Dat dere Ovum

Boring but necessary introduction

Aside from my unoriginal introductory title (and my hyperoriginal article title, a combination of Latin and Bro), this is going to be a fairly straight forward and serious article.

Basically, do eggs cause an increase in cholesterol? If they do, why? If they do, is this enough to either negate their benefits or to otherwise avoid consumption of them? Is there a limit to how much you can eat a day? Are there people who should never eat eggs?

All those answers, and more, lay below.

What exactly is in the egg?

I’m not going to go too into depth on an egg’s nutritional composition. A simple Wolfram Alpha search yields enough information. Eggs tend to be 60% fat by caloric total and 40% protein with negligible carbohydrate content.

Expanding the fatty acid distribution shows about 30% of the total fat is saturated, 40% is monounsaturated (primarily oleic acid) and about 20% is polyunsaturated (with about an 8:1 ratio of omega-6 to omega-3). Trans fats round out the 10% (primarily as vaccenic acid and conjugated linoleic acid, or CLA; elaidic acid, the one problematic to health, is not found in naturally occurring eggs). Excluding oleic acid and to a degree, the saturated fat ‘palmitic acid’ (which can be synthesized in vivo from the hen) other fat sources seem to be correlated with the hen’s diet; the percentage stays relatively the same, but individual fatty acids may differ. [x] So at least in regards to fatty acids, we have a fairly nice distribution although it is not theoretically perfect and quite variable.

In the yolk also exists the cholesterol. This is the main talking point that people address for health because, as we see above, the actual saturated and trans fat content is fairly negligible (its weird to think that eggs are the second best source of oleic acid, since the main source is olive oil and they taste very different).

The protein content is typical of most animal products (higher in branched-chain amino acids and glutamine), but eggs have quite a high leucine content in the yolk especially; where all the fatty acids and cholesterol are. The yolk truly is the center of the egg in as much a nutritional sense as a physical sense.

Keep in mind that the above information is based on standards, and may change depending on where you get your eggs and the diet the hens were fed. Looking at the Examine page for Eggs (Yes, it exists) we can see that there is also a lot more information that exists on egg composition, including the shell, that I won’t go into for this article.

Direct Epidemiological Studies on Egg Consumption

There are large studies on both sides of the pond here, some studies argue that there is no association [x] [x] whereas other studies state that there is a positive correlation [x] [x] (Although one of these only found a correlation in women).

When looking at the above studies, it was noted that interindividual differences exist. However, even in those that have spikes in cholesterol and Low Density Lipoprotein (LDL-C) that High Density Lipoprotein (HDL-C) levels also increase, usually enough to match and preserve the ratio.[x] Overall, this matching of lipoprotein levels does not significantly affect risk for heart disease or endothelial (blood vessel) health for most persons. [x] [x] [x]

Indeed, this individual difference seems to be relatively key. It seems that some individuals with a genetic polymorphism (different shape) of the gene that encodes for Apolipoprotein E (a compound needed for proper metabolism of cholesterol and fats) seem to have an increased serum cholesterol level in response to dietary stressors. [x] It seems to alter the blood response from cholesterol [x] but not fatty acids. [x] These people are referred to as Hyper-Responders.

The best I can conclude this section with is “If you have a family history of high blood cholesterol (genetics) and you are pretty damn sure that it is due to genetics rather than Granma’s Apple Pies, then at least acknowledge that eggs may increase your cholesterol levels”.

More info on Hyper-responders

In regards to age cohorts, this review noted that at least in the populations of children [x], young adults of both genders [x] [x], and older individuals [x] [x] that about one third of persons were hyperresponders to egg consumption and experienced LDL increases. That being said, all subjects had an increase in HDL levels and preserved the ratio of LDL-C/HDL-C, indicating no real increase in risk for heart disease as mentioned earlier.

