Dietary single cell protein reduces fatty liver in obese Zucker rats

A chicken protein hydrolysate exerts anti-atherosclerotic effect beyond plasma cholesterol-lowering activity in Apoe-/- mice

Chicken protein hydrolysates (CPHs) generated from rest raw materials through enzymatic hydrolysis using Corolase PP or Alcalase were shown to reduce inflammation and stimulate hepatic mitochondrial fatty acid oxidation in high-fat-fed mice. This study investigates the effect of CPH diets in atherosclerosis-prone apolipoprotein E-deficient (Apoe-/-) mice. Apoe-/- mice were divided into three groups of 12 animals and fed high-fat diets with casein (control), Alcalase CPH, or Corolase PP CPH. After 12 weeks, mice were sacrificed, blood samples were collected, and aorta was dissected for subsequent én face analysis. Mice fed Corolase PP CPH but not Alcalase CPH had significantly lower % atherosclerotic plaque area in the aortic arch compared to controls (p = .015 and p = .077, respectively). Plasma and liver cholesterol and triacylglycerol remained constant, but levels of the fatty acid C20:5n-3 were increased, accompanied by an elevated delta-5 desaturase index in both CPHs groups. Moreover, a significant reduction of plasma MCP-1 was detected in Corolase PP CPH compared to control. Overall, our data show that protein hydrolysates from chicken reduced atherosclerosis and attenuated systemic risk factors related to atherosclerotic disorders, not related to changes in the level of plasma cholesterol.

Short-term Dietary Interventions for the Management of Nonalcoholic Fatty Liver

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) affects millions of individuals on a global scale and currently no gold standard treatment exists. The risk of developing NAFLD is considerably higher with increasing body mass index. Consequently, weight loss should be recommended to all overweight patients with fatty liver. However, lifestyle interventions, irrespective of weight status, may also influence the condition. The aim herein is to present examples of short-term interventions which assess direct effects of dietary-related components on hepatic steatosis.

METHODS

This review includes studies with short-term dietary-related interventions of up to 16 weeks that evaluate their efficacy in reducing intrahepatic lipid contents (hepatic steatosis). This review primarily focuses on the three main macronutrients: dietary carbohydrates, fats and proteins.

RESULTS

High saturated fat intake and high consumption of carbohydrates, particularly from simple sugars such as fructose are reported as risk factors for hepatic steatosis. Overall, shortterm hypocaloric diets have shown beneficial effects in reducing intrahepatic lipid contents. Macronutrient manipulations such as carbohydrate restriction as well as the consumption of unsaturated fatty acids are also reported to have efficacious effects.

CONCLUSION

This review highlights the different dietary interventions that can influence hepatic steatosis in the short term, illustrating both pro and anti-steatotic effects.

Dietary fish protein hydrolysates containing bioactive motifs affect serum and adipose tissue fatty acid compositions, serum lipids, postprandial glucose regulation and growth in obese Zucker fa/fa rats

The world's fisheries and aquaculture industries produce vast amounts of protein-containing by-products that can be enzymatically hydrolysed to smaller peptides and possibly be used as additives to functional foods and nutraceuticals targeted for patients with obesity-related metabolic disorders. To investigate the effects of fish protein hydrolysates on markers of metabolic disorders, obese Zucker fa/fa rats consumed diets with 75 % of protein from casein/whey (CAS) and 25 % from herring (HER) or salmon (SAL) protein hydrolysate from rest raw material, or 100 % protein from CAS for 4 weeks. The fatty acid compositions were similar in the experimental diets, and none of them contained any long-chain n-3 PUFA. Ratios of lysine:arginine and methionine:glycine were lower in HER and SAL diets when compared with CAS, and taurine was detected only in fish protein hydrolysate diets. Motifs with reported hypocholesterolemic or antidiabetic activities were identified in both fish protein hydrolysates. Rats fed HER diet had lower serum HDL-cholesterol and LDL-cholesterol, and higher serum TAG, MUFA and n-3:n-6 PUFA ratio compared with CAS-fed rats. SAL rats gained more weight and had better postprandial glucose regulation compared with CAS rats. Serum lipids and fatty acids were only marginally affected by SAL, but adipose tissue contained less total SFA and more total n-3 PUFA when compared with CAS. To conclude, diets containing hydrolysed rest raw material from herring or salmon proteins may affect growth, lipid metabolism, postprandial glucose regulation and fatty acid composition in serum and adipose tissue in obese Zucker rats.

