Sugar, Saturated Fat, and Science

Today's Health Meets Yesterday's News

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I am writing today to warn you about, and ideally, help protect you from, three extremely common and quite grave mistakes about diet and health. The first is to fixate on some particular nutrient or ingredient. The second is to believe it when someone suggests that everything we thought we knew until yesterday was wrong. The third is to be distracted from health by talk of a disease.

I’ll break that all down for you momentarily, but first, here’s the bottom line, for those rushing off to other errands before making it to the actual bottom: eat wholesome foods in sensible combinations and the rest will take care of itself.

Eat a diet made up mostly of minimally processed vegetables, fruits, whole grains, nuts, seeds, beans, and lentils- and all nutrients, not just the one that is currently fashionable, will sort themselves out. An optimal diet, which means any reasonable variant on the well-established theme of optimal eating, will reliably promote health, and that means defending you against all chronic diseases, not just one. The prize is not avoiding one disease to get another, but being healthy and vital. That’s the prize because healthy people have more fun.

Now, back to the peril of those three common errors, and both how and why to navigate around them.

Fixating on One Thing

Regarding the first, I am not sure how, or why, opinions about diet became encumbered with religious-like zeal, but they have. The result is exceedingly intense, mutually exclusive passions about some particular aspect of nutrition.

I have impassioned correspondents who send me reams of material to confirm that sugar truly is the principal cause of our dietary ills. I have other, equally passionate pen pals who bombard me with information about the adverse effects of saturated fats, and the strong association between elevated LDL cholesterol and heart disease.

There are other fixations, too, such as omega-6 fats; but we can limit ourselves here to sugar and saturated fat.

Believing that Everything You Used to Think is Wrong

If either contention is right- one of these nutrients is the source of all our ills- then the other is wrong. But the only reason to think we have to make any such choice in the first place is the second peril: the idea that to know something today, we have to renounce everything we knew up until yesterday. This is, in a word, nonsense. In several words, it is anathema to the very process of science that brings us our knowledge in the first place.

Science does not proceed from one, complete understanding to another, jumping over voids of ignorance in between. Rather, it proceeds incrementally. A single study almost never completely alters our understanding, but every good study contributes to it. For that contribution to be processed meaningfully, it must be processed in the context of what we knew before- not in the absence of it.

These days, many prominent experts in cardiology are striving to remind the public that LDL cholesterol remains a clear, strong predictor of heart disease risk and that high intake of saturated fat in the diet is associated with elevated LDL and heart disease. They are struggling to be heard over the now popular, noisy meme that saturated fat and LDL are yesterday’s news.

They are, indeed, yesterday’s news, now that attention has turned to sugar. But that’s my very point about science: yesterday’s news is still relevant today! We need to add today’s news to yesterday’s, not replace the one with the other. We have been making that mistake for decades and the result is, bluntly, just this: we keep inventing new ways to eat badly, and keep getting fatter and sicker while Big Food laughs about our gullibility all the way to the bank!

In general, a high intake of saturated fat is ill-advised for many reasons. First, if you eat wholesome foods in sensible combinations, you simply don’t wind up with a high intake of saturated fat per se. So, if you do wind up with a high intake of saturated fat, it is likely your diet has wandered off the theme of optimal eating. That is really what matters. Second, saturated fat has never been shown to promote health. At best, there is evidence that an excess of saturated fat may not be any worse than an excess of refined starch and added sugar; along with evidence that some saturated fatty acids are likely harmless. But compare this to the evidence we have about the health-promotion associated with other foods and other fats, and one is really left to ask: so what? When did “not necessarily worse” get translated into: “eat up!” I never got that memo, and if you did, shred it.

Fixating on One Disease Instead of Overall Health

Finally, the goal of eating well is to be well, feel well, and live well. The goal is more years in life, more life in years. The goal is certainly not about avoiding one disease just to get another. That’s the third prevailing mistake, the notion that fixating on any one disease can stand in for attending to overall health.

When the arguments about saturated fat and LDL get most passionate, for instance, they tend to suggest that not only was it wrong to abandon our concerns about them, but they are really all that matters. I hear arguments, for instance, that high saturated fat diets propagate the growth of plaque in coronary arteries, whereas low-fat diets, even if high in sugar, have no such effect. At one extreme, then, is the idea that any starch and even sugar are fine because they don’t raise LDL or directly grow atherosclerotic plaque.

This, too, is nonsense. The evidence is very clear that there are harms of excess sugar intake, perhaps varying with the kind of sugar. If nothing else, the food industry uses sugar and sweeteners to increase palatability and increase how much we eat. In a world of epidemic obesity, where excess body fat is on the causal pathway to every major chronic disease, sugar could be indicted if only as a source of excess calories. But there is more. Excess sugar intake is associated with insulin resistance and diabetes, even in the absence of obesity.

So, should we choose between heart disease risk and diabetes risk? That would be a dubious proposition if it were even possible, but it is not. Diabetes itself is one of the strongest risk factors of all for heart disease. So let’s do the simple math.

If you ignore the evidence we have long had about saturated fat and LDL, your diet is apt to contribute directly to heart disease risk. If, instead, you ignore the widespread concerns about sugar and refined starch, you may get diabetes instead of heart disease, and then get heart disease because of the diabetes. Confetti, anyone?

Closing Thoughts

We can do much better than choosing which serious, chronic disease to get, by avoiding the three prevailing mistakes about nutrition. In science, yesterday’s news is part of today’s news. Today’s news only makes sense in context. Science advances incrementally, even as competing, hyperbolic headlines suggest it is a game of Ping Pong. Don’t play- you’ll lose.

Eat wholesome foods in sensible combinations. There will surely be some saturated fat in the mix, and that’s fine; it won’t be too much if your overall dietary pattern is sound. There will surely be some sugar in the mix, and ditto. Focus on the big picture, and stick with the fundamentals that are a product of the weight of evidence, widespread expert consensus, and that have stood the test of time.

The alternative is to get caught up in fads, fashions, and today’s competing sound bites. The only likely result of that is that your health, like that of so many others in our culture, will be yesterday’s news.

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