Incorporation of Dairy Lipids in the Diet Increased Long-Chain Omega-3 Fatty Acids Status in Post-weaning Rats

In human nutrition, optimized the status of n-3 long-chain polyunsaturated fatty acids (LCPUFA) and especially docosahexaenoic acid (DHA) during growth appears to be one of the most important goal. We investigated the potential impact of a partial incorporation of dairy lipids (DL) in the diet to increase the n-3 LCPUFA content in tissues, compared to a mixture of vegetable oils. Rats were fed with vegetable oil diet or DL diet, supplemented or not supplemented with DHA, from weaning for 6 weeks. All diets provided the same quantity of 2.3% of total fatty acids of precursor α-linolenic acid. LCPUFA levels in brain, retina, liver, heart, red blood cells and epididymal adipose tissue, Δ-6 desaturase activity and mRNA expression in liver, and plasma cholesterol were measured. Rats fed a DL diet increased their DHA content in brain and retina compared with rats fed a vegetable oil diet and reached the same level than rats directly supplemented with DHA. The status of n-3 docosapentaenoic acid increased with DL diet in heart, red blood cells and liver. The n-3 docosapentaenoic acid specifically discriminated DL diets in the heart. DL diet increased α-linolenic acid content in liver and epididymal adipose tissue, provided specific fatty acids as short- and medium-chain fatty acids and myristic acid, and increased plasma cholesterol. We hypothesized that dairy lipids may increase the n-3 LCPUFA enrichment in tissues by preserving precursor α-linolenic acid from β-mitochondrial oxidation, associated with the presence of short- and medium-chain fatty acids in DL diets. In conclusion, a partial incorporation of dairy lipids in the diet with an adequate α-linolenic acid content improved the n-3 LCPUFA status, especially DHA in brain and retina.

Western-diet consumption induces alteration of barrier function mechanisms in the ileum that correlates with metabolic endotoxemia in rats

Obesity and its related disorders have been associated with the presence in the blood of gut bacteria-derived lipopolysaccharides (LPS). However, the factors underlying this low-grade elevation in plasma LPS, so-called metabolic endotoxemia, are not fully elucidated. We aimed to investigate the effects of Western diet (WD) feeding on intestinal and hepatic LPS handling mechanisms in a rat model of diet-induced obesity (DIO). Rats were fed either a standard chow diet (C) or a Western Diet (WD, 45% fat) for 6 wk. They were either fed ad libitum or pair-fed to match the caloric intake of C rats for the first week, then fed ad libitum for the remaining 5 wk. Six-week WD feeding led to a mild obese phenotype with increased adiposity and elevated serum LPS-binding protein (LBP) levels relative to C rats, irrespective of initial energy intake. Serum LPS was not different between dietary groups but exhibited strong variability. Disrupted ileal mucus secretion and decreased ileal Reg3-γ and -β gene expression along with high ileal permeability to LPS were observed in WD compared with C-fed rats. Ileal and cecal intestinal alkaline phosphatase (IAP) activity as well as Verrucomicrobia and Bifidobacterium cecal levels were increased in WD-fed rats compared with C-fed rats. WD consumption did not impact mRNA levels of LPS-handling hepatic enzymes. Correlation analysis revealed that ileal passage of LPS, IAP activity, Proteobacteria levels and hepatic aoah gene expression correlated with serum LPS and LBP, suggesting that ileal mucosal defense impairment induced by WD feeding contribute to metabolic endotoxemia.