Dose-Dependent Increases in Liver Cholesterol but Not Plasma Cholesterol from Consumption of One to Five Whole Eggs and No Effects from Egg Whites on Liver or Plasma Cholesterol in Hamsters

The Association of Dietary Cholesterol from Egg Consumption on Cardiovascular Diseases Risk Varies from Person to Person

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.

Health Functions of Egg Protein

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

Effect of Long-Term Consumption of Poultry Egg Products on Growth, Body Composition, and Liver Gene Expression in Zebrafish, Danio rerio

BACKGROUND

Poultry eggs are a low-cost, high-protein nutrient package that can be consumed as part of quality diets. However, consumption of poultry egg products is historically contentious, which highlights the importance of investigating impacts of long-term egg consumption on metabolic health.

OBJECTIVE

Our study utilized the zebrafish, Danio rerio, a newly defined model of human metabolic health, to understand the metabolic consequence of consuming egg products in lieu of other well-described protein sources.

METHODS

Reference diets were formulated to contain multisource protein with casein and fish protein hydrolysate (CON; control protein sources), the protein sources that have been historically utilized in numerous reference diets. These proteins were then partially replaced with either whole egg (WE; protein and lipid source), egg white (EW; protein source), wheat gluten (WG; cereal protein source), or a high-lipid-content diet containing a multisource protein with casein and fish protein hydrolysate (HFCON; isonitrogenous and isolipidic with the WE diet) in a 34-wk trial (n = 8 tanks, 10 fish per tank). Daily feeding was initiated at the early juvenile life stage and terminated at the late reproductive adult stage.

RESULTS

The amino acid composition of control versus egg product diets did not vary substantially, although methionine and lysine were apparently limiting in fish fed WG. At termination, fish fed EW as the protein source had weight gain and body composition similar to those fed the CON diet. Fasting and postprandial blood glucose did not differ between any dietary treatment. Assessment of the liver transcriptome using RNAseq revealed no differential gene expression between zebrafish fed CON or WE diets. Zebrafish fed WG had lower weight gain in males.

CONCLUSIONS

Long-term consumption of egg products promoted metabolic health equal to that of historically relevant proteins. These data support the value of egg products for maintaining long-term metabolic health in animal diets.

Egg and Dietary Cholesterol Consumption and Mortality Among Hypertensive Patients: Results From a Population-Based Nationwide Study

Background: Hypertensive patients are sensitive to the amount of dietary cholesterol intake, especially cholesterol from the whole eggs. Whether whole egg and dietary cholesterol consumption are suitable for hypertensive patients is still controversial.

Aim: The objective of the study was to examine the associations of intake of eggs as well as the dietary cholesterol with total mortality in a Chinese nationwide cohort.

Methods: We utilized data from the China Health and Nutrition Survey (CHNS) from the year of 1991 to 2015. Cumulative averages of egg and cholesterol intake were calculated to represent the consumption of the long-term diet of the participants in each available round of the survey. Cox regression models were employed to estimate the effects of eggs and dietary cholesterol from the different sources on mortality among hypertensive patients.

Results: A total of 8,095 participants were included in the final analysis and followed up for a mean of 11.4 years. Finally, 927 cases of death were detected. After adjustment for the multivariate factors, consuming more than seven eggs per week was related to 29% lower mortality among the hypertensive patients compared with the consumers with not more than two eggs per week [hazard ratio (HR): 0.71; 95% CI: 0.59–0.85; P < 0.001]. Similarly, the egg-sourced cholesterol intake was inversely associated with mortality (P = 0.002) whereas intake of the dietary cholesterol from the non-egg sources was significantly related to the higher mortality (P < 0.001). However, total cholesterol intake was not related to mortality among hypertensive patients. Substituting eggs for an equivalent amount of non-egg-sourced protein-abundant foods was also associated with lower mortality.

Conclusion: Higher consumption of eggs and egg-sourced dietary cholesterol was associated with lower mortality among the enrolled Chinese hypertensive patients but non-egg-sourced cholesterol intake was related to higher mortality. Therefore, our findings do not support the view that hypertensive patients should avoid whole egg consumption for the purpose of restricting dietary cholesterol intake.

