Milk Odd and Branched Chain Fatty Acids in Dairy Cows: A Review on Dietary Factors and its Consequences on Human Health

This review highlights the importance of odd and branched chain fatty acids (OBCFAs) and dietary factors that may affect the content of milk OBCFAs in dairy cows. Historically, OBCFAs in cow milk had little significance due to their low concentrations compared to other milk fatty acids (FAs). The primary source of OBCFAs is ruminal bacteria. In general, FAs and OBCFAs profile in milk is mainly affected by dietary FAs and FAs metabolism in the rumen. Additionally, lipid mobilization in the body and FAs metabolism in mammary glands affect the milk OBCFAs profile. In cows, supplementation with fat rich in linoleic acid and α-linolenic acid decrease milk OBCFAs content, whereas supplementation with marine algae or fish oil increase milk OBCFAs content. Feeding more forage rather than concentrate increases the yield of some OBCFAs in milk. A high grass silage rate in the diet may increase milk total OBCFAs. In contrast to saturated FAs, OBCFAs have beneficial effects on cardiovascular diseases and type II diabetes. Furthermore, OBCFAs may have anti-cancer properties and prevent Alzheimer’s disease and metabolic syndrome.

The intestinal circadian clock drives microbial rhythmicity to maintain gastrointestinal homeostasis

Diurnal (i.e., 24-hour) oscillations of the gut microbiome have been described in various species including mice and humans. However, the driving force behind these rhythms remains less clear. In this study, we differentiate between endogenous and exogenous time cues driving microbial rhythms. Our results demonstrate that fecal microbial oscillations are maintained in mice kept in the absence of light, supporting a role of the hosts circadian system rather than representing a diurnal response to environmental changes. Intestinal epithelial cell-specific ablation of the core clock gene Bmal1 disrupts rhythmicity of microbiota. Targeted metabolomics functionally link intestinal clock-controlled bacteria to microbial-derived products, in particular branched-chain fatty acids and secondary bile acids. Microbiota transfer from intestinal clock-deficient mice into germ-free mice altered intestinal gene expression, enhanced lymphoid organ weights and suppressed immune cell recruitment. These results highlight the importance of functional intestinal clocks for circadian microbiota composition and function, which is required to balance the hosts gastrointestinal homeostasis.

mmBCFA C17iso ensures endoplasmic reticulum integrity for lipid droplet growth

In eukaryote cells, lipid droplets (LDs) are key intracellular organelles that dynamically regulate cellular energy homeostasis. LDs originate from the ER and continuously contact the ER during their growth. How the ER affects LD growth is largely unknown. Here, we show that RNAi knockdown of acs-1, encoding an acyl-CoA synthetase required for the biosynthesis of monomethyl branched-chain fatty acids C15iso and C17iso, remarkably prevented LD growth in Caenorhabditis elegans. Dietary C17iso, or complex lipids with C17iso including phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol, could fully restore the LD growth in the acs-1RNAi worms. Mechanistically, C17iso may incorporate into phospholipids to ensure the membrane integrity of the ER so as to maintain the function of ER-resident enzymes such as SCD/stearoyl-CoA desaturase and DGAT2/diacylglycerol acyltransferase for appropriate lipid synthesis and LD growth. Collectively, our work uncovers a unique fatty acid, C17iso, as the side chain of phospholipids for determining the ER homeostasis for LD growth in an intact organism, C. elegans.

PSXV-25 Effects of multiple grass-fed and grain-fed beef systems on meat fatty acid composition

Retail sales of labeled fresh grass-fed beef in the U.S. have grown from $17 million in 2012 to $272 million in 2016. The objective of present study was to investigate the effect of four typical grass-fed and conventional beef systems raised in the western United States on beef fatty-acid composition. Treatments included: 1) steers stocked on pasture then finished in a feedyard (CON), 2) steers grass-fed for 20 months (GF20), 3) steers grass-fed for 20 months with a 45-day grain finish (GR45), and 4) steers grass-fed for 25 months (GF25). Fatty acids were analyzed with GC using a 100 m CPSil 88 capillary column. All statistical analyses were performed using a GLM procedure in R. Saturated fatty acid (SFA) concentrations were significantly different across treatments (P < 0.05) with GR45 having the lowest SFA of 43% and GF25 having the highest SFA at 46%. Cis-monounsaturated fatty acid (c-MUFA) particularly oleic acid, which is known as a heart healthy fatty acids, were highest for CON at 44% and lowest for GF20 at 37% (P < 0.05). Conjugated linoleic acids (CLA) were significantly lower for the grain-fed treatments (0.54 CON and 0.63 GR45; P < 0.05) compared to grass-fed treatments (0.93 GF20 and 0.86 GF25; P < 0.05). The grass-fed treatments were higher in n-3 PUFA (3.67 GF20 and 2.29 GF25) than CON (0.79; P < 0.05), however feeding grain for a short period of time did not decrease n-3 PUFA concentrations to the CON level (GF45 2.51; P < 0.05). In conclusion, our findings show that beef from grain-fed beef management systems is higher in c-MUFA, while grass-fed is significantly higher in bioactive fatty acids including CLA and branched chain fatty acids. Additional studies are needed to determine if fatty acid profiles between grass-fed and grain-fed beef would result in different health outcomes for the consumers.

