Friday, July 6, 2012

Some Egg (Dietary) Facts

Some folks have been a bit surprised that we (as a family) go through 3 to 4 dozen eggs a week. Maybe the surprise is just from the large consumption of a single item, or maybe it is because eggs have gotten a bad wrap, or maybe both. To the former, I just really like eggs. Eggs are tasty and highly portable and a breeze to cook when you are in a hurry. They are also very nutritious! Some weeks I consume a lot less just because I want to try something new, but generally this is the norm.

"What?", you say. Aren't they high in fat and cholesterol .. sure .. but read on.

So as to the cholesterol issue, sure eggs contain a decent amount of cholesterol. However cholesterol is an important nutrient in your body. It is a precursor to various hormones (especially sex hormones) as well as being vital to cellular repair. It is so important that every cell in your body has the ability to produce it by itself. Your body will also vary the amount of cholesterol it produces based the amount of dietary (i.e. exogenous) cholesterol you consume!

Other than a specific portion of the population (termed "hyper responders") most folks will NOT see an increase in serum cholesterol levels in the body based on increased intake of dietary cholesterol. While I do not have exact numbers, I would assume a decent amount of those hyper responders would be those with Familial Hypercholesterolemia, which is a genetic disorder whereby the LDL receptors in the liver do not recycle cholesterol properly (or at all). That is a huge simplification of the condition, but sufficient for my point.

So, to put it simply, I don't view the cholesterol levels in eggs to be even relevant for most folks eating a  healthy diet.

Peter Attia has a great series on cholesterol over on this website at if you are interested in learning more.

Consumption of saturated fat is frequently blamed as being a risk factor for cardiovascular disease. However a 2010 meta-analysis of 21 epidemiological studies that was published in the American Journal of Clinical Nutrition concluded that "there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat". There are hypothesis' that overconsumption of carbohydrate may be to blame since excess glucose will be converted to palmatic acid (the body's storage form of saturated fat) when your body's glycogen levels are already full, but I have not been able to find a study that supports this. That is not to say that it does not exist, only that my Google Fu is lacking in that area :)

Saturated fat is also routinely blamed for increasing cholesterol levels. While this is true, saturated fat tends to increase both HDL and Total Cholesterol and generally results in a more favourable TC:HDL ratio, which is a much better predictor of CVD than TC alone.

If you do some digging around PubMed you will likely find that a lot of the current CVD risk research is focusing on LDL particle size and oxidative stress. Saturated fat is actually the least prone to oxidation, followed by mono-unsaturated and then polyunsaturated. When you consume fat some of it is used for fuel by your body and some of it is incorporated into your cells (as well as other uses). Consumption of fat that is already oxidized, or that can easily become oxidized in your body, would increase the amount of oxidative stress on your body (thus depleting anti-oxidant levels such as glutathione which are needed to deal with the free radicals). I will let you draw your own conclusion here but the conclusion of many in the Paleo realm is that saturated (from healthy fat sources like coconut and animals that were responsibly raised) is an ideal source of fat for this reason and many others. Monounsaturated and polyunsaturated fats from good sources are healthy too (polyunsaturated fats contain DHA and EPA for one, which are essential fatty acids that we need to consume) but one should not shun saturated fat!

Now that I've dispensed with some common objections to egg consumption, let us look at why you should be eating eggs (other than the fact they are delicious)! The image below shows a list of common nutrients found in eggs, split into white and yolk. I have left the table split since I do not want folks to think they can simply get all this from the white alone! Notably missing from the chart is choline. A 100g serving of egg yolk contains about 683mg of choline in the yolk and about 1.1mg in the white. A single egg generally contains about 250mg of choline which is about 25% of the daily recommended intake.

Bottom line: eggs are a nutritious and delicious part of a healthy diet!

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