells (TBC); afferent fibers from TBC to taste processing regions of the brain; perception independent of other taste qualities; and downstream physiological effects. The breakdown products of the macronutrients carbohydrates (sugars) and protein (amino acids) are responsible for activation of sweet and umami tastes respectively. Following the same logic the breakdown products of fat being fatty acids are the likely class of stimuli for fat taste. Indeed, psychophysical studies have confirmed fatty acids of varying chain length and saturation are orally detectable by humans. The most likely fatty acid receptor candidates located on TBC are CD36, G protein-coupled receptor 120. Once the receptors are activated by fatty acids a series of transduction events occurs causing the release of neurotransmitters towards afferent fibers signalling the brain. Whether fatty acids elicit any direct perception independent of other taste qualities is still open to debate with only poorly defined perceptions for fatty acids reported. Others suggest that the fatty acid taste component is at detection threshold only and any perceptions are associated with either aroma or chemesthesis. It has also been established that oral exposure to fat via sham feeding stimulates increases blood triacylglycerol concentrations in humans. Therefore, overall, with the exception of an independent perception, there is consistent emerging evidence that fat is the sixth taste primary. The implications of fatty acid taste go further into health and obesity research with the gustatory detection of fats and their contributions to energy and fat intake receiving increasing attention. There appears to be a coordinated bodily response to fatty acids throughout the alimentary canal; those who are insensitive orally are also insensitive in the gastrointestinal tract and overconsume fatty food and energy. The likely mechanism linking fatty acid taste insensitivity with overweight and obesity is development of satiety after consumption of fatty foods.

Fatty acid-specific alterations in leptin, PPARα, and CPT-1 gene expression in the rainbow trout

It is known that fatty acids (FA) regulate lipid metabolism by modulating the expression of numerous genes. In order to gain a better understanding of the effect of individual FA on lipid metabolism related genes in rainbow trout (Oncorhynchus mykiss), an in vitro time-course study was implemented where twelve individual FA (butyric 4:0; caprylic 8:0; palmitic (PAM) 16:0; stearic (STA) 18:0; palmitoleic16:1n-7; oleic 18:1n-9; 11-cis-eicosenoic 20:1n-9; linoleic (LNA) 18:2n-6; α-linolenic (ALA) 18:3n-3; eicosapentenoic (EPA) 20:5n-3; docosahexaenoic (DHA) 22:6n-3; arachidonic (ARA) 20:4n-6) were incubated in rainbow trout liver slices. The effect of FA administration over time was evaluated on the expression of leptin, PPARα and CPT-1 (lipid oxidative related genes). Leptin mRNA expression was down regulated by saturated fatty acids (SFA) and LNA, and was up regulated by monounsaturated fatty acids (MUFA) and long chain PUFA, whilst STA and ALA had no effect. PPARα and CPT-1mRNA expression were up regulated by SFA, MUFA, ALA, ARA and DHA; and down regulated by LNA and EPA. These results suggest that there are individual and specific FA induced modifications of leptin, PPARα and CPT-1 gene expression in rainbow trout, and it is envisaged that such results may provide highly valuable information for future practical applications in fish nutrition.

Observable essential fatty acid deficiency markers and autism spectrum disorder

Autism Spectrum Disorder (ASD) has been associated with essential fatty acid (EFA) deficiencies, with some researchers theorising that dysregulation of phospholipid metabolism may form part of the biological basis for ASD. This pilot study compared observable signs of fatty acid status of 19 children with an ASD diagnosis to 23 of their typically developing siblings. A pregnancy, birth and breastfeeding history was also obtained from their parents, which included a measure of infant intake of fatty acid rich colostrum immediately post-partum. When considered within their family group, those infants not breastfed (with colostrum) within the first hour of life and who had a history of fatty acid deficiency symptoms were more likely to have an ASD diagnosis. Other variables such as formula use, duration of breastfeeding, gestational age and Apgar scores were not associated with group membership. The results of this study are consistent with previous research showing a relationship between fatty acid metabolism, breastfeeding and ASD such that early infant feeding practices and the influence this has on the fatty acid metabolism of the child may be a risk factor for ASD.

Omega-3 fatty acid production from enzyme saccharified hemp hydrolysate using a novel marine thraustochytrid strain

In this work, a newly isolated marine thraustochytrid strain, Schizochytrium sp. DT3, was used for omega-3 fatty acid production by growing on lignocellulose biomass obtained from local hemp hurd (Cannabis sativa) biomass. Prior to enzymatic hydrolysis, hemp was pretreated with sodium hydroxide to open the biomass structure for the production of sugar hydrolysate. The thraustochytrid strain was able to grow on the sugar hydrolysate and accumulated polyunsaturated fatty acids (PUFAs). At the lowest carbon concentration of 2%, the PUFAs productivity was 71% in glucose and 59% in the sugars hydrolysate, as a percentage of total fatty acids. Saturated fatty acids (SFAs) levels were highest at about 49% of TFA using 6% glucose as the carbon source. SFAs of 41% were produced using 2% of SH. This study demonstrates that SH produced from lignocellulose biomass is a potentially useful carbon source for the production of omega-3 fatty acids in thraustochytrids, as demonstrated using the new strain, Schizochytrium sp. DT3.