The focus on nutrition in our popular culture is, alas, incredibly simple-minded. For decades, we have listed as a culture from adding oat bran to cutting fat, renouncing carbs to relying on superfoods, blaming everything on sugar, or some particular variety of sugar or gluten. When nutrition experts are asked to comment on any given nutrition topic for popular consumption, editors and producers push on us to take a stand: is dairy good or bad? Is the ONE thing wrong with our diets saturated fat, or sugar? Are all the products of genetic modification our salvation, or demise?
Maybe the origins of this stark duality, and either/or, good/evil way of thinking reside in religion, but that can be a topic for another day. Maybe it is simply the best way to have us tune in every morning for the latest diet advice, and buy yet another magazine next month to see how the celebrities are eating this week. If ever we actually understood, it would be hard to sell us the next batch of overcooked nonsense.
Summary judgment about most topics in nutrition in the form “pick good, or bad” is both silly and wrong for any number of reasons. Effects vary among us, by context and circumstance. There are trade-offs, pros and cons, subtleties and nuance. And there is, even, uncertainty- which is not a reason for shame. Bertrand Russell was entirely right to contend that only fools and fanatics are ever absolutely certain. Room for uncertainty and doubt only ever means room for thought, rather than the closed confines of folly, fanaticism, and predatory profiteering where foregone conclusions are the walls of a tiny mind.
There are, to be sure, fundamental truths of eating well- and they even constitute the vast bulk of all that matters. But there are innumerable uncertainties, provisos, and qualifications, as I know full well across the expanse of nutrition matters, having just turned in the draft of my next book on the topic.
Across that full expanse, perhaps no subject is a source of more concentrated ambiguity than alcohol consumption and health. Consider the irony and intrinsic contradictions of the widespread practice, across many cultures and languages, and, candidly, my own family table- of toasting to one another’s health with a product that the American Society of Clinical Oncology (ASCO) just told us constitutes a significant cancer risk.
The position statement just released, rightly receiving high-profile media attention, does not represent new research. Rather, the Cancer Prevention Committee of ASCO apparently judged that the aggregated evidence available was sufficient to make a statement, and that a reality check on the topic was timely.
Their basic conclusion, leaving aside the diverse and unambiguous harms of alcohol excess, is that even moderate and light alcohol intake contribute meaningfully to cancer risk. Moderate alcohol intake is defined as up to one drink (1.5oz of distilled spirits; 5oz of wine; or 12oz of beer) daily for women, up to two for men. The difference is based in science, not sexism, of course; even when body size is comparable, men have higher levels of the key, metabolizing enzyme, alcohol dehydrogenase, than women. Less than that threshold is light drinking; more is heavy. Achieving that “average” by having 6 or 7 drinks on both Friday and Saturday night is binge drinking.
The ASCO report tells us that roughly 3.5% of all cancer deaths in the United States are attributable to drinking alcohol. Moderate alcohol consumption roughly doubles the risks of oral and esophageal cancer, and contributes meaningfully but less to the risk of colorectal and laryngeal cancer. Light to moderate alcohol intake increases the risk of breast cancer in women between about 5% and 20%.
The immediate temptation is to call these “sobering” statistics, and allow that characterization to have two meanings. But these risks, while real and worthy of attention, require context. The lifetime risk of esophageal cancer in the U.S., for instance, is less than 1% in men, and less than 0.25% in women. A doubling of such risk is certainly not trivial, but the product is still a small number.
Another important consideration is the lifestyle pattern in which alcohol intake figures. Drinking might be accompanied by smoking, or even just routine exposure to second-hand tobacco smoke. That smoke is the far more carcinogenic of the two exposures, and the harms of alcohol are much compounded by the pairing. Drinking might accompany a poor diet, lack of exercise, or obesity- each of which contributes to cancer risk. Obesity on its own has been associated with increased risk for almost every cancer, and is thought to account for some 14% of cancer deaths in men, 20% of those in women in the U.S.
Or, to the contrary, moderate alcohol intake might take place in the context of a generally healthful lifestyle and healthy weight. This, apparently, is the pattern in the Blue Zone populations where wine intake is customary, notably Ikaria, Greece. The Ikarians have low rates of all chronic disease, cancer included, and like all Blue Zone populations, live to 100 and die peacefully in their sleep far more often than the rest of us.
Does this mean that Ikarians are somehow selectively immune to any harmful effects of alcohol? Certainly not. Rather, it means that, within reason, the overall impact of lifestyle is greater than a component in isolation. Cancer risk is reduced if obesity is rare, if smoking is rare, if other chronic disease is rare, and perhaps even if stress is at low levels. If alcohol increases cancer risk from its baseline, a lower baseline means lower absolute risk with drinking. Perhaps the Ikarians would have even less cancer if they gave up that wine.
But would they have better overall health? That remains the most contentious point of debate, and the most challenging matter of data. Light to moderate drinking is associated with reduced heart disease and overall mortality compared to no drinking at all. This might be because alcohol actually confers health benefit as well as harm, and when the dose is right, reduces heart disease risk by more than it increases cancer risk. There are established mechanisms for this, from elevations of HDL, to elevations of a clot-dissolving substance called endogenous TPA, to the concentrated antioxidants like resveratrol in red wine. Light to moderate alcohol intake may confer net benefit, along with harm.
There are potential social mechanisms as well. The psychological effects of positive human interaction and mood reverberate importantly through our immune system. Perhaps alcohol, acting as a social lubricant in the context of family and community routines, fosters health by means of conviviality or relaxation.
But there is an alternative view of the same epidemiology. Perhaps the message that alcohol intake can be health promoting is as wrong as it is popular. The result is that health-conscious people might be inclined to drink moderately- and thus bring their natively low risk for cancer and heart disease into the epidemiologic mix with alcohol. Low disease risk in this scenario is despite the effects of alcohol, not because of it. A further complication is that people with established health concerns may give up drinking, making it appear that abstinence contributes to disease risk, when in fact causality runs the other way.
Studies to sort out these subtleties range from challenging to impossible. The timeline for chronic disease development is long. Long-term randomized trials of routine alcohol intake versus abstinence, all other practices matched, are not easily conducted.
Which brings us back to where we started: uncertainty. Moderate alcohol intake may confer health benefit, whether by means of mood, metabolism, or the balm of communion; or good health may occur despite rather than partly due to the influence of alcohol. Even moderate alcohol convincingly confers harm, too, the ASCO message, and one to which we should attend. Net effects on individual health will doubtless vary in many subtle ways with all the variations in baseline health and native vulnerabilities.
Drinking alcohol for the sake of health, per se, seems misguided to me; there are far more reliable ways to get there from here. But I confess I consider a fine Bordeaux with a great meal one of life’s signature pleasures, and pleasure is good for health. Perhaps more importantly, pleasure and overall quality of life is why health matters in the first place. Other things being equal, healthy people have more fun- or health would be less important than it is.
Dose matters. Tradeoffs are likely. Uncertainty is inescapable. Pleasure and health both matter, and interact. To that constellation, I raise a toast.
Director, Yale University Prevention Research Center; Griffin Hospital
Immediate Past-President, American College of Lifestyle Medicine
Senior Medical Advisor, Verywell.com
Founder, The True Health Initiative