Eggs and Heart Health: A Review of the Latest Research and Reports

Nutrient-rich eggs are part of heart-healthy diet patterns, according to findings from leading researchers and health authorities

By: Mickey Rubin, PhD

In 2015, the Dietary Guidelines Advisory Committee (DGAC) removed
dietary cholesterol from the list of nutrients of public health concern.1
Up until that point, there had historically been a limit of 300 milligrams per
day for dietary cholesterol, even though eggs were listed as a nutrient-rich
food and part of healthy dietary patterns in previous guidelines.2

In making this decision, the 2015 DGA committee referenced,
among other sources, a 2013 systematic review that examined the relationship
between egg consumption and cardiovascular disease in almost 350,000
participants across 16 studies.3 The review and meta-analysis found
no relationship between egg intake and cardiovascular disease, ischemic heart
disease, or stroke.

Since 2015, the science evaluating the relationship between
dietary cholesterol, eggs, and cardiovascular health has continued to grow,
with several new research studies and authoritative reports building on our
existing knowledge.


LATEST RESEARCH FINDINGS FROM OBSERVATIONAL COHORTS

There are often competing headlines in nutrition science,
with one study showing one thing, and another study showing the opposite. This
is often true with a nutrient like cholesterol – or a food like eggs – in which
our knowledge has evolved considerably over the years. Rather than getting
caught with nutrition science whiplash, it is important to not focus too much
on any one study, but rather view the research in totality.

For example, one observational study of U.S. cohorts
published early in 2019 found a small but statistically significant increase in
cardiovascular risk with egg consumption.4 However, another observational
study published just a few weeks later and analyzing data from over 400,000 men
and women in Europe for over an average of 12 years, found a small but
statistically significant decrease in
risk for ischemic heart disease with egg intake.5 While these two
examples appear similar in design and provide conflicting results, additional
studies published later in the year had design aspects that provided unique
insights.

PURE Cohort Results
Reinforce Earlier Findings and Identify New Insights

A study published in the American
Journal of Clinical Nutrition
assessed the association of egg consumption
with blood lipids, cardiovascular disease, and mortality in three large
international cohorts.6 In one cohort, the Prospective Urban Rural
Epidemiology (PURE) study, egg consumption was assessed in 146,011 individuals
from 21 countries. The researchers also studied 31,544 patients with vascular
disease in 2 multinational studies: ONTARGET and TRANSCEND, both of which were
originally designed to test treatments for hypertension.

The findings from the
PURE cohort found no link between egg consumption and cardiovascular disease
outcomes
. In fact, in the PURE cohort, researchers found that higher egg intake was associated with a lower risk of myocardial infarction,
a finding that is consistent with other recent studies of cohorts outside the
U.S.5  In the ONTARGET and
TRANSCEND cohorts of individuals with vascular disease, the researchers also
reported no link between egg consumption and cardiovascular events.

Thus, these findings from the PURE investigators reinforce
previous research regarding egg consumption in otherwise healthy individuals,
but took a big step forward in our understanding of this relationship in
individuals with vascular disease.

Harvard School of Public Health
Findings Reveal Decades of Strong Evidence

Yet
another study was published in 2020 that was a follow-up to a landmark
investigation first published in 1999. The original study, led by Hu and
colleagues from the Harvard School of Public Health, reported no relationship
between egg intake and coronary heart disease or stroke in women from the
Nurses’ Health Study (NHS) cohort and men from the Health Professionals
Follow-Up Study (HPFS) cohort.7 At that time the researchers concluded that an egg a day did
not impact heart disease or stroke risk
.

The
current study, an updated analysis of the study published in 1999, includes up
to 24 additional years of follow-up and extends the analysis to the younger
cohort of Nurses’ Health Study II.8 Thus, this latest analysis
included 83,349 women from NHS; 90,214 women from NHS II; and 42,055 men from
HPFS. Additionally, to compare these new findings to the extensive literature
base on the topic of egg intake and cardiovascular risk, the researchers
performed a systematic review and meta-analysis of 27 other published studies
from the U.S., Europe, and Asia.

Results
from the updated analysis from NHS, NHS II, HPFS, as well as the updated
meta-analysis of global cohorts are consistent:

  • Egg
    consumption of one egg per day on average is not associated with
    cardiovascular disease risk overall

    • Results were similar for coronary heart
      disease and stroke
  • Egg
    consumption seems to be associated with a slightly lower cardiovascular disease
    risk among Asian cohorts

An important strength of this study is the use of repeated
dietary assessments over the course of several decades in contrast to some
observational cohorts which utilize only a single dietary measure at
enrollment. According to the authors, it is desirable to have repeated dietary
assessments over time to account for variation of dietary intake and other
factors that contribute to atherosclerosis.

The studies from the PURE cohort and Harvard School of
Public Health make significant contributions to the scientific literature on
egg intake and cardiovascular health. These results are also consistent with
the 2015 Dietary Guidelines recommendation that cholesterol is not a nutrient
of public health concern.


NEW RECOMMENDATIONS FROM LEADING HEALTH AUTHORITIES

In the past year, we have also had multiple recommendations
from leading health authorities that have assessed the totality of evidence for
dietary cholesterol and cardiovascular disease, as well as the role of eggs in
heart healthy diet patterns across the lifespan. A common theme from these authoritative
recommendations is that eggs can be a part of heart healthy diet patterns, and
in some cases nutrient dense eggs should be emphasized in diet patterns due to
their unique nutrient package.

