Egg yolk consumption and carotid plaque
Highlights
► Carotid total plaque area (TPA) increases linearly with age. ► TPA increases exponentially with smoking pack-years. ► TPA increases exponentially with egg-yolk years. ► The effect size of egg yolks appears to be approximately 2/3 that of smoking. ► Probably egg yolks should be avoided by persons at risk of vascular disease.
Introduction
The underpinning of what used to be the step 2 diet and later became the diet recommended for CHD risk reduction by NCEP ATP III was a diet low in saturated fat (<7%) and dietary cholesterol (<200 mg) [1]. This diet if strictly applied tended to drive the consumer towards a more plant based diet with other potential advantages in terms of CHD risk reduction. In addition to saturated fat in meat (especially red meat) and full fat dairy products, eggs were also restricted due to their significant cholesterol content.
Currently, however, serious doubts have been expressed over the relevance of these dietary components to cardiovascular disease [2], [3]. In the case of cholesterol much of the debate has been focused on the lack of clear consensus on whether egg consumption consistently raises serum cholesterol [4], [5], [6], [7], [8] or impacts negatively on postprandial events, including vascular reactivity [9], [10]. Most importantly the association of egg consumption with CHD events in cohort studies has been inconsistent [11], [12], [13], [14]. We recently reviewed the evidence that consumption of cholesterol and egg yolk should not be considered benign in patients at risk of vascular disease [15]. Much of the controversy in this area is about effects of egg yolk consumption on fasting lipids; however the main impact of diet is on the post-prandial state, not on the fasting state [15], [16].
To address the key issue of whether egg yolk intake relates to vascular damage we report the association of egg consumption with carotid plaque area assessed by ultrasound as an indication of atheromatous change in patients attending vascular clinics at an University Hospital. To provide perspective on the magnitude of the effect, we also analysed the effect of smoking (pack-years).
Section snippets
Methods
Patients in the database had been referred to vascular prevention clinics since we routinely began measuring carotid total plaque area (TPA) in 1995 [17], [18]. Plaque area was measured as previously described [19]: each plaque identified in the common, external and internal carotid artery on both sides was measured in a longitudinal view, in the plane in which it was biggest. The perimeter of each plaque was traced using a cursor on the screen to measure the area of the plaque, and the sum of
Results
There were 2831 patients with data on egg yolk consumption. Of these, consent to use the data, and data on pack-years of smoking and carotid total plaque area were available in 1231 patients. The mean age was 62 years; 47% were women. Baseline characteristics of the patients are shown in Table 1. Table 2 shows the baseline characteristics of the patients grouped by quintiles of egg-yolk years.
Fig. 1A shows that carotid atherosclerotic plaque burden increases linearly after age 40, among
Interpretation
Our data suggest a strong association between egg consumption and carotid plaque burden. The exponential nature of the increase in TPA by quintiles of egg consumption follows a similar pattern to that of cigarette smoking. The effect of the upper quintile of egg consumption was equivalent in terms of atheroma development to 2/3 of the effect of the upper quintile of smoking. In view of the almost unanimous agreement on the damage caused by smoking, we believe our study makes it imperative to
Conclusion
Our findings suggest that regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease. This hypothesis should be tested in a prospective study with more detailed information about diet, and other possible confounders such as exercise and waist circumference.
Acknowledgements
Carotid plaque area measurements were performed by Maria DiCicco RVT and Janine DesRoches RVT. Data on egg consumption were converted from text fields in the database to egg-yolk years by Timothy Spence during a summer job at the Stroke Prevention & Atherosclerosis Research Centre.
The maintenance of the database was made possible by funding from the Heart & Stroke Foundation of Ontario, including grant numbers T2956, T5017, NA4990, T5704, NA6018, and NA5912. It was also supported by donations
References (46)
- et al.
Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease
Am J Clin Nutr
(2010 Mar) - et al.
The influence of egg consumption on the serum cholesterol level in human subjects
Am J Clin Nutr
(1977 May) - et al.
Egg consumption and endothelial function: a randomized controlled crossover trial
Int J Cardiol
(2005 Mar 10) - et al.
Eggs, serum cholesterol, and coronary heart disease
Am J Clin Nutr
(1982 Oct) - et al.
