Research on Eggs

Old, Outdated Research

Since the 1970s eggs have always been associated with a higher risk of cardiovascular disease. These initial associations were based on observational studies [3], a research method which isn’t very good at proving cause and effect relationships. In fact, eggs have been studied in many different patient populations, and shown to have no negative effects, and in some instances even to be beneficial.

Egg Consumption in Healthy Individuals

Studies looking at healthy individuals showed 3 eggs a day didn’t affect blood cholesterol at all [4], [7]. In addition, eggs improved HDL, increased plasma antioxidants, increased plasma choline levels and favored less atherogenic LDL particle profiles [4], [7]. All of these are good outcomes!

Egg Consumption in Individuals at High Risk for Cardiovascular Disease

High risk is determined by a combination of factors, including: hypertension, diabetes, dyslipidemia, age and family history.

One study looked at people with high risk of cardiovascular disease. Half the people were given 2 whole eggs a day, while the other half were given a cholesterol-free egg substitute. The trial lasted only 1 month. The findings showed that eggs improved cholesterol profiles [4], whereas the cholesterol-free egg-substitute did not. Total cholesterol in the egg group did go up, but HDL went up and the LDL profile favored the less dangerous, large buoyant LDL particles [4]. Again, the egg group showed favorable outcomes.

Egg Consumption in Diabetics

A systematic review, looking at multiple studies on diabetic patients, those with prediabetes, insulin resistance or metabolic syndrome have found that egg consumption did not affect cardiovascular risk factors [8]. Studies have looked at consuming from 6-12 eggs per week and found no impact on plasma concentrations of total cholesterol, LDL, triglycerides, fasting glucose, insulin or c-reactive protein. To further show eggs’ importance in this population, 66% of the studies looked at showed an increase to HDL, showing its protective effects on heart health [8]. Nutrition advice for diabetics and anyone else with blood sugar dysregulation should encourage eggs, but they should be part of an otherwise healthy diet in the context of cardiovascular and diabetic health promotion.

Furthermore, egg consumption has no link to causing diabetes [9] or inducing blood sugar dysregulation in non-diabetic individuals. Studies have been done on overweight and obese patients and consuming 3 eggs a day for 12 weeks did not impair glucose metabolism [10]. The same is true for healthy individuals – eggs do not negatively affect glucose or insulin concentrations [4].

Egg Consumption in Obese, Diabetic Individuals

Studies have looked at a 3-egg breakfast versus bagel-based breakfast in obese diabetics. The eggs proved to be advantageous in helping HDL-C and having no effect on the bad LDL-C [11]. This experiment was done in the context of a calorie restricted diet to promote weight loss. To further prove eggs' efficacy, eggs also enhanced fat loss versus the bagel breakfast [11].

In another study, looking at how many eggs to eat, it was found that eating anywhere from 2-4 eggs a day increased HDL-C and had favourable effects on LDL-C. This study lasted 4 weeks [12].

Egg Consumption in Patients with Metabolic Syndrome

Metabolic syndrome is characterized by a combination of dyslipidemia, impaired endothelial function and vascular stiffening [4]. These patients typically have dyslipidemia, hypertension and diabetes and are known to have a high risk of cardiovascular events. These are the typical patients being told to avoid eggs at all costs. Well, research shows otherwise.

In one study with 2 eggs a day for breakfast, there was no negative effect on endothelial function (assessed by flow mediated dilation) in obese individuals with metabolic syndrome, proving to have no detriment to vascular health [13].

Another study provided 3 eggs a day, which improved inflammatory markers (CRP and TNF-a). They compared it to cholesterol-free egg substitute – which had no such effect [4].

Eggs Consumption and Stroke Risk

Stroke is the 4^th leading cause of death and is often associated with sub-optimal diet. Although having too much cholesterol is a risk factor, a big study called NHANE-1 found that eating more than 6 eggs a week did not increase risk for stroke [14].

Egg Consumption and Overeating

In addition to the improvements in cholesterol profiles mentioned above, eggs have also been shown to help with satiety (the feeling of fullness) after a meal. Those having eggs for breakfast versus oatmeal showed improved satiety – meaning they were less likely to snack and overeat throughout the rest of the day [4], [15].

Hyper-Responders

Most people eat eggs and nothing significantly changes in their cholesterol values [4].

Hyper-responders are the minority of people (about 20%) who do experience a change in plasma (blood) cholesterol. However, the increase tends to be both HDL and LDL lab values. This equates to the same cholesterol ratio. As you may know, the ratio between HDL and LDL is the most important predictor for heart health.

Summary

Eggs can be part of a healthy diet. All of the studies I referenced in this article were done on humans and prove eggs (and their cholesterol) are not a driving force behind cardiovascular disease.

Eggs can be safely eaten as part of a healthy diet – in healthy populations and those with atherosclerosis, hypertension or diabetes.

It's true eggs may increase dietary cholesterol, but has no effect on serum (blood) cholesterol and cardiovascular events. Studies have shown up to 3 eggs a day to be beneficial to health, and this is a number I recommend to most patients who want to incorporate eggs back into their diet.