Diet-related news tends to say something different every week, even though the fundamental truths of a health-promoting diet have been quite stable for decades, if not generations. This week, the news is saying: cheese.
That’s because of 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. Click-bait headlines are, predictably, 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.
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.
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 to data, 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?
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.
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. That said, 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. So say cheese occasionally at mealtime because you like it, not because of likely health benefit- but without much likelihood of harm, either.
-fin Dr. David L. Katz;www.davidkatzmd.com; founder, True Health Initiative