Preventive Medicine Column
Dr. David L. Katz
The USDA announced last week that eggs are 14% lower in cholesterol than previously thought. And, by the way, they are also 64% higher in vitamin D. A clear explanation for this is not provided, although the best informed guesses relate to changes in chicken feed. We are what we eat- and so is the chicken, and the egg.
By itself, the announcement is potentially important news, with wide implications for the American diet. The newly released Dietary Guidelines, for instance, recommend a limit of 300mg of cholesterol per day for healthy adults, and 200mg per day for adults with, or at high risk for heart disease. The new, lower cholesterol content of eggs (about 185mg per large egg) means that 1 to 2 eggs per day is under the wire for all adults, and an egg a day is acceptable even for adults with heart disease.
My view, though, is that news about less cholesterol is just one reason among several for … eggsonerating the egg.
First, we were probably wrong about the harms of dietary cholesterol in the first place. Over the past decade or so, numerous studies, both interventions in small populations and observations in large ones, have suggested that dietary cholesterol in general, and eggs in particular, do not contribute meaningfully to blood cholesterol levels, or cardiac risk. My own lab has contributed two such studies to the literature- one in which we saw no harms from two eggs daily in healthy adults, and another in which we saw no harm from two eggs daily in adults with high cholesterol.
We are currently running a trial to assess the effects of two eggs daily on health in adults with coronary heart disease, and are hypothesizing there will once again be no harms. If interested in this study, please call 203-732-1265 or visit www.yalegriffinprc.org.
My interest in all this, by the way, does not derive from the fact that I have three egg-laying hens living in my backyard! (I do.) Rather, I am interested in being right about the means of optimizing health through optimizing diet, and have long been concerned that banishing eggs was not among them.
I once believed it was right — and excluded eggs from my own diet for the better part of 20 years. But I watched the science as it evolved, and did what scientists are supposed to do: kept pace with it. I have reintroduced eggs back into my own diet, and into the advice I offer patients.
Evolved is especially relevant, because Paleoanthropologists who study our native diet tell us, in essence, that we are well adapted to consume dietary cholesterol. Our Stone Age ancestors got cholesterol from eggs, as well as bone marrow and organ meats- so cholesterol is ‘native’ to the human diet. Saturated fat is far less so, being rather rare in nature; and the trans fat produced when oils are partially hydrogenated is truly alien, and thus a predictably bad actor.
There is one final addition to the defense of eggs. Foods we don’t eat have implications for foods we do. So banishing eggs begs the question: what do we typically eat instead?
To my knowledge, there has been no systematic study of this. But I have seen coronary care units that scrupulously avoid serving eggs to their patients provide them trays of pancakes, or waffles, or white toast. I certainly have patients who have avoided eggs, but not thought twice about eating donuts, Danish, bagels, or muffins.
What we don’t eat has implications for what we do, and I think it very likely that general advice to avoid eggs actually served to lower overall diet quality — by increasing intake of refined starches and added sugars. We have a study protocol currently under review that will examine the question: do you wind up with better overall diet quality and health with advice to exclude, or include, eggs? You know which way I’m betting.
I hasten to add that a diet can certainly be optimal without including eggs. (If people swapped out egg breakfasts for mixed berries, walnuts, and oatmeal — I would have no objection; but I have not seen much of that!) A balanced vegan diet, for example, is a powerful force for good health. But well-informed and dedicated vegans are a vanishingly small part of the population.
Most Americans, and much of the world’s population, eat mixed diets in which eggs are not taboo. Eggs have been avoided by members of these groups not because of cultural prohibitions, but in an attempt to avoid a concentrated source of dietary cholesterol, and its potential harms.
We have long had cause to reconsider such harms; they are, at most, feeble and uncommon — and there is a good chance they are truly negligible, or simply don’t exist. We have also long known that eggs, other than their cholesterol content, are highly nutritious overall. As of last week, we also know they contain less cholesterol than we thought.
There, then, is the case for eggsoneration. The defense rests.
Dr. David L. Katz; www.davidkatzmd.com