Abstract Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the USA are enriched in soybean oil, composed of unsaturated fatty acids (FAs), either linoleic or oleic acid. Here we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high (HF) or low (LF) in high-linoleic-acid soybean oil as the sole source of fat. All mice, including germfree, gained relative fat weight and consumed more calories on the HF versus LF soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso -C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet, and show that microbial colonization influences liver sphingolipid pools.
Objective To investigate nutritional treatment in the intensive care unit (ICU) of the mainland China. Methods A cross-sectional study was conducted in 116 ICUs of 118 mainland hospitals on April 26th, 2017. All patients of these ICUs were investigated at 0 o'clock on April 26th. Demographic and clinical parameters of those patients on April 25th (the investigation day) were recorded, including the dates of hospitalization, ICU admission and nutrition initiation and clinical outcome on 28 days after the investigation day. Results A total of 1953 patients were collected, including 631 females and 1306 males. The mean age was (64.1±19.3) years old (1950 cases). The means of Glasgow Coma Scale (GCS), Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation Ⅱ (APACHEⅡ) scores were (10.76±4.35)(1749 cases), (5.65±3.52)(1783 cases), (17.14±7.31)(1792 cases), respectively. The outcomes of 28 days after the investigation day were 1483 survivors (75.9%), 312 non-survivors (16.0%) and 158 cases (8.1%) being lost to follow-up. There were no significant differences between the males and the females in age, severity of disease and clinical outcomes of 28 days but in height and weight. There were 73.7%(1440 cases) of patients with normal or mildly injured gastrointestinal function, 10.8%(210 cases) with moderately or severely injured function, 1.7%(33 cases) with gastrointestinal failure and 13.2%(258 cases) without evaluation. To the investigation day, enteral nutrition (EN) had been initiated in 69.4%(1356 cases) of patients and parenteral nutrition (PN) in 36.4%(711 cases) of patients. There were 1720(88.1%) patients with EN administration on the investigation day. The proportion of patients with nausea, vomit/regurgitation, aspiration, abdominal pain, abdominal distention and diarrhea was 4.8%(93 cases), 5.4%(105 cases), 0.9%(17 cases), 8.7%(170 cases), 27.5%(538 cases) and 4.3%(84 cases) respectively, while that of patients using EN was 3.1%(40 cases), 4.25%(54 cases), 0.79%(10 cases), 4.41%(56 cases), 26.85%(341 cases) and 5.43%(69 cases) correspondingly. The proportion of cases starting EN within 24, 48 and 72 hours after ICU entry was 22.4%(437/1953), 38.6%(754/1953) and 46.6%(911/1953), respectively. The proportion of cases receiving ≥80% estimated energy target (=past body weight ×25 kcal/kg.d) within 3, 7 and 14 days after ICU entry was 12.9%(78/607), 18.7%(189/1010) and 23%(305/1325) respectively, while that of cases with EN was 9.9%(60/607), 15.0%(151/1010) and 18.6%(246/1325) correspondingly. Conclusions Nowadays, most of patients in the mainland ICUs receive nutrition therapy and the EN usage rate is much higher than the PN rate. However, the time of EN initiation and the target-reaching rate of energy are suboptimal and an individualized plan of nutrition therapy is still missing. Details of energy delivery still need to be improved.
DOI: 10.11855/j.issn.0577-7402.2019.05.05
Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the United States America are enriched in soybean oil, composed of unsaturated fatty acids, either linoleic or oleic acid. Here, we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high or low in high-linoleic-acid soybean oil as the sole source of fat. Conventional and germfree mice gained relative fat weight and all mice consumed more calories on the high fat vs. low fat soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso-C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet and that microbial colonization influences liver sphingolipid pools regardless of diet.