Oral Administration of Succinoglycan Riclin Improves Diet-Induced Hypercholesterolemia in Mice

Epidemiological studies have demonstrated that hypercholesterolemia is associated with an elevated risk of atherosclerosis and cardiovascular diseases. In addition to the available cholesterol-lowering drugs, nutritionally balanced diets containing functional foods have attracted much interest as potential candidates to improve hypercholesterolemia. In the study, we demonstrated that dietary succinoglycan riclin effectively alleviated diet-induced hypercholesterolemia. Compared with the high-cholesterol-diet (HCD) group, the high-riclin group significantly decreased levels of the serum total cholesterol, low-density lipoprotein cholesterol (LDL-C), and hepatic cholesterol (34, 40, and 51%, respectively), consequently improving hepatic steatosis and reducing proinflammatory cytokine expressions. ¹H nuclear magnetic resonance (NMR)-based lipidomics and metabolomics analyses revealed that the riclin group partially reversed metabolic profile changes induced by the HCD, approaching that of the normal diet (ND) group. Riclin has no direct effects on cholesterol metabolism-related gene expression among the three HCD model groups. Basically, riclin increased the solution viscosity and interfered in the process of bile acid-cholesterol emulsification, decreasing cholesterol digestion and promoting cholesterol and bile acid excretion in the feces. These results suggested potential therapeutic utility of succinoglycan riclin as a food additive for people suffering from hypercholesterolemia and related diseases.

Plasma Cholesterol-Lowering Activity of Soybean Germ Phytosterols

Soybean germ phytosterols (SGP) largely exist in soybean germ oil. Our previous study demonstrated that soybean germ oil was effective in reducing plasma cholesterol. However, it remains unknown if its phytosterols are the active ingredients responsible for the plasma cholesterol-lowering activity. The present study aimed to test the effect of SGP on plasma cholesterol and to investigate its associated underlying mechanisms using hamsters as animal model. Male hamsters (n = 40) were randomly divided into five groups (n = 8/group) and fed one of the five diets: a non-cholesterol diet (NCD), a high cholesterol diet (HCD), a HCD diet containing 0.5% cholestyramine (PC), and two HCD diets containing 0.1% (LP) and 0.2% (HP) SGP, respectively, for six weeks. Results showed that SPG reduced plasma cholesterol level in a dose-dependent manner, whereas it dose-dependently increased the excretion of both fecal neutral and acidic sterols. SGP was also effective in displacing cholesterol from micelles. It was concluded that SGP possessed hypocholesterolemic activity, likely by inhibiting cholesterol absorption in the intestine and promoting fecal sterol excretion.

Heated egg white has no effect, but lactic fermented and unheated egg white reduces abdominal fat in rats

Background

We previously reported the abdominal fat-reducing effect of unheated egg white proteins (EWP); however, unheated egg white is actually rarely consumed. We thus investigated the effect of heated egg white on abdominal fat in rats.

Methods

Male SD rats were divided into two groups that were allowed to consume different dietary preparations containing casein or heated egg white for 4 weeks (Trial 1). We studied whether a heated form and a lactic fermented form of egg white (FLE) are as effective as unheated egg white for reducing abdominal fat. For this, we divided male SD rats into four groups that were allowed to consume different dietary preparations containing casein, unheated egg white, heated egg white, or lactic fermented egg white for 4 weeks (Trial 2).

Results

Animals in the heated egg white group showed no significant difference in abdominal fat weight compared with those in the casein group (Trial 1). Animals in the unheated egg white group and the FLE group had significantly lower levels of abdominal fat weight than those in the casein group (Trial 2). Ovalbumin in heated egg white was degraded by pepsin, whereas ovalbumin in unheated egg white and lactic acid fermented egg white was not degraded appreciably by pepsin. It was reported that EWP inhibit triglyceride absorption in rat. In the present study, EWP pepsin hydrolysate inhibited the micellar solubility of fatty acids in vitro. In particular, ovalbumin inhibited the micellar solubility of fatty acids.

Conclusions

These results indicate that lactic fermented egg white reduces visceral fat in rats and suggest that different levels of susceptibility of ovalbumin to pepsin digestion underlie the varying effectiveness among the egg white preparations.

Soybean germ oil reduces blood cholesterol by inhibiting cholesterol absorption and enhancing bile acid excretion

Soybean germ oil is beneficial in management of hypercholesterolemia in hamsters fed a high cholesterol diet.