Egg White Hydrolysate Can Be a Low-Allergenic Food Material to Suppress Ectopic Fat Accumulation in Rats Fed an Equicaloric Diet

Abstract

Summary Egg white (EW) is known as a nutritional protein but can induce allergic reactions in humans. We investigated the dietary effects of EW and its hydrolysate (EWH), which contains less allergen, on body fat accumulation in Wistar rats fed an equicaloric high-fat and high-sucrose diet for 8 wk (Exp A). The pair-feeding of EW and equicaloric-feeding of EWH increased fecal fat excretion and suppressed lipid accumulation in the liver and muscles but not in the abdominal adipose tissues, carcass, or total body. Dietary EWH also suppressed the serum glucose level and alkaline phosphatase activity. Further, we showed a higher dispersibility of EW and EWH in physicochemical assay (Exp B). Next, we investigated the suppressive effects of a single administration of EW and EWH on lipid-induced hypertriglyceridemia and small intestinal meal transit in ddY mice (Exp C). However, a single administration of EW or EWH did not suppress the lipid-induced hypertriglyceridemia nor did it delay the rate of small intestinal transit. These findings indicated that dietary EW and EWH reduce hepatic and muscular (ectopic) fat accumulation mainly by suppressing fat absorption and supplying fat to the liver and muscles. Therefore, the low-allergenic EWH can be effective for the prevention of high-fat-diet-induced obesity.

Egg White Hydrolysate Improves Glucose Tolerance in Type-2 Diabetic NSY Mice

“…Ovalbumin, an abundant protein in EW, was responsible for the lowering activities of TG and CHO because ovalbumin was resistant to pepsin digestion in the gut and passed through the intestine and had a lipase inhibitory activity (26,27). However, ovalbumin as well as ovotransferrin and lysozyme in the EWH used in the present study was previously hydrolyzed enzymatically according to our previous report (3). The higher excretion of fecal TG and CHO in the EWH diet group can be caused by other proteins and hydrolyzed peptides in EW via inhibition of lipid digestion, intestinal absorption, and/or chylomicrons secretion, but their candidate proteins or peptides have not yet been clarified.…”

“…Fecal excretion of TG and CHO was numerically higher in the NE and NEH groups than that in the NH groups although the fecal weights and fecal total lipids content were equal (Table 2). From the results of lipids analyses, EW clearly suppressed CHO accumulation, which is supposed to be caused by lower lipid absorption and fat synthesis (1)(2)(3)26). EWH slightly suppressed the CHO accumulation, but the effect was weakened compared to EW.…”

“…Plasma glucose level during OGTT, ITT, and ipGTT and final plasma levels of glucose, triacylglycerol (TG), total cholesterol (CHO) (Wako), glucagon-like peptide 1 (GLP-1), insulin (Shibayagi Co., Ltd., Gunma, Japan), and total adiponectin (Otsuka Pharmaceutical Co., Ltd., Tokyo) were measured using appropriate commercial kits. The homeostasis model assessment of insulin resistance (HOMA-IR) and insulin secretion (HOMA-b) was calculated as previously described (3). Total lipids in feces, liver, and gastrocnemius muscle were extracted as described by Folch et al (9).…”

“…We previously developed EW enzymatic hydrolysate (EWH), which contains less allergenic proteins and has similar physicochemical properties to EW (3). We have also reported that EWH improves fasting serum glucose and insulin levels in diabetic Goto-Kakizaki (GK) rats (1) and Wistar rats (2).…”

“…EW has been reported to suppress food intake, dietary fat absorption, and fat accumulation in rats in our previous studies (1)(2)(3); therefore, EW can be considered for the prevention and treatment of obesity and type 2 diabetes mellitus (T2DM) in humans. However, egg-specific proteins in EW are well known to be major allergens in humans.…”