Effect of sardine proteins on hyperglycaemia, hyperlipidaemia and lecithin:cholesterol acyltransferase activity, in high-fat diet-induced type 2 diabetic rats

Gut Microbiota and Nutrition: Strategies for the Prevention and Treatment of Type 2 Diabetes

The prevalence of diabetes has increased in last decades worldwide and is expected to continue to do so in the coming years, reaching alarming figures. Evidence have shown that patients with type 2 diabetes (T2D) have intestinal microbial dysbiosis. Moreover, several mechanisms link the microbiota with the appearance of insulin resistance and diabetes. Diet is a crucial factor related to changes in the composition, diversity, and activity of gut microbiota (GM). In this review, the current and future possibilities of nutrient-GM interactions as a strategy to alleviate T2D are discussed, as well as the mechanisms related to decreased low-grade inflammation and insulin resistance. A bibliographic search of clinical trials in Pubmed, Web of Science, and Scopus was carried out, using the terms "gut microbiota, diet and diabetes." The data analyzed in this review support the idea that dietary interventions targeting changes in the microbiota, including the use of prebiotics and probiotics, can improve glycemic parameters. However, these strategies should be individualized taking into account other internal and external factors. Advances in the understanding of the role of the microbiota in the development of metabolic diseases such as T2D, and its translation into a therapeutic approach for the management of diabetes, are necessary to allow a comprehensive approach.

Dietary supplementation of inulin alleviates metabolism disorders in gestational diabetes mellitus mice via RENT/AKT/IRS/GLUT4 pathway

BACKGROUND

Gestational diabetes mellitus (GDM) has significant short and long-term health consequences for both the mother and child. There is limited but suggestive evidence that inulin could improve glucose tolerance during pregnancy. This study assessed the effect of inulin on glucose homeostasis and elucidated the molecular mechanisms underlying the inulin-induced antidiabetic effects during pregnancy.

METHOD

Female C57BL/6 mice were randomized to receive either no treatment, high-dose inulin and low-dose inulin for 7 weeks with measurement of biochemical profiles. A real-time² (RT²) profiler polymerase chain reaction (PCR) array involved in glycolipid metabolism was measured.

RESULTS

Inulin treatment facilitated glucose homeostasis in a dose-dependent manner by decreasing fasting blood glucose, advanced glycation end products and total cholesterol, and improving glucose tolerance. Suppressing resistin (RETN) expression was observed in the inulin treatment group and the expression was significantly correlated with fasting blood glucose levels. The ratios of p-IRS to IRS and p-Akt to Akt in liver tissue and the ratio of p-Akt to Akt in adipose tissue as well as the expression level of GLUT4 increased significantly after inulin treatment.

CONCLUSIONS

Our findings indicated improvement of glucose and lipid metabolism by inulin was to activate glucose transport through the translocation of GLUT4 which was mediated by insulin signaling pathway repairment due to decreased expression of RETN and enhanced phosphorylation of IRS and Akt in GDM mice.

Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial

BACKGROUND

Fish could play a role in preventing type 2 diabetes (T2D) but there has been little specification about the type of fish and the preventive mechanism involved in its health claim. The sardine is a source of omega-3 and taurine that, in isolation or in synergy, would produce T2D-delaying through different molecular mechanism.

HYPOTHESIS

The consumption of twice a week of sardine, during one year would reduce T2D-developing risk in a population with prediabetes (preDM) and old age.

DESIGN

152 subjects with fasting glucose between 100-124 mg/dL aged ≥65 yo were recruited from three primary care centers in Barcelona and were randomly distributed among two interventional groups: control group (CG) and sardine group (SG). Both groups received same T2D-prevention nutritional during a year but only SG had to add 200 g of sardine per week. All variables were collected before to start and at the end of the diet. (ClinicalTrials.gov: NCT03557541).

RESULTS

152 people were randomized into CG (n=77) and SG (n=75) with 18 and 12 drop outs respectively. Subjects in SG, significantly compared to CG, decreased percentage classified-individuals in a very high risk group to develop T2D according to FINDRISC (p=0.035). In addition to increasing HDL-cholesterol and adiponectin and decreasing triglycerides (p<0.05) and blood pressure (<0.05), SG showed a lower HOMA-IR (p=0.032). The consumption of sardine characteristics nutrients as omega-3, EPA and DHA, vitamin D, fluorine and taurine were higher for SG (p<0.05). These results agreed with the increased of taurine, fatty acid (FA) omega-3 and bile acids circulating metabolites (p<0.05). Changes erythrocyte membrane FA were detected only in SG with a decrease of 5 omega-6 FA (p<0.001) and an increase of 3 omega-3 FA types (p<0.001).

