Fan Zhang

Our previous study suggested that increasing the phospholipid‐to‐cholesterol intake ratio might mitigate the negative effects of cholesterol intake, based on a comparison of lipid metabolism changes in mice fed chow diets containing egg yolk low‐density lipoprotein (LDL) and high‐density lipoprotein (HDL). This benefit might stem from the involvement of phospholipids, leading to reduced food efficiency, decreased body weight, and increased bile acid excretion. In this study, we further investigated the effects of this ratio on lipid metabolism under a high‐fat diet (HFD) using egg yolk LDL and HDL, which differ in the proportions of phospholipids and cholesterol. Both LDL and HDL intake led to increased body weight and adipose tissue weight in mice, with significant effects observed in the HFD‐LDL3 group. Accordingly, these groups exhibited overall increases in food efficiency. Lipid biomarkers indicated that both LDL and HDL intake significantly elevated plasma and liver triglyceride (TG) levels. Cholesterol in the blood might be stored with TGs in adipose tissue. No significant differences were observed in lipid biomarkers between the HFD‐LDL and HFD‐HDL groups under the same cholesterol dose. Western blot results showed upregulated cholesterol synthesis following LDL and HDL intakes. Bile acid excretion also increased, though not significantly. Fecal metabolite analysis further revealed changes in polyunsaturated fatty acids, pregnane‐type steroids, and bile acids. Compared to our previous findings, increasing the phospholipid‐to‐cholesterol intake ratio under an HFD had a weaker beneficial effect on lipid metabolism than under a chow diet, possibly due to the lower proportion of phospholipids in the total lipids.

Recent evidence increasingly indicates that moderate egg consumption (up to one egg per day) poses no significant risk of cardiovascular diseases in healthy individuals, leading researchers to speculate whether other lipids in eggs affect lipid metabolism. In this research, C57BL/6J mice were given chow diets containing egg yolk low‐density lipoprotein (LDL) and high‐density lipoprotein (HDL), two natural components with different proportions of phospholipids and cholesterol, to explore the effects of the phospholipids‐to‐cholesterol intake ratio on lipid metabolism. Increases in liver weight and liver index were observed following LDL intake, while body weight and epididymal fat decreased after HDL intake in a dose‐dependent manner. The food efficiency of chow diets decreased with increasing phospholipids content. Lipid biomarkers indicated that LDL intake significantly increased plasma LDL cholesterol and liver cholesterol levels. At equivalent cholesterol doses, the cholesterol‐raising effects of HDL were weaker than those of LDL. Higher protein expression of cytochrome P450 family 7 subfamily A member 1 in the HDL groups suggested increased bile acid excretion at higher phospholipids‐to‐cholesterol intake ratios. Fecal metabolite analysis revealed significant changes in lipid composition, primarily involving glycerophospholipids, sphingolipids, and sterol lipids, consistent with the lipid profiles of LDL and HDL. The upregulation of cholic acid and deoxycholic acid in feces further confirmed increased bile acid excretion. This study highlights the differences in lipid metabolism in mice under varying phospholipids‐to‐cholesterol intake ratios, which may be associated with changes in dietary energy supply and bile excretion following phospholipids involvement.

Due to imbalanced demand favoring egg whites, the egg industry faces a surplus of egg yolk, limiting overall growth. This study designed a feasible process for the crude extraction of livetins and phosvitin (PV) and revealed the related separation mechanisms. Our method utilized a 1:9 egg yolk dilution at pH 6.15–6.29, incubated at 4–7.5 °C, to reduce the dispersibility of lipoproteins in the water-soluble fraction (WSF). Adding 0.04–0.05% (w/v) sodium alginate to WSF at pH 5.40 effectively removed suspended low-density lipoprotein (LDL) through electrostatic complexation, increasing livetins electrophoretic bands from 51.90% to 91.04%. The dispersion of the high-density lipoprotein (HDL)-PV complex was jointly affected by NaCl and pH, with phosphocalcic bridges fully disrupted when NaCl concentration exceeded 7.5% (w/v). Na⁺ and Ca²⁺ were adsorbed onto the negatively charged protein surface at pH 5–8, inducing strong hydration repulsion, thereby resulting in the individual dispersion of HDL and PV. Based on the solubility difference in low ionic strength solutions at neutral pH, HDL could be effectively removed after dialysis, increasing PV electrophoretic bands from 8.45% to 61.50%. This simple and feasible separation process may provide a reliable foundation for further purification via membrane filtration and chromatography.

