Are eggs harmful to our health?
How much cholesterol is there in eggs? What is the connection between egg consumption and diabetes and heart disease? What is the danger of salmonella and dioxins found in eggs? Review data and studies on the health implications of egg consumption.
Kerem Avital | Clinical Dietitian
Cholesterol in Eggs: Between Rumors and Facts | Eggs and risk of diabetes, heart disease and mortality | Hazardous Substances In Eggs: Dioxins And Antibiotics | Salmonella and egg poisoning | Breaking the myth: Who needs eggs anyway? | Summary and Conclusions
The impact of eggs on health is controversial. Eggs are known to contain a lot of cholesterol, but in recent years, consumers of eggs and the egg industry have been trying to improve their image. A systematic review of the research in the field shows that a high consumption of eggs is not recommended, especially for diabetics and heart disease patients with high cholesterol. According to the Ministry of Health, about 20% of the population has high cholesterol, and the problem is especially common in adults: more than 50% of women aged 65 and over and 40% of men aged 65 and over have high cholesterol levels. Eggs are very easy to reduce and even to stop consuming, which can help lower blood cholesterol levels. Low egg consumption may not cause great health damage, but it is difficult to claim that it is a healthy food, given that it is also a source of fat and cholesterol, and with a significant risk of various contaminants and salmonella in eggs.
Cholesterol in eggs: between rumors and facts
Large egg = 260 mg cholesterol
In recent years, there have been claims in the media that consuming one egg per day is harmless. However, people who consume an egg a day can easily exceed the maximum cholesterol level recommended by health authorities. According to the US Department of Health and Agriculture’s dietary recommendations, it is recommended to limit cholesterol consumption to 200 mg of cholesterol per day for people at risk of heart disease, and 300 mg a day for a healthy population. It is therefore crucial to recognise that a small egg has more than 200 mg of cholesterol. Therefore, by consuming one egg per day, it is very easy to pass the daily cholesterol quota, especially if you eat meat and milk products that also contain cholesterol, and if you consider foods containing eggs – cakes, pies, patties, etc.
Is Cholesterol Harmful To Us?
Cholesterol is an essential substance for the body. It is an important component of cell membranes, in various hormones such as estrogen and progesterone, as well as in the bile fluid that allows the absorption of fat in our bodies. Since the liver is capable of producing sufficient cholesterol on its own, there is no need for ready-made cholesterol in foods.
As has been shown beyond doubt, high levels of blood cholesterol and especially LDL (a particle responsible for carrying cholesterol and liver fat for other body organs, also called “bad cholesterol”) are detrimental to cardiovascular health. The first important study to prove this is the famous Framingham study, followed by a series of studies that have established this point repeatedly. With the exception of a small, too vocal minority of people who allegedly adhere to the early human diet (and mysteriously believe it included red meat, butter and eggs in vast quantities – but this is another topic), there is a wide consensus that high blood cholesterol is dangerous to our health, and medical officials are finding ways to reduce it.
Effect of egg consumption on blood cholesterol levels
Cholesterol from one’s diet is not the only factor responsible for blood cholesterol. Saturated fat intake, low fiber consumption and genetics are equally significant and perhaps even more important. However, there is currently a trend among professionals to reduce the severity of the cholesterol risk from food consumed.
This trend has been of concern, among other things, to a group of leading Canadian cardiologists who have published a critical article on a medical journal, highlighting the fact that many researches and reviews have been funded by the egg industries, which of course have an interest in reducing the perceived effect of cholesterol from the diet on blood cholesterol.
Researchers emphasize that keeping low cholesterol is also important for healthy people at risk for heart disease, as they say “quitting egg consumption after a heart attack or stroke is similar to quitting smoking only after diagnosing lung cancer: a necessity, but too late.”
Researchers are also investigating how cholesterol tests are used in field research – tests are performed after fasting, and the question is asked how high cholesterol intake affects blood cholesterol levels when we are not fasting; that is, most of the time. This is an important point because the cholesterol absorbed in the intestine reaches the liver, which sends it to the bloodstream in components called lipoproteins, most notably LDL cholesterol. This means that after a high cholesterol meal, your blood cholesterol levels are likely to rise for a while as we will see below. The Canadian group is no exception to fasting blood tests, and in recent years a number of studies have indicated that high levels of cholesterol and undiagnosed fats may be a more accurate predictor of heart disease and heart disease mortality.
