How many eggs can we safely eat?

Did you know that current FDA guidelines forbid labeling eggs as “healthful” and “nutritious”?  Because they say, these adjectives can be used only to describe foods that are low in fat/cholesterol and rich in beneficial nutrients such as vitamin D, potassium, calcium, iodine, iron, and so on.

However, eggs still provide plenty of proteins, micronutrients (phosphorus, calcium, iron, zinc), and vitamins (A, E, D, B2, B6, B9, biotin or vitamin H; vitamin H – H stands for Haut und Haar, German for skin and hair). Eggs also contain choline, a nutrient essential for all cells in our body, lutein, and zeaxanthin – two powerful antioxidants (called the eye vitamins) and carbohydrates, fats, and cholesterol.

Although eggs contain omega-3 polyunsaturated fatty acids (which are not bad), they have a high content of cholesterol in the yolk, and that’s where their bad reputation comes from.

And the numbers below illustrate cholesterol content in the whole egg (mg/100 g):

• Whole egg: 450
• Egg white: 0!
• Yolk: 1260!

Dietary Cholesterol and Blood Cholesterol

Apart from cholesterols, egg yolk contains mono and polyunsaturated fatty acids, which are thought to be good for our health. Omega-3 polyunsaturated fatty acids are said to be cardioprotective and can potentially lower the blood pressure, as well as triglycerides and cholesterol levels by increasing liver uptake of LDL (bad cholesterol) from the blood. The latter is known as the infamous promoter of coronary diseases.

However, for now, such beneficial effects of eggs are only theorized. Not scientifically proven.

However, to reduce the health risk and to set more unanimous guidelines, researchers say they need to further investigate how (and whether) the egg cholesterol influences the total cholesterol levels in our blood. 

The following surveys show that it can be a daunting task.

Namely, two randomized, controlled study, that measured cholesterol absorption in adults after a meal consumption (using TRL fractions of Triacylglycerol concentration) found no relation between the whole egg intake and blood cholesterol concentration.

However, the participants of the above study were healthy individuals without gastrointestinal disorders and had no food allergy.

The study findings mean that concentrations of total and LDL cholesterol in human blood don’t depend much on the amount of cholesterol we eat, there is only a weak link. The majority of blood cholesterol – 75 percent of it, comes from cholesterol synthesis in the liver.

Interestingly, another study called the China Calorie Biobank (CKB) study, which recruited participants from both urban and rural sites across China, found that “daily egg consumption of 5.32 eggs/week compared to no eggs or rare consumption of 2.03 eggs/week, resulted in a risk for IHD of 12%.” This means that eating eggs every day will put you at an increased risk of infarction and stroke.

It seems a more accurate chain of events, with all due respect to individual differences in response to dietary cholesterol and fat intake (you know, the situation when digestion of fatty meals for some people becomes a nightmare, while others feel more refreshed).

However, eggs are usually not recommended for people with gallbladder issues. Additionally, they shouldn’t neglect the signals their body is sending them persistently (after eggs are eaten). More importantly, these facts should not be overlooked by their doctors.

Self-made cholesterol in our liver

The cholesterol from the liver is made up of carbohydrates, fats, and proteins, because cholesterol is a crucial membrane element of every single cell in or body, and is essential for their functioning. Also, cholesterol is used as a precursor for the synthesis of steroid hormones, liposoluble vitamins, and bile acids. Cholesterol gets incorporated into particles in the liver, called lipoproteins, along with other fats and proteins on their journey through the bloodstream, to perform numerous functions across the organism. LDL is one of five types of these particles and its role is transferring cholesterol from the liver to the peripheral tissues, like blood vessels for example (if LDL is elevated and oxidized, there is a risk of atherosclerosis).

Why the liver produces excessive levels of LDL cholesterol in the first place?

The possible answer is – excessive intake of dietary fats, saturated and trans fats. Researchers say that these fats, which can be found in red and processed meat, instant food, butter, bacon, french fries, and other foods, are associated with coronary heart disease and other health disorders.

However, not only fats but poor eating habits in combination with other factors such as genetics, a sedentary lifestyle, smoking, and alcohol consumption, might be common causative factors.

To sum it up – we can eat eggs sparingly, but this can’t be our everyday menu. If you can’t live without it, instead of frying, try boiling them. Or, even better – combine eggs (or only egg whites), with whole-grains and vegetables, because fibers and plant sterols reduce cholesterol absorption. 

Whole grain cereals like oatmeal or buckwheat mixed with some nuts and fresh fruits will be a much better breakfast option, as consuming these nutrients full of vitamins, minerals, and fiber can promote our health and, therefore, reduce the risk of a certain type of cancers.

Again, individuals who are diagnosed with gallstones, or had their gallbladder removed, need to adjust their eating habits accordingly and avoid fatty foods (such as eggs), at all costs. They should have in mind that after the gallbladder removal, a biliary obstruction can occur again, but this time within the smaller tubes in the liver, which can lead to life-threatening infection. Certain food, rich in fats and cholesterol, can potentially provoke such problems. Generally, plant-based foods are a much better option for individuals with gallbladder issues.

Finally – cooked or raw?

As we know, heating usually causes depletion of nutrients, like vitamins and antioxidants, at least to some extent.

However, when it comes to eggs, the level of proteins remains the same in a cooked and raw egg; and denaturation of proteins caused by the heat, which changes its structure, makes it even easier for digestion and absorption. In fact, denaturation unfolds protein from its three-dimensional shape and this process allows human digestive enzymes better access to protein bonds. Also, proteins now lose their biological activity. For example, a protein named avidin in raw form binds to a nutrient important in sugar and fat metabolism – biotin, and blocks its resorption in the small intestine, making it unavailable for the body to use it.

According to the “Journal of Nutrition”, researches found that our body can absorb 91% of egg protein in a cooked egg, while absorption of raw egg protein is only 50% over a 24-hour period. Another study found that consuming whole eggs helps to build our muscles post-workout in higher percent compared to consuming only egg whites in equivalent amounts (because egg yolk elevates the body’s capacity to use that protein in the muscle).

When we talk about food safety, cooking eggs is definitely a better option. An infected hen can pass bacteria Salmonella enterica to the egg. This bacteria can cause a range of symptoms – from high temperature, vomiting, cramps, and diarrhea to more severe ones; it can be even fatal for children or the elderly population. Heat above 160 C degrees destroys the bacteria and prevents poisoning, even if egg white and yolk are both contaminated. Therefore, the ideal way to enjoy the food is to cut the amount of fat by boiling or poaching them.

And lastly, but most importantly:

Testing egg for freshness: “floating egg”

1. Put the egg in a ½ cup of tap water.
2. If the egg remains at the bottom (horizontal) of the bowl, it is fresh and edible.
3. If it stands vertical on the bottom it can be eaten but after hard-boiling.
4. If the egg is off the bottom floating, it should be thrown away.