Are Eggs Healthy? Know the Components of this Food and its Impact on Health

This analysis is based on evidence and references from 27 scientific articles.

Eggs can be considered healthy. They can have disadvantages, depending on the amount you consume and your health, but are generally safe to consume.

What is the content of an egg?

An egg contains the following elements:

Albumin

Albumin (the white of the egg) is made primarily of protein . It contains B vitamins but also avidin, a protein that can bind certain B vitamins, such as biotin, and thus prevent their absorption.

Fortunately, a considerable portion of avidin is destroyed by prolonged heating (including pasteurization), so the loss of nutrients can be mitigated.

Albumin is mainly water and protein. Unfortunately, it contains avidin which is an anti-nutrient.

Since heat can destroy avidin, egg whites must be cooked to avoid possible loss of nutrients.

The yolk

The fat in egg yolk is approximately 46% oleic acid, an omega-9 monounsaturated fat commonly found in olive oil, 38% saturated fat, and 16% polyunsaturated fat (PUFA).

The PUFA ratio will depend on how the chickens were raised.

Since most chickens are fed omega-6 PUFA-rich grains, the eggs at your local grocery store are typically much higher in omega-6 than omega-3 PUFAs, while grass-fed or grass-fed chickens Special omega -3 diet will have a more balanced PUFA ratio.

Alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are omega-3 PUFAs.

In humans, ALA is converted to the more active EPA and DHA, but this conversion is not very efficient and decreases even more as we age, so adding EPA and DHA to our diets is considered more beneficial than adding ALA .

Most chickens fed an omega-3 diet receive ALA. Less fish oil, which contains EPA and DHA; the “fishy” taste and smell of their eggs tend to make them less popular.

The omega-3 content of the yolks can be increased by altering the hens’ diet through supplemental omega-3 fats in the form of ALA or EPA + DHA.

Eggs fortified with EPA + DHA (via fish oil) are considered more beneficial, but their less fishy taste and smell tend to make them less popular.

The yolks also have high levels of carotenoids (mainly lutein and zeaxanthin) that are capable of increasing carotenoid concentrations both in plasma and in specific tissues such as the eyes.

Perhaps most importantly, yolks are among the richest sources of choline, a nutrient associated with a number of health benefits.

Finally, although the yolk contains less protein than albumin, it has higher concentrations of the essential amino acid leucine.

The yolk is composed primarily of fatty acids, cholesterol, and fat-soluble nutrients. Although it is lower in protein than albumin, it contains higher concentrations of leucine, an essential amino acid.

Heart health

Cholesterol

Cholesterol is a fat-like substance present in all of our cells. It serves many functions, such as providing the raw material for pregnenolone, from which many other hormones are derived such as:

Cholesterol is carried throughout the body by two types of carriers made of fat on the inside and protein on the outside:

  • Low-density lipoproteins (LDL, often called the “bad cholesterol”).
  • High-density lipoproteins (HDL, often called the »good cholesterol«).

Cholesterol levels measured by typical blood tests reflect both the cholesterol we make and the cholesterol we eat (most people make more cholesterol than they eat).

Cholesterol can form small crystalline aggregates, which are found in atherosclerotic plaques. Immune cells called macrophages can take up these crystals, thereby activating the NLRP3 inflammasome.

Supporting this idea, other crystals such as silica and uric acid have been shown to trigger inflammasome activation.

Inflammasome activation in turn triggers the release of several pro-inflammatory cytokines, including IL-1beta and IL-18, which appear to be critical for the progression of atherosclerosis.

It is mechanistically possible for cholesterol to form crystals that can trigger an inflammatory response that can promote atherosclerosis.

Cardiovascular diseases

Observational studies in middle-aged Japanese and people on a Mediterranean diet found no association between egg consumption and risk of cardiovascular disease.

Another observational study found no increased risk of stroke or coronary artery disease in people who ate 1-6 eggs per week, while “more than 6 eggs per week” appeared to increase the risk of coronary artery disease only in diabetics.

