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New dietary guidelines ‘represent a nearly evidence-free zone,’ says a leading cardiologist

Jaryl Cabuco
Dr. Steven Nissen: “I recently observed a large bag of fat-free gummy bears sitting on a grocery store shelf with the unmistakable implication that ‘fat-free’ equates to heart-healthy.”

In a scathing commentary published Tuesday in the Annals of Internal Medicine, one of the country’s leading cardiologists — Dr. Steven Nissen of the Cleveland Clinic — rips apart the supposed scientific rationale for the latest installment of the Dietary Guidelines for Americans, which were released in their finalized form to the public earlier this month.

“A detailed review of the new guidelines confirms a disturbing reality: the nearly complete absence of high-quality randomized, controlled clinical trials (RCTs) studying meaningful clinical outcomes for dietary interventions,” he writes. “The report repeatedly makes recommendations based on observational studies and surrogate end points, failing to distinguish between recommendations based on expert consensus rather than high-quality RCTs.”

“Unfortunately,” he adds, “the current and past U.S. dietary guidelines represent a nearly evidence-free zone.”

It is long past time, Nissen says, for the nutrition establishment to transition from the evidence-free zone “to an era where dietary recommendations are based on the same quality evidence that we demand in other fields of medicine.”

If not, he adds, dietary advice will continue to be left “to cult-like advocates, often with opposite recommendations.”

The Minnesota ‘misadventure’

In the commentary, Nissen focuses his criticism primarily on the guidelines’ recommendation about dietary fat and cholesterol. That particular “decades-long misadventure,” he says, can be traced back to the famous Seven Counties Study led by University of Minnesota physiology professor and obesity researcher Ancel Keys.

Writes Nissen:

Begun in 1956 and funded by a grant from the U.S. Public Health Service, the study was first published in 1970 and linked intake of saturated fat and cholesterol to the risk for coronary disease. Before the study, Keys had already aggressively promoted the concept that dietary fat and cholesterol were closely related to the development of heart disease. He even appeared on the cover of Time magazine in 1961, advocating a low-fat diet as the solution to the coronary heart disease epidemic.

Critics have suggested that the Seven Countries Study was biased in favor of the hypothesis that dietary fat and cholesterol were critical factors in coronary disease. The study examined heart disease rates in Italy, Greece, Yugoslavia, Finland, the Netherlands, Japan, and the United States. Yet data were available for 22 countries. The researchers omitted countries, such France, where consumption of total and saturated fat are very high but the risk for heart disease remains low.

So convincing was Keys that even before his study was published, “the American Heart Association (AHA) took up the cause, recommending that Americans reduce dietary fat intake and substitute corn or soybean oil for butter,” Nissen adds. “Soon, margarine (with large amounts of trans fats) became the “heart-healthy” alternative to butter, eggs synonymous with unhealthy eating patterns, and low-fat diets the answer to the soaring rates of heart disease.”

Consequences and remedies

The promotion of low-fat, low-cholesterol diets has had serious consequences, according to Nissen.

“We reduced dietary fat but binged on carbohydrates and became increasingly obese,” he writes. “Type 2 diabetes grew into an epidemic that is now threatening to reverse decades of progress in reducing coronary heart disease incidence.”

“The obsession with low-fat diets has resulted in some extraordinary and bizarre food-marketing practices,” he adds. “I recently observed a large bag of fat-free gummy bears sitting on a grocery store shelf with the unmistakable implication that ‘fat-free’ equates to heart-healthy.”

In reality, says Nissen, we know very little about whether low-fat diets prevent heart disease. “The best available evidence,” he says, “does not clearly support the widely held belief that Americans should limit saturated fat and cholesterol in the diet.”

Nissen calls for federal agencies, such as the National Institutes of Health and the Centers for Disease Control and Prevention, to fund randomized, controlled clinical trials that test various dietary interventions.

“Properly performed studies may demonstrate that saturated fat and cholesterol are indeed nutrients of concern, but the opposite conclusion is also possible,” he says.