Hypolipidemic effect of dietary water-soluble protein extract from chicken: impact on genes regulating hepatic lipid and bile acid metabolism

BACKGROUND

Amount and type of dietary protein have been shown to influence blood lipids. The present study aimed to evaluate the effects of a water-soluble fraction of chicken protein (CP) on plasma and hepatic lipid metabolism in normolipidemic rats.

METHODS

Male Wistar rats were fed either a control diet with 20 % w/w casein as the protein source, or an experimental diet where casein was replaced with CP at 6, 14, or 20 % w/w for 4 weeks.

RESULTS

Rats fed CP had markedly reduced levels of triacylglycerols (TAG) and cholesterol in both plasma and liver, accompanied by stimulated hepatic mitochondrial fatty acid oxidation and carnitine palmitoyltransferase 2 activity in the 20 % CP group compared to the control group. In addition, reduced activities and gene expression of hepatic enzymes involved in lipogenesis were observed. The gene expression of sterol regulatory element-binding transcription factor 1 was reduced in the 20 % CP-fed rats, whereas gene expression of peroxisome proliferator-activated receptor alpha was increased. Moreover, 6, 14, and 20 % CP-fed rats had significantly increased free carnitine and acylcarnitine plasma levels compared to control rats. The plasma methionine/glycine and lysine/arginine ratios were reduced in 20 % CP-treated rats. The mRNA level of ATP-binding cassette 4 was increased in the 20 % CP group, accompanied by the increased level of plasma bile acids.

CONCLUSIONS

The present data suggest that the hypotriglyceridemic property of a water-soluble fraction of CP is primarily due to effects on TAG synthesis and mitochondrial fatty acid oxidation. The cholesterol-lowering effect by CP may be linked to increased bile acid formation.

Effects of a whey protein supplementation on intrahepatocellular lipids in obese female patients

BACKGROUND & AIMS

High protein diets have been shown to improve hepatic steatosis in rodent models and in high-fat fed humans. We therefore evaluated the effects of a protein supplementation on intrahepatocellular lipids (IHCL), and fasting plasma triglycerides in obese non diabetic women.

METHODS

Eleven obese women received a 60 g/day whey protein supplement (WPS) for 4-weeks, while otherwise nourished on a spontaneous diet, IHCL concentrations, visceral body fat, total liver volume (MR), fasting total-triglyceride and cholesterol concentrations, glucose tolerance (standard 75 g OGTT), insulin sensitivity (HOMA IS index), creatinine clearance, blood pressure and body composition (bio-impedance analysis) were assessed before and after 4-week WPS.

RESULTS

IHCL were positively correlated with visceral fat and total liver volume at inclusion. WPS decreased significantly IHCL by 20.8 ± 7.7%, fasting total TG by 15 ± 6.9%, and total cholesterol by 7.3 ± 2.7%. WPS slightly increased fat free mass from 54.8 ± 2.2 kg to 56.7 ± 2.5 kg, p = 0.005). Visceral fat, total liver volume, glucose tolerance, creatinine clearance and insulin sensitivity were not changed.

CONCLUSIONS

WPS improves hepatic steatosis and plasma lipid profiles in obese non diabetic patients, without adverse effects on glucose tolerance or creatinine clearance.

TRIAL NUMBER

NCT00870077, ClinicalTrials.gov.