CONCLUSION

We conclude that a year T2D-prevention diet with sardine supplementation has a greater protective effect against developing T2D and CV events.

Beneficial Effects of Algerian Green Alga Ulva lactuca and Its Hydroethanolic Extract on Insulin Resistance and Cholesterol Reverse Transport in High-Fat/Streptozotocin Diabetic Rats

The aim of this study was to evaluate the impact of the green algae Ulva lactuca and its hydroethanolic extract on insulin resistance and cholesterol reverse transport in type 2 diabetic (T2D) rats. Rats had T2D induced by a high-fat diet (HFD) for 5 weeks followed by intraperitoneal injection of streptozotocin. Diabetic rats were divided into three groups and were fed a HFD in the presence or absence of 1% alga (HFD-Alg) or 1% of its hydroethanolic extract (HFD-Ext), for 4 weeks. The control group consumed 20% casein combined with 5% lipids. Hyperglycemia, insulin resistance, hypercholesterolemia, and hypertriglyceridemia were noted in HFD rats vs control rats. Whole alga and its extract decreased these parameters vs the HFD. Moreover, fecal total cholesterol and triacylglycerols levels were lowered in HFD group vs C group, but were increased with HFD-Alg vs HFD. Compared with the Control, the HFD group had decreased lecithin:cholesterol acyltransferase (LCAT) activity, apolipoprotein A-I (ApoA-I), high-density lipoprotein (HDL₃)-phospholipids (PL), and HDL₂-cholesteryl ester (CE) levels, but increased HDL₃-unesterified cholesterol (UC) levels. Furthermore, compared with the HFD group, the HFD-Alg and HFD-Ext groups had increased LCAT activity, ApoA-I, HDL₃-PL, and HDL₂-CE levels and decreased HDL₃-UC levels. In addition, in the HFD-Ext group, LCAT activity and ApoA-1 levels were decreased vs the HFD-Alg whereas HDL₃-UC levels were increased. In conclusion, these results indicate that U. lactuca and its hydroethanolic extract have curative effect on T2D. Therefore, this alga could be considered a functional food supplement for the treatment and prevention of diabetes.

Advances in the Study of Marine Products with Lipid-Lowering Properties

With twice the number of cancer's deaths, cardiovascular diseases have become the leading cause of death worldwide. Atherosclerosis, in particular, is a progressive, chronic inflammatory cardiovascular disease caused by persistent damage to blood vessels due to elevated cholesterol levels and hyperlipidemia. This condition is characterized by an increase in serum cholesterol, triglycerides, and low-density lipoprotein, and a decrease in high-density lipoprotein. Although existing therapies with hypolipidemic effects can improve the living standards of patients with cardiovascular diseases, the drugs currently used in clinical practice have certain side effects, which insists on the need for the development of new types of drugs with lipid-lowering effects. Some marine-derived substances have proven hypolipidemic activities with fewer side effects and stand as a good alternative for drug development. Recently, there have been thousands of studies on substances with lipid-lowering properties of marine origin, and some are already implemented in clinical practice. Here, we summarize the active components of marine-derived products having a hypolipidemic effect. These active constituents according to their source are divided into algal, animal, plant and microbial and contribute to the development and utilization of marine medicinal products with hypolipidemic effects.

Fish protein supplementation in older nursing home residents: a randomised, double-blind, pilot study

Background

Age-related loss of muscle mass and function is common in older adults, and studies investigating if dietary proteins may protect and possibly build lean body mass are needed. We assessed the feasibility of conducting a nutritional intervention study in older nursing home residents to investigate the effects of fish protein supplementation on markers of glucose metabolism and inflammation.

Methods

This was a double-blind randomised controlled pilot study. Twenty-four nursing home residents, without major cognitive impairment, received a daily oral nutritional supplement containing 5.2 g of fish protein or placebo for 6 weeks. Anthropometric measurements were conducted at baseline. Participants were screened for nutritional risk using the Mini Nutritional Assessment and activities of daily living using the Barthel index and dietary intake was registered. Hand grip strength was measured and fasting blood samples collected at baseline and endpoint.

