Browsing Food Biosciences by Funder "BBSRC"
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Dietary alpha-lactalbumin alters energy balance, gut microbiota composition and intestinal nutrient transporter expression in high-fat diet fed miceRecently there has been a considerable rise in the frequency of metabolic diseases, such as obesity, due to changes in lifestyle and resultant imbalances between energy intake and expenditure. Whey proteins are considered as potentially important components of a dietary solution to the obesity problem. However, the roles of individual whey proteins in energy balance remain poorly understood. This study investigated the effects of a high fat diet (HFD) containing alphalactalbumin (LAB), a specific whey protein, or the non-whey protein casein (CAS), on energy balance, nutrient transporters expression, and enteric microbial populations. C57BL/6J mice (n = 8) were given a HFD containing either 20% CAS or LAB as protein sources or a low-fat diet (LFD) containing CAS for 10 weeks. HFD-LAB fed mice showed a significant increase in cumulative energy intake (P=0.043), without differences in body weight, energy expenditure, locomotor activity, respiratory exchange ratio or subcutaneous and epididymal adipose tissue weight. HFD-LAB intake led to a decrease in the expression of glucose transporter glut2 in the ileum (P=0.05)and in the fatty acid transporter cd36 (P<0.001) in both ileum and jejunum. This suggests a reduction of absorption efficiency within the small intestine in the HFD-LAB group. DNA from faecal samples was used for 16S rRNA-based assessment of intestinal microbiota populations; the genera Lactobacillus, Parabacteroides and Bifidobacterium were present in significantly higher proportions in the HFD-LAB group. These data indicate a possible functional relationship between gut microbiota, intestinal nutrient transporters and energy balance, with no impact on weight gain.
Oral Delivery of Nisin in Resistant Starch Based Matrices Alters the Gut Microbiota in MiceThere is a growing recognition of the role the gastrointestinal microbiota plays in health and disease. Ingested antimicrobial proteins and peptides have the potential to alter the gastrointestinal microbiota; particularly if protected from digestion. Nisin is an antimicrobial peptide that is used as a food preservative. This study examined the ability of nisin to affect the murine microbiota when fed to mice in two different starch based matrices; a starch dough comprising raw starch granules and a starch gel comprising starch that was gelatinized and retrograded. The effects of the two starch matrices by themselves on the microbiota were also examined. Following 16S rRNA compositional sequencing, beta diversity analysis highlighted a significant difference (p = 0.001, n = 10) in the murine microbiota between the four diet groups. The differences between the two nisin containing diets were mainly attributable to differences in the nisin release from the starch matrices while the differences between the carriers were mainly attributable to the type of resistant starch they possessed. Indeed, the differences in the relative abundance of several genera in the mice consuming the starch dough and starch gel diets, in particular Akkermansia, the relative abundance of which was 0.5 and 11.9%, respectively (p = 0.0002, n = 10), points to the potential value of resistance starch as a modulator of beneficial gut microbes. Intact nisin and nisin digestion products (in particular nisin fragment 22–31) were detected in the feces and the nisin was biologically active. However, despite a three-fold greater consumption of nisin in the group fed the nisin in starch dough diet, twice as much nisin was detected in the feces of the group which consumed the nisin in starch gel diet. In addition, the relative abundance of three times as many genera from the lower gastrointestinal tract (GIT) were significantly different (p < 0.001, n = 10) to the control for the group fed the nisin in starch gel diet, implying that the starch gel afforded a degree of protection from digestion to the nisin entrapped within it.
Protein quality and quantity influence the effect of dietary fat on weight gain and tissue partitioning via host-microbiota changesWe investigated how protein quantity (10%–30%) and quality (casein and whey) interact with dietary fat (20%–55%) to affect metabolic health in adult mice. Although dietary fat was the main driver of body weight gain and individual tissue weight, high (30%) casein intake accentuated and high whey intake reduced the negative metabolic aspects of high fat. Jejunum and liver transcriptomics revealed increased intestinal permeability, low-grade inflammation, altered lipid metabolism, and liver dysfunction in casein-fed but not whey-fed animals. These differential effects were accompanied by altered gut size and microbial functions related to amino acid degradation and lipid metabolism. Fecal microbiota transfer confirmed that the casein microbiota increases and the whey microbiota impedes weight gain. These data show that the effects of dietary fat on weight gain and tissue partitioning are further influenced by the quantity and quality of the associated protein, primarily via effects on the microbiota.
Whey protein effects on energy balance link the intestinal mechanisms of energy absorption with adiposity and hypothalamic neuropeptide gene expressionWe tested the hypothesis that dietary whey protein isolate (WPI) affects the intestinal mechanisms related to energy absorption and that the resulting energy deficit is compensated by changes in energy balance to support growth. C57BL/6 mice were provided a diet enriched with WPI with varied sucrose content, and the impact on energy balance-related parameters was investigated. As part of a high-sucrose diet, WPI reduced the hypothalamic expression of pro-opiomelanocortin gene expression and increased energy intake. The energy expenditure was unaffected, but epididymal weight was reduced, indicating an energy loss. Notably, there was a reduction in the ileum gene expression for amino acid transporter SLC6a19, glucose transporter 2, and fatty acid transporter 4. The composition of the gut microbiota also changed, where Firmicutes were reduced. The above changes indicated reduced energy absorption through the intestine. We propose that this mobilized energy in the adipose tissue and caused hypothalamic changes that increased energy intake, acting to counteract the energy deficit arising in the intestine. Lowering the sucrose content in the WPI diet increased energy expenditure. This further reduced epididymal weight and plasma leptin, whereupon hypothalamic ghrelin gene expression and the intestinal weight were both increased. These data suggest that when the intestine-adipose-hypothalamic pathway is subjected to an additional energy loss (now in the adipose tissue), compensatory changes attempt to assimilate more energy. Notably, WPI and sucrose content interact to enable the component mechanisms of this pathway.