Elsevier

Clinical Nutrition

Volume 36, Issue 4, August 2017, Pages 1015-1021
Clinical Nutrition

Original article
Egg consumption and cardiovascular disease according to diabetic status: The PREDIMED study

https://doi.org/10.1016/j.clnu.2016.06.009Get rights and content

Summary

Background

Eggs are a major source of dietary cholesterol and their consumption has been sometimes discouraged. A relationship between egg consumption and the incidence of cardiovascular disease (CVD) has been suggested to be present exclusively among patients with type2 diabetes.

Aims

To assess the association between egg consumption and CVD in a large Mediterranean cohort where approximately 50% of participants had type 2 diabetes.

Methods

We prospectively followed 7216 participants (55–80 years old) at high cardiovascular risk from the PREDIMED (PREvención con DIeta MEDiterránea) study for a mean of 5.8 years. All participants were initially free of CVD. Yearly repeated measurements of dietary information with a validated 137-item food-frequency questionnaire were used to assess egg consumption and other dietary exposures. The endpoint was the rate of major cardiovascular events (myocardial infarction, stroke or death from cardiovascular causes).

Results

A major cardiovascular event occurred in 342 participants. Baseline egg consumption was not significantly associated with cardiovascular events in the total population. Non-diabetic participants who ate on average >4 eggs/week had a hazard ratio (HR) of 0.96 (95% confidence interval, 0.33–2.76) in the fully adjusted multivariable model when compared with non-diabetic participants who reported the lowest egg consumption (<2 eggs/week). Among diabetic participants, the HR was 1.33 (0.72–2.46). There was no evidence of interaction by diabetic status. HRs per 500 eggs of cumulative consumption during follow-up were 0.94 (0.66–1.33) in non-diabetics and 1.18 (0.90–1.55) in diabetics.

Conclusions

Low to moderated egg consumption was not associated with an increased CVD risk in diabetic or non-diabetic individuals at high cardiovascular risk. This trial was registered at controlled-trials.com as ISRCTN35739639.

Introduction

Eggs are a major source of dietary cholesterol. However, they are also an inexpensive source of unsaturated fat, high-quality protein, folate, and other vitamins and minerals [1], [2]. Dietary cholesterol contributes modestly to plasma concentration of low-density lipoprotein (LDL) cholesterol [3], an well-known risk factor for cardiovascular disease (CVD) [4]. Dietary cholesterol has also been directly associated with a higher risk of CVD [5]. Because egg yolk is rich in cholesterol, egg consumption is usually not recommended to subjects with hypercholesterolemia, high cardiovascular risk or established CVD [6], [7].

Egg consumption was directly associated with carotid plaque area in a cross-sectional study conducted among Canadian subjects at high cardiovascular risk [8], but not in a cohort of middle-aged Finnish participants without coronary heart disease [9]. On the other hand, the association between egg consumption and the risk of CVD is controversial. Li et al. [10], found in a meta-analysis that egg consumption was directly associated with CVD. However, in another meta-analysis of prospective cohort studies, Shin et al. [11], found that egg consumption was not associated with CVD risk in the general population. In a third meta-analysis of prospective cohort studies, Rong et al. [12], reported that higher consumption of eggs was also unassociated with coronary heart disease or stroke. Interestingly, the three meta-analyses consistently found a direct association between egg consumption and CVD in diabetic individuals. However, most studies included in these meta-analyses were from the U.S. and other Western countries, but studies from Mediterranean countries are scarce [13].

The PREDIMED study provides a unique opportunity to assess prospectively the association between egg consumption and CVD in participants who were at high cardiovascular risk, nearly 50% of whom had type 2 diabetes. This half-and-half distribution of exposure to diabetes allowed us to obtain an ideal setting to ascertain the association between egg consumption and CVD incidence according to diabetic status. We aimed to examine the association between egg consumption and CVD in a high cardiovascular risk cohort stratified by diabetic status.

Section snippets

Study design and subjects

The current cohort study was conducted within the framework of the PREDIMED study (PREvención con DIeta MEDiterránea). The PREDIMED study is a parallel-group, multicenter, randomized, and controlled field trial. Details of the trial design have been published elsewhere [14], [15]. The primary aim of the trial was to test the efficacy of two Mediterranean diets (enriched with extra-virgin olive oil or mixed nuts), compared to advice on a control (low-fat) diet, on primary cardiovascular events

Results

A total of 8713 candidates were screened for eligibility, and 7447 participants were randomly assigned to one of the three intervention groups. Of them, 153 subjects who were outside the limits for total energy intake at baseline were excluded. We also excluded 78 participants with missing baseline dietary information. Thus the analyses were carried out on 7216 participants.

After a mean follow-up of 5.8 years, 342 participants had a myocardial infarction, a stroke or died from a cardiovascular

Discussion

Higher baseline egg consumption was not associated with CVD in our Mediterranean cohort of older subjects at high cardiovascular risk. Egg consumption in this cohort was lower than that reported in others studies [7], [8], [9]. Indeed, only 3% of the participants in our study consumed >4 eggs/week at baseline. In our study, egg consumption was unrelated to an increased risk of CVD in patients with diabetes and in those without diabetes. However, when we compared extreme categories of

Conclusions

In this cohort of elderly subjects at high cardiovascular risk and with high adherence to a Mediterranean dietary pattern, low to moderated egg consumption was unrelated to CVD risk in both diabetic and non-diabetic individuals. The relationship between egg consumption and CVD remains inconclusive.

Funding disclosure

Supported by the official funding agency for biomedical research of the Spanish Government, Instituto de Salud Carlos III (ISCIII), through grants provided to research networks specifically developed for the trial (RTIC G03/140, to RE; RTIC RD 06/0045, to Miguel A. Martínez-González) and through Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBERobn), and by grants from Centro Nacional de Investigaciones Cardiovasculares (CNIC 06/2007), the Fondo de

Role of the funders

Funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.

Conflict of interest

None.

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    PREDIMED trial was registered at controlled-trials.com as ISRCTN35739639.

    1

    The PREDIMED (Prevención con Dieta Mediterránea) study investigators are listed in the Appendix.

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