Egg consumption as part of an energy-restricted high-protein diet improves blood lipid and blood glucose profiles in individuals with type 2 diabetes

Efficacy of a High-Protein Diet to Lower Glycemic Levels in Type 2 Diabetes Mellitus: A Systematic Review

Diabetes is a metabolic disease with a high worldwide prevalence and an important factor in mortality and disability in the population. Complications can be reduced or prevented with lifestyle changes in physical activity, dietary habits, and smoking cessation. High-protein diets (HPDs, >30% or >1.0 g/Kg/day) decrease hyperglycemia in part due to their content of branched-chain amino acids (BCAAs), mainly leucine. Leucine (and other BCAAs) improve glucose metabolism by directly signaling in the medio-basal hypothalamus (MBH), increasing liver insulin sensitivity. To determine the effectiveness of an HPD to lower hyperglycemia, we analyzed the results of published clinical studies focusing on the levels of fasting plasma glucose and/or glycosylated hemoglobin (HbA1c) in patients with type 2 diabetes mellitus (T2DM). We carried out a systematic search for clinical studies using HPDs. We searched five databases (Scopus, Web of Science, PubMed, Epistemonikos, and Cochrane), collecting 179 articles and finally selecting 8 articles to analyze their results. In conclusion, HPDs are an effective alternative to reduce hyperglycemia in patients with T2DM, especially so-called Paleolithic diets, due to their higher-quality protein from animal and vegetal sources and their exclusion of grains, dairy products, salt, refined fats, and added sugars.

Dietary cholesterol intake is not associated with the development of chronic kidney disease: Results from two Korean cohort studies

BACKGROUND AND AIMS

Although dyslipidemia is a major risk factor for chronic kidney disease (CKD), the relationship between dietary cholesterol and CKD remains unknown. We investigated the association between cholesterol intake and CKD risk.

METHODS AND RESULTS

The Korea National Health and Nutrition Examination Survey (KNHANES) 2019-2021 (n = 13,769) and the Korean Genome and Epidemiology Study (KoGES) (n = 9225) data were used for this study. Cholesterol intake was assessed using a 24-h recall food frequency questionnaire, and participants were categorized into three groups (T1, T2, and T3) based on cholesterol intake. Primary outcomes were prevalence and incidence of CKD. Higher cholesterol intake was modestly associated with increased serum levels of total, low-density lipoprotein, and high-density lipoprotein cholesterol in the KNHANES. However, we found no significant association between cholesterol intake and CKD prevalence in the KNHANES, regardless of a history of hypercholesterolemia. In the KoGES, during a median follow-up of 11.4 years, cholesterol intake was not associated with incident CKD in participants without hypercholesterolemia (hazard ratio [HR] per 10 mg increase, 1.00; 95 % confidence interval [CI], 0.99-1.01) and in those with hypercholesterolemia (HR, 1.01; 95 % CI, 0.98-1.04). Egg consumption also showed no significant association with the risk of incident CKD. Additionally, cholesterol intake had no significant interaction on the relationships between serum cholesterol levels and incident CKD.

CONCLUSION

Although cholesterol intake was associated with increased serum cholesterol levels, it was not associated with CKD prevalence and incidence. Our findings suggest that reducing cholesterol intake alone may not be sufficient to prevent CKD.

Debunking the Myth: Eggs and Heart Disease

Eggs, which are often considered a complete food, have recently been scrutinized by the media as a potential cause of cardiovascular disease. However, the media hasn't shown the same enthusiasm for processed foods high in fructose, the consumption of refined cooking oil, seed oils, and carbohydrate-rich meals, the connection between these factors and metabolic diseases, or the potential long-term impacts on population comorbidities, as they have for criticizing egg yolks as a cause for cardiovascular disease in recent times. This review investigates the relationship between eggs and lipid levels, glucose levels, atherosclerosis, and antioxidant properties, as well as comparing them to cholesterol-free egg controls. We conducted the review in response to a recent trend of discarding nutritious and energy-rich egg yolks due to the belief propagated by the media that removing egg yolks from a normal diet is cardioprotective after the media started to blame egg yolks as the cause of the recent surge in heart attacks. However, the media fails to highlight the fact that eggs have been an integral part of the human diet since the domestication of hens. On the other hand, recent additions to the human diet a few decades ago, such as fructose-rich breakfast cereals, coffee beverages with sugar levels comparable to candy bars, protein supplements for diabetics that are notorious for raising blood glucose levels, and the heightened consumption of seed oil, which causes inflammation, have been responsible for the surge in cardiovascular events in recent times. Social media platforms often showcase visually appealing junk food products and sugary beverages as a sign of wealth, promoting unhealthy processed food and ultimately causing a decline in an individual's lifespan and overall health.

The effect of whole egg consumption on weight and body composition in adults: a systematic review and meta-analysis of clinical trials

BACKGROUND

A limited number of studies have directly examined the effect of whole eggs on body weight and composition in adults, and they have led to inconsistent results. This study aimed to summarize the evidence on the effect of whole egg consumption on body weight and body composition in adults from clinical trials.

METHODS

Online databases were searched from inception to April 2023 for clinical trials that directly or indirectly assessed the effect of whole eggs consumption on anthropometric measures including body weight, body mass index (BMI), waist circumference (WC), and fat-free mass (FFM) in adults. A random effects model was used for meta-analysis.

RESULTS

In total, 32 controlled clinical trials were included in the systematic review. The analyses revealed that whole egg consumption has no significant effect on body weight (n = 22), BMI (n = 13), WC (n = 10), and FFM (n = 4, P > 0.05). The subgroup analyses showed that whole egg consumption has an increasing effect on body weight and BMI in studies that lasted more than 12 weeks and in unhealthy participants (P < 0.05). A significant increasing effect on BMI was found in studies that the control group did not receive any egg (P < 0.05). Moreover, in studies that there was no significant difference in energy intake between the intervention and control groups, weight, and WC were significantly increased (P < 0.05). Additionally, in studies that participants in the control group received another food or supplement, studies with calorie restriction, and studies on healthy subjects, whole egg intake significantly decreased BMI (P < 0.05).

CONCLUSIONS

Although whole egg consumption had no adverse effect on body composition and body weight, in overall, it might increase body weight in long term. Egg consumption beneficially affects BMI in healthy people and during weight loss diet.

SYSTEMATIC REVIEW REGISTRATION

This systematic review and meta-analysis is registered in the International Prospective Register of Systematic Reviews (PROSPERO, Registration number: CRD42022308045).

Postprandial effects of dietary protein source on metabolic responses, appetite, and arterial stiffness indices in overweight and obese men: the study protocol for a randomized crossover clinical trial

BACKGROUND

Different dietary protein sources are supposed to have various effects on metabolic responses and arterial stiffness in the postprandial period. This study aims to assess the postprandial effects of dietary protein sources, including animal-based protein (AP) and plant-based protein (PP), as part of a high-protein breakfast on appetite response, energy metabolism, and arterial stiffness in overweight and obese men.

METHODS

This acute randomized crossover clinical trial will be conducted at the Persian study research center at Imam Reza Hospital, affiliated with the Mashhad University of Medical Sciences, located in the northeast of Iran. Forty-six healthy overweight, and obese men aged 18-60 years will be enrolled based on the eligibility criteria. The subjects will complete two interventions (high-protein AP and PP meals) with 1 week washout period. The primary outcome will be the acute effect of the two test meals on appetite response, energy metabolism parameters, including resting metabolism rate (RMR), diet-induced thermogenesis (DIT), and substrate oxidation (SO), and arterial stiffness indices, including pulse wave velocity (PWV) and pulse wave analysis (PWA). The secondary outcomes include changes in lipemia, glycemia, and insulinemia.

DISCUSSION

The findings of this study will provide novel insight regarding the acute effects of different protein sources on energy metabolism, appetite, and arterial stiffness as a significant cardiovascular disease (CVD) risk factor. It will help dieticians develop effective and efficient meal plans to improve weight reduction and maintenance in overweight/obese individuals.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials; code: IRCT20211230053570N1; registered on February 10, 2022.