There are not many studies in recent years that have systematically examined cholesterol levels after egg consumption that have not been financed or conducted by the egg industry itself. One of the few studies on the subject was published more than 20 years ago, and the graph below shows the clear effect that cholesterol consumption has in the two hours after egg consumption and up to about seven hours later. In comparison, fasting tests are done about 10-12 hours after the meal.
In the experiment, ten healthy men aged 22-33 were given meals with eggs that included varying levels of fat and cholesterol, followed by a blood test once per hour for 7 hours. The graph in the picture shows the change in blood lipid levels over time: after consuming 45 grams of fat and 280 mg of cholesterol (equivalent to one large egg) or 700 mg of cholesterol, blood cholesterol levels rise and peak after three hours.
Furthermore, in several pilot cases from the 1990s, dietary cholesterol was found to increase the oxidation of LDL, increasing its risk of damaging blood vessels. These studies were done on a small population, so it is difficult to draw conclusive conclusions, but this is another angle that will allow us to understand the results of the larger studies.
Graph blood lipid levels
The graph shows the change in blood lipid levels after eating different meals. In people who consume half an egg or more, blood lipid levels rise and peak after 3 hours (it should be noted that fat values are usually measured in mg / dl rather than mmol / L – that is, the peak increase due to one egg intake is about 30 mg / dl).
Eggs and risk of diabetes, heart disease and mortality
According to the recommendations of Harvard Nutrition, the world’s leading research university, heart patients and people taking cholesterol-lowering drugs should limit egg consumption and avoid eating the yolk completely, as should people with diabetes.
The position of the Cardiologists Association in Israel and Futur Association (Nutritionists and Dietitians Association in Israel) states that consuming up to 5 eggs per week does not increase the risk of heart disease in a healthy population, but states that in high-balanced and unbalanced cholesterol, heart disease or diabetes, consumption should be limited to 3 eggs a week, including eggs in pastries or desserts. It also states that there is a large population variation in the effect of dietary cholesterol on blood cholesterol levels. This is an important point, since in the field of research there is no distribution of participants according to the way cholesterol reacts in the body, nor is there a test that can allow such a distribution. For some people, even a small amount of an egg or two a week may be dangerous.
Egg consumption and risk of heart disease and mortality
High cholesterol is one of the causes of cardiovascular disease. A 2013 meta-analysis published in the journal Atherosclerosis that weighed the results of research conducted in the field, found that high egg consumption increases 19% of the risk of heart disease. Another meta-analysis published in the journal BMJ found no association with heart disease and stroke in the general population, but found that high egg consumption increases the risk of heart disease amongst diabetics.
A large Harvard University study that tracked the diet of more than 50,000 nurses for 18 years found high cholesterol and early mortality: Consuming 100 mg of cholesterol in 1000 calories was associated with a 17% increase in the risk of premature mortality ( That is, a statistical neutralization of all other risk factors such as age, weight, smoking and more.) This suggests that a woman who consumes 1500 calories and 150 mg of cholesterol (less than a small egg) per day is at risk of premature mortality of about 17% more than a woman who consumes less cholesterol in her diet.
Eggs are a risk factor for diabetes
For several decades, the world of medicine has known that diabetes is not only a high blood sugar problem, and that the risk of diabetes also exists as a result of other dietary variables such as saturated fat, cholesterol, obesity, endocrine disruptors such as dioxins (to which I will refer below) and excess iron in the diet. A number of studies have found a link between high egg consumption and diabetes risk. Furthermore, consumption of eggs and high-fat saturated foods has been linked to the increased risk of complications in diabetics, primarily cardiovascular disease.
The most prominent research in the field was done by Harvard University as part of the famous Physicians and Nurses study, published several years ago in the journal Diabetes Care. The study, which was conducted on more than 20,000 doctors and 36,000 nurses, found that the risk of diabetes increased by several percent by consuming 5 eggs or more per week in men, and consuming one egg per day or more has been associated with an increased risk of diabetes to 60% higher in men and close to 80% higher in women compared to a group that did not consume eggs at all, after eliminating many variables (including age, BMI and physical activity. In women, the effect of red meat intake, saturated fat, vegetables and fruits and total calories on the menu was also eliminated.) Especially among participants with high cholesterol (almost double in men, but the results were not significant in women).
