A commentary in the current issue of the British Medical Journal (BMJ) suggests that saturated fat is not really so bad after all. The article has the media buzzing, with headlines exonerating saturated fat sprouting like mushrooms throughout cyberspace and print media alike. My most recent Google search of “saturated fat” limited to news retrieved 20,000 sites.
Since the new paper is just a commentary- one doc’s opinion- and not a new study, and since this opinion has been asserted many times already, I’m not sure I really get the reaction- but hey, I just work here. Let’s deal with it.
Is it, in fact, time to absolve saturated fat? No, it’s not. But then again, it was never time to demonize it in the first place. I will lay out my case that we are ill-served to think of saturated fat as either scapegoat, or martyred saint.
1) Ancel Keys was never really wrong.
The case against saturated fat, its implication in the development of atherosclerosis, inflammation, and chronic diseases, notably heart disease, involves a vast expanse of research over many years by thousands of researchers around the world. But dealing with all of that in this column would be a terrible bother, so let’s just blame it all on Ancel Keys. Keys was certainly among the first to emphasize the association between saturated fat intake and heart disease.
The temptation to absolve saturated fat comes along with a temptation to indict Dr. Keys of crimes against dinner. But, Ancel Keys, while perhaps not quite right, was never really wrong.
Keys looked at rates of disease around the world and correctly noted that heart disease was more common in societies that ate more meat and dairy. His mistake may have been to look past that dietary pattern for the “active ingredient” in it, which led to the convictions of dietary cholesterol, saturated fat, and to a lesser extent overall dietary fat.
There’s much that could be said about this. Whole columns could be written about dietary cholesterol, dietary fat, and saturated fat and ways we went wrong. In fact, I- along with innumerable others- have written just such columns. Simply click the inserted links.
But for now, here’s the key point about Keys: I bet he never imagined Snackwell cookies! Keys was comparing the health of people eating meat and cheese and ice cream, to the health of people eating mostly plants, and to other people eating lots of plants along with nuts, and seeds, and fish. Nobody was eating low-fat junk food, because it hadn’t been invented yet.
When it was invented, to exploit the interest in limiting fat intake in general, and saturated fat intake specifically, it created a whole new way of eating badly. Yes, we can reduce our intake of saturated fat and replace it with sugar and starch and glow-in-the-dark food chemicals, and not wind up healthier. Is anyone really shocked about this? My kingdom to anyone who can find and verify the recommendation, attributed to Dr. Keys: “eat Snackwell cookies!”
2) Ancel Keys wasn’t entirely right.
Saturated fat is not one food component; it’s a category. Just as polyunsaturated fats include the anti-inflammatory omega-3s, and the pro-inflammatory omega-6s (and even that is over simplified), so does the saturated fat class contain a diversity of members. One of them, stearic acid, found in dark chocolate among other places, is now clearly established to be innocuous. Another, lauric acid, predominant in coconut oil among other places, may prove to be as well. But still others, such as palmitic acid and myristic acid, appear to be substantially guilty as charged, contributing to inflammation and atherosclerosis. The body of relevant evidence is expansive.
What this means is that even if there are harms attached to some saturated fats, summary judgment against the whole clan was never valid. The combination of parsing and over-simplification invites the devils in the details to run amok. That clearly happened here.
Some saturated fat simply isn’t harmful. Some is.
3) Saturated fat and ALL dietary fat should never have been conflated.
Our penchant for summary judgments took us further into the realm of folly. Whatever the legitimacy of efforts to cut saturated fat, there was never any in extending this thinking to all fat, and that too, happened. Even Keys could have noted that some of the healthiest populations in his studies were eating a liberal amount of total fat from nuts, seeds, olives, avocadoes, fish, and seafood. We do note that now, and call this the Mediterranean diet, and have situated it conclusively on the short list of contenders for “best diet” laurels.
Our errant actions with regard to dietary fats now invite, in predictable Newtonian fashion, a commensurate and opposite reaction. That doesn’t make it right.
4) You don’t rise from lateral moves.
If you interpret advice to stop playing with fire as a license to start playing with sulfuric acid, you may not improve your risks of getting burned. But that would hardly be a basis to conclude that fire is harmless. This, in essence, is what we are at risk of doing with saturated fat. We could have cut it by improving our diets. But we didn’t; we did, in fact, start eating Snackwell cookies and the like. All this means is that there is more than one way to eat badly. Again, anyone inclined to shock at that revelation?
5) You can’t assert that X doesn’t lead to Y if X never happened in the first place.
Consider this line, taken ver batim from the new BMJ commentary:
"In the past 30 years in the U.S. the proportion of energy from consumed fat has fallen from 40% to 30% (although absolute fat consumption has remained the same), yet obesity has rocketed."