Eggs: Healthy or Risky? A Review of Evidence from High Quality Studies on Hen's Eggs

Hen's eggs (from Gallus gallus domesticus) provide choline, folate, vitamin D, iodine, B vitamins and high-quality protein and are no longer viewed by national bodies as a risk factor for hypercholesterolaemia and cardiovascular disease (CVD). Yet, questions remain about the benefits and risks of eating eggs regularly. This review evaluates recent high-quality evidence from randomised controlled trials (RCT) and meta-analyses of observational studies and considers new areas of interest, such as weight management, protein metabolism, allergy risk and sustainability. In several RCT, eggs increased muscle protein synthesis and lowered fat mass, which could support optimal body composition. Eggs within a meal improved satiety, which could translate into lower energy intakes, although more RCT are needed. In observational studies, higher egg consumption was associated with a null effect or a modest reduced risk of CVD. For type 2 diabetes (T2D) incidence and risk of CVD in people with T2D, there were inconsistencies between observational and RCT data, with the former noting positive associations and the latter seeing no effect of higher egg intake on markers of T2D and CVD. Sustainability metrics suggest that eggs have the lowest planetary impact amongst animal proteins. To lower allergy risk, earlier introduction of eggs into weaning diets is warranted. In conclusion, the balance of evidence points to eggs being a nutritious food suggesting there are broad health benefits from including eggs in the diet at intakes higher than that currently consumed by European populations.

Egg Intake Is Associated with Lower Risks of Impaired Fasting Glucose and High Blood Pressure in Framingham Offspring Study Adults

The association between egg consumption and cardiometabolic risk factors such as high blood pressure (HBP) and impaired fasting glucose (IFG) or type 2 diabetes (T2D) is still under debate. This study examines the association between egg consumption and these outcomes among 2349 30-64 year-old adults in the prospective Framingham Offspring Study. Diet was assessed using three-day dietary records. Potential confounders retained in the final models included age, sex, body mass index, and other dietary factors. The analysis of covariance and Cox proportional hazard's models were used to assess the relevant continuous (i.e., FG, SBP, DBP) and categorical (i.e., T2D, HBP) outcomes. Consuming ≥5 eggs per week was associated with lower mean FG (p = 0.0004) and SBP (p = 0.0284) after four years of follow-up. Higher egg intakes led to lower risks of developing IFG or T2D (HR: 0.72; 95% CI: 0.51-1.03) and high blood pressure (HBP) (HR: 0.68; 0.50-0.93). The beneficial effects of egg consumption were stronger in combination with other healthy dietary patterns. This study found that regular egg consumption as part of a healthy diet had long-term beneficial effects on blood pressure and glucose metabolism and lowered the long-term risks of high blood pressure and diabetes.

Is There a Correlation between Dietary and Blood Cholesterol? Evidence from Epidemiological Data and Clinical Interventions

Dietary cholesterol has been a topic of debate since the 1960s when the first dietary guidelines that limited cholesterol intake to no more than 300 mg/day were set. These recommendations were followed for several years, and it was not until the late 1990s when they were finally challenged by the newer information derived from epidemiological studies and meta-analysis, which confirmed the lack of correlation between dietary and blood cholesterol. Further, dietary interventions in which challenges of cholesterol intake were evaluated in diverse populations not only confirmed these findings but also reported beneficial effects on plasma lipoprotein subfractions and size as well as increases in HDL cholesterol and in the functionality of HDL. In this review, we evaluate the evidence from recent epidemiological analysis and meta-analysis as well as clinical trials to have a better understanding of the lack of correlation between dietary and blood cholesterol.

Egg Consumption in the Context of Plant-Based Diets and Cardiometabolic Risk Factors in Adults at Risk of Type 2 Diabetes

BACKGROUND

Plant-based diets (PBDs) are typically recommended to those at risk of type 2 diabetes mellitus (T2DM).

OBJECTIVES

We examined how including eggs, compared with excluding them from PBDs, affected cardiometabolic risk factors in adults at risk of T2DM.

METHODS

This was a randomized, controlled, single-blind, crossover trial of 35 adults (mean age: 60.7 y; 25 women, 10 men) at risk of T2DM assigned to 1 of 2 sequence permutations of 2 dietary treatments (plant-based plus eggs, and exclusively plant-based), with a 4-wk washout period. A dietitian counseled participants to exclude or include 2 eggs daily in the context of PBDs for a 6-wk interval. Our primary outcome measure was endothelial function (EF) measured as flow-mediated dilatation. Secondary outcome measures included lipid profile, blood pressure, insulin sensitivity, anthropometry, and dietary intake. Data were analyzed using generalized linear models.

RESULTS

Compared with egg exclusion, egg inclusion in the context of PBDs did not adversely affect EF (-1.7% ± 6.5% compared with -1.8% ± 7.5%; P = 0.9805). Likewise, egg inclusion, compared with egg exclusion, did not adversely affect (P = 0.1096-0.9781) lipid profile, blood pressure, insulin sensitivity, or anthropometry. Egg inclusion, compared with egg exclusion, improved reported intakes of selenium (23.1 ± 30.3 μg/d compared with 2.3 ± 34.9 μg/d; P = 0.0124) and choline (172.0 ± 96.0 mg/d compared with -3.4 ± 68.1 mg/d; P < 0.0001).

CONCLUSIONS

Consuming 2 eggs daily in the context of PBDs does not adversely affect cardiometabolic risk factors among adults at risk of T2DM. Eggs could be used as an adjuvant to enhance PBDs that are typically recommended for those at risk of T2DM.This trial was registered at clinicaltrials.gov as NCT04316429.

Egg and saturated fat containing breakfasts have no acute effect on acute glycemic control in healthy adults: a randomized partial crossover trial

BACKGROUND/OBJECTIVES

High egg consumption is associated with poor glycemic control. Considering the widespread consumption of eggs, it is crucial to determine causality in this association. We tested if egg consumption acutely alters glucose disposal in the absence or presence of saturated fat, which is frequently consumed with eggs.

SUBJECTS/METHODS

In a randomized partial crossover clinical trial, 48 subjects (consuming ≥ 1 egg/week) received two of four isocaloric, macronutrient-matched breakfasts. The groups were defined based on the main ingredient of the breakfasts offered: eggs (EB); saturated fat (SB); eggs and saturated fat (ES); and control, which included a cereal based breakfast (CB). The breakfasts were offered in two testing sessions spaced seven days apart. Six blood samples (pre breakfast (fasting); 30, 60, 90, 120, and 180 minutes post breakfast) were collected to measure glucose and insulin levels. Area under the curves (AUC) were analyzed controlling for the baseline concentrations using mixed-effects models accounting for within-subject dependencies to compare these across breakfast assignments.

RESULTS

Forty-eight patients (46% males, age 25.8 ± 7.7 years, BMI 25.7 ± 4.6 kg/m²) were included. Neither EB, SB nor ES was associated with a significant difference in AUC of glucose or insulin compared to CB (p > 0.1).

CONCLUSIONS

Acutely, consumption of egg breakfast with or without accompanying saturated fat does not adversely affect glucose disposal in healthy adults. While this is reassuring for continued egg consumption, a long-term evaluation of egg intake with or without saturated fat would be the next step.

Egg, cholesterol and protein intake and incident type 2 diabetes mellitus: Results of repeated measurements from a prospective cohort study

BACKGROUND & AIMS

Epidemiological evidence on the associations of egg, cholesterol and protein intake with risk of type 2 diabetes is inconsistent. Therefore, we conducted this study to explore these associations among Chinese adults.

