08/14/2014 05:19 pm ET | Updated Oct 14, 2014

The Keys to Good Health

Gentl and Hyers via Getty Images

First, the good news. As a board-certified physician in preventive medicine/public health, president of the American College of Lifestyle Medicine, and someone who has practiced what he preaches for a lifetime and been the beneficiary of it: yes, I think we know just what the keys to good health are. And better still, I think you can get your hands on them, and unlock the doors that lead to vitality, more years of life, and more life in years. You can take those you love with you.

We'll get back to all that, but first we need to talk about other keys; namely, Ancel Keys, a leading 20th-century epidemiologist once credited, and these days more often discredited, for noting the association between a high-fat diet and heart disease. There is a booming cottage industry in the indictment of Keys for crimes against the food supply, and in my view -- that is among the obstacles between you and those keys to good health.

No, I'm not here to defend Dr. Keys, per se. Others have done that, quite robustly. I am not here to bury Dr. Keys either, as that is long done -- he died nearly 10 years ago. I have come neither to praise, nor bury this particular Caesar.

Rather, leaving aside the swirl of aspersions that likely has Dr. Keys turning in his grave if such things are possible, I simply want to note that his work is... moot. It doesn't matter whether Keys was all right, all wrong, or inevitably -- somewhere in between.

Why? Because we have more decisive nutrition and epidemiologic research since Keys presented his provocative findings roughly 70 years ago (yes; that's 70 years ago...) than we had accumulated in all the time up to Keys.

Since the parsing of Keys' decades-old data, and the ulterior motives behind it, are the very things to which I am objecting, I won't belabor the particulars here. But for those unfamiliar with the story line, the gist is as follows. Keys noted that populations with high intake of animal foods (e.g., meat, butter, cheese; a dietary pattern abbreviated as "high fat") generally had high rates of heart disease; and those with, instead, preferential intake of plant foods (abbreviated "low fat") had low rates of heart disease. This led to the recommendation to eat less meat and more produce, which was translated into "cut intake of saturated fat."

Public awareness of the different kinds of fat was quite limited those decades ago, so that was further translated into "cut dietary fat." At that unfortunate level of generalization, the guidance was encumbered by the failure to distinguish baby from bathwater, and for some span of years, Americans were reluctant to eat even nuts and avocados, which are now among foods clearly established to be health-promoting and cardioprotective.

Avoiding highly nutritious foods rich in healthful fats was the lesser problem, albeit an important one in its own right. The greater was drinking the proverbial bathwater. When Keys and others advised low-fat eating, the only thing it could mean was more naturally low-fat, highly nutritious foods such as vegetables, fruits, whole grains, and lean meats -- because the entire category of low-fat junk food had not yet been invented. That category was invented to exploit the "cut fat" advice, and misdirected it entirely. We have been living, and dying, on a diet of unintended consequences ever since.

Without a doubt, what Keys got right, what Keys got wrong, and in particular how his sensible advice was twisted into nonsense by the forces of pop culture (Keys NEVER recommended eating Snackwell's cookies!), had an influence on behaviors and the food supply. But what it has no lingering influence on, and no power over, is the science of human nutrition. That science is far from perfect, of course; but we are equally far from clueless about the basic care and feeding of Homo sapiens. And what we now know, we would know just as well with or without the contributions of Keys.

In other words, the fussing about the work of Keys is an absurd, perilous distraction -- as if the progress of nutritional epidemiology had actually stopped 70 years ago. If it had, sorting out the work of Keys might be among the keys to eating well. But of course it did not. It says something about the desperate search for the next best-seller when disagreements about 70-year-old research are fabricated into a modern conspiracy theory.

The evidence has moved on since Keys, gathering into a vast, ever-evolving trove. No one person could hope to read it all. But those of us who presume to call ourselves "experts" are obligated to read enough of it to know which way the weight of evidence tips. We are obligated to keep up with the evidence as it incrementally advances, and contribute to it as best we can.

And the message there is perfectly clear. Based on everything from cell culture experiments to observational epidemiology, global ethnographic surveys to randomized controlled trials, mechanistic experiments and animal models to transcultural time trends, translational trials to meta-analyses -- we know the basic theme of healthful eating for human beings. There is ample room for variations on that theme, but no evidence of any kind supports a diet preferentially featuring 'meat, butter, and cheese' despite the currently rampant, giddy enthusiasm for that misguided notion.

The theme need not be low fat by any means, as some rather high-fat Mediterranean diets are clearly on it. But so, too, are the very low-fat diets Keys had in mind: rich in vegetables, fruits, beans, lentils, and whole grains. None of the diets on the theme is high in saturated fat, because various assemblies of wholesome foods, mostly plants, in sensible combinations tend not to be high in saturated fat.

As someone with routine recourse to the vast trove of modern nutrition research, I find the dredging of Keys' work about as constructive as resurrecting the archival VHS vs. Betamax debate. We are all watching BluRay now; what different does it make?

For whatever it is now worth, to my read, Keys' messages were mostly right, a bit wrong, and horribly vulnerable to the distortions of mercenary marketing and mass gullibility. What mote of science or modicum of sense ever supported the notion that Snackwell's cookies would make us healthy? None, whatsoever.

Most importantly, Keys' work is history, literally.

Or it would be, if we treated it as such. Ironically, one of the keys to good health is not bogging down in pointless parsing of Dr. Keys' important, but increasingly archaic legacy.

The other keys to good health -- being physically active, not smoking, sleeping enough, managing stress, and prioritizing love in our loves -- are a whole lot less controversial. Feeding ourselves well has been encumbered by both pseudo-controversy, and oddly misdirected religious zeal. Getting past these to the simple truths that tip with the weight of evidence -- wholesome foods in sensible combinations -- is among the keys to health. Canonizing Ancel Keys, or convicting him -- is not.

Such are the keys, and the doors await. Unlock the opportunity as the spirit moves you.


David L. Katz, MD, MPH, FACPM, FACP has authored roughly 200 scientific papers including a recently commissioned review of the literature to answer the question: can we say what diet is best for health? He has authored 15 books, including three editions of a nutrition textbook for health care professionals; the third edition of Nutrition in Clinical Practice, due out next month, includes nearly 10,000 citations to the peer-reviewed literature. He is also the author of 'Disease Proof,' which details the skill-power for healthy living, and eating, on which he has personally relied for decades. Snackwells are not on the menu.