Is eating eggs good or bad for my cholesterol ?

Eggs and Cholesterol

The Framingham Heart Study 1) has investigated the effect of host and environmental factors on the development of coronary heart disease since 1949. It concluded that within the range of egg intake of this population, differences in egg consumption were unrelated to blood cholesterol level or to coronary heart disease incidence. Most healthy people can eat up to seven eggs a week with no increase in their risk of heart disease. Some studies have shown that this level of egg consumption may actually prevent some types of strokes.

For years, the public have gotten the message that they should go easy on the egg especially the egg yolks. Long-vilified for their high cholesterol content by well-meaning doctors and scientists researching heart disease, eggs now seem to be making a bit of a comeback. So what changed ?

The evidence to date doesn’t say you should ban eggs from your plate. In most studies so far, an egg a day does not have a negative impact on health 2).

While it’s true that just one egg yolk has about 200 mg of cholesterol—making it one of the richest sources of dietary cholesterol—eggs also contain additional nutrients that may help lower the risk for heart disease. In addition, the moderate amount of fat in an egg, about 4.5 grams, is mostly monounsaturated and polyunsaturated fat, a fat that you need to be healthy. An egg contains only about 1.65 g of saturated fat and no trans fat. It’s also crucial to distinguish between dietary cholesterol and cholesterol in the blood, which are only weakly related. The focus on dietary cholesterol alone was de-emphasized as more attention was placed on the influence of saturated and trans fat on blood cholesterol. Accordingly, the Dietary Guidelines for Americans 2015 removed the prior recommendation to limit consumption of dietary cholesterol to 300 mg per day 3).

The egg is a powerhouse of disease-fighting nutrients like lutein and zeaxanthin. These carotenoids may reduce the risk of age-related macular degeneration, the leading cause of blindness in older adults. And brain development and memory may be enhanced by the choline content of eggs.

But the full health benefits of eggs can only be realized if you store them properly — in the refrigerator — and cook them thoroughly to kill any potential bacteria.

Brown eggs are not more nutritious than white. The color and size of an egg are determined by the breed of hen, which can produce white, cream, brown, blue, green or speckled eggs. The color of the yolk is also not reflective of nutritional value but the type of poultry feed.

As part of a healthy balanced diet you can eat up to 6 eggs each week without increasing your risk of heart disease.

Chicken eggs are high in cholesterol, but the effect of egg consumption on blood cholesterol is minimal when compared with the effect of trans fats and saturated fats. According to the U.S. Department of Agriculture, one large egg has about 186 mg milligrams (mg) of cholesterol — all of which is found in the yolk.

According to the U.S. Department of Agriculture, one large egg has about 186 mg milligrams (mg) of cholesterol — all of which is found in the yolk.

When deciding whether to include eggs in your diet, consider the recommended daily limits on cholesterol in your food:

  • If you are healthy, consume no more than 300 mg of cholesterol a day.
  • If you have diabetes, high cholesterol or cardiovascular disease, limit the daily cholesterol intake to no more than 200 mg a day (<200 mg/ day).

If you like eggs but don’t want the extra cholesterol, use only the egg whites. Egg whites contain no cholesterol. You may also use cholesterol-free egg substitutes, which are made with egg whites.

Some people are more sensitive to eating cholesterol in their diet and its effect on their blood cholesterol level. This means that when they eat food containing cholesterol, their LDL (bad) cholesterol levels rise more than other people.

egg composition

Eggs and Health

Research on moderate egg consumption in two large prospective cohort studies (nearly 40,000 men and over 80,000 women) found that up to one egg per day is not associated with increased heart disease risk in healthy individuals 4). Of course, this research doesn’t give a green light to daily three-egg omelets. While a 2008 report from the Physicians’ Health Study supports the idea that eating an egg a day is generally safe for the heart, it also suggests that going much beyond that could increase the risk for heart failure later in life 5). You also need to pay attention to the “trimmings” that come with your eggs. To your cardiovascular system, scrambled eggs, salsa, and a 100% whole-wheat English muffin is a far different meal than scrambled eggs with cheese, sausages, home fries, and white toast.

People who have difficulty controlling their total and LDL cholesterol may also want to be cautious about eating egg yolks and instead choose foods made with egg whites. The same is true for people with diabetes. In studies including the Nurses’ Health Study and Health Professionals Follow-up Study, heart disease risk was increased among men and women with diabetes who ate one or more eggs a day 6), 7). For people who have diabetes and heart disease, it may be best to limit egg consumption to no more than three yolks per week.

Furthermore, to truly assess eggs and heart health, we need to examine how they stack-up to foods you might choose in their place—the classic nutrition substitution analysis.