METHODS

Data from 4 waves (2004, 2006, 2009 and 2011) of the China Health and Nutrition Survey were used. A multistage random-cluster sampling method was employed to recruit the participants in both rural and urban areas. We included individuals who participated in 2004 and any waves afterwards. Those 1) below 18 years of age; 2) with diabetes at baseline; or 3) with extreme energy intake (men: <800 kcal or >6000 kcal; women: <600 kcal or >4000 kcal) were excluded. Respondents were classified into four groups according to quartiles of egg, cholesterol and protein intake per day. Numbers of eggs per day were calculated by dividing egg intake in grams by 50 g. Diagnosis of type 2 diabetes was self-reported. Logistic generalized estimation equation models were employed.

RESULTS

There were 7312 individuals included in 2004, 6390 in 2006, 4826 in 2009 and 4963 in 2011. The mean age of participants at baseline was 48.3 years and 47.2% were men. Over an average of 5.8-y follow-up, 209 developed type 2 diabetes. After adjustment for demographic, lifestyle and dietary confounders, the odds ratio of type 2 diabetes for those in the highest compared with the lowest protein intake quartile was 2.38 (95% CI: 1.43, 3.98). The odds ratio of individuals with ≥3 eggs/day versus none was 3.76 (95% CI, 2.05, 6.90). Cholesterol intake was not associated with type 2 diabetes.

CONCLUSIONS

Individuals with the highest protein intake had over a 2-fold increased risk of type 2 diabetes compared with those with the lowest protein intake. A high intake of egg, but not dietary cholesterol, was associated with type 2 diabetes. This association warrants further investigation.

Postprandial effects of macronutrient composition meals on the metabolic responses and arterial stiffness indices of lean and obese male adults: a protocol of a pilot study

BACKGROUND

Prior studies have shown that meal composition may affect the metabolic responses and arterial stiffness indices, and these responses may be different in lean and obese adults. The primary objective of this study is to determine the feasibility of conducting a trial to compare the effect of three test meals in lean and obese men. Due to the lack of a comprehensive study that concurrently compares metabolic responses and vascular stiffness indices after receiving three different meals in lean and obese men, this pilot study will be conducted with a three-phase parallel design, aiming to investigate the effects of meal composition on the metabolic parameters and arterial stiffness indices of lean and obese adults.

METHODS

This pilot, a parallel clinical trial will be performed on 24 male adults aged 18-35 years since January 2021 and will continue until March 2021 who are disease-free and selected based on the inclusion and exclusion criteria at Mashhad University of Medical Sciences, Iran. The subjects will complete three interventions at a 1-week interval, including high carbohydrate (70% carbohydrates, 10% protein, 20% fat), high protein (30% protein, 50% carbohydrates, 20% fat), and high-fat meal (50% fat, 40% carbohydrates, 10% protein). Postprandial effects will be assessed within 360 min after each meal, including the energy expenditure component (resting energy expenditure, thermic effects of feeding, respiratory quotient, and substrate oxidation) and arterial stiffness indices (augmentation index and pulse wave velocity). In addition, blood sampling will be performed to measure glucose, insulin, free fatty acids, and lipid profile.

DISCUSSION

The differences in the postprandial responses can affect the metabolic and vascular parameters due to different meal compositions, thereby providing beneficial data for the establishment of new strategies in terms of nutritional education and metabolic/vascular improvement. Also, the results from this pilot study will inform intervention refinement and efficacy testing of the intervention in a larger randomized controlled trial.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials; code: IRCT20190818044552N1 ; registered on August 26, 2019.

Interactive associations of the INAFM2 rs67839313 variant and egg consumption with type 2 diabetes mellitus and fasting blood glucose in a Chinese population: A family-based study

BACKGROUND

INAFM2 rs67839313 was associated with type 2 diabetes (T2DM) in Japanese populations but not in other populations. We aimed to validate the association of rs67839313 with T2DM and explore interactive associations of INAFM2 rs67839313 and egg consumption with T2DM and fasting blood glucose (FBG) in a Chinese population.

METHODS

In total, 7175 participants (4202 T2DM cases) from 3980 families were included and categorized into two groups (<4 and ≥4 eggs/week) according to the median egg consumption. Multilevel logistic regression and linear regression models were performed to estimate the genetic associations of rs67839313 with T2DM and FBG, respectively. The crossproduct term between the variant and egg was included in the models for interaction analysis.

RESULTS

We found that rs67839313_T was associated with an increased risk of T2DM (1.22 [95% CI: 1.17-1.27], P < 0.001). Among individuals with the rs67839313_T genotype, those with egg consumption <4/week (1.37 [1.25-1.51]) had a higher T2DM risk than those with egg consumption ≥4/week (1.17 [1.11-1.23]). A significant interactive effect between rs67839313_T and egg consumption on T2DM risk was identified (P = 0.008). Moreover, among participants without T2DM, rs67839313_T was associated with FBG, with a 0.188 mmol/l increase and a 0.152 mmol/l decrease among those consuming <4 eggs/week and ≥4 eggs/week, respectively. The interaction between rs67839313_T and egg consumption was observed to be significantly associated with FBG (P = 0.003).

CONCLUSIONS

INAFM2 rs67839313_T was associated with increased T2DM risk and FBG levels in Chinese individuals, and consuming more eggs may eliminate the associated genetic risk. This finding has important implications for understanding the genetic pathogenesis of T2DM and for the precision nutrition management of T2DM.

Association between daily egg intake and lipid profiles in adults from the Henan rural cohort study

BACKGROUND AND AIMS

The association between daily egg intake and dyslipidemia remains a contentious issue. Therefore, our study was aimed to explore the relation of daily egg intake to lipid profile; and whether the association was mediated by body mass index (BMI).

METHODS AND RESULTS

A total of 39,021 participants (18-79 years) were enrolled from the Henan Rural Cohort Study. Data on egg consumptions and blood lipid indices were collected with standardized processes. Logistic regression and restricted cubic splines were used to estimate the odds ratio (OR) and 95% confidence intervals (95% CI). Mediation analysis using bootstrap was performed to examine the contribution of BMI to daily egg intake and HDL-C. The participants were divided into 3 egg intake groups (＜26.79 g/d, 26.79-62.50 g/d, ＞62.5 g/d). According to our results, comparing with the low daily egg consumption group, medium and high egg intake tertiles were related with increased high-TC (OR_medium = 1.546, 95%CI (1.417,1.688); OR_high = 1.902,95%CI (1.703, 2.124)), high LDL-C (OR_medium = 1.224, 95%CI (1.121, 1.337); OR_high = 1.368,95%CI (1.220, 1.534)) and non-HDL-C(OR_medium = 1.486,95%CI(1.358,1.625); OR_high = 1.715,95%CI (1.499, 1.888)), as well as inversely associated with high-TG (OR_medium = 0.825, 95% CI(0.778, 0.875); OR_high = 0.778,95%CI(0.718,0.844)) and low HDL-C (OR_medium = 0.914, 95%CI (0.858, 0.973); OR_high = 0.756,95%CI(0.693,0.825)). Moreover, mediation analysis showed that both of BMI and WC partly mediated the relationship between daily egg intake and HDL-C.

CONCLUSIONS

Our results suggested that the daily egg intake may have a role in effect on lipid profiles, and the effect of daily egg intake on HDL-C may be partly mediated by BMI and WC.

The Debate Over Egg Consumption and Incident Cardiovascular Disease

There is a great debate regarding the association of cholesterol intake from egg consumption and the incidence of cardiovascular disease (CVD). Most studies show that moderate egg consumption is not associated with a significant increase in CVD, stroke, heart failure, and type 2 diabetes mellitus (T2DM), whereas others dispute this fact and state that there is an association with increased egg consumption, especially if they are consumed with saturated fats. In addition, the recent relaxation of cholesterol intake to greater than 300 mg/d by the American College of Cardiology/American Heart Association Nutritional Guidelines has fueled this debate. In order to get a current perspective on the significance of moderate egg consumption with the primary incidence of CVD, a focused Medline search of the English language literature was conducted between 2010 and March 2020 using the terms, cholesterol intake, egg consumption, coronary artery disease, CVD, and T2DM. Nineteen pertinent articles were retrieved, and these, together with collateral literature, will be discussed in this review article. The analysis of data from the articles retrieved indicated that several studies showed that moderate egg consumption (1 egg/d) is not associated with adverse cardiovascular effects in subjects free of CVD or T2DM, whereas other studies showed a positive association, especially in patients with preexisting CVD or T2DM. Therefore, at present, there is no unanimous agreement on this subject, and the controversy will continue until new confirmatory evidence becomes available.

