Herring Milt and Herring Milt Protein Hydrolysate Are Equally Effective in Improving Insulin Sensitivity and Pancreatic Beta-Cell Function in Diet-Induced Obese- and Insulin-Resistant Mice

Abstract

Although genetic predisposition influences the onset and progression of insulin resistance and diabetes, dietary nutrients are critical. In general, protein is beneficial relative to carbohydrate and fat but dependent on protein source. Our recent study demonstrated that 70% replacement of dietary casein protein with the equivalent quantity of protein derived from herring milt protein hydrolysate (HMPH; herring milt with proteins being enzymatically hydrolyzed) significantly improved insulin resistance and glucose homeostasis in high-fat diet-induced obese mice. As production of protein hydrolysate increases the cost of the product, it is important to determine whether a simply dried and ground herring milt product possesses similar benefits. Therefore, the current study was conducted to investigate the effect of herring milt dry powder (HMDP) on glucose control and the associated metabolic phenotypes and further to compare its efficacy with HMPH. Male C57BL/6J mice on a high-fat diet for 7 weeks were randomized based on body weight and blood glucose into three groups. One group continued on the high-fat diet and was used as the insulin-resistant/diabetic control and the other two groups were given the high-fat diet modified to have 70% of casein protein being replaced with the same amount of protein from HMDP or HMPH. A group of mice on a low-fat diet all the time was used as the normal control. The results demonstrated that mice on the high-fat diet increased weight gain and showed higher blood concentrations of glucose, insulin, and leptin, as well as impaired glucose tolerance and pancreatic β-cell function relative to those on the normal control diet. In comparison with the high-fat diet, the replacement of 70% dietary casein protein with the same amount of HMDP or HMPH protein decreased weight gain and significantly improved the aforementioned biomarkers, insulin sensitivity or resistance, and β-cell function. The HMDP and HMPH showed similar effects on every parameter except blood lipids where HMDP decreased total cholesterol and non-HDL-cholesterol levels while the effect of HMPH was not significant. The results demonstrate that substituting 70% of dietary casein protein with the equivalent amount of HMDP or HMPH protein protects against obesity and diabetes, and HMDP is also beneficial to cholesterol homeostasis.

Microalgae as Sources of High-Quality Protein for Human Food and Protein Supplements

“…Consumers are increasingly aware of the impact of specific nutrients on health and disease and this trend has, in turn, been driving food market growth, in particular the sector of functional foods, dietary supplements, and nutraceuticals. It is emerging that consumption of fat and carbohydrates is associated with the onset and progression of metabolic diseases, while protein intake, generally, is not [ 13 , 14 , 15 ]. Consistently, the global market for protein ingredients was USD 38.5 billion in 2020 and is anticipated to experience a compound annual growth rate (CAGR) of 10.5% from 2021 to 2028 ( (accessed on 28 November 2021)).…”

Effects of Herring Milt Hydrolysates and Fractions in a Diet-Induced Obesity Model

“…The previous study did not show such results for HMH2, which would be explained by the lower doses given to the mice [ 17 ]. Interestingly, a recent study showed that replacing 70% dietary casein protein with herring milt hydrolysate (dose not specified) in comparison to a high-fat diet reduced in vivo obesity, fasting glycemia, and fasting serum insulin, and improved glucose tolerance [ 28 ]. The HMH supplements in the present study did not show such positive results.…”

Anti-Obesity and Anti-Hyperglycemic Effects of Meretrix lusoria Protamex Hydrolysate in ob/ob Mice

“…Blood samples were collected from tail veins of normal and experimental ob / ob mice at 0, 30, 60, 90, 120, and 180 min. Changes in blood glucose levels in different groups were confirmed using a glucose meter (Accu-Chek Performance Kit, Roche Diagnostics Korea Co., Ltd., Seoul, Korea) [ 17 ].…”

“…The result was normalized against the β-actin mRNA signal. The primer sequences used in this study are listed in Table 4 [ 17 ].…”

“…Recently, Kang et al [ 16 ] identified potential antioxidants from the proteins of sea snails ( Turbo cornutus ), comprising nine distinct low molecular bioactive peptides with H 2 O 2 scavenging ability, suggesting that T. cornutus might be employed as a functional food for human health. Wang et al [ 17 ] demonstrated that herring milt enzymatic protein hydrolysate (HMPH) and dried ground herring milt products (HMDP) could provide beneficial effects in high-fat-diet-induced obese mice. Herring milt treatment can significantly improve insulin resistance and glucose homeostasis.…”