Another study, based on physician research data, found that among patients with diabetes the mortality risk of consuming 5 eggs or more per week was more than double compared to subjects consuming less than one egg per week. These findings, together with the findings of other studies, were combined into two meta-analyses mentioned above. Both found that the risk of diabetes was several percent higher by consuming 5-7 eggs a week. It has also been found that among diabetics the risk of diabetes is about 70-80% higher in those who consume an egg per day compared to those who do not consume eggs at all.
There are also findings suggesting an association between egg consumption and gestational diabetes, a condition of high blood sugar levels during pregnancy, where both the woman and the newborn are at increased risk of obesity and diabetes, as well as at increased risk of various pregnancy and birth complications. A study published in 2011 as part of the Omega study conducted on more than 3,000 pregnant women in Sweden found an increased risk of gestational diabetes of almost 80% amongst women who consumed an egg a day or more (after statistically neutralizing variables such as woman’s age, calories, BMI, meat intake, fibre, vitamin C and saturated fat).
Hazardous Substances in Eggs: Dioxins and Antibiotics
Antibiotics in eggs
Eggs are particularly susceptible to infections, amongst other things, because any harmful or infectious bacteria in the chickens’ food (forage) usually goes directly to the eggs. The annual surveys of the Ministry of Agriculture and the Ministry of Health for the detection of contaminant residues in animal foods have consistently, since 2008, found clopidol antibiotic residues in eggs. Deviations from the standard are usually 20% to 25% of the eggs tested, and there have also been years when abnormalities were found in about 50% of the eggs. The Ministry of Agriculture promised to take steps to correct the deficiencies but so far no significant changes have been made.
At the end of 2013, veterinary services audited various forage blends, which examined 30 samples from 10 institutes (a tiny amount relative to industry size). In 60% of institutes (6 out of 10), the industry is laundered by the antibiotic industry.
It should be noted that the European standard for such infections in the egg food industry is zero. However, the Ministry of Agriculture did not consider it appropriate to stop these institutes. Instead of significant enforcement, the handful of veterinary services repeatedly reveal in the survey conclusion that “the interstitials are required to build a risk management plan to streamline and improve cross-contamination monitoring and prevention.” There is no mention of a schedule to run the program or any sanctions for those who do not run such a program.
Dioxins in eggs
Dioxins, PCBs and similar substances are a general name for a long series of carcinogenic toxins that are byproducts of various materials (such as pesticides, herbicides, plastics, metals) and waste incinerators- for convenience we will include them here under the term “dioxins”. Contrary to popular belief, most exposure to these materials is not from polluted air or sprayed vegetables, but from animal products due to their tendency to accumulate in organisms as they rise in the food chain. In a 2013 Diocese Detection Survey, eggs were found to be particularly contaminated with dioxins: about a quarter of the eggs sampled exceeded the European standard- the average amount of dioxins found in the samples was 342 picograms.
Salmonella and egg poisoning
Many are aware of the risk of salmonella infection in uncooked eggs (in sauces, sunnyside-up, etc.). This danger is especially high for populations whose immune systems are weak – pregnant women, children and the elderly, for whom food poisoning can be particularly dangerous. Absurdly, these are also the populations that tend to consume a lot of eggs as they need larger amounts of protein (as we will see below, protein can be easily obtained from safer sources).
The source of salmonella in eggs is found in a bacterium that resides in the natural digestive system of chickens. Since the chickens’ laying pipe is also the opening through which the feces is excreted, it often stays glued to the eggshell and the bacteria along with it. There are warnings against egg washing, fearing that the bacterium will penetrate the shell (the egg shell is not sealed but full of small nozzles through which the chick in the fertilised egg breathes).
An article published in 2014 in a journal dealing with infectious diseases by the University of Cambridge, called ‘Epidemiology and Infection’ confirms the health and sanitary findings seen in the Channel 2 investigation. This is a study conducted in Israel comparing 263 children who became ill with Salmonella to 263 children who did not become ill (when each child who fell ill was compared to a child of the same age and gender and who lived in the same neighborhood).
