Elsevier

Atherosclerosis

Volume 235, Issue 2, August 2014, Pages 273-280
Atherosclerosis

Egg consumption and carotid atherosclerosis in the Northern Manhattan Study

https://doi.org/10.1016/j.atherosclerosis.2014.04.019Get rights and content

Highlights

  • The association between egg intake and carotid plaque phenotypes was studied.

  • Frequent egg consumption was inversely related to several atherosclerosis phenotypes.

  • No association with clinical vascular events was detected among frequent egg eaters.

  • Our findings do not support limiting egg consumption for vascular health promotion.

Abstract

Background

The evidence supporting recommendations to limit intake of cholesterol rich foods is inconclusive. We aimed to examine the association between egg consumption and carotid atherosclerosis phenotypes, and the association with clinical vascular events in a prospective, urban, multi-ethnic population.

Methods and results

The Northern Manhattan Study is a population based cohort to determine stroke incidence, risk factors and prognosis. A sub-cohort of 1429 NOMAS participants with both carotid ultrasounds and comprehensive dietary information was evaluated (mean ± SD age of participants 65.80 ± 8.80, 40% male, 18% white, 20% black, 60% Hispanic). The association between egg consumption and carotid intima media thickness (cIMT) was assessed with linear regression. Logistic and quantile regression was used to examine the association between egg consumption and carotid plaque presence, thickness, and area. The relation between egg consumption and clinical vascular events (N = 2669) was examined with Cox models. The mean total cIMT was 0.91 ± 0.08 mm and 58% had carotid plaque present. Increasing egg consumption was inversely associated with cIMT, plaque presence, thickness, and area, in models adjusted for demographics, vascular risk factors and diet. For every additional egg consumed per week, the risk of plaque decreased by 11% (95% CI 3%–18%). No association was detected between egg consumption and risk of clinical vascular outcomes, over a mean follow up of 11 years and after adjustment for covariates.

Conclusions

Frequency of egg consumption in the low to moderate range was inversely related to several markers of carotid atherosclerosis. No association with clinical vascular events, including stroke, was detected. Our findings do not support current vascular health guidelines suggesting the extreme limitation or avoidance of egg consumption due to its cholesterol content.

Introduction

Diet is a complex and irrefutable risk factor for cardiovascular disease (CVD). In keeping with the diet-heart hypothesis which invoked dietary cholesterol as a major CVD risk factor, dietary guidelines have advised limiting the intake of cholesterol rich foods. Egg is a significant source of cholesterol, containing an average of 213 mg per egg. Since the 1970's, egg consumption in the United States has been particularly discouraged by health stakeholders in the absence of empirical data. The American Heart Association guidelines no longer restrict egg consumption, but the allotted cholesterol allowance of <200 mg/day for individuals at high risk of CVD, and <300 mg/day for otherwise healthy individuals, precludes significant egg intake when guidelines are followed in the context of an omnivorous western diet. European and Canadian guidelines, in contrast, do not restrict cholesterol, as the literature suggests that saturated and trans-fat restriction is a more effective means of CVD risk reduction [1], [2].

Egg is a low glycemic index, whole-food that has been part of the human diet since early mankind. It is an inexpensive source of protein, essential fatty acids, antioxidants, vitamins, and minerals, and is one of the few dietary sources of choline, a potent anti-oxidant. Benefits of egg consumption are well described in the literature, including: the formation of larger, less atherogenic LDL and HDL particles [3], [4], increased HDL-C formation [5], [6], and protection against macular degeneration and cataracts [40], [41], [42].

A growing body of evidence supports the claim that egg consumption ≤1/day in healthy individuals is not associated with increased risk of CVD, yet inconsistent data remains. A recent study by Spence et al. described increased carotid plaque area, an imaging biomarker of atherosclerosis, in high risk individuals for CVD, consuming 3 or more eggs per week [7]. The study concluded that regular consumption of egg yolk should be avoided by individuals at high risk for CVD. This study contrasts starkly with the findings of other large, well-controlled, population based cohort studies which concluded that consumption of up to one egg per day does not increase CVD risk [8], [9], [10].

Because of conflicting evidence, guidelines, and the declining overall health and nutritional status of North Americans, it is important to understand the effect of egg consumption in a healthy, ethnically diverse population. The relationship between egg consumption and atherosclerosis in particular requires further study. Stroke and other vascular events are etiologically heterogeneous and atherosclerosis is likely an important pathway linking diet with clinical vascular events. Therefore, in this cross sectional study we examined the association between egg consumption with carotid atherosclerosis phenotypes, including carotid plaque cIMT, and with clinical vascular events in an urban, multi-ethnic population-based cohort.

Section snippets

Study population

NOMAS is a prospective cohort study designed to determine stroke incidence, risk factors, and prognosis in a multi-ethnic urban population. Study details have been published previously [11].

Eligible subjects: a) had never been diagnosed with ischemic stroke; b) were >40 years old; and c) resided in Northern Manhattan for ≥3 months, in a household with a telephone. Subjects were identified by random-digit dialing, and interviews were conducted by trained bilingual research assistants. The

Results

In the subcohort with carotid ultrasound measured, the mean age was 65.8 ± 8.8 years, 40% were male, 18% white, 20% black, and 60% Hispanic. In response to the frequency of whole egg consumption with a medium portion size of 2 eggs, 23% of the cohort reported that they consumed eggs less than once per month, 26% 1 time/month, 16% 2–3 times/month, 30% 1 times/week, 3% 2 times/week, 2% 3–4 times/week, 1% 5–6 times/week, and nobody reported consuming eggs daily. Table 1 shows the distribution of

Discussion

In this multi-ethnic population-based cohort study, we observed an inverse association between egg consumption and several distinct imaging biomarkers of carotid atherosclerosis including carotid IMT, plaque presence, plaque thickness, and total plaque area. The inverse association persisted without attenuation after adjustment for demographics, traditional vascular risk factors, dietary habits, and inflammation. Our results suggest that egg consumption, in the low to moderate range, is not

Funding sources

This work was supported by the National Institute of Neurological Disorders and Stroke [R37 NS 29993]; NIH [K24 to T.R. and RO1 013094 to M.E.]; and Evelyn McKnight Brain Institute.

Disclosure

Responsibility for (a) the accuracy of statements of fact, (b) the authenticity of scientific findings or observations, and (c) expressions of scientific or other opinion published in the journal rests solely with the author(s) of the article. No responsibility for such matters is assumed by the journal or its owners, publishers, reviewers or staff.

Acknowledgment

We wish to thank the staff of the Northern Manhattan Study, particularly the project manager Ms.Janet DeRosa.

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