The differences in lipoprotein metabolism also result in different pharmacokinetics for the carotenoids lutein and zeaxanthin, in a manner which can be seen as protective. It could be argued that if eggs increase your cholesterol (hyper-responder) that you are one of the lucky ones, although this topic is beyond this article. [x]

There doesn’t seem to be much concern about being a hyperresponder, per se. 

Direct interventions on different populations

So we have established that eggs do appear to increase cholesterol in some, but it is due to genetic reasons and does not necessarily increase the rate of heart disease. Going for a worst case scenario perspective, could intervention studies show different?

When looking into adults with high blood cholesterol and lipids, egg consumption (2-3 eggs, not exclusive source of cholesterol) was not found to exacerbate the unhealthy state, although it seems to slightly suppress getting better. [x] A recent review article [x] tended to paint egg consumption in a bad light. Its a free text read and would be worth your time, but the Tl;Dr (Too long; Didn’t read) of it is that in patients of heart disease (the metabolically unhealthy) they already have a very pro-oxidant and unhealthy state of the blood vessels. Putting more cholesterol into this state only leads to more oxidation and screwing up of the elevated LDL-C levels, and it would be best to avoid dietary cholesterol if you are metabolically unhealthy.

Alternate Theories and Mini-Devils Advocate

Building off of that review article (biased, but sourceful), it is possible that putting a relatively harmless cholesterol molecule into a hyperesponder who is also unhealthy could result in an abnormal blood vessel environment.

Low density lipoproteins (which are spiked in a third of persons) independent of HDL do exhibit multiple shapes and forms and are subject to changes based on the rest of the diet. [x] Of concern is their biotransformation into the smaller, denser molecules (seen as more artherogenic and thus of concern) in direct relation to dietary sugars.

So this spike in LDL-C that we see here with egg consumption, is it a good or bad form of LDL-C?

That answer is not dependent on eggs sadly. It is dependent on the person consuming the eggs and everything else consumed alongside the eggs. LDL-C is modified mainly by pro-oxidant conditions (induced from lack of veggies, CoQ10, vitamin E, etc.) or molecules in the blood which can directly damage the lipoproteins (like Advanced Glycemic End products, seen in diabetes). The former are correlated with those who have metabolic syndrome, the latter is pathophysiology of metabolic syndrome.

Although a blanket statement, it can be somewhat generalized that those who consume a lot of veggies and meat products and not too much junk food will have good LDL-C, whereas those who could be confused for having metabolic syndrome (or Diabesity, whichever term you like better) tend to have worse (more artherogenic) LDL-C.

In hyperresponders who also consume copious amounts of sugars and/or are metabolically unhealthy, then egg consumption could potentially increase the risk for heart disease. This is mainly via elevation of serum lipoproteins and cholesterol, followed by acute suppression of their subsequent degradation (aka, insulin is preventing them from being taken up by the liver and body tissues like they should be) all multiplied by time and an obesogenic environment. Like usual, the ‘bad’ is not carbs or fats here. Its both of them, combined in high amounts, and in excess of energy expenditure.

Summary Bullets

  • Eggs are hated on for some reason; yet they are amazing nutrient vessels
  • Eggs can increase cholesterol levels in some, labelled hyperesponders
  • This increase in cholesterol does not per se increase the risk of heart disease
  • Eggs could contribute to an increase in heart disease through a subpar diet, but cannot have blame placed fully upon them in isolation
  • If you are healthy and eat a well-balanced diet, eggs are fine and may still be fine even if they spike your cholesterol. If you have a history of heart disease and you are not in the best of shape, it may be prudent to avoid eggs until you are healthier. Perhaps get some CoQ10 in you ASAP.
Summarizing the summary, eggs appear to be the ephedrine of the nutritional world. Used and loved by many, correlated indirectly with the death of a few, recipient of relentless societal hatred for said correlation.

 

 

 

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Comments

  1. Ferrar1 says:

    As I’m of Greek background and growing up with fresh eggs my entire life, this was a great read!

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