Using some common breakfast options as an example:

  • While eggs may be a much better choice than sugary, refined grain-based options like sweetened breakfast cereals, pancakes with syrup, muffins, or bagels, they may fall short of other options. A bowl of steel-cut oats with nuts and berries, for example, will be a much better choice for heart health than an egg-centric breakfast. Consumption of whole grains and fruit predict lower risk of heart disease, and when it comes to protein, plant sources like nuts and seeds are related to lower cardiovascular and overall mortality, especially when compared to red meat or eggs 8).

The bottom line: while eggs may not be the optimal breakfast choice, they are certainly not the worst, falling somewhere in the middle on the spectrum food choice and heart disease risk. For those looking to eat a healthy diet, keeping intake of eggs moderate to low will be best for most, emphasizing plant-based protein options when possible.

how much cholesterol in eggs

Figure 1. Egg nutrition facts

egg-nutrition-facts
[Source 9)]

Do Eggs Cause High Cholesterol ?

Eggs were previously associated with heart disease risk as a result of their high cholesterol content. However, a solid body of research shows that for most people, cholesterol in food has a smaller effect on blood levels of total cholesterol and harmful LDL cholesterol than does the mix of fats in the diet 10), 11), 12). Dietary cholesterol and egg yolks do raise fasting levels of LDL cholesterol, by around 10%, in a dose-dependent manner 13), 14). But most healthy people don’t need to worry about eating eggs and their cholesterol. The cholesterol in eggs has almost no effect on our blood cholesterol levels. Your cholesterol levels are more influenced by the saturated and trans fat (and the added sugar) you eat. That is the saturated fat has a much greater effect on fasting LDL when it is consumed with cholesterol 15); this has been called the “bacon and egg” effect 16). In other words, your risk of heart disease may be more closely tied to the foods that accompany the eggs in a traditional American breakfast — such as the sodium in the bacon, sausages and ham, and the saturated fat or oils with trans fats used to fry the eggs and the hash browns.

People believed that if you ate cholesterol, that it would raise cholesterol in the blood and contribute to heart disease. It turns out that it isn’t that simple. The more you eat of cholesterol, the less your body produces instead. So the total amount of cholesterol in the body changes only very little (if at all), it is just coming from the diet instead of from the liver 17), 18).

Most healthy people can eat up to seven eggs a week with no increase in their risk of heart disease. Some studies have shown that this level of egg consumption may actually prevent some types of strokes 19).

  • The majority of studies found that egg consumption did not affect major cardiovascular disease risk factors. Consumption of 6 to 12 eggs per week had no impact on plasma concentrations of total cholesterol, low-density (LDL) lipoprotein-cholesterol, triglycerides, fasting glucose, insulin or C-reactive protein in all studies that reported these outcomes in comparison with control groups 20). An increase in high-density (HDL) lipoprotein-cholesterol with egg consumption was observed in 4 of 6 studies. Results from randomized controlled trials suggest that consumption of 6 to 12 eggs per week, in the context of a diet that is consistent with guidelines on cardiovascular health promotion, has no adverse effect on major cardiovascular disease risk factors in individuals at risk for developing diabetes or with type 2 diabetes. The studies reported inconclusive results regarding the relationship between egg consumption (and dietary cholesterol) and the risk for cardiovascular diseases in individuals with type 2 diabetes.
  • A review of egg consumption and heart health 21), it was concluded that consuming three eggs per day for 12 weeks did not increase cardiovascular disease risk in individuals with metabolic syndrome. Consuming a cholesterol free egg substitute does not decrease an individuals risk for developing cardiovascular disease risk factors, relative to whole eggs. Eggs are a bioavailable source of xanthophyll carotenoids, which have been shown to play a role in decreasing inflammation.
  • This review 22) addresses the effect of eggs on cardiovascular disease risk from both epidemiological research and controlled prospective studies, in people with and without cardio-metabolic disease. It also examines the nutritional qualities of eggs and whether they may offer protection against chronic disease. The evidence suggests that a diet including more eggs than is recommended (at least in some countries) may be used safely as part of a healthy diet in both the general population and for those at high risk of cardiovascular disease, those with established coronary heart disease, and those with type 2 diabetes mellitus. In conclusion, an approach focused on a person’s entire dietary intake as opposed to specific foods or nutrients should be the heart of population nutrition guidelines.

But in another conflicting study 23), it was found that the very high cholesterol content of egg yolk, the phosphatidylcholine in egg yolk leads, via action of the intestinal microbiome, to production of trimethylamine n-oxide (TMAO), which causes atherosclerosis in animal models. Levels of trimethylamine n-oxide (TMAO) in the top quartile after a test dose of two egg yolks were associated with a 2.5-fold increase in the 3-year risk of stroke, death, or myocardial infarction among patients referred for coronary angiography. Persons at risk of cardiovascular disease should limit their intake of cholesterol and egg yolk. The authors concluded that gegular consumption of egg yolks should be avoided by people at risk of cardiovascular disease and “in our opinion, stopping egg consumption after a myocardial infarction or stroke would be like quitting smoking after lung cancer is diagnosed: a necessary act, but late.”