Egg consumption in relation to cardiovascular disease and mortality: the physicians' health study
Am J Clin Nutr
(2008 Apr) - et al.
Dietary cholesterol and egg yolks: not for patients at risk of vascular disease
Can J Cardiol
(2010 Nov) - et al.
An approach to ascertain probands with a non traditional risk factor for carotid atherosclerosis
Atherosclerosis
(1999) Serum cholesterol response to dietary cholesterol
Am J Clin Nutr
(1984 Aug)- et al.
Quantitative effects of dietary fat on serum cholesterol in man
Am J Clin Nutr
(1965 Nov) - et al.
Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: a meta-analysis
Am J Clin Nutr
(2001 May)
Egg consumption, serum cholesterol, and cause-specific and all-cause mortality: the national integrated project for prospective observation of non-communicable disease and its trends in the aged, 1980 (NIPPON DATA80)
Am J Clin Nutr
Effect of egg yolk feeding on the concentration and composition of serum lipoproteins in man
Atherosclerosis
Effects of dietary fat and fatty acids on coronary artery disease risk and total and lipoprotein cholesterol concentrations: epidemiologic studies
Am J Clin Nutr
Dietary cholesterol from eggs increases plasma HDL cholesterol in overweight men consuming a carbohydrate-restricted diet
J Nutr
Phenotypic heterogeneity of sitosterolemia
J Lipid Res
The ABCG5 polymorphism contributes to individual responses to dietary cholesterol and carotenoids in eggs
J Nutr
Cholesterol absorption efficiency declines at moderate dietary doses in normal human subjects
J Lipid Res
Low-carbohydrate-diet score and risk of type 2 diabetes in women
Am J Clin Nutr
Mediterranean diet and public health: personal reflections
Am J Clin Nutr
Executive summary of the third report of the national cholesterol education program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel III) general cardiovascular risk profile for use in primary care: the Framingham heart study
J Am Med Assoc
Revisiting dietary cholesterol recommendations: does the evidence support a limit of 300 mg/d?
Curr Atheroscler Rep
Increased dietary cholesterol does not increase plasma low density lipoprotein when accompanied by an energy-restricted diet and weight loss
Eur J Nutr
A double-blind, randomized, controlled trial of the effects of two eggs per day in moderately hypercholesterolemic and combined hyperlipidemic subjects taught the NCEP step I diet
J Am Coll Nutr
Cited by (68)
Restoration of immunity by whole egg was superior to egg white or egg yolk in a cyclophosphamide-induced immunocompromised mouse model
2022, Food BioscienceCitation Excerpt :Compared to consuming eggs without yolks, whole eggs were more beneficial in lowering blood sugar, blood lipids, and blood pressure in people with diabetes (Diez-Espino, Basterra-Gortari, Salas-Salvado et al., 2017; X. Wang, Wang, Wu, et al., 2021). However, several studies demonstrated that large amounts of egg yolks were not suitable for people with hyperlipidemia because the yolks affected blood cholesterol levels (Spence, Jenkins, & Davignon, 2012). Interestingly, consuming both egg white and egg yolk in the form of whole egg did not raise cholesterol in obese patients.
Egg white consumption increases GSH and lowers oxidative damage in 110-week-old geriatric mice hearts
2020, Journal of Nutritional BiochemistryResponse to the Letter to the Editor From Dr. Spence, “Egg Consumption and Cardiovascular Risk”
2018, Canadian Journal of DiabetesThe Gut Microbiota as a Mediator of Metabolic Benefits after Bariatric Surgery
2017, Canadian Journal of DiabetesCitation Excerpt :Trimethylamine-N-oxide (TMAO) is synthesized in the liver by a reaction catalyzed by the enzyme flavin monooxygenase, and its substrate is trimethylamine (TMA), a product generated exclusively by the gut microbiota from dietary choline, phosphatidylcholine, L-carnitine or gamma-butyrobetaine. There is strong evidence that circulating TMAO is linked to atherogenesis and major adverse cardiovascular events (39–42), but the mechanism is not yet well understood. Although animal studies have reported increased urinary TMAO and fecal TMA in rat models of RYGB (24), studies in humans have found an increase in circulating TMAO 1 year (43) and 9 years after RYGB (18).
Egg consumption and cardiovascular disease according to diabetic status: The PREDIMED study
2017, Clinical Nutrition