Last year, Canadian researchers published a study that claimed eating eggs is “as bad as” cigarette smoking for stroke risk. The study got a lot of press. And it got everyone worried about eggs all over again.
But it shouldn’t have. The research is flawed. Plain and simple. And so is the comparison.
First of all, the real science says that light-to-moderate cigarette smoking is not as bad as it is made out to be in the first place.
But eggs?
How could any real scientist conceivably bad-mouth one of the most nutritious foods on Earth?
But they did.
For the study, researchers surveyed a group of middle-aged and elderly stroke patients. They asked the patients about their lifelong egg intake and their smoking history.
This was just about the weakest kind of statistical study. Researchers call it a case-control study. It asked patients who already had a disease to go back in time and try to remember every last egg they ever ate. Something like that would be impossible even if the participants had superhuman memories to begin with.
But in reality, no one does.
And, by definition, many of these stroke patients had some level of cognitive impairment… by virtue of the stroke they already had, in order to be included in the study!
Plus, as I explained in a Daily Dispatch called “Garbage In, Garbage Out” even dietary questionnaires based upon recall over the past day are limited–in people with fully functioning cognitive abilities. The simple fact is, people cannot accurately remember the past 24 hours in the so-called “24-hour diet recall.” And very often, they’re not truthful either.
But I digress.
In the new study, the researchers pinpointed–with truly amazing precision–that eating exactly 4.68 egg yolks per week is the tipping point for having a stroke.
The researchers did try to control for sex, blood lipids, blood pressure, smoking, body mass index, and the presence of diabetes. But they didn’t bother to account for other important confounding variables.
They didn’t factor in physical activity. But exercise reduces the thickness of the wall of the carotid artery. This artery supplies blood to the brain. And blockages in the carotid artery are a major cause of stroke.
Physical activity also reduces inflammation. And inflammation looks to be a major factor in the development of heart disease and stroke. In fact, the role of inflammation may be a key to understanding what really causes atherosclerotic heart disease and stroke.
The researchers also never measured the study participants’ waist circumferences. Yet your waist size strongly predicts your risk of developing atherosclerosis of the carotid artery (again, a major cause of stroke). And the larger your waist size, the greater your risk.
And, as usual, the researchers totally ignored the number one major risk factor for stroke–stress.
High psychological levels of demand, perceived lack of control, and lack of accurate feedback are all useful measures of stress. Doesn’t this sound just like living in the mid-to-late 20th century?
Yet none of this was considered.
Despite all these holes in their methodology, the study authors still tried to draw a sweeping conclusion.
Remember, this statistical miscarriage of a study was all about the eggs. They wanted to connect the dots between eating eggs and having a stroke.
And they did just that.
But the politically correct “causes” of heart disease and stroke that the government has seized on over the past three decades don’t really measure up. “Causes” such as cholesterol, eggs, salt, saturated fat, and even light-to-moderate smoking. Of course, these government wars were never based on real science anyway. Let alone on a genuine understanding of nutrition and the human diet.
Now, want to hear some real, sensible science about eggs?
In a 2005 crossover study, men and women ate two eggs a day for six weeks. Then they had a four-week “wash out” period. After that, they ate a bowl of oatmeal every day for six weeks.
These crossover studies are quite strong. They are “before and after” studies where all participants serve as their own controls in real time observations. They perfectly account for any and all confounding factors.
And the results of this study showed that two eggs daily did not harm endothelial function. The endothelium is the lining of the arteries that affects flow of blood. Nor did eating two eggs daily increase total cholesterol. Or LDL cholesterol. As I have said many times, there is no relationship between the cholesterol in the food we eat and the levels of cholesterol in our blood.
In fact, eating two eggs a day did not show any effect on cardiovascular health when compared to eating oatmeal–the dietary darling of NIH and politically correct food consumers.
In another study, researchers found that eating several hard-boiled eggs a day had no effect on endothelial function in patients who already had high cholesterol.
In yet another study, obese patients with heart disease ate high amounts of saturated fat. But they ate zero grams of starch (carbohydrates) each day. And lots of vegetables. Oh yes, and they also ate three or four eggs a day.
And they experienced massive weight loss. Without any negative effects on their blood lipids or cholesterol. This study used to be available on the Mayo Clinic website–but it was mysteriously taken down.
Finally, one more question for the misguided researchers of this recent egg-bashing study: Did they consider the source of the eggs the subjects ate?
In a 2008 study, hens fed grains containing the omega-6 fats, found in commercially grown soy and corn, produced less healthful eggs. That’s compared to hens fed a more natural diet low in omega-6 fats.
But the unnatural, omega-6 diet is the industry-standard.
And according to this study, when participants ate two eggs from the soy- and corn-fed hens, their LDL or “bad” cholesterol levels increased by a whopping 40 percent! Subjects who ate two of the natural eggs each day–low in omega-6 fats–had normal levels of LDL cholesterol. That’s comparable to subjects in the control group, who consumed only two to four eggs per week.
Experts believe that oxidation of LDL cholesterol in the blood contributes to atherosclerosis of the arteries. So it’s conceivable that eating regular, commercially produced, “industrialized” eggs could have a negative effect on carotid arteries as well. But the researchers for this study failed to consider this possibility.
Oh, and by the way–one final note about the recent egg/stroke study…
Two of the researchers have extensive ties to the statin drug industry. I’m not surprised. Are you?
It looks like this is another example of a half-baked statistical study that simply laid an egg.
Sources:
1. Atherosclerosis Volume 224, Issue 2 , Pages 469-473, October 2012
2. Int J Cardiol. 2005 Mar 10;99(1):65-70.
3. Nutr J. 2010 Jul 2;9:28. doi: 10.1186/1475-2891-9-28.
4. Mayo Clin Proc. 2003 Nov;78(11):1331-6.
5. Journal of Agricultural and Food Chemistry, 2008; 56 (10): 3688