When Low-Risk Means High-Risk

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

How else can we make decisions for ourselves and our families, but by the best available balance of evidence? The latest meta-analysis, pooling data from more than a dozen studies involving more than 300,000 people, indicates that there’s a “dose-[dependent] association between egg consumption and the risk of [cardiovascular disease] and diabetes.” But, that doesn’t mean every single individual study showed evidence of harm.

Even though the totality of evidence points to harm, the egg industry can certainly cherry-pick out studies that show no apparent effects. If eggs are harmful, though, why don’t all studies on heart disease and egg consumption show significant harm? It may have to do with “Rose’s concept of a ‘sick population.'” If an entire population is sick, then “the range of ‘health’ may not be sufficiently broad to establish a significant association.” Let me explain. This is one of the most famous papers ever written in preventive medicine; should be required reading for all medical students.

Imagine “[i]f everyone smoked 20 cigarettes a day.” If everybody smoked, “then clinical [studies], case-control [studies],…cohort studies…would [all] lead us to conclude that lung cancer was a genetic disease; and in one sense, that would be true.” Right? Some smokers get cancer; others smoke their whole lives, and don’t. But, if everybody smoked, we’d never know that smoking was a risk factor.

Thankfully, “[i]n the case of cigarettes and lung cancer it so happened that the original study populations contained about equal numbers of smokers and non-smokers.” And, in that situation, studies are “able to identify” the main risk factor.

But, take cholesterol. Here’s the cholesterol levels of the people without heart disease in the famous Framingham Heart Study. And, here’s the cholesterol levels of those that did develop heart disease. It’s hardly any different, because practically everybody’s cholesterol was too high; it’s like everyone was a smoker. The painful truth is that even someone at “low risk” for heart disease is likely to die of heart disease. “Everyone [who eats the standard Western diet], in fact, is a high-risk individual” when it comes to heart disease.

In a sick population like ours, where nearly everyone is eating lots of saturated fat and cholesterol, adding some more saturated fat and cholesterol (in the form of eggs) may just take us from one sorry state—probably dying from heart disease—to another sorry state—still probably dying from heart disease.

So, when the federal guidelines say we need to really restrict dietary cholesterol—especially if we’re at high risk for heart disease, we need to realize that nearly all Americans that live past middle age are at high risk of dying from heart disease—it’s our #1 cause of death. “A 20-year old man might feel [it’s] safe to smoke and eat egg yolks, because his [heart attack] is 45 [or so] years…in the future – but why would he want to accelerate the progression of [the] atherosclerotic plaque to bring it on sooner? ‘Stopping egg yolks after the heart attack would be like quitting smoking after lung cancer is diagnosed’.”

There may, in fact, be a plateau of risk for smoking, too. Whether we smoke for 25 years, or 35 years, our risk of lung cancer may be about the same—really high, but about the same. So, the tobacco industry could truthfully tell someone who’s smoked for most of their lives, for the last 25 years, “Keep smoking; don’t worry. You can keep smoking, and your risk of lung cancer won’t go up”—conveniently just failing to mention that “You’re already really at high risk, and if you quit completely, your risk would drop dramatically.”

In the same way, the egg industry can design a study showing that adding eggs doesn’t make much of a difference, but make the same convenient omission. Imagine if you took a raging drunk, and had them take a shot of whiskey. In someone who’s hammered, it might not make much of a difference. But, to a teetotaler, a couple shots could have quite an effect. So, it’s like the alcohol industry with a group of drunks saying, “See, couple shots; no big deal.” But, that doesn’t mean it’s not better to be sober.

Instead of going from high-risk to high-risk, better to go to low-risk, or no-risk.

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• J D Spence, D J A Jenkins, J Davignon. Egg yolk consumption, smoking and carotid plaque: Reply to letters to the Editor by Sean Lucan and T Dylan Olver et al. Atherosclerosis 2013 227(1):189 – 191.
• Y Li, C Zhou, X Zhou, L Li. Egg consumption and risk of cardiovascular diseases and diabetes: A meta-analysis. Atherosclerosis 2013 229(2):524 – 530.
• G Rose. Sick individuals and sick populations. International journal of epidemiology 2001 30(3):427 – 432.
• V Gajalakshmi, R J Hung, A Mathew, C Varghese, P Brennan, P Boffetta. Tobacco smoking and chewing, alcohol drinking and lung cancer risk among men in southern India. Int J Cancer 2003 107(3):441 – 447.
• USDA. Dietary Guidelines for 2010. USDA 2010 1 – 112.

• alcohol
• alternative medicine
• cancer
• cardiovascular disease
• cholesterol
• complementary medicine
• diabetes
• dietary guidelines
• eggs
• Framingham Heart Study
• heart disease
• LDL cholesterol
• lifestyle medicine
• lung cancer
• prediabetes
• saturated fat
• smoking
• standard American diet