What the Evidence Says About Eating Eggs Every Day

Okay, so there were two egg-related questions, one from Lisa and one from Stephanie. Both ask whether it is bad to consume eggs every day and how many eggs people can consume daily. People such as Dr. Michael Greger say that eating eggs every day has negative effects on health. So the question is: are eggs bad for you? I have addressed eggs in several Q&As. You can go back to Q&A number 37 and Q&A number 25, in which I discussed eggs. Dr. Greger cited a study about replacing 3% of egg protein with plant protein. The original study was developed at the National Cancer Institute to improve our understanding of the relationship between diet and health, including eggs as part of the diet.

It was a very large prospective study that looked at data from more than 400,000 people followed for 16 years. The data were extensively adjusted for confounders, including physical activity, vitamin-supplement use, energy intake, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, trans fats, fiber, vegetables, and fruits. But these were food-frequency questionnaires, so people were filling out questionnaires about those factors. The study found that plant-protein intake was significantly and inversely associated with mortality from all causes. There was a 12% reduction and a 14% reduction in all-cause mortality for every 10-gram increase in plant-protein intake in women and men. In contrast, animal-protein intake was not significantly associated with mortality in either men or women.

When the researchers looked more specifically at the animal-protein data in a sensitivity analysis, they examined what happened when people substituted plant protein for 3% of the energy from animal protein. They found 21% and 24% reductions in all-cause mortality in women and men, respectively. There was a smaller but significant reduction when plant protein replaced red meat and dairy products, but not when it replaced white meat. It seemed that the association between plant-protein substitution and lower all-cause mortality applied only when plant protein replaced red meat and dairy products. There are a couple of ways to interpret this study. One extreme view would be that animal proteins are always a health risk compared with plant proteins and should be avoided completely. On the other hand, this is observational data, which has many problems. The study did not distinguish different types of meat, such as processed meat, which we know is bad and is typically red meat. Maybe part of the reason replacing red meat with 3% plant protein was associated with lower mortality is that people were no longer eating some processed meats. We do not really know. Another very large study found that people who ate animal proteins but had no unhealthy lifestyle factors had the same all-cause mortality as people who ate plants.

Well, maybe that is because people who are unhealthy and eat a lot of meat on top of that, and who are sedentary, are not using those amino acids to build muscle. Amino acids are growth signals. Maybe they are growth signals that allow damaged cells to become cancer cells, right? There is a lot of nuance here, and observational studies do not always capture that nuance. I think that is important to keep in mind. There was another large study, and this was—this was also—oh, sorry, no, that was the same study. Okay, so what I meant to say is that the other large study I just mentioned was also very large and found no difference in mortality. Again, when you look only at people who are healthy, have no unhealthy lifestyle factors, and eat meat and eggs, they have the same mortality as plant eaters. You really have to think about all the data and nuance and say, “Okay, well, maybe it is not so unhealthy to eat eggs and meat as long as I am not partaking in other unhealthy lifestyle factors.” If you are sedentary or overweight, smoke, or have another unhealthy lifestyle factor, stop doing that, or you are probably better off not eating a lot of meat and eggs. I think that is also the take-home.

Let’s go back to eggs because their nutritional composition was the main part of the question. Eggs are packed with nutrition. They have many micronutrients and macronutrients. They are high in choline, which is good for the brain, and contain energy-related B vitamins. The egg yolk contains choline. Eggs also contain pantothenic acid for metabolism, phosphorus for bones, vitamins A and D, iodine, and selenium. These micronutrients support processes ranging from vision to immune function. Eggs are also a good source of protein and monounsaturated fat.

A medium-sized egg contains about 1.3 grams of saturated fat and 177 milligrams of dietary cholesterol, which used to raise concerns about cardiometabolic health. However, we now know that dietary cholesterol is not a major contributor to total cholesterol and LDL cholesterol in the body. Saturated and trans fats are the major dietary factors that increase total and LDL cholesterol. One large analysis examined 40 studies involving more than 3.6 million people to assess how eating eggs affects health. Specifically, it examined what happens when people eat one additional 50-gram egg each day. The study initially suggested that eating an additional egg each day could slightly increase the risk of death from heart-related causes.

However, after considering the amount of cholesterol consumed from all dietary sources, eggs alone were not associated with higher mortality rates. So again, it indicates that the broader context of one’s diet and different factors play a role in affecting someone’s risk of cardiovascular disease. There have also been a variety of randomized controlled trials looking at egg intake and biomarkers. One meta-analysis of 27 randomized controlled trials included people who consumed anywhere from five eggs per week to three eggs per day in the intervention groups. It showed that eating a lot of eggs per day can increase LDL and HDL. It can increase many of the lipoproteins. For example, there was a mean increase in LDL of about 5.6 milligrams per deciliter and an HDL increase of about 2.13 milligrams per deciliter compared with the control groups. Overall, eating eggs in moderation, I think, is unlikely to have any significant adverse effect on cholesterol, and it did seem to have at least a beneficial effect on HDL.

Obviously, there are people who are very sensitive to saturated fat and some who are sensitive to dietary cholesterol. Even though dietary cholesterol is not a major regulator of cardiometabolic health for most people, some people are very sensitive to it. The American Heart Association put together an advisory board that analyzed a variety of studies involving eggs. It looked at dietary cholesterol intake and cardiovascular risk from egg consumption. The board found that, overall, consuming eggs was not significantly associated with the risk of developing cardiovascular diseases in the general population. It stated that eggs can be part of a balanced diet and do not necessarily increase the risk of heart disease for most people. In a more detailed analysis of several studies, people who ate a high number of eggs, seven or more per week, had a slightly lower risk of stroke than people who ate fewer than one egg per week. This was about a 9% reduction in stroke risk. It is not huge, but it is still something beneficial. Eating eggs did not significantly affect the risk of developing coronary heart disease in the general population.

However, people with type 2 diabetes did have an association between egg consumption and increased coronary heart disease risk. There could be a rationale for why people with type 2 diabetes might be at higher risk if they eat a lot of eggs. Again, that comes down to the other studies: if researchers are not looking specifically at people who have diabetes, maybe some participants have not yet been classified as having it or are prediabetic. Those factors affect observational data. A meta-analysis of 17 randomized controlled trials looked at eating three to seven eggs per day. Egg intake raised total cholesterol, LDL cholesterol, and HDL cholesterol, as I mentioned, but it did not seem to increase coronary heart disease risk significantly. People who are very sensitive to elevations in LDL or total cholesterol may need to monitor that more closely. Generally, the debate about whether eggs are bad for health or heart health is somewhat settled: they are not bad for most people. Some individuals may want to limit egg consumption for genetic reasons, because they are sensitive to dietary cholesterol, or because they have type 2 diabetes.

Generally, I do not think the data support the statement that eggs are bad for your health. They are a high-quality source of vitamins and protein. But do you have to eat five eggs every day? Not necessarily. If eating eggs raises your LDL or ApoB and you are trying to lower it, every step that reduces ApoB is useful. Maybe instead of eating four eggs a day, you eat one or two. Walter is asking about free-range eggs. Pasture-raised chickens lay eggs with much higher levels of micronutrients, including lutein, although those levels still pale in comparison with kale. You will find higher levels of all the vitamins I mentioned, and the eggs are higher quality. You can see the difference in the yolk. An egg from a pasture-raised chicken has a deep-orange yolk, while an egg from a conventional chicken fed corn has a light-yellow yolk. They are very different.