Mythbuster: Are Egg Yolks Really Bad For You?

Mythbuster: Are Egg Yolks Really Bad For You?

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Consuming foods high in cholesterol has long been thought to increase your serum cholesterol and increase your risk of heart attack and stroke. Egg yolks, for better or worse, became the poster child of unhealthy foods because of their reputation for being high in dietary cholesterol. As a result of this bad rap, some folks may avoid egg yolks while others avoid eggs entirely. The purpose of this video is to evaluate the notion that egg yolks are bad for your health. And for the simplicities sake, we’ll be focused exclusively on chicken eggs.

Nutritional Content of 1 Egg Yolk

  • Approximately 60 calories, which is 3x the calories of the egg white
  • Contains 2.7 g protein, 210 mg cholesterol, 0.61 g carbohydrates, and 4.51 g total fat
  • Fat breakdown
    • Unsaturated Fat: Oleic acid (47%)
    • Saturated Fat: Palmitic acid
  • 90% of vitamins in minerals are found in the yolk
    • Vitamins A, D, E and K
    • B vitamins: Thiamin, B6, Folate, B12
    • Minerals: Calcium, Iron, Phos, Zinc

 

Ok, so here is where it gets dicey. We know that increased levels of total cholesterol and LDL cholesterol in your blood correlate with increased risk of forming plaques (atherosclerosis), clogged arteries, heart attacks (myocardial infarction) and stroke (cerebrovascular accident). Conventional wisdom dating back more than 60-70 years ago was that any foods high in cholesterol would increase your blood cholesterol and thus your risk of these diseases. For this reason, eggs were vilified by even the most well intentioned physician or researcher.

The first notion to dispel here is that dietary cholesterol intake correlates well with the cholesterol in your blood. Fortunately for us, they do not. Let me state that clearly, dietary cholesterol does not correlate well to the cholesterol in your blood that causes disease. The reasons for this are far beyond the scope of this lecture.

What about fat content?

There is a fair amount of dietary fat in the form of unsaturated and saturated fat in 1 egg yolk. If you eat 4 egg yolks, you get 25% of your recommended daily intake. We have known for a long time that unsaturated fat was good for you. We used to think that saturated fat was bad, however more recently the evidence is less clear. Although the landscape is evolving, the current body of evidence suggests that at worse, saturated fat is not bad for you and may have some benefit as well. Check out my video on the subject to learn more.

What does the research say?

A systematic review published in 2013 looked to address the relationship between egg consumption and cardiovascular disease. In this publication, they combined data from 16 studies and concluded “egg consumption is not associated with the risk of CVD and cardiac mortality in the general population”. They do mention that egg consumption may be associated with increased risk of type 2 diabetes and may increase risk of cardiovascular disease in diabetic patients. Another meta-analysis published in 2013 drew similar conclusions. They also found that egg consumption was not associated with increased risk of stroke. They too noted an increased risk of heart disease in diabetic patients. These two studies are linked in the discussion section for you to check out.

Just to be clear, there are more than 30 articles on the subject that draw the same conclusions. These two just happen to be the gold standard way to present them all at once and are much easier to review here.

So how should you interpret this information?

Well, if you’re not a diabetic you can consume egg yolks with virtual impunity. There is both a systematic review and meta-analysis from clearly stating that they are not associated with cardiovascular disease or stroke.  Now, if you have a family history of diabetes or are diabetic, or have been told you are at risk of diabetes, you should talk to a nutritionist or your physician.

Now the other side of the coin isn’t just that the cholesterol and fat’s aren’t bad for you, it’s all the other nutritional content of the yolk. As much as 90% of the nutritional value of 1 egg is found in the yolk!! If you just eat the egg whites, you’re missing out on 90% of the good stuff. The yolk are densely packed with protein, multiple B vitamins, Vitamins A, D, E and K as well as the minerals calcium, iron, phosphate and zinc.

And I don’t think I can overstate this enough. With the exception of diabetics and those at risk, the nutritional value of egg yolks far outweighs the now-debunked risks associated with the cholesterol in the yolk.

References

Shin JY, Xun P, Nakamura Y, He K. Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis. American Journal of Clinical Nutrition 2013:146–159.

Rong Y, Chen L, Zhu T, et al. Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies. Bmj 2013.

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