Results

Compliance was high and dropout was low, but participant recruitment was challenging. Serum concentrations of monocyte chemoattractant protein-1 decreased, and C-reactive protein increased in the intervention group compared to control, with no changes in markers of glucose metabolism between groups.

Conclusion

Conducting a nutritional intervention using fish protein supplementation in older nursing home residents is feasible but should be conducted as a multi-centre study to account for the low recruitment rate observed in the present study. A full-scale study is needed to gain more knowledge on the potential effects of fish proteins on markers of glucose metabolism and inflammation in relation to the age-related loss of muscle mass and function.

Trial registration

ClinicalTrials.gov NCT03529344 18.05.2018 (retrospectively registered)

The impact of human breast milk components on the infant metabolism

BACKGROUND & AIMS

Breastfeeding is beneficial for mothers and infants. Underlying mechanisms and biochemical mediators thus need to be investigated to develop and support improved infant nutrition practices promoting the child health. We analysed the relation between maternal breast milk composition and infant metabolism.

METHODS

196 pairs of mothers and infants from a European research project (PreventCD) were studied. Maternal milk samples collected at month 1 and month 4 after birth were analysed for macronutrient classes, hormone, and fatty acid (FA) content. Phospholipids, acylcarnitines, and amino acids were measured in serum samples of 4-month old infants. Associations between milk components and infant metabolites were analysed with spearman correlation and linear mixed effect models (LME). P-values were corrected for multiple testing (PLME).

RESULTS

Month 1 milk protein content was strongly associated with infant serum lyso-phosphatidylcholine (LPC) 14:0 (PLME = 0.009). Month 1 milk insulin was associated to infant acetylcarnitine (PLME = 0.01). There were no associations between milk protein content and serum amino acids and milk total fat content and serum polar lipids. Middle- and odd-chain FA% in breast milk at both ages were significantly related to serum LPC and sphingomyelins (SM) species in infant serum (all PLME<0.05), while FA% 20:5n-3 and 22:6n-3 percentages were significantly associated to serum LPC 22:6 (PLME = 1.91×10-4/7.93×10-5) in milk only at month 4. Other polyunsaturated fatty acids and hormones in milk showed only weak associations with infant serum metabolites.

CONCLUSIONS

Infant serum LPC are influenced by breast milk FA composition and, intriguingly, milk protein content in early but not late lactation. LPC 14:0, previously found positively associated with obesity risk, was the serum metabolite which was the most strongly associated to milk protein content. Thus, LPC 14:0 might be a key metabolite not only reflecting milk protein intake in infants, but also relating high protein content in milk or infant formula to childhood obesity risk.

[Sardine purified proteins improve blood pressure, glycemic control, anti-atherogenic metabolic pathways and antioxidant capacity in obese rats]

AIM OF THE STUDY

The effects of sardine by-products (SBy-P) and fillet proteins (SF-P) were compared to casein (Cas) ; these effects were assessed on blood pressure, glycemic control, reverse cholesterol transport, lipid peroxidation and total antioxidant capacity in obese rats.

MATERIALS AND METHODS

Eighteen male Wistar rats were subjected for three months, to a high-fat diet. The obese rats were divided into three groups and consumed the same high-fat diet for 28 days after addition of either, 20% SBy-P, SF-P or Cas.

RESULTS

The sardine proteins (SBy-P and SF-P) compared respectively to Cas, reduced diastolic (-14%, -11% P<0.05) and systolic pressures (-12%, -8% P<0.05), blood glucose (-24%, -21% P<0.05), glycated hemoglobin (-28%, -21% P<0.05), insulinemia (-29%, -18% P<0.05) and HOMA-IR index (-29%, -18% P<0.05). They improve the reverse cholesterol transport by increasing the lecithin: cholesterol acyltransferase (LCAT) activity (+43%, +30% P<0.05) and high-density lipoproteins in cholesterol esters (+108%, +88% P<0.05), and decreasing the atherogenicity ratios and membrane fluidity (P<0.05). Furthermore, SBy-P and SF-P induced a reduction of reactive thiobarbituric acid substances concentrations in heart (-45%, -25% P<0.05), aorta (-62%, -41% P<0.05), liver (-40%, -21% P<0.05) and adipose tissue (-50%, -37% P<0.05) with an improvement in antioxidant capacity.