Profiles of Odd- and Branched-Chain Fatty Acids and Their Correlations With Rumen Fermentation Parameters, Microbial Protein Synthesis, and Bacterial Populations Based on Pure Carbohydrate Incubation in vitro

The objectives of this study were to evaluate changes in profiles of odd- and branched-chain fatty acids (OBCFA), including pentadecanoic acid (C15:0), 13-methyltetradecanoic acid (iso-C15:0), 12-methyltetradecanoic acid (anteiso-C15:0), 14-methylpentadecanoic acid (iso-C16:0), heptadecanoic acid (C17:0), 15-methylhexadecanoic acid (iso-C17:0), and 14-methylhexadecanoic acid (anteiso-C17:0) during in vitro fermentation of pure carbohydrates mixtures in the buffer-rumen fluid. The second objective was to correlate the changes in the OBCFA profile to the corresponding changes in ruminal fermentation parameters, microbial crude protein (MCP) synthesis, and bacterial populations. Five pure carbohydrates mixtures containing different cellulose: starch (C:S) ratios, i.e., 0:100, 25:75, 50:50, 75:25, and 100:0, were incubated for 6, 12, 18, and 24 h in vitro. The results showed that there was significant interaction (P < 0.05) between C:S and incubation time for changes in all OBCFA profiles, except iso-C17:0. The highest concentration of total OBCFA (3.94 mg/g dry matter; DM) was observed in the residues after 24 h of fermentation when the C:S was 0:100, while the lowest concentration of OBCFA (1.65 mg/g DM) was produced after 6 h of incubation when the C:S was 50:50. The correlation analysis revealed that the concentration of iso-C16:0 might be a potential marker for the estimation of total volatile fatty acids (ρ = 0.78) and MCP synthesis (ρ = 0.82) in the rumen. Compared to starch degrading bacteria, cellulolytic bacteria had stronger correlations with OBCFA concentrations, and the strongest correlation was found between the population of Ruminococcus flavefaciens with C15:0 concentration (ρ = 0.70). Notably, this is the first paper reporting relationship between OBCFA with rumen fermentation products and microbial protein synthesis based on fermentation of pure carbohydrates mixtures in vitro, and thus avoid confounding interference from dietary protein and fat presence in the in vivo studies. However, more in-depth experiments are needed to substantiate the current findings.

Functional Genomic Insights into Probiotic Bacillus siamensis Strain B28 from Traditional Korean Fermented Kimchi

Bacillus siamensis strain B28 was previously isolated from traditional Korean fermented kimchi and inhibited expression of the microphthalmia-associated transcription factor and β-catenin in human embryonic kidney 293 cells. Here, we determined the complete genome sequence of strain B28 and compared it with other strains to elucidate its potential probiotic properties. Strain B28 does not contain antibiotic resistance-, hemolysin- or enterotoxin-encoding genes. The genome includes genes related to survival in extreme conditions, adhesion in the gut, and synthesis of the bacteriocin. Considering the potential for enhancement of human health, the strain B28 genome encodes genes related to production of eight essential amino acids, γ-aminobutyric acid, branched-chain fatty acids, γ-glutamyltransferase, and subtilisin. There are genes for the synthesis of uracil, lipoteichoic acid, glutathione, and several reactive oxygen species-scavenging enzymes. Experimentally, strain B28 exhibited sensitivity to eight antibiotics and antibacterial activity against seven foodborne pathogens. B. siamensis B28 is a safe strain with potential for development as a probiotic.

Chicken-eaters and pork-eaters have different gut microbiota and tryptophan metabolites

This study was aimed to evaluate the differences in the composition of gut microbiota, tryptophan metabolites and short-chain fatty acids in feces between volunteers who frequently ate chicken and who frequently ate pork. Twenty male chicken-eaters and 20 male pork-eaters of 18 and 30 years old were recruited to collect feces samples for analyses of gut microbiota composition, short-chain fatty acids and tryptophan metabolites. Chicken-eaters had more diverse gut microbiota and higher abundance of Prevotella 9, Dialister, Faecalibacterium, Megamonas, and Prevotella 2. However, pork-eaters had higher relative abundance of Bacteroides, Faecalibacterium, Roseburia, Dialister, and Ruminococcus 2. In addition, chicken-eaters had high contents of skatole and indole in feces than pork-eaters, as well as higher contents of total short chain fatty acids, in particular for acetic acid, propionic acid, and branched chain fatty acids. The Spearman’s correlation analysis revealed that the abundance of Prevotella 2 and Prevotella 9 was positively correlated with levels of fecal skatole, indole and short-chain fatty acids. Thus, intake of chicken diet may increase the risk of skatole- and indole-induced diseases by altering gut microbiota.

Feeding diversified protein sources exacerbates hepatic insulin resistance via increased gut microbial branched-chain fatty acids and mTORC1 signaling in obese mice

Animal models of human diseases are classically fed purified diets that contain casein as the unique protein source. We show that provision of a mixed protein source mirroring that found in the western diet exacerbates diet-induced obesity and insulin resistance by potentiating hepatic mTORC1/S6K1 signaling as compared to casein alone. These effects involve alterations in gut microbiota as shown by fecal microbiota transplantation studies. The detrimental impact of the mixed protein source is also linked with early changes in microbial production of branched-chain fatty acids (BCFA) and elevated plasma and hepatic acylcarnitines, indicative of aberrant mitochondrial fatty acid oxidation. We further show that the BCFA, isobutyric and isovaleric acid, increase glucose production and activate mTORC1/S6K1 in hepatocytes. Our findings demonstrate that alteration of dietary protein source exerts a rapid and robust impact on gut microbiota and BCFA with significant consequences for the development of obesity and insulin resistance.