Whole Egg Consumption Decreases Cumulative Weight Gain in Diet-Induced Obese Rats

BACKGROUND

Whole egg (WE) consumption has been demonstrated to attenuate body weight (BW) gain and adiposity in genetic animal models of type 2 diabetes (T2D). This finding was accompanied by increased food consumption.

OBJECTIVES

This study aimed to examine the effects of long-term WE intake on BW gain, fat distribution, and food intake in a rat model of diet-induced obesity (DIO).

METHODS

Male Sprague Dawley rats (n = 24) were obtained at 5 wk of age and were randomly weight-matched across 1 of 4 dietary intervention groups (6 rats per group): a casein-based diet (CAS), a high-fat high-sucrose CAS diet (HFHS CAS), a whole egg-based diet (EGG), or a high-fat high-sucrose EGG diet (HFHS EGG). All diets provided 20% (w/w) protein and were provided for 33 wk. HFHS diets provided ∼61% of kilocalories from fat and 10% from sucrose. Daily weight gain and food intake were recorded, biochemical parameters were measured via ELISA, and epididymal fat pad weights were recorded at the end of the study.

RESULTS

At 33 wk, cumulative BW gain in DIO rats fed HFHS EGG resulted in 23% lower weight gain compared with DIO rats fed HFHS CAS (P < 0.0001), but no significant differences in BW gain were observed between the HFHS EGG group and the control EGG and CAS groups (P = 0.71 and P = 0.61, respectively). Relative food intake (grams per kilogram BW) was 23% lower (P < 0.0001) in rats fed HFHS CAS compared with CAS, whereas there was no difference in food intake within the EGG dietary groups. DIO rats fed HFHS EGG exhibited a 22% decrease in epididymal fat weight compared with their counterparts fed the HFHS CAS.

CONCLUSIONS

Our data demonstrate that consumption of a WE-based diet reduced BW gain and visceral fat in the DIO rat, similar to our previous findings in a genetic rat model with T2D.

The responses of different dosages of egg consumption on blood lipid profile: An updated systematic review and meta-analysis of randomized clinical trials

Diverse notions exist regarding egg intake, which is one of the main sources of dietary cholesterol, and its effect on blood lipids. We conducted this study to update the previous meta-analysis for their flaw in calculated effect size. PubMed, Scopus, ISI, and Cochrane were searched up to April 2019, for relevant randomized controlled clinical trials. Mean changes in total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglyceride (TG), very low-density lipoprotein cholesterol (VLDL-C), LDL-C/HDL-C, TC/HDL-C, apolipoprotein (apo)A1, and apoB100 were assessed. Meta-analysis of 66 RCTs with 3,185 participants revealed that egg consumption can significantly increase TC, LDL-C, HDL-C, TC/HDL-C, apoA1/and B100, but there was no significant effect on other serum lipids. Dose-response analysis showed a linear effect for TC, HDL-C, ApoA1, ApoB100, and nonlinear for LDL-C, and TC/HDL-C. In conclusion, intake of more than one egg daily in less than 12 weeks may increase some blood lipids without any changes in the ratio of LDL-C/HDL-C. PRACTICAL APPLICATIONS: There are controversies reports for egg intake, which is one of the main sources of dietary cholesterol. This study provides comprehensive information about the effect of the number of eggs consumed per day (dietary cholesterol) on blood lipids for nutritionists, physicians, researchers, and the general population. In this regard, our results indicated that there is a linear correlation between consumption of greater than one egg per day in a short time (no long time) and increasing lipid profiles which may increase the risk of cardiovascular diseases. However, consumption of one egg daily can be safe and this can be a useful recommendation for prevention of cardiovascular disease and promotion of healthy life which indeed are the potential or actual uses of this research.

Nutrition and the aging retina: A comprehensive review of the relationship between nutrients and their role in age-related macular degeneration and retina disease prevention

Age-related macular degeneration (AMD) is the leading cause of severe vision loss in developed countries and is highly common among aging individuals. Considering the rate at which the global population is aging, the increasing prevalence of AMD and age-related eye disease is cause for concern. AMD is associated with the degeneration of the macula, the most central region of the retina, leading to a loss of central vision. A wide array of research has focused on the ability of lipid soluble nutrients to prevent and mitigate the harmful effects of AMD. These nutrients in question tend to be highly saturated within retinal tissues including the carotenoids lutein and zeaxanthin and the polyunsaturated fatty acid docosahexaenoic acid (DHA). Additionally, the unique presence of very long chain polyunsaturated fatty acids (VLCPUFAs, C24-C36) in the retina may be essential to prevent retinal degeneration as demonstrated by abnormal retinal functioning in the absence of these novel fatty acids. Existing literature has suggested that lutein, zeaxanthin and DHA consumption tend to enhance the health of the retina, protecting against the development of AMD. However, little improvement to the previously deteriorated retina is demonstrated and more research is required to understand the role of these nutrients in the retina and for the prevention of AMD. Considering the global impact of AMD and age-related eye disease, utilizing nutrients to prevent the formation of these debilitating diseases is a highly affordable and promising strategy.

Egg consumption and human health: an umbrella review of observational studies

Egg consumption has been an area of controversy regarding its impact on human health largely due to the content in cholesterol and its potential role in cardio-metabolic outcomes. This study aimed to summarise the level of evidence of egg consumption on various health outcomes. A systematic search for meta-analyses was performed: study design, dose-response relationship, heterogeneity and agreement of results over time, and identification of potential confounding factors were considered to assess the level of evidence. Results from this umbrella review showed a substantial no association between egg consumption and a number of health outcomes, including cancer, cardiovascular and metabolic disorders. In contrast, evidence of possible beneficial effects toward stroke risk has been found. In conclusions, egg may be part of a healthy diet; however, additional studies exploring confounding factors are needed to ascertain the potential detrimental effects.

Effect of Egg Consumption on Blood Pressure: a Systematic Review and Meta-analysis of Randomized Clinical Trials

PURPOSE OF REVIEW

We identified and quantified the results of randomized controlled trials (RCTs) that have assessed the impact of egg consumption on blood pressure in adults.

RECENT FINDINGS

We conducted a comprehensive search of medical bibliographic databases up to February 2019 for RCTs investigating the effect of egg consumption on blood pressure in adults. Fifteen RCTs were included with a total of 748 participants. Overall, egg consumption had no significant effect on systolic blood pressure (weighted mean difference (WMD) = 0.046 mmHg; 95% CI - 0.792, 0.884) and diastolic blood pressure (WMD = - 0.603 mmHg; 95% CI - 1.521, 0.315). Subgroup analyses had no effect on pooled results and no heterogeneity was found among included studies. Egg consumption has no significant effects on systolic and diastolic blood pressure in adults. Due to several limitations among existing studies, general conclusions cannot be drawn regarding the beneficial or neutral impact of egg consumption on blood pressure in adults.