The public and scientists remain skeptical about egg consumption, given that cardiovascular diseases (CVDs) are the leading causes of death in worldwide. This review mainly explained the recurrence of contradictory conclusions about relationships between egg consumption and CVD risk and discussed effects of egg cholesterol intake on cholesterol homeostasis. Factors including individual health status and cholesterol sensitivity, dietary pattern, region, and race should be distinguished when understanding generalized conclusions. Identified compensatory mechanisms in response to dietary cholesterol and the resulting balance in cholesterol biosynthesis, absorption, and efflux supported the view that moderate egg consumption had no substantial overall impacts on cholesterol homeostasis in healthy people. Excessive cholesterol intake is not recommended in individuals with distempered metabolism. More than cholesterol metabolism, impacts of egg consumption as a part of overall diet on CVD risk should be considered from aspects of nutrient intake, lipid metabolism, and energy supply in the future.

Selenium-enriched egg white peptides (Se-EWP) were prepared by pre-heat treatment and enzymatic hydrolysis in this study. In addition, their selenopeptide sequence identification and immunomodulatory effect were investigated. Results showed that the yield of Se-EWP obtained from alkaline-neutral protease treatment reached 76.90%, and peptides with a molecular weight of 200-1000 Da accounted for 98.33%. Four characteristic selenopeptides, including SeCys-Trp-Leu-Glu, Trp-Ser-SeCys, SeMet-Ala-Pro, and SeMet-Leu, were identified by HPLC-ESI-MS/MS, which were rich in hydrophobic and branched-chain amino acids. Se-EWP (750 mg/kg/d) could effectively retard the decrease of immune organ index in immunosuppressed mice induced by cyclophosphamide. Moreover, supplementation of Se-EWP could promote a higher content of Se in liver, the number of white blood cells, and the levels of serum cytokines (IL-6, IL-2, and TNF-α) as compared with EWP groups, indicating that Se-EWP could effectively alleviate immunosuppression induced by cyclophosphamide. These findings suggested that Se-EWP exhibited great potential as functional foods for immunomodulatory effect.

To expand the utilization of oyster protein (OP), the effects of high pressure (100 to 500 MPa) on chemical forces, structure, microstructure, and digestibility properties were investigated. High pressure (HP) treatment enhanced the electrostatic repulsion (from −13.3_Control to −27.8_HP200 mV) between protein molecules and avoided or retarded the formation of protein aggregates. In addition, the HP treated samples showed uniform distribution and small particle size. The changes in electrostatic interaction and particle size contributed to the improvement of solubility (from 10.53%_Control to 19.92%_HP500 at pH 7). The stretching and unfolding of protein were modified by HP treatment, and some internal hydrophobic groups and -SH groups were exposed. HP treatment modified the secondary structure of OP. The treated samples contained less α-helix and β-sheet structures, whereas the proportions of β-sheet and random coil structures were increased. The treated samples have high digestibility in the stomach (from 26.3%_Control to 39.5%_HP500) and in the total digestive process (from 62.1%_Control to 83.7%_HP500). In addition, the total digestive production showed higher percentages of small peptides (<1 kDa) after HP treatment. The protein solubility and digestibility were increased after HP treatment, and high solubility and high digestibility might increase the chance that OP become a kind of protein supplement.