  • Dietary cholesterol and egg yolks have important harmful effects in the post-prandial state, and increase the risk of cardiovascular events. New understanding of the role of the intestinal microbiome will revolutionize our approaches to diet and cardiovascular disease. Regular consumption of egg yolks should be avoided by people at risk of cardiovascular disease, which essentially means all North Americans who expect to live past middle age. “Stopping the consumption of egg yolks after a stroke or myocardial infarction would be like quitting smoking after a diagnosis of lung cancer.” 24).
  • Much more important than the effects on fasting lipids are the post-prandial effects 25). Diet is not just about fasting cholesterol; it is mainly about the postprandial effects of cholesterol, saturated fats, oxidative stress and inflammation. In human subjects, endothelial function is impaired for approximately 4 h after consumption of a high-fat/high-cholesterol meal; this effect is probably due to oxidative stress 26).
  • Dietary cholesterol above 140 mg in a single meal markedly potentiates post-prandial lipemia 27). High dietary intake of cholesterol increases LDL oxidation by nearly 40% 28), 29), and impairs endothelial function for several hours, probably through oxidative stress 30), 31), 32).
  • A high-cholesterol meal increases vascular inflammation for several hours 33), and an egg-white-based substitute improved endothelial function compared with whole eggs 34).
  • In Greece, where the diet is much more healthy, it was easier to show harm from egg consumption. A study by Trichopoulou et al. in Greek diabetics showed that an egg a day increased coronary risk 5-fold, and each 10 g of egg per day (about a 6th of a large egg) doubled cardiovascular risk.
  • In this large prospective study, the authors have demonstrated that daily consumption of at least one egg is associated with an increased risk of type 2 diabetes in both men and women, independently of traditional risk factors for type 2 diabetes 35).
  • In a prospective cohort study of 21,275 participants from the Physicians’ Health Study I, where study was trying to find the association between egg consumption and heart failure risk. After an average follow up of 20.4 years, while egg consumption up to 6 times per week was not associated with incident heart failure, egg consumption of 7 or more per week was associated with an increased risk of heart failure. Their data suggested that infrequent egg consumption is not associated with the risk of heart failure. However, consumption of 1 or more eggs per day (more than 7 eggs per week) is related to an increased risk of heart failure among US male physicians.
egg and cholesterol

Nutrition Content of Eggs

2 x 60g eggs

% Recommended Dietary Intakes (RDI)

Nutrients

RDI*

Per 100g

Per serve

%RDI

Energy (kJ)

8,700

559

581

7%

Protein (g)

50

12.2

12.7

25%

Fat (g)

70

9.9

10.3

15%

Sat fat (g)

24

3.3

3.4

14%

Mono fat (g)

n/a

5.1

5.3

n/a

Poly fat (g)

n/a

1.6

1.7

n/a

Cholesterol (mg)

n/a

383

398

n/a

Carbohydrate (g)

310

1.3

1.4

0%

Sugars (g)

90

0.3

0.3

0%

Sodium (mg)

2300

136

141

6%

Potassium (mg)

2800 (f), 3800 (m)^

133

138

4-5%

Magnesium (mg)

320

12

13

4%

Calcium (mg)

800

47

49

6%

Phosphorus (mg)

1000

200

208

21%

Iron (mg)

12

1.6

1.7

14%

Selenium (µg)

70

39

41

59%

Zinc (mg)

12

0.5

0.5

4%

Iodine (µg)

150

41

43

29%

Thiamin (Vitamin B1) (mg)

1.1

0.12

0.12

11%

Riboflavin (Vitamin B2) (mg)

1.7

0.5

0.5

29%

Niacin (mg)

10

<0.01~

<0.01~

n/a

Vitamin B6 (mg)

1.6

0.05

0.05

3%

Vitamin B12 (µg)

2

0.8

0.8

40%

Pantothenic acid (vitamin B5) (mg)

5

2

2.1

42%

Folate (µg)

200

93

97

49%

Vitamin A (Retinol) (µg)

750

230

239

32%

Vitamin D (Cholecalciferol) (µg)

10

0.8

0.8

8%

Vitamin E (Alpha-tocopherol) (mg)

10

2.3

2.4

24%

Omega – 3 fatty acids (total) (g)

0.89 (f), 1.46 (m)^

0.17

0.18

12-20%

Short chain Omega-3s (ALA) (g)