Effect of egg consumption on inflammatory markers: a systematic review and meta-analysis of randomized controlled clinical trials

There is little evidence about whether eggs affect inflammation. The aim of this meta-analysis was to explore the effects of egg consumption on inflammation. A systematic search of online databases (Institute for Scientific Information (ISI), Scopus, Ovid, PubMed, Cochrane) was used to gather clinical trials that assessed the effect of egg consumption on circulating inflammatory biomarkers. Using a random-effects model, pooled weighted mean differences (WMD) and corresponding standard deviations (SD) were calculated. Of the 21 eligible studies found, nine trials were eligible for analysis. Eight trials assessed high-sensitivity C-reactive protein (hs-CRP), four trials assessed interleukin-6 (IL-6), and five trials assessed tumor necrosis factor-alpha (TNF-α). Egg consumption did not affect hs-CRP (WMD 0.24 mg/L; 95% CI: -0.43, 0.90; I²  = 53.8; P = 0.48), IL-6 (WMD 0.20 pg/mL; 95% CI: -0.71, 1.11; I² = 69.3; P = 0.50), and TNF-α (WMD: -0.38 pg/mL; 95% CI: -0.87, 0.10; I² = 0.00; P = 0.12) relative to controls. Overall, this meta-analysis revealed that egg consumption had no significant effect on serum biomarkers of inflammation in adults. © 2019 Society of Chemical Industry.

The Association between Maternal Dietary Protein Intake and Risk of Gestational Diabetes Mellitus

BACKGROUND

The amount and type of dietary protein affect glucose metabolism. However, the association between dietary protein intake and gestational diabetes mellitus (GDM) risk is vague. We examined this association. Methods: We included 152 GDM and 168 non-GDM participants (total 320), age 18-45 years from Arash Women's Hospital, Tehran, Iran. Protein intake was ascertained from 168-item Food Frequency Questionnaire at 24-40 weeks' gestation. GDM was defined as fasting blood sugar >95 mg/dL and/or oral glucose tolerance test >155 mg/dL. Dietary data were assessed using N4 software and statistical analysis was performed using SPSS 21. We tested the association between the amount of protein consumed from red and processed meat, poultry, dairy, egg, seafood, and vegetable plus sociodemographic and lifestyle covariates and GDM risk using multivariate logistic regression analysis.

RESULTS

There was a significant association between the physical activity (P < 0.035), socioeconomic status (P < 0.013), body mass index, age, and each trimester's weight (P < 0.001), and risk of GDM. No significant association was observed between the intake of protein from major protein sources and risk of GDM. The only significant association was observed for egg consumption which was lower in GDM participants (P = 0.004), yet this association turned nonsignificant after adjustment for confounders, except for the fourth quartile (odds ratio: 0.43, 95% confidence interval: 0.208, 0.893).

CONCLUSIONS

According to our findings, dietary intake of total and major protein sources could not affect the GDM risk. Differences between Iranian and Western population and the reverse causality might be the main reasons for this nonsignificant association.

Dietary Whole Egg Reduces Body Weight Gain in a Dose-Dependent Manner in Zucker Diabetic Fatty Rats

BACKGROUND

We previously reported that a whole-egg-based diet attenuated weight gain in rats with type 2 diabetes (T2D) and more effectively maintained vitamin D status than an equivalent amount of supplemental cholecalciferol.

OBJECTIVES

The objective of this study was to determine the lowest dose of whole egg effective at maintaining vitamin D homeostasis and attenuating the obese phenotype in T2D rats.

METHODS

Zucker diabetic fatty (ZDF) rats (n = 40; age 6 wk; prediabetic) and their lean controls (n = 40; age 6 wk) were randomly assigned to a diet containing 20% casein (CAS) or 20%, 10%, 5%, or 2.5% protein from whole egg (20% EGG, 10% EGG, 5% EGG, and 2.5% EGG, respectively). All diets contained 20% total protein (wt:wt). All rats received their respective diets for 8 wk, at a stage of growth and development that translates to adolescence in humans, until 14 wk of age, a point at which ZDF rats exhibit overt T2D. Weight gain was measured 5 d/wk, and circulating 25-hydroxyvitamin D [25(OH)D] was measured by ELISA. Mean values were compared by 2-factor ANOVA.

RESULTS

The 20% EGG diet maintained serum 25(OH)D at 30 nmol/L in ZDF rats, whereas the 10%, 5%, and 2.5% EGG diets did not prevent insufficiency, resulting in mean serum 25(OH)D concentrations of 24 nmol/L in ZDF rats. Body weight gain was reduced by 29% (P < 0.001) and 31% (P < 0.001) in ZDF rats consuming 20% and 10% EGG diets, respectively, and by 16% (P = 0.004) and 12% (P = 0.030) in ZDF rats consuming 5% and 2.5% EGG diets, respectively, compared with CAS.

CONCLUSIONS

Whole-egg-based diets exerted a dose-dependent response with respect to attenuating weight gain. These data could support dietary recommendations aimed at body weight management in individuals predisposed to obesity and T2D.

Protein Intake at Twice the RDA in Older Men Increases Circulatory Concentrations of the Microbiome Metabolite Trimethylamine-N-Oxide (TMAO)

Higher dietary protein intake is increasingly recommended for the elderly; however, high protein diets have also been linked to increased cardiovascular disease (CVD) risk. Trimethylamine-N-oxide (TMAO) is a bacterial metabolite derived from choline and carnitine abundant from animal protein-rich foods. TMAO may be a novel biomarker for heightened CVD risk. The purpose of this study was to assess the impact of a high protein diet on TMAO. Healthy men (74.2 ± 3.6 years, n = 29) were randomised to consume the recommended dietary allowance of protein (RDA: 0.8 g protein/kg bodyweight/day) or twice the RDA (2RDA) as part of a supplied diet for 10 weeks. Fasting blood samples were collected pre- and post-intervention for measurement of TMAO, blood lipids, glucose tolerance, insulin sensitivity, and inflammatory biomarkers. An oral glucose tolerance test was also performed. In comparison with RDA, the 2RDA diet increased circulatory TMAO (p = 0.002) but unexpectedly decreased renal excretion of TMAO (p = 0.003). LDL cholesterol was increased in 2RDA compared to RDA (p = 0.049), but no differences in other biomarkers of CVD risk and insulin sensitivity were evident between groups. In conclusion, circulatory TMAO is responsive to changes in dietary protein intake in older healthy males.

Impact of whole egg intake on blood pressure, lipids and lipoproteins in middle-aged and older population: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Effects of whole egg consumption on cardiovascular diseases (CVD) risk in the middle-aged and older population remain unclear due to inconsistent findings from observational and randomized controlled trials (RCTs). This meta-analysis aimed to assess the impacts of whole egg and egg category (whole eggs versus egg substitutes) intake quantity on CVD risk factors from systematically searched RCTs. Egg substitutes were hypothesized to have minimal effects of the blood lipid and lipoprotein profile as they are void of dietary cholesterol.

METHODS AND RESULTS

As many as 434 studies identified from PubMed, Cochrane Library, CINAHL and Medline (Ovid) databases were screened and data were extracted from 8 selected RCTs. Quality of the selected studies were assessed and the overall effect sizes of weighted mean differences (WMD) were calculated using a random effects model. Non-differential effects in blood pressures, lipids and lipoproteins were observed when >4 whole eggs/week compared to ≤4 whole eggs/week were consumed. Intake of >4 whole eggs/week compared to equivalent amounts of egg substitutes caused greater elevations in blood total cholesterol (WMD: 0.198 mmol/L; 95% CIs: 0.056, 0.339), HDL cholesterol (WMD: 0.068 mmol/L; 95% CIs: 0.006, 0.130) and LDL cholesterol (WMD: 0.171 mmol/L; 95% CIs: 0.028, 0.315) but did not differentially affect triglycerides concentration.

CONCLUSION

Overall, the results support the notion that quantity of whole egg intake does not affect CVD risk factors and consuming egg substitutes may also be beneficial compared to whole eggs on lowering CVD risk in the middle-aged and older population.

Whole Egg Consumption Impairs Insulin Sensitivity in a Rat Model of Obesity and Type 2 Diabetes

BACKGROUND

The literature regarding the relation between egg consumption and type 2 diabetes (T2D) is inconsistent and there is limited evidence pertaining to the impact of egg consumption on measures of insulin sensitivity.

OBJECTIVES

The aim of this study was to investigate the effect of dietary whole egg on metabolic biomarkers of insulin resistance in T2D rats.

