Blessed, so Monty Python tells us, are the cheese makers. They go on to clarify that this particular Messianic assertion in the Life of Brian is allegorical, and actually connotes all participants in the manufacture of dairy products. I have colleagues who agree emphatically with that contention, others who just as emphatically denounce it. So it tends to go in all matters of religious fervor, diet salient among them these days.
The reactions from both camps to a new meta-analysis of observational studies of cheese intake suggesting a health benefit from “some” (stay tuned for more on that) cheese in the diet are entirely as one would expect. The perennial proponents of all things dairy are cheering, and evidently ignoring all of the concerns they raise routinely about both observational studies and meta-analyses of such studies, whenever they happen not to like the conclusion. The we-are-way-too-cheesey-as-is crowd has been quick to point out the flaws in observational epidemiology, and meta-analyses of such studies, which they are far more prone to overlook when they favor the conclusions.
And, of course, click-bait headlines are telling people just what they want to hear: eating cheese is good for you now! But is it, really?
That’s complicated- because diets are complicated, diet research is complicated, and cheese is complicated.
Let’s start with cheese. In general, cheese is a highly concentrated source of saturated fat, which despite the spate of pop culture nonsense over recent months, remains reliably implicated in crimes against coronary arteries. Cheese is also a concentrated source of animal protein, which some, notably T. Colin Campbell, contend is the actual health threat saturated fat appears to be. Since the two reside in foods together so routinely, it is challenging at best to disentangle their effects. Some large studies addressing that matter have found higher rates of premature death from all causes with increases in either saturated fat, or animal protein.
Then there’s the salt. Here, too, the truth is clear despite a lot of sound and fury: consumers of modern, highly processed diets consume way too much. A massive study examining all deaths in the United States in 2012 and dietary factors associated with them identified excess salt intake as the number one dietary peril. For reference, there is more than 300mg of sodium in less than one ounce of Feta cheese.
Finally, in the tally of negatives, cheese is a concentrated source of calories- which, of course, do count, and contribute to the ever-rising rates of obesity. Unlike plain nuts, where energy density has been shown to be offset by a high capacity to satiate, a compensatory satiety benefit to exonerate the calories of cheese is less evident.
But, cheese is a fermented product. That means there are active, fermenting cultures, as with yogurt, and that may change everything. Fermented and cultured products, from cheddar to kimchi, have potential effects on the microbiome. These effects can be beneficial, and when they are, may enhance the other beneficial effects of a food, or compensate partly or fully for harmful effects. The net effect of cheese ingestion on health is thus likely born in a mix of both adverse and favorable factors, and depends on what cheese displaces in the diet- and perhaps on the native state of your microbiome as well.
Moving on from dairy, then, to data, we have the complications of observational epidemiology and meta-analysis. Observational studies can reveal associations, but have important limitations with regard to establishing cause and effect. The particular studies included in this analysis made highly variable adjustments for dietary factors other than cheese. Some analyzed variation in just a few, select foods. Others analyzed variation in a wide array of foods. Still others made no allowance at all for dietary variance. That’s a serious limitation.
Did “cheese eaters,” and in particular dose-attentive cheese eaters (the apparent benefits of cheese in the new study, despite the wildly hyperbolic headlines, were both very modest, and capped at 40grams daily; above that, benefits disappeared and harms emerged. That 40gram dose is less than two slices of Swiss cheese) have better dietary patterns overall? Did they eat fewer chips, or Fries?
Observational epidemiology is always challenging, and never more so than when applied to diet. Among the routinely ignored but essential questions about any given food, ingredient, or nutrient, is: instead of what? In what overall context of diet and lifestyle?
Imagine a study about standing up a few times a day, concluding that doing so is good for our health. In fact, no need to imagine- we’ve seen just such studies. The obvious question they raise, though, is: good for us compared to what? In the case of a “stand up from time to time” study, that comparison is built in from the start: sitting all day long. Obviously, just standing up occasionally is NOT good for us compared to walking briskly, or hiking, or biking, or swimming. Standing up is relatively good for us compared to the prevailing, and quite awful alternative: spending unending daily hours on our backsides.
Just the same question should assert itself in a study of cheese, or any aspect of diet. Compared to what? While it may be tempting to think that eating cheese is an alternative to “not eating cheese,” that’s naïve- since everyone eats 100% of what they eat. If less of that total is cheese, then more of it is…something else. What something else? In modern diets like those of the U.S. the answer is unlikely to be lentils, kale, or raw walnuts. The answer is far more likely to be donuts, French fries, and Coke. Is a bit of cheese better in the place of any of those? Almost certainly.
Meta-analyses are complicated, too; and perhaps particularly meta-analyses of observational dietary studies, which must aggregate datasets as holey as Swiss cheese itself. This could be a lengthy topic, but let’s simply note that pooled data are never better than the data being pooled. Meta-analyses can be quite powerful, but also epitomize the perils of “garbage in, garbage out.”
This new meta-analysis does not and cannot tell us what foods cheese replaced. It does not and cannot tell us how variation in cheese intake correlated with overall diet quality. It cannot, because it is pooling data from prior studies, and those studies failed to answer these questions consistently, and in many cases, did not address them at all.
Real cheese (as opposed to cheese-like stuff) is pricey; maybe habitual cheese intake is a marker for the health benefits of affluence. Perhaps a small daily intake of cheese indicates an effort to adopt the famously healthful Mediterranean diet. If that were true (and we neither know that it is, nor that it isn’t)- then any apparent health benefits of modest cheese intake would actually indicate the health benefit of moving away from a typical American diet, and toward a Mediterranean diet.
I suppose I might typify that scenario personally. My wife is from southern France, and uses small amounts of cheese in some of her recipes. I would thus show up in the cheese data as a dose-attentive cheese eater. However, my diet is overwhelmingly made up of vegetables, fruits, whole grains, beans, legumes, nuts, and seeds. I drink plain water when I am thirsty. I consume very little dairy overall, some fish and seafood, poultry almost never, and mammals- not at all. I drink no soda, eat no fast food, and, by the way, exercise vigorously every day. I might show up in a data set suggesting health benefits of “a bit of cheese,” but that would seriously misrepresent what’s going on with my diet and lifestyle. Cheese makes a cameo appearance.
So, are the eaters of cheese blessed with less heart disease? Probably not because of cheese if so. Certainly, there are far better ways to reduce your risk of heart disease than by adding cheese to your diet. Ditch soda and drink water. Replace beef with beans. The list goes on.
But this study does suggest that the inclusion of a small amount of cheese in the diet is not necessarily harmful, and might confer modest, selective benefit. That makes sense, since a small amount of cheese turns up in some, but not all, of the diets associated with the famously enviable Blue Zone combination of longevity and vitality.
Leaving aside the environmental and ethical implications of dairy production, very important topics in their own right, my conclusion is that diets associated with optimal health outcomes can include or exclude cheese, but are never optimal because of cheese. Still, that means we have choices- and that, I suppose, is a blessing.
David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and current President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.