0.8 (f), 1.3 (m)^

0.06

0.06

5-8%

Long chain Omega-3s (DHA/DPA) (mg)

90 (f), 160 (m)^

110

114

71-127%

Omega-6 fatty acids (g)

8 (f), 13 (m)^

1.37

1.42

11-18%

Lutein (mg)

n/a

0.38

0.40

n/a

Zeaxanthin (mg)

n/a

0.13

0.14

n/a

Lutein + zeaxanthin (mg)

n/a

0.51

0.53

n/a

Biotin (µg)

30

<8~

<8~

n/a

Fluoride (mg)

3 (f), 4 (m)^

<1~

<1~

n/a

Chromium (mg)

0.2

<0.01~

<0.01~

n/a

Copper (mg)

3

<0.02~

<0.02~

n/a

Manganese (mg)

5

0.023

0.024

0%

Molybdenum (mg)

0.25

0.012

0.012

5%

Vitamin K (µg)

80

<2~

<2~

n/a

Eggs contain the highest quality protein and are often used as a standard to measure the quality of other protein sources. A single large egg provides 12 percent of the daily requirement of protein for 70 calories 36). Eggs also have the highest biological value of any protein, meaning that the essential amino acids they provide are used very efficiently by the body. Eggs also contain varying amounts of vitamins A, D, E, K, B6, B12, folate, and a variety of minerals (particularly riboflavin, phosphorus, and iron). Because eggs are very easy to digest, they are frequently included in therapeutic diets.

The yolk makes up just over one third of an egg. It provides three-fourths of the calories, all of the fat-soluble vitamins (A, D, E, and K), and all of the choline, lutein, and zeaxanthin. The yolk also provides most of the phosphorus, iron, and folate and almost half of the protein and riboflavin. The white (albumen) provides more than half of the total protein and riboflavin. Choline, an essential nutrient, is shown to be important for proper brain development in the fetus and newborn and may play a role in memory function throughout life and into old age. Lutein and zeaxanthin may prevent macular degeneration, a leading cause of blindness in the elderly in the U.S.

Though these nutrients are present only in small amounts in eggs, research shows that they may be more bioavailable, or absorbed and utilized by the body, when obtained from egg yolk than from richer sources.

When deciding whether to include eggs in your diet, consider the recommended daily limits on cholesterol in your food:

  • If you are healthy, consume no more than 300 mg of cholesterol a day.
  • If you have diabetes, high cholesterol or cardiovascular disease, limit the daily cholesterol intake to no more than 200 mg a day.
  • If you like eggs but don’t want the extra cholesterol, use only the egg whites. Egg whites contain no cholesterol. You may also use cholesterol-free egg substitutes, which are made with egg whites.

The risk of heart disease may be more closely tied to the foods that accompany the eggs in a traditional American breakfast — such as the sodium in the bacon, sausages and ham, and the saturated fat or oils with trans fats used to fry the eggs and the hash browns.

Tips for eating eggs 37)

  • The healthiest ways to cook eggs are to boil, poach or scramble them using reduced fat milk.
  • Eggs are always available and easy to cook quickly – faster than getting takeaway.
  • Eggs make great lunchbox fillers for adults and children and are very portable when hard boiled.

To lower cholesterol levels the National Heart Foundation recommends the following:

  • Be smoke-free
  • Achieve and maintain a healthy body weight
  • Choose polyunsaturated or monounsaturated oils
  • Choose foods such as wholegrain bread and cereals, brown rice, wholemeal, pasta, vegetables, fruits, legumes (e.g. chick peas, kidney beans and lentils), lean meats and poultry, oily fish and reduced, low or no fat dairy  products
  • Consume plant sterol enriched foods as part of a health eating plan
  • Limit cholesterol-rich foods if advised to do so
  • Limit alcohol intake to no more than 2 standard drinks per day for men and women
  • Get at least 30 minutes of moderate intensity physical activity on most, if not all, days of the week.

Conclusion

Eggs are really nutritious and it’s fine to have them regularly as part of a healthy diet. Eggs contain of disease-fighting nutrients like lutein and zeaxanthin. These carotenoids may reduce the risk of age-related macular degeneration, the leading cause of blindness in older adults. And brain development and memory may be enhanced by the choline content of eggs. Eggs contain good quality protein, 11 vitamins and minerals, and are a source of healthy fats including omega-3 fats.

As part of a healthy balanced diet you can eat up to 6 eggs each week without increasing your risk of heart disease.

However, if you have high cholesterol, type 2 diabetes or cardiovascular disease, limit your egg daily cholesterol intake to no more than 200 mg a day (<200 mg/ day).

References   [ + ]

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