American Heart
Association: Eggs Fit in Heart Healthy Diet Patterns

In late 2019, the American Heart Association (AHA) Nutrition
Committee published a science advisory on Dietary Cholesterol and
Cardiovascular Risk.9 According to the authors, “the elimination of
specific dietary cholesterol target recommendations in recent guidelines has
raised questions about its role with respect to cardiovascular disease.” This
review examined evidence from observational cohorts and randomized controlled
trials and concluded that “a
recommendation that gives a specific dietary cholesterol target within the
context of food-based advice is challenging for clinicians and consumers to
implement; hence, guidance focused on dietary patterns is more likely to
improve diet quality and to promote cardiovascular health
.” The science
advisory recommends heart-healthy eating patterns such as the
Mediterranean-style and DASH (Dietary Approaches to Stop Hypertension)–style
diets. Specifically, regarding eggs, the advisory concluded:

  • Healthy
    individuals can include up to a whole egg daily in heart-healthy dietary
    patterns.
  • For older healthy individuals, given the
    nutritional benefits and convenience of eggs, consumption of up to 2 eggs per
    day is acceptable within the context of a heart-healthy dietary pattern.
  • Vegetarians who do not consume meat-based
    cholesterol-containing foods may include more eggs in their diets within the
    context of moderation.

Australian Heart Foundation: No Evidence
to Limit Egg Consumption

It
wasn’t only the American Heart Association that clarified the role of eggs in a
heart healthy diet, but the Australian Heart Foundation (AHF) made similar
recommendations with a new position statement on eggs and cardiovascular
health.10The AHF summary of
evidence concluded there is no evidence to suggest any limit on egg consumption
for normal, healthy individuals
. The review does suggest a limit to fewer
than 7 eggs per week for those with type 2 diabetes or cardiovascular disease
that require LDL cholesterol- lowering interventions.

Both
the AHA and AHF guidelines were clearly a step forward, building on the
knowledge that dietary cholesterol is not a nutrient of concern in healthy individuals.


SUMMARY

The science on
dietary cholesterol and eggs continues to grow and demonstrates that eggs are
an important part of healthy dietary patterns across the lifespan
. Overall,
these data support the value of eggs as a nutrient dense food within healthy
dietary patterns. As a good or excellent source of eight essential nutrients
including choline, six grams of high quality protein, 252 mcg of the
carotenoids lutein and zeaxanthin, the 70 calories of an egg can be viewed as
so much more than just a source of dietary cholesterol.

See our recipes that fit into a heart-healthy diet or heart health toolkit for more information.


References

  1. Dietary Guidelines Advisory Committee. Scientific Report of the 2015 Dietary
    Guidelines Advisory Committee: Advisory Report to the Secretary of Health and
    Human Services and the Secretary of Agriculture,
    . 2015
  2. Dietary Guidelines Advisory Committee. Scientific Report of the 2010 Dietary
    Guidelines Advisory Committee: Advisory Report to the Secretary of Health and
    Human Services and the Secretary of Agriculture,
    . 2010
  3. Shin, J.Y., et al., Egg consumption in
    relation to risk of cardiovascular disease and diabetes: a systematic review
    and meta-analysis. Am J Clin Nutr,
    2013. 98(1): p. 146-59.
  4. Zhong, V.W., et al., Associations of Dietary
    Cholesterol or Egg Consumption with Incident Cardiovascular Disease and
    Mortality. JAMA, 2019. 321(11): p.
    1081-1095.
  5. Key, T.J., et al., Consumption of Meat, Fish,
    Dairy Products, Eggs and Risk of Ischemic Heart Disease: A Prospective Study of
    7198 Incident Cases Among 409,885 Participants in the Pan-European EPIC Cohort.
    Circulation, 2019. 18;139(25):2835-2845.
  6. Dehghan M, Mente A, Rangarajan S, et al.
    Association of egg intake with blood lipids, cardiovascular disease, and
    mortality in 177,000 people in 50 countries. Am J Clin Nutr. 2020;111(4):795-803.
  7. Drouin-Chartier JP, Chen S, Li Y, et al. Egg
    consumption and risk of cardiovascular disease: three large prospective US
    cohort studies, systematic review, and updated meta-analysis. BMJ.
    2020;368:m513. Published online 2020 Mar 4.
  8. Hu FB, Stampfer MJ, Rimm EB, et al. A
    prospective study of egg consumption and risk of cardiovascular disease in men
    and women. JAMA. 1999;281(15):1387-1394.
  9. Carson JAS, Lichtenstein AH, Anderson CAM,
    Appel LJ, Kris-Etherton PM, Meyer KA, Petersen K, Polonsky T, Van Horn L; on
    behalf of the American Heart Association Nutrition Committee of the Council on
    Lifestyle and Cardiometabolic Health; Council on Arteriosclerosis, Thrombosis
    and Vascular Biology; Council on Cardiovascular and Stroke Nursing; Council on Clinical
    Cardiology; Council on Peripheral Vascular Disease; and Stroke Council. Dietary
    cholesterol and cardiovascular risk: a science advisory from the American Heart
    Association. Circulation. 2019;140:
    e-pub ahead of print.
  10. Australian
    Heart Foundation; Eggs and Cardiovascular Health: Summary of Evidence. 2019.

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