Fatty acid analysis of food lipids containing branched chain fatty acids (BCFAs) are complex because of unavoidable gas chromatography (GC) co-elution. We demonstrate a method for convenient quantitative GC coupled to novel solvent-mediated chemical ionization (CI) mass spectrometry (MS) that enables resolution of co-eluting peaks by mass. The relevant masses yield uniform responses for C14-20 normal fatty acids and BCFAs, eliminating the need for rare purified BCFA standards essential for unpredictable responses, as for electron ionization (EI). CI-tandem mass spectrometry analysis of MH+ yields fragments characteristic of the branch position. Application of the measurement to BCFAs in salami samples demonstrates consistent results for the novel method and EI-MS. A higher proportion of C17-18 BCFAs was found in beef compared to milkfat, possibly indicative of fatty acid elongation, endogenous in the beef animal. This method enables straightforward structure elucidation and quantification of food BCFAs and similar chain length normal fatty acids without purified standards.
Saturated branched chain fatty acids (BCFA) terminating with either a prop‐2‐yl ( iso ) or sec‐butan‐2‐yl ( anteiso ) group are common bioactive food components consumed from beef, fish, and dairy products. Little is known about the endogenous metabolism of BCFA and the enzymes mediating their interconversions. By using transient transfection studies, we report for the first time the substrate specificity of the elongase of very long chain fatty acids (ELOVL)1‐7 toward anteiso ‐15:0 and iso ‐18:0, and assessed competition between BCFA and normal saturated fatty acids (n‐SFA). ELOVL6 mediates elongation of anteiso ‐15:0→ anteiso ‐17:0, while ELOVL3 is active toward iso ‐18:0→ iso ‐20:0. Competition studies reveal n‐16:0 competes with anteiso ‐15:0 for ELOVL6, while n‐18:0 competes with iso ‐18:0 for ELOVL3. These competitions for elongation may have implications in specialized tissues where both BCFA and n‐SFA are present at comparable levels.
Vernix caseosa, the white waxy coating found on newborn human skin, is thought to be a uniquely human substance. Its signature characteristic is exceptional richness in saturated branched chain fatty acids (BCFA) and squalene. Vernix particles sloughed from the skin suspended in amniotic fluid are swallowed by the human fetus, depositing BCFA/squalene throughout the gastrointestinal (GI) tract, thereby establishing a unique microbial niche that influences development of nascent microbiota. Here we show that late-term California sea lion (Zalophus californianus) fetuses have true vernix caseosa, delivering BCFA and squalene to the fetal GI tract thereby recapitulating the human fetal gut microbial niche. These are the first data demonstrating the production of true vernix caseosa in a species other than Homo sapiens. Its presence in a marine mammal supports the hypothesis of an aquatic habituation period in the evolution of modern humans.
The biological functions of fatty acids and the lipids in which they are esterified are determined by their chain length, double bond position and geometry and other structural motifs such as the presence of methyl branches. Unusual isomeric features in fatty acids of human foods such as conjugated double bonds or chain branching found in dairy products, some seeds and nuts, and marine foods potentially have important effects on human health. Recent advancements in identifying fatty acids with unusual double bond positions and pinpointing the position of methyl branches have empowered the study of their biological functions. We present recent advances in fatty acid structural elucidation by mass spectrometry in comparison with the more traditional methods. The double bond position can be determined by purely instrumental methods, specifically solvent-mediated covalent adduct chemical ionization (SM-CACI) and ozone induced dissociation (OzID), with charge inversion methods showing promise. Prior derivatization using the Paternò-Büchi (PB) reaction to yield stable structures that, upon collisional activation, yield the double bond position has emerged. The chemical ionization (CI) based three ion monitoring (MRM) method has been developed to simultaneously identify and quantify low-level branched chain fatty acids (BCFAs), unattainable by electron ionization (EI) based methods. Accurate identification and quantification of unusual fatty acid isomers has led to research progress in the discovery of biomarkers for cancer, diabetes, nonalcoholic fatty liver disease (NAFLD) and atherosclerosis. Modulation of eicosanoids, weight loss and the health significance of BCFAs are also presented. This review clearly shows that the improvement of analytical capacity is critical in the study of fatty acid biological functions, and stronger coupling of the methods discussed here with fatty acid mechanistic research is promising in generating more refined outcomes.
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