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:
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.10 The 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.
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.
- 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
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Australian Heart Foundation; Eggs and Cardiovascular Health: Summary of Evidence. 2019.