Similar results were found in an observational study in diabetics that compared one egg per week and others without eggs.

Another study found no connection between egg consumption and cardiovascular disease, but found stronger associations in diabetics between egg consumption and increased mortality.

Observational studies looking specifically at egg consumption (and not total dietary cholesterol) have not found it to be associated with any form of cardiovascular disease, except perhaps in diabetics.

Although observational evidence may suggest a link between egg consumption and heart disease in diabetics, randomized controlled trials have found no such link.

In a 3-month study, 140 people with diabetes or prediabetes were randomly assigned to eat 2 eggs six times a week or 2 or fewer eggs throughout the week. No differences were found in HDL, LDL, triglyceride levels or glycemic control.

In a 5-week randomized crossover study, 29 people with type 2 diabetes ate 1 egg with vegetables and bread or half a cup of oatmeal with milk for breakfast.

No differences were found in plasma glucose, insulin sensitivity, blood pressure, inflammatory markers, or plasma lipids between the egg and oat periods.

In a 12-week study, 37 people with type 2 diabetes and metabolic syndrome were put on a moderately carbohydrate-restricted diet and then randomized into two groups: one that ate 3 whole eggs per day; the other 3 albumins per day.

Both groups lost weight and saw improvements in insulin sensitivity and lipid profiles, but the whole egg group saw an improvement in their lipid profiles in some respects: they had more HDL, less VLDL, and a better LDL and HDL diameter profile. than the albumin group.

A follow-up analysis from the same study also found more improvements in inflammation markers in the whole egg group than in the albumin group.

A controlled trial of hyperlipidemic patients consuming eggs (relative to other dietary sources of cholesterol and fat) did not associate negative effects with egg consumption, although replacing eggs with nutrient-containing egg proteins was considered beneficial.

Similarly, risk factors did not get worse in healthy people when eggs were added to their diet.

These students were randomized to eat either a 2-egg or no-egg breakfast five times a week for 14 weeks. Otherwise, they were allowed to eat whatever they wanted, although people in the “no eggs” group were encouraged not to eat any eggs.

By the end of the study, both groups had gained weight and had worse blood lipid profiles, with no significant differences between the groups.

In controlled trials, either in healthy people or in people with diabetes or hyperlipidaemia, egg consumption was not associated with an increase in risk markers for cardiovascular health, insulin sensitivity, or blood glucose.

Diabetes

As we have seen, observational evidence may suggest a link between egg consumption and heart disease in diabetics.

Observational evidence may also suggest a link between egg consumption and the risk of developing diabetes.

In one study, eggs in the diet (“almost never” to “almost daily”) did not appear to be associated with an increased risk of developing diabetes.

However, other studies noted a positive association, with controls being education, family history of diabetes, and reference biomarkers for disease states (such as plasma triglycerides).

Finally, two studies reported a stronger association in women than in men.

If we look only at the observational evidence, it appears that there is some connection between egg consumption and the risk of developing diabetes.

Weightloss

Healthy population

In a 14-week study, healthy college students randomized to eat 2 eggs five times a week or no eggs gained weight equally.

Diabetics

In a 12-week study, two groups of obese diabetics began a weight loss diet.

One group ate 2 eggs per day; the other, neither. Both groups saw an equal decrease in LDL and total cholesterol, but the egg group enjoyed a greater increase in HDL.

There were no differences in blood pressure or blood glucose between the groups, but the reduction in fasting insulin seen with weight loss was less in the egg group.

In a 5-week randomized crossover study, 29 people with type 2 diabetes ate 1 egg with vegetables and bread or half a cup of oatmeal with milk for breakfast.

As previously noted, no differences were found in plasma glucose, insulin sensitivity, blood pressure, inflammatory markers, or plasma lipids between the egg and oat periods.

There were also no differences in body weight, body fat, or BMI.

Studies in diabetics have not noted adverse effects of egg consumption on different health markers.