METHODS

Male Zucker diabetic fatty (ZDF) rats (n = 12; 6 wk of age) and age-matched lean controls (n = 12) were randomly assigned to be fed a casein- or whole egg-based diet. At week 5 of dietary treatment, an insulin tolerance test (ITT) was performed on all rats and blood glucose was measured by glucometer. After 7 wk of dietary treatment, rats were anesthetized and whole blood was collected via a tail vein bleed. Following sedation, the extensor digitorum longus muscle was removed before and after an intraperitoneal insulin injection, and insulin signaling in skeletal muscle was analyzed by Western blot. Serum glucose and insulin were analyzed by ELISA for calculation of the homeostatic model assessment of insulin resistance (HOMA-IR).

RESULTS

Mean ITT blood glucose over the course of 60 min was 32% higher in ZDF rats fed the whole egg-based diet than in ZDF rats fed the casein-based diet. Furthermore, whole egg consumption increased fasting blood glucose by 35% in ZDF rats. Insulin-stimulated phosphorylation of key proteins in the insulin signaling pathway did not differ in skeletal muscle of ZDF rats fed casein- and whole egg-based diets. In lean rats, no differences were observed in insulin tolerance, HOMA-IR and skeletal muscle insulin signaling, regardless of experimental dietary treatment.

CONCLUSIONS

These data suggest that whole body insulin sensitivity may be impaired by whole egg consumption in T2D rats, although no changes were observed in skeletal muscle insulin signaling that could explain this finding.

Mechanism and Potential of Egg Consumption and Egg Bioactive Components on Type-2 Diabetes

Type-2 diabetes (T2D) is one of the major global health challenges and a substantial economic burden. Egg and egg-derived components have been indicated to possess antioxidant, anti-inflammatory, anti-hypertensive, immunomodulatory, and anti-cancer activities. However, the scientific evidence about the benefits of egg on T2D is debatable. The relationship between egg consumption and the risk of T2D from observational epidemiological studies is not consistent. Interventional clinical studies, however, provide promising evidence that egg consumption ameliorates the risk of T2D. Current research progress also indicates that some egg components and egg-derived peptides might be beneficial in the context of T2D, in terms of insulin secretion and sensitivity, oxidative stress, and inflammation, suggesting possible application on T2D management. The current review summarizes recent clinical investigations related to the influence of egg consumption on T2D risk and in vivo and in vitro studies on the effect and mechanism of egg components and egg-derived peptides on T2D.

Co-ingestion of whole eggs or egg whites with glucose protects against postprandial hyperglycaemia-induced oxidative stress and dysregulated arginine metabolism in association with improved vascular endothelial function in prediabetic men

Replacing a portion of a glucose challenge with whole eggs (EGG) or egg whites (WHITE) was shown to protect against glucose-induced impairments in vascular function. We hypothesised in the present study that previously observed vasoprotection following co-ingestion of EGG or WHITE with glucose was attributed to limiting postprandial hyperglycaemia-induced oxidative stress that improves NO∙ bioavailability. Prediabetic men completed a randomised, cross-over study in which they ingested isoenergetic meals containing 100 g glucose (GLU), or 75 g glucose with 1·5 EGG, seven WHITE or two egg yolks (YOLK). At 30 min intervals for 3 h, we assessed plasma NO∙ metabolites, the lipid peroxidation biomarker malondialdehyde, antioxidants, arginine and its methylated metabolites (asymmetric dimethylarginine and symmetric dimethylarginine), tetrahydrobiopterin redox status, vasoconstrictors and inflammatory markers. Compared with GLU, malondialdehyde was lower and NO∙ metabolites were greater in EGG and WHITE, but YOLK was not different from GLU. Malondialdehyde was inversely correlated with NO∙ metabolites and vascular function, whereas NO∙ metabolites were positively correlated with vascular function. Compared with GLU, arginine was greater, but asymmetric and symmetric dimethylarginine and angiotensin-II were lower in all egg-based meals. Antioxidants, tetrahydrobiopterin redox status and inflammatory markers did not differ among treatments. Thus, while each egg-based meal improved arginine metabolism, only EGG and WHITE limited lipid peroxidation. This suggests that vasoprotection mediated by EGG and WHITE likely occurs in an NO∙-dependent manner by improving arginine metabolism and attenuating oxidative stress that otherwise limit NO∙ biosynthesis and bioavailability to the vascular endothelium.

Egg consumption is associated with a lower risk of type 2 diabetes in middle-aged and older men

BACKGROUND/OBJECTIVES

This prospective study examined gender-specific associations between egg intake and the risk of developing type 2 diabetes using data from a large-scale cohort study.

SUBJECTS/METHODS

A total of 7,002 Korean adults (40–69 years) without type 2 diabetes at baseline were analyzed. Dietary intake was evaluated by a food frequency questionnaire administered at baseline (2001–2002) and the second follow-up examination (2005–2006). Type 2 diabetes was diagnosed as a fasting glucose concentration ≥ 126 mg/dL or current use of glucose-lowering medications or insulin injection. Multivariate Cox proportional hazard models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for incident type 2 diabetes according to egg consumption or cholesterol intake.

RESULTS

During a 14-year follow up period, 857 subjects developed type 2 diabetes. In men, frequent egg intake (2- < 4 servings/week) was associated with a 40% lower risk of developing type 2 diabetes than infrequent egg intake (0- < 1 serving/week) (HR = 0.60, 95% CI: 0.37–0.97), whereas no association between egg intake and incidence of type 2 diabetes was observed in women (HR = 0.61, 95% CI: 0.27–1.37). There was no association between cholesterol intake and risk of incident type 2 diabetes in either men or women.

CONCLUSIONS

Egg consumption was inversely related to the risk of incident type 2 diabetes in men, but not in women, suggesting gender differences in the relationship between diet and disease risk.

Impact of Dietary Cholesterol on the Pathophysiology of Infectious and Autoimmune Disease

Cellular cholesterol metabolism, lipid raft formation, and lipoprotein interactions contribute to the regulation of immune-mediated inflammation and response to pathogens. Lipid pathways have been implicated in the pathogenesis of bacterial and viral infections, whereas altered lipid metabolism may contribute to immune dysfunction in autoimmune diseases, such as systemic lupus erythematosus, multiple sclerosis, and rheumatoid arthritis. Interestingly, dietary cholesterol may exert protective or detrimental effects on risk, progression, and treatment of different infectious and autoimmune diseases, although current findings suggest that these effects are variable across populations and different diseases. Research evaluating the effects of dietary cholesterol, often provided by eggs or as a component of Western-style diets, demonstrates that cholesterol-rich dietary patterns affect markers of immune inflammation and cellular cholesterol metabolism, while additionally modulating lipoprotein profiles and functional properties of HDL. Further, cholesterol-rich diets appear to differentially impact immunomodulatory lipid pathways across human populations of variable metabolic status, suggesting that these complex mechanisms may underlie the relationship between dietary cholesterol and immunity. Given the Dietary Guidelines for Americans 2015⁻2020 revision to no longer include limitations on dietary cholesterol, evaluation of dietary cholesterol recommendations beyond the context of cardiovascular disease risk is particularly timely. This review provides a comprehensive and comparative analysis of significant and controversial studies on the role of dietary cholesterol and lipid metabolism in the pathophysiology of infectious disease and autoimmune disorders, highlighting the need for further investigation in this developing area of research.

Effect of a high-egg diet on cardiometabolic risk factors in people with type 2 diabetes: the Diabetes and Egg (DIABEGG) Study-randomized weight-loss and follow-up phase

Background

Some country guidelines recommend that people with type 2 diabetes (T2D) limit their consumption of eggs and cholesterol. Our previously published 3-mo weight-maintenance study showed that a high-egg (≥12 eggs/wk) diet compared with a low-egg diet (<2 eggs/wk) did not have adverse effects on cardiometabolic risk factors in adults with T2D.

