Wednesday, November 10, 2010

Rethinking Eggs

I was taken in by the Incredible, Edible Egg.
"There's no reason you can't enjoy them for breakfast every day."
- American Egg Board
Indoctrinated with the risks of egg consumption in my academic years, I resurfaced with the notion that dietary cholesterol in general, and egg consumption in particular, wasn't that bad - its impact on serum cholesterol was minor, its contribution to atherosclerosis and heart disease inconsequential. How did I come to believe that?

This recent commentary in the Canadian Journal of Cardiology tells me I was hoodwinked by the Egg Board's propaganda:
Dietary Cholesterol And Egg Yolks: Not For Patients At Risk Of Vascular Disease, The Canadian Journal of Cardiology, November 2010

Spence et al. says that eggs are not harmless for people at risk for cardiovascular disease (CVD). They say that messages the Egg Board is propagating are based on effects in healthy people - people who would need to be followed for longer periods of time before ill effects became apparent.

However, those very same Egg-Board-quoted studies did find increased CVD risk in people with diabetes:

A Prospective Study Of Egg Consumption And Risk Of Cardiovascular Disease In Men And Women, Journal of the American Medical Association, 1999
"The apparent increased risk of CHD associated with higher egg consumption among diabetic participants warrants further research."

Regular Egg Consumption Does Not Increase The Risk Of Stroke And Cardiovascular Diseases, Medical Science Monitor, 2007
"The increased risk of coronary artery disease associated with higher egg consumption among diabetics warrants further investigations."

Both of the studies above showed a doubling of CVD risk in a non-healthy population (diabetes). The first one also showed that regular egg consumption actually increased the risk for diabetes, as do these two:

Food Intake Patterns Associated With Incident Type 2 Diabetes: The Insulin Resistance Atherosclerosis Study, Diabetes Care, 2009
Finding: Consumption of eggs increased risk for type 2 diabetes.

Egg Consumption And Risk Of Type 2 Diabetes In Men And Women, Diabetes Care, 2009
Finding: Consumption of eggs increased risk for type 2 diabetes.

Here's one that found regular egg consumption doubled mortality:

Egg Consumption In Relation To Cardiovascular Disease And Mortality: The Physicians' Health Study, American Journal of Clinical Nutrition, 2008
"Egg consumption was positively related to mortality, more strongly so in diabetic subjects."

The Problem Is...

The problem with eggs, Spence et al. says, is three-fold. Dietary cholesterol:
  1. Increases the susceptibility of LDL to oxidation "by 37% in one study and by 39% in another." (Oxidized LDL contributes to the formation of plaque.)
  2. Increases postprandial lipemia. (Increased triglycerides and other lipid particles.)
  3. Potentiates the adverse effects of dietary saturated fat. (This is called the "bacon and egg effect" or the "egg and cheese effect." At high cholesterol intake, a high saturated fat diet leads to higher LDL than if you paired the same saturated fat diet to a lower cholesterol intake.)
There's another point Spencer raises, a point that has become apparent in my work with diabetes. Postprandial (after meal) measurements may be more telling than fasting measurements. (In diabetes, you may have a fasting glucose below 100 mg/dl, but your glucose during the day, unbeknownst to you, may rise and stay elevated long enough to cause damage.) Although fasting measurements are still important:
"In people consuming a low cholesterol diet, egg-yolk intake increased fasting serum cholesterol level by 40 mg/dl."
We measure fasting levels because they are less affected by meals; standards can be developed. But what happens after meals is equally important:
"In human subjects, endothelial function is impaired for approximately 4 hours after consumption of a high-fat/high-cholesterol meal."
Function deteriorates in the presence of oxidative stress and inflammation. This is one reason why antioxidants in foods and supplements are beneficial. They can partially mitigate the damage to arteries after a high-fat meal.* That's why it's valuable to study dietary patterns in addition to single nutrients.

Eat a fatty, cholesterol-laden meal every 3 or 4 hours during the day and you may significantly and chronically compromise the function of your arteries.

So, if you're going to keep your cholesterol intake to below 200 mg a day, as recommended by the National Cholesterol Education Program (NCEP) and the American Heart Association (AHA), you'll be hard-pressed to fit eggs into your diet at all ... as one large egg can contain between 215 to 275 mg cholesterol.

For relativity sake:
"The yolk of a large egg provides more than the 210 mg. of cholesterol in a Hardee's Monster Thickburger, which contains two-thirds of a pound of beef, three slices of cheese and four strips of bacon."

* Related post: The Stomach As Bioreactor, Fat Oxidation Takes Off In A Chain Reaction. "Heating food causes oxidation of the food's fat. But so does the environment of the gut, which is warm and acidic and full of oxidizing chemicals."


Mike said...

This is a matter more of re-thinking cholesterol versus re thinking eggs. In 70% of the population, the cholesterol from eggs doesn't affect blood cholesterol. More importantly, in the 30% it does, it causes an increase in large particle LDL, which is neutral as far as cardiovascular risk. Hence the "re-thinking" of cholesterol. As long as we are only using TC, HDL, and LDL, studies will be worthless, and subsequent treatments and effects will only bring negative results.

For the past 3 years, I've eaten at least 4 eggs a day, poached in coconut oil. My labs are as follows:
My TC is 245, LDL 162, and HDL 72; all three values have climbed higher each year for the past 3 years. (yet my Trig/HDL ratio is 0.8) I’ve also gotten leaner, at 7% body fat, reduced all forms of flu/URI to zero, and have gotten faster and stronger.

By all accounts, I should be ready to have a massive myocardial infarction at 37. My physician is at odds with what to do, as by conventional standards I should be on a statin. If I had access, though, an LDL particle size count and Lp(a) value, along with C-RP, would shed more insight, but that's not "standard" treatment.

So, even in light of the prestigious Canadian Cardiology study (note sarcasm), I'll carry on with my 4 eggs a day and elevated HDL and LDL.

I do agree, though, that intake of oxidized cholesterol is of concern. I personally avoid scrambling and high-high cooking eggs, along with pasteurized milk---7-ketocholesterol is nasty stuff.

Ronald said...

I always say to get CVD you have to break a few eggs.

Claudia said...

Latest egg recall:

Cholesterol isn't the only reason not to eat them. There's also factory farming. Look at that pic!

Bix said...

4 eggs. Wow. Mike, you reminded me of a point I wanted to make.

Bix said...

Claudia ... that photo ... ugh.

Mike said...

I'll be interested to hear it, Bix.