Researchers have tried to identify risk factors for Salmonella Infantis, which is the most common type of morbidity in recent years, and found that egg consumption is a significant risk factor for this type of Salmonella. Incidentally, the thawing and soaking of chicken in water was also a risk factor, though statistically more borderline.
The Ministry of Health even issued a warning in 2014 about using egg cartons for artwork in kindergartens and daycare centers for the elderly, due to concerns about the spread of Salmonella bacteria. The question then arises, if you can’t play with egg cartons, how can you put them in our kitchen?
Breaking the myth: Who needs eggs anyway?
Some believe (perhaps under the influence of industry) that eggs are a good source of protein and other essential components. But a simple examination of the components reveals that this is an entirely baseless claim. For example, half a cup of cooked legumes has the same amount of protein as an egg (about 7 grams). You will also find the same amount of protein in 30 grams of chickpea flour, (which has become a popular ingredient for making vegan omelets in recent years), in 100 grams of tofu (one third of a package, from which you can make excellent tofu scrambled eggs) or in a tablespoon of soy chips before cooking. Legumes and whole grains are also sources of iron and zinc, which are found in eggs. The egg industry is seeking ways to highlight the health benefits of egg consumption and distributing publications that relate to antioxidants, especially lutein and ziaxanthin (which are often found together in food), which relate to eye health, among other things. The American Optometrists Association recommends consuming about 10,000 mcg of lutein and 2,000 mcg of ziaxcine a day. In reality, these are fairly common ingredients. One tablespoon of cooked spinach has 1,800 mcg of lutein and zeaxanthin, while in an extra large egg, there is only 292 mcg and in a medium egg- 221 mcg. In order to comply with the American Optometrists Association we would need to eat 40 eggs a day, or 6 tablespoons of spinach.
Don’t like spinach? Here is a list of a few other random foods containing lutein and zeaxtrantine in high quantities, that equate to dozens of eggs: pumpkin, corn, peas, broccoli, lettuce, onions, carrots, red pepper, green and yellow beans, cornflakes, pistachios, tomato sauce, okra. In short, if you want to keep your eyes on, it is best to focus on eating 5-6 servings of vegetables at least a day, instead of an unruly amount of eggs.
Spoonfuls vs eggs
Another nutritional component that the egg industry pushes to attention is choline. Choline is known to be an important substance for our bodies, found to be associated with the brain development of embryos and it is likely that a deficiency in this is indirectly linked to atherosclerosis. Choline is found in many animal and plant foods, and the liver can also produce it in certain amounts (which is apparently inadequate). But it turns out that excess choline can be dangerous. Large amounts of choline are found in animal foods and especially in eggs. A group of American researchers recently published groundbreaking research on the subject in the journals ‘Nature’ and ‘The New England Journal of Medicine’. Research has shown that the interaction between the gut bacteria and choline creates a chain reaction that can eventually lead to heart disease, stroke and eventually death. In a study published in NEJM in 2013, more than 4,000 people participated, and a quarter of participants with high blood TMAO (choline metabolite) levels had a heart attack, stroke or died within three years.
The gut bacteria using phosphocholine secrete a substance called Trimethylamine (TMA), which in turn reaches the liver and undergoes a process of oxidation
Excreted into the blood as oxidized TMA, this substance is found to cause an increase in the sclerosis plaque that causes cardiovascular disease and heart attacks.
Summary and Conclusions
For the purpose of this article, dozens of studies and analyses are listed in the sources list at the bottom of the page. I preferred not to mention the egg-funded studies. The industry has been funding quite a bit of research and reviews in recent years as well as working behind the scenes to influence the policies of various healthcare organizations. As the industry’s unpublished research and published research in leading scientific journals show, eggs are, at least in relation to our health, unnecessary, and in some cases, even harmful. Are they a ‘Culinary Necessity’?
It is easy to replace them with plant-based components. If you like shakshuka, you can enjoy its sauce and instead of the eggs use crushed tofu. In cakes, flour and water help the mixture and a combination of baking soda and / or baking powder with a little vinegar can create an airy texture!
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