Objective

The current study follows the previously published 3-mo weight-maintenance study and assessed the effects of the high-egg compared with the low-egg diets as part of a 3-mo weight-loss period, followed by a 6-mo follow-up period for a total duration of 12 mo.

Design

Participants with prediabetes or T2D (n = 128) were prescribed a 3-mo daily energy restriction of 2.1 MJ and a macronutrient-matched diet and instructed on specific types and quantities of foods to be consumed, with an emphasis on replacing saturated fats with monounsaturated and polyunsaturated fats. Participants were followed up at the 9- and 12-mo visits.

Results

From 3 to 12 mo, the weight loss was similar (high-egg compared with low-egg diets: -3.1 ± 6.3 compared with -3.1 ± 5.2 kg; P = 0.48). There were no differences between groups in glycemia (plasma glucose, glycated hemoglobin, 1,5-anhydroglucitol), traditional serum lipids, markers of inflammation (high-sensitivity C-reactive protein, interleukin 6, soluble E-selectin), oxidative stress (F2-isoprostanes), or adiponectin from 3 to 12 mo or from 0 to 12 mo.

Conclusions

People with prediabetes or T2D who consumed a 3-mo high-egg weight-loss diet with a 6-mo follow-up exhibited no adverse changes in cardiometabolic markers compared with those who consumed a low-egg weight-loss diet. A healthy diet based on population guidelines and including more eggs than currently recommended by some countries may be safely consumed. This trial is registered at http://www.anzctr.org.au/ as ACTRN12612001266853.

Egg consumption and the risk of cardiovascular disease and all-cause mortality: Guangzhou Biobank Cohort Study and meta-analyses

PURPOSE

Eggs are highly nutritious but concerns over their cholesterol content have led to dietary avoidance among many. There are also important international differences in relevant dietary guidance. We conducted the first prospective study in China investigating the association of egg consumption, cardiovascular disease (CVD) mortality, and a meta-analysis.

METHODS

We included 28,024 participants without CVD at baseline (2003-8) in Guangzhou Biobank Cohort Study. All-cause and CVD mortality were identified through record linkage. We used Cox proportional hazards regression. We followed the Meta-analysis Of Observational Studies in Epidemiology reporting guidelines.

RESULTS

During 275,343 person-years follow-up (average 9.8 years), we found 2685 all-cause and 873 CVD deaths. We found no significant difference in all-cause mortality between higher (7+ eggs/week) and low consumption (< 1 egg/week) [adjusted hazard ratio (HR) 1.08, 95% confidence interval (CI) 0.93-1.24], and mortality from CVD (0.99, 95% CI 0.76-1.27), ischemic heart disease (IHD) (0.92, 95% CI 0.63-1.36), or stroke (0.88, 95% CI 0.57-1.35). The updated meta-analyses including our results showed that 7+ eggs/week was not associated with all-cause mortality (HR 1.09, 95% CI 0.997-1.200) or IHD (HR 0.97, 95% CI 0.90-1.05), but associated with a small reduction in stroke (HR 0.91. 95% CI 0.85-0.98).

CONCLUSIONS

Eating one egg daily is not associated with increase in CVD or all-cause mortality. The small observed reduction in stroke risk needs to be confirmed. Our findings support current guidelines recommending eggs as part of a healthy diet, and should be considered in other dietary recommendations.

Dietary Cholesterol, Serum Lipids, and Heart Disease: Are Eggs Working for or Against You?

The relationship between blood cholesterol and heart disease is well-established, with the lowering of serum low-density lipoprotein (LDL)-cholesterol being the primary target of preventive therapy. Furthermore, epidemiological studies report lower risk for heart disease with higher concentrations of high-density lipoprotein (HDL)-cholesterol. There has also been considerable interest in studying the relationship between dietary cholesterol intake and heart disease risk. Eggs are one of the richest sources of cholesterol in the diet. However, large-scale epidemiological studies have found only tenuous associations between the intake of eggs and cardiovascular disease risk. Well-controlled, clinical studies show the impact of dietary cholesterol challenges via egg intake on serum lipids is highly variable, with the majority of individuals (~2/3 of the population) having only minimal responses, while those with a significant response increase both LDL and HDL-cholesterol, typically with a maintenance of the LDL/HDL cholesterol ratio. Recent drug trials targeting HDL-cholesterol have been unsuccessful in reducing cardiovascular events, and thus it is unclear if raising HDL-cholesterol with chronic egg intake is beneficial. Other important changes with egg intake include potentially favorable effects on lipoprotein particle profiles and enhancing HDL function. Overall, the increased HDL-cholesterol commonly observed with dietary cholesterol feeding in humans appears to also coincide with improvements in other markers of HDL function. However, more investigation into the effects of dietary cholesterol on HDL functionality in humans is warranted. There are other factors found in eggs that may influence risk for heart disease by reducing serum lipids, such as phospholipids, and these may also modify the response to dietary cholesterol found in eggs. In this review, we discuss how eggs and dietary cholesterol affect serum cholesterol concentrations, as well as more advanced lipoprotein measures, such as lipoprotein particle profiles and HDL metabolism.

Egg consumption may improve factors associated with glycemic control and insulin sensitivity in adults with pre- and type II diabetes

Daily consumption of one large egg for 12 weeks improves fasting blood glucose, ATP-binding cassette protein family A1, and apolipoprotein A1 in overweight or obese individuals with pre- and type II diabetes.

Effects of Weight Loss on Advanced Glycation End Products in Subjects with and without Diabetes: A Preliminary Report

Advanced glycation end-products (AGEs) are formed endogenously as a normal ageing process and during food processing. High levels of AGEs have been implicated in the development of both macrovascular disease and microvascular disease. The purpose of this secondary analysis was to determine whether a major AGE species, N^ε-carboxymethyllysine (CML), was reduced after weight loss. CML values decreased by 17% after weight loss. Participants with diabetes and pre-diabetes had a lower CML values at baseline and a smaller change in CML than overweight participants without diabetes. We conclude that, in addition to the known health benefits, weight loss may reduce AGEs. Randomized studies of the effect of weight loss on AGE in people with and without type 2 diabetes are needed to confirm these results.

Effects of Egg Consumption on Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

BACKGROUND

It is widely agreed that egg consumption only modestly influences serum lipid concentrations. However, there is no meta-analysis summarizing existing randomized controlled trials.

OBJECTIVE

The purpose of this study was to conduct a meta-analysis of published randomized controlled trials to explore the quantitative effect of egg consumption on serum lipid concentrations.

DESIGN

Online databases including MEDLINE, Proquest and Google Scholar were systematically searched. Studies that were published after 2000 and compared serum lipids concentrations in egg-consumers and non egg-consumers were included. The data were obtained from 28 studies. Weighted mean differences were calculated as the ultimate effect using random effects model.

RESULTS

Overall, egg consumption increased total cholesterol (TC) by 5.60 mg/dL (95% CI: 3.11, 8.09; P<0.0001), low density lipoprotein-cholesterol (LDL-C) by 5.55 mg/dL (95% CI: 3.14, 7.69; P<0.0001) and high density lipoprotein-cholesterol (HDL-C) by 2.13 mg/dL (95% CI: 1.10, 3.16; P<0.0001) compared with the control group. Heterogeneity found between studies was explained partly by study design and participant response to dietary cholesterol. No effect of increased egg consumption on LDL-C:HDL-C and TC:HDL-C ratios, and triglyceride (TG) concentrations were found. No association was observed between number of eggs consumed per day or study duration and any of the serum lipid markers.

CONCLUSION

Consumption of egg increases total cholesterol, LDL-C and HDL-C, but not LDL-C:HDL-C, TC:HDL-C and TG compared with low egg control diets. To assess the risk of coronary events, future studies should focus on the postprandial effect of egg consumption and effects on coronary risk.