The author of the commentary, Dr. Malhotra, adds the “yet” at the end of this line as if to indicate this is a surprise outcome. We cut dietary fat, but got fatter! But in implying this, he also seems to be implying that he failed to read what he just wrote. Re-read his line.
If the percent of calories from fat went down, but total fat intake did not (this is exactly what he is saying, and yes, it is true)- it leads inexorably to only one conclusion: total calorie intake went up, diluting down the percent of calories coming from fat. Can you imagine not rolling your eyes at a statement, pretending to be provocative, that read: “our calorie intake went up and yet we got fatter!” The only reasonable reaction to that assertion is: duh!
It seems pretty clear that most journalists covering this story ignored the implications of this line. But more surprisingly, the author himself ignored the implications of what he wrote. We never really cut our fat intake-we simply diluted it as a percent of total calories by eating more sugar and starch. So we kept the saturated fat, replaced some of it in time with trans fat, and applied a generous icing of starch and high-fructose corn syrup. And yet, amazingly, we didn’t wind up healthier. Well then, yes, clearly saturated fat must be good for us! Or not.
6) Sat fat can’t sing the blues.
I trust you’ve heard of the Blue Zones, and the diets found there. These are the dietary patterns consumed by the population groups around the world that experience the longest lives and the most vitality. There are no high sat-fat diets in the Blue Zones. Period.
There are low-fat, plant-based diets. And there are higher-fat, Mediterranean diets- but these are diets rich in monounsaturated fat, and a mix of polyunsaturated fats including a generous dose of omega-3s. Saturated fat is at rather low levels.
So, the idea that you should liberalize your intake of saturated fat is more conjectural and less based in epidemiology than the argument to cut it ever was. Perhaps we can eat a lot of saturated fat and live a long, healthy life, but there is no real-world experience to validate the claim; it’s just a hypothesis. If you choose to test it, you are casting yourself as guinea pig in your own research. If you’re still here and I’ve checked out, I guess you get the last laugh- but I won’t be around to hear you chuckle. On the other hand, if you check out and I keep going, I guess I get to say I told you so. But you won’t be around to hear me pontificate.
I suppose, for the sake of word count if nothing else, that will do. So where does it leave us?
We vilified saturated fat, and were almost certainly silly to do so. Now, some seem on a mission to canonize it- and that is at least as silly. Diets can be lower, or higher, in saturated fat content and be crummy either way. There is no evidence of long-term health benefit from the willful addition to the diet of saturated fat.
We must recall that all dietary fat is not created equal, and all saturated fat is not created equal either. A lot of opportunity for better health is let down the drain when we fail to distinguish baby from bathwater.
The world’s best diets, associated with the world’s best health outcomes, encompass both higher and lower levels of total dietary fat. But all such diets are relatively low in saturated fat, as our native Stone Age diet was thought to be. And in case you are wondering about the basis for my assertions here, I can provide these: (1) I am currently completing work on the 3 edition of my nutrition textbook for health care professionals, which encompasses well over 5,000 citations. I have been obligated, and privileged, to view the scientific literature on diet and health from altitude as few others have. And, (2) I have recently completed an invited paper, now in press at the journal Annual Review in Public Health, entitled “Can We Say What Diet is Best for Health?” That was a lesser effort than the book, but with similar obligations. And finally, I have no dog in the fight. I don’t care what diet is best- I just care that we all have access to the best information about diet and health.
If we focus only on cutting saturated fat, we can find new ways to eat badly. We have, over the years, done exactly that. Of note, we can do the same when cutting carbs, or gluten, or fructose, or sugar, or meat, or grains, or salt, or wheat, too. Diet never was, and never will be, a single ingredient enterprise. The whole recipe matters.
There is no need to obsess about cutting saturated fat. But I advise against any particular effort to add saturated fat to your diet. In fact, don’t waste much time focusing on saturated fat per se. Rather, focus on eating well, as the Okinawans have long done with a very low-fat plant-based diet, or as the Mediterraneans have long done with a much higher-fat, but still mostly plant-based diet. If we choose wholesome foods, we will wind up with better diets and better health. Incidentally, our saturated fat intake will not be more than moderate.
Demonizing saturated fat never helped us much. Canonizing it now won’t help us any either. All who share a concern for eating well and the health advances that can come from it must band together to renounce the perennial branding of this, that, or the other food component as scapegoat, or saint.
It is, and always was, the big picture- the overall dietary pattern, and for that matter lifestyle pattern- that matters. We could cut saturated fat and eat better, or worse, depending on what we eat instead. A bounty of science along with an application of sense points very reliably to variations on the theme of optimal eating for Homo sapiens. We could all get there from here, and by so doing, add years to life, add life to years, and love food that loves us back. None of this will happen though if we replace the follies of history with old mistakes in new directions.
CULLED
No comments:
Post a Comment