Doug Cook RD
Nutrition Demystified. Health Exemplified
Nutrition advice that makes sense. Separating hype from reality.

Eating egg yolks as bad as smoking? Are they serious?

Egg-yolk-in-separater-300x232

The poor egg. If ever there was a case for low self-esteem, our nutritious, gold-standard protein egg would take the prize for feeling unworthy.

The latest example comes from a study published in the journal Atherosclerosis which concluded that “eating egg yolks accelerates atherosclerosis [plaque build up in the blood vessels] in a manner similar to smoking cigarettes”.

To quote Liz Lemon from 30 Rock: “What the what?”

As the saying goes, the devil is in the details, details that are always left out whenever these sound bites hit the ‘air waves’. The reports failed to describe critical aspects of the study such as the characteristics of the subjects, how the information on diet was collected and if they controlled for, or used statistics, to remove the impact of other aspects of the subjects that might skew the results…something as important as age.

Study details

Researchers gathered lifestyle information from the study subjects AFTER they had a stroke. Once the subjects were well enough to participate in the study, they asked them to remember, and give an estimate, of the number of eggs they had eaten, and how many packs of cigarettes they had smoked, in their life time leading up to the stroke versus a study enrolling a group of healthy people, without established disease, and then following them over time, say 5 to 10 years while collecting and tracking information on lifestyle such as diet, alcohol use, smoking, exercise, etc. Recall for the best of us is hugely unreliable let alone in those recovering from a stroke.

They did not include any healthy people at all, they included those who had well established blood vessel disease that was decades in the making – big red flag.

Another thing the researchers didn’t do was asked about other lifestyle factors that affect the health of blood vessels like stress, exercise, or other dietary components weren’t assessed like omega 3 fats, whether or not they consumed an excess of omega 6 [pro-inflammatory fats], sugar, refined flour products, sources of trans fat, vitamin D intake or levels, vitamin C, fruit and vegetable intake etc – all of which have been implicated in cardiovascular health – another big red flag.

Another limitation of the study was the fact that there were too many differences between the two groups, categorized as those eating the most eggs and those eating the least amount of eggs. Normally, you don’t want major differences between two groups of people in research, or when you are making any kind of comparison in general hence the expression ‘compare apples to apples, and not to oranges.

In this case, they compared apples to oranges.

Those who ate the most eggs, which were later blamed on promoting atherosclerosis, were, on average 70 years old versus 55 years of age in the lowest egg consuming group. Those who ate the most eggs also reported smoking the most, and had higher rates of diabetes. Both smoking and diabetes are known to be two of the worst, if not the worst, offenders when it comes to blood vessel health and both increase the risk for stroke significantly.

Ironically [or so it seems for the egg and dietary cholesterol-phobes] those who ate the most eggs had the lowest levels of total and LDL cholesterol and the highest levels of HDL and had the lowest BMI [an indirect measure of body fat]. Elevated LDL cholesterol is more susceptible to oxidation which is the pivotal first step in atherosclerosis so having healthy/normal levels LDL reduces the risk because less LDL is hanging around the blood being damaged.

Do egg yolks protect against stroke?

Another take on the results suggests that eggs may protect against stroke since those who reported the highest egg consumption were older, had more diabetes, and smoked more [three major things stacked against them] yet had strokes roughly 14 years later than those in the group who ate the least amount of eggs. We know that egg yolks and egg consumption increases the levels of the protective HDL cholesterol and that higher egg consumption increases the production of the least harmful form of LDL. Many don’t know that LDL is a broad classification for many different sizes of LDL cholesterol and eating eggs helps the liver to make the better kind.

Of note, smoking is well known to deplete antioxidants in the blood such as vitamin C, vitamin E, beta-carotene, and more, all of which help to protect LDL from oxidation, or being damaged, which gets the atherosclerosis ball rolling. If fact, smokers have higher requirements for vitamin C because it’s used up neutralizing the damaging effects of cigarette smoke.

Vitamin C has been shown to also prevent plaque ruptures, which ultimately leads to heart attacks or strokes by helping the body to produce collagen, a vital protein that helps to keep plaque stable. Think of collagen like a layer of paper mache providing a protect coat to prevent plaque particles form braking off into the blood stream. Perhaps this is nothing more than a study that showed those who reported smoking the most were more likely to have unstable plaques from a sub-clinical vitamin C deficiency and egg consumption was an innocent bystander, or rather the victim of a very poor study design.

The last study from this group said one egg yolk was worse than a KFC Double Down.

I can’t help but wonder if there is a vegetarian bias but have not confirmed this.

The bulk of the evidence is clear. The cholesterol from food has little to know meaningful impact on blood cholesterol and the consensus is that regular egg consumption does not increase the risk for cardiovascular disease. Any cautionary advice for those with diabetes etc is nothing more than being conservatively safe, it’s not based on hard science.

Egg yolks carry the nutrients of an egg; vitamins A, D, B12, folate, lutein, selenium and choline to name a few. When it comes to eggs, egg yolks crush egg white in overall nutrition but there’s no need for a case of sibling rivalry, and the whole egg should be eaten – often.

 

Leave a Reply