Egg consumption, cardiovascular diseases and type 2 diabetes

Eggs are rich in nutrients and a source of essential fatty- and amino acids, and the food item with highest cholesterol content. Since the 1970s dietary recommendations have advised limiting egg intake to 2-4 a week for the healthy population, and in those diagnosed with cardiovascular disease (CVD) and type 2 diabetes (T2D) an even more restricted consumption. The aim of the present paper was to assess the recommendation to lower the dietary intake of cholesterol and especially the intake of egg to reduce the risk of CVD and T2D. We performed three web-based literature searches on human studies (observational and interventional) published within the past 10 years during spring 2015. High-quality intervention studies have found nonsignificant effects of increasing the consumption of eggs on risk markers for CVD and T2D in healthy subjects and subjects with T2D. The risk associations found in the observational studies are more likely to be attributed to a dietary pattern often accompanying high egg intake and/or the cluster of other risk factors in people with high egg consumption. Dietary patterns, physical activity and genetics affect the predisposition of CVD and T2D more than a single food item as eggs. In conclusion, up to seven eggs per week can safely be consumed, but in patients with established CVD or T2D only with special emphasis on a healthy lifestyle.

Dietary Whole Egg Consumption Attenuates Body Weight Gain and Is More Effective than Supplemental Cholecalciferol in Maintaining Vitamin D Balance in Type 2 Diabetic Rats

Background: Type 2 diabetes (T2D) is characterized by vitamin D insufficiency owing to excessive urinary loss of 25-hydroxycholecalciferol [25(OH)D]. We previously reported that a diet containing dried whole egg, a rich source of vitamin D, was effective at maintaining circulating 25(OH)D concentrations in rats with T2D. Furthermore, whole egg consumption reduced body weight gain in rats with T2D.Objective: This study was conducted to compare whole egg consumption with supplemental cholecalciferol with respect to vitamin D balance, weight gain, and body composition in rats with T2D.Methods: Male Zucker diabetic fatty (ZDF) rats (n = 24) and their lean controls (n = 24) were obtained at 5 wk of age and randomly assigned to 3 treatment groups: a casein-based diet (CAS), a dried whole egg-based diet (WE), or a casein-based diet containing supplemental cholecalciferol (CAS+D) at the same amount of cholecalciferol provided by WE (37.6 μg/kg diet). Rats were fed their respective diets for 8 wk. Weight gain and food intake were measured daily, circulating 25(OH)D concentrations were measured by ELISA, and body composition was analyzed by dual X-ray absorptiometry.Results: Weight gain and percentage of body fat were reduced by ∼20% and 11%, respectively, in ZDF rats fed WE compared with ZDF rats fed CAS or CAS+D. ZDF rats fed CAS had 21% lower serum 25(OH)D concentrations than lean rats fed CAS. In ZDF rats, WE consumption increased serum 25(OH)D concentrations 130% compared with CAS, whereas consumption of CAS+D increased serum 25(OH)D concentrations 35% compared with CAS.Conclusions: Our data suggest that dietary consumption of whole eggs is more effective than supplemental cholecalciferol in maintaining circulating 25(OH)D concentrations in rats with T2D. Moreover, whole egg consumption attenuated weight gain and reduced percentage of body fat in ZDF rats. These data may support new dietary recommendations targeting the prevention of vitamin D insufficiency in T2D.

Egg Consumption and Risk of Metabolic Syndrome in Korean Adults: Results from the Health Examinees Study

Metabolic syndrome (MetS) is defined as a cluster of metabolic alterations such as abdominal obesity, dyslipidemias, elevated fasting glucose, and hypertension. Studies on the association between egg consumption and MetS are limited and inconsistent. A cross-sectional analysis was conducted to examine the association of egg consumption with MetS among Korean adults aged 40–69 years. A total of 130,420 subjects (43,682 men and 86,738 women) from the Health Examinees Study were selected for the final analysis. Egg consumption was estimated using a validated 106-item food frequency questionnaire. MetS was defined using the National Cholesterol Education Program, Adult Treatment Panel III. Logistic regression analyses were performed to identify the association of egg consumption with MetS via odds ratios (ORs) and 95% confidence intervals (CIs) after adjusting for potential variables. Among 130,420 subjects, 34,039 (26.1%) people had MetS. Consumption of more than 7 eggs/week was associated with a lower odds of MetS risk compared to those who consumed less than one egg/week in women (OR: 0.77, 95%CI: 0.70–0.84, p trend < 0.0001). Higher egg consumption was inversely associated with the MetS components: elevated waist circumference (OR: 0.80, 0.75–0.86), elevated triglyceride (OR: 0.78, 0.72–0.85), reduced high-density lipoprotein cholesterol (HDL-C) (OR: 0.82, 0.77–0.88), elevated blood pressure (OR: 0.86, 0.80–0.92), and elevated fasting glucose (OR: 0.94, 0.83–0.99) in women; reduced HDL-C (OR: 0.89, 0.80–1.00) in men. Our results suggest that higher egg consumption may be associated with a reduction in the odds for MetS and all five metabolic components in women, and the risk of reduced HDL-C in men.

Impact of Egg Consumption on Cardiovascular Risk Factors in Individuals with Type 2 Diabetes and at Risk for Developing Diabetes: A Systematic Review of Randomized Nutritional Intervention Studies

Observational studies have reported inconclusive results regarding the relationship between egg consumption (and dietary cholesterol) and the risk for cardiovascular diseases (CVDs) in individuals with type 2 diabetes, which has led to inconsistent recommendations to patients. We reviewed the evidence of egg consumption on major CVD risk factors in individuals with or at risk for type 2 diabetes (prediabetes, insulin resistance or metabolic syndrome). We performed a systematic search in the databases PubMed, MEDLINE, EMBASE and Web of Science in January 2016. Inclusion criteria included randomized controlled trials in which the amount of egg consumed was manipulated and compared to a control group that received no-egg or low-egg diets (<2 eggs/week). We found 10 articles (6 original trials) that met our inclusion criteria. The majority of studies found that egg consumption did not affect major CVD risk factors. Consumption of 6 to 12 eggs per week had no impact on plasma concentrations of total cholesterol, low-density lipoprotein-cholesterol, triglycerides, fasting glucose, insulin or C-reactive protein in all studies that reported these outcomes in comparison with control groups. An increase in high-density lipoprotein-cholesterol with egg consumption was observed in 4 of 6 studies. Results from randomized controlled trials suggest that consumption of 6 to 12 eggs per week, in the context of a diet that is consistent with guidelines on cardiovascular health promotion, has no adverse effect on major CVD risk factors in individuals at risk for developing diabetes or with type 2 diabetes. However, heterogeneities in study design, population included and interventions prevent firm conclusions from being drawn.

Egg consumption and heart health: A review

Cardiovascular disease is the leading cause of death in the United States. Until recently, reducing dietary cholesterol has been a part of the American Heart Association (AHA) and American College of Cardiology (ACC) guidelines on lifestyle management, despite inconclusive evidence to support the recommendation. Considering eggs are a rich source of dietary cholesterol (typically containing 141-234 mg per egg), individuals with increased risk for CVD are advised not to consume eggs. Furthermore, based on the 2012 AHA/ACC guidelines, individuals with lower risk for CVD have previously been advised to avoid consuming eggs due to the high content of dietary cholesterol. Rather than strictly limiting cholesterol intake, the AHA and ACC guidelines now recommend dietary patterns that emphasize fruits, vegetables, whole grains, low-fat dairy products, poultry, fish, and nuts as an approach to favorably alter blood lipid levels. Of note, the 2015-2020 Dietary Guidelines for Americans have removed the recommendation of limiting cholesterol intake to no more than 300 mg per day; however, the guidelines advise that individuals should eat as little dietary cholesterol as possible while consuming a healthy eating pattern. The purpose of this review is to summarize the documented health risks of egg consumption in individuals with low and high risk for CVD and determine whether current recommendations are warranted based on the available literature. We also aim to provide guidance for future studies that will help further elucidate the health modulating effect of eggs.