CONCLUSION

Sardine proteins, in particular those extracted from by-products, because of their hypotensive, hypoglycemic, anti-atherogenic and antioxidant properties, may have protective effects against the cardiovascular risk associated with obesity.

Water-Soluble Fish Protein Intake Led to Lower Serum and Liver Cholesterol Concentrations in Obese Zucker fa/fa Rats

Proteins from different fish species and different raw materials such as fish fillets and by-products have shown promising cardioprotective effects in rodents and humans, including effects on cholesterol metabolism. Blue whiting is used mainly to produce fish meal for the feed industry and during this production, a water-soluble protein fraction, containing small peptides that are easily absorbed and may hold bioactive properties, is isolated. The effects of water-soluble fish protein on cholesterol metabolism were investigated in twelve male obese Zucker fa/fa rats. Rats were fed diets with water-soluble protein from blue whiting (BWW) as 1/3 of the total protein and the remaining 2/3 as casein (BWW group) or with casein as the sole protein source (control group). After 5 weeks intervention, the BWW group had lower serum total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol concentrations and lower cholesteryl ester concentration compared to controls. Hepatic concentrations of cholesterol, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, and LDL receptors were also lower in the BWW group. The groups had a similar concentration of serum total bile acids and similar fecal excretions of cholesterol and bile acids. To conclude, the BWW diet led to lower concentrations of serum and liver cholesterol in obese Zucker fa/fa rats, probably due to lower hepatic cholesterol synthesis.

Chicory inulin ameliorates type 2 diabetes mellitus and suppresses JNK and MAPK pathways in vivo and in vitro

SCOPE

Chicory inulin is a naturally occurring fructan that is conducive to glucose and lipid metabolism in patients with diabetes mellitus. This study aims to investigate the mechanism by which chicory inulin improves glucolipid metabolism in diabetic conditions.

METHODS AND RESULTS

Rats were injected with streptozotocin and fed with high fat diet to induce diabetes, and then administrated with different doses of chicory inulin for 8 weeks. The glycometabolism and lipid metabolism parameters were determined, the activity of insulin receptor substrate (IRS) and mitogen-activated protein kinase (MAPK) pathways were examined by western blot. The effect of chicory inulin on glucose uptake of myoblast and hepatocyte were also measured in vitro. Data were analyzed by student's t-test or one-way analysis of variance followed by the Bonferroni post-hoc testing. The results showed that chicory inulin improved glucolipid metabolism, and it activated IRS but suppressed the MAPK pathways in vivo and in vitro.

CONCLUSION

Our study demonstrates that chicory inulin, as a nutritional supplement, may be beneficial for the patients with type 2 diabetes mellitus, and the metabolism-modulatory effect seems to be related with the inhibition of JNK and P38 MAPK pathways.

Differential Effects of Cod Proteins and Tuna Proteins on Serum and Liver Lipid Profiles in Rats Fed Non-Cholesterol- and Cholesterol-Containing Diets

Fish muscles are classified into white and red muscles, and the chemical composition of the two fish muscles have many differences. Few reports have assessed the health-promoting functions of white fish muscle proteins (WFP) and red fish muscle proteins (RFP). We therefore evaluated the mechanisms underlying the alteration of lipid profiles and cholesterol metabolism following the intake of WFP prepared from cod and RFP prepared from light muscles of tuna. Male Wistar rats were divided into six dietary groups: casein (23%), WFP (23%), and RFP (23%), with or without 0.5% cholesterol and 0.1% sodium cholate. Compared to the WFP-containing diet, the RFP-containing diet supplemented with cholesterol and sodium cholate significantly increased serum and liver cholesterol contents. However, in the RFP groups, an alteration in cholesterol metabolism including an increased tendency to excrete fecal sterols and hepatic cholesterol 7α-hydroxylase was related to the reduction of hepatic cholesterol contents. This phenomenon might be related to the tendency of an increased food intake in RFP-containing diets. These results highlight the differential effects of WFP and RFP on serum and liver lipid profiles of Wistar rats fed non-cholesterol- or cholesterol-containing diets under no fasting condition.