Until we have good, solid evidence, the American public is left, he adds, with “the current state of confusion.”

FMI: Unfortunately, the Annals of Internal Medicine has the full commentary behind a paywall, but you can read the first page on the journal’s website.

Comments (10)

  1. Submitted by Dennis Tester on 01/20/2016 - 09:13 am.

    My diet

    Eat what you want. Just not too much of it.

  2. Submitted by Ray Schoch on 01/20/2016 - 11:15 am.

    Once again

    …I’m on the same page as Mr. Tester. And so is food guru Michael Pollan, whose mantra is: “Eat food, not too much, mostly plants.” Dr. Nissen is on to something, and I hope the medical establishment (I won’t hold my breath waiting for the various diet and food industries to climb on board) will follow his suggestions. The public is not well-served by dietary suggestions, whether “official” or not, that whipsaw people back-and-forth regarding foods that are healthy one day, then deemed death-inducing the next.

  3. Submitted by Ann Spencer on 01/20/2016 - 12:25 pm.

    At last..

    Mr. Tester, I agree with you 100%. One thing is certain, these guidelines will be superseded by other guidelines, perhaps with diametrically opposed advice, within a few years. I’ve lived through several rounds of starch (carbs) bad, protein good, fat bad, carbs good, some fat good, other fat bad, some carbs good, other carbs bad…..and round and round we go.

  4. Submitted by Ron Gotzman on 01/20/2016 - 05:11 pm.

    Please forward to M. Obama

    But M. Obama said her dietary regulations for our children are based on settled science?

  5. Submitted by Susan Lesch on 01/20/2016 - 06:04 pm.

    Hold on please

    Hold on a minute please. I’m sorry I can’t read his article, but as it is presented here, Dr. Nissen doesn’t add any new information. I guess he’s jumping on a “critique the Dietary Guidelines” bandwagon.

    Today Dr. Dariush Mozaffarian’s study of 186 countries seems to say that polyunsaturated fats are good for people. It also says reducing saturated fats will decrease heart disease.

    • Submitted by Rick Prescott on 01/21/2016 - 12:23 am.

      Um, not quite…

      Susan, the article you’ve linked does not in any way say that “polyunsaturated fats are good for people.” Well, the article hints at that conclusion, but the study it is reporting on most definitely does not.

      In fact, this study is just one notch above junk science. The article admits openly that the study was not designed to find a causal link. More to the point, however, is that not a word is written about how they measured people’s fat intake. That suggests that it was probably self-reporting, a notoriously unreliable source of information.

      In other words, that study, while a little bit interesting, doesn’t really add much to our knowledge either. The conclusions hinted at by the article and the talking heads it quotes could be true, or they might not. There’s just no real science behind any of it.

      And that is exactly Dr. Nissen’s point about the new dietary guidelines. Until someone actually does the real science, we’re left to twist in the wind. (And it would help if we all were able to recognize the difference between “truly useful” and “just kind of interesting” studies — the difference between real and pseudo science.)

      • Submitted by Susan Lesch on 01/21/2016 - 10:06 am.

        Denial gets you nowhere

        Nossir. From the introduction, “In particular, higher intakes of trans fat (TFA) and of saturated fat (SFA) replacing ω‐6 (n‐6) polyunsaturated fat (PUFA) are associated with increased CHD, whereas higher intake of PUFA replacing either SFA or carbohydrate is associated with lower risk.” You can read Dr. Mozaffarian’s study and the work on which it depends until the cows come home (all free full texts).

  6. Submitted by Rick Prescott on 01/21/2016 - 05:38 pm.

    You Misread It

    The phrase you are misreading is “associated with.” This phrase does not, in any way, imply that one is caused by the other. It means, quite literally, that they are observed to happen together at the specified frequency (which is, in this case, not even specified).

    As such, the information is marginally interesting, but not very useful.

    This is a very common error, and a very important principle which is very commonly misunderstood.

  7. Submitted by Susan Lesch on 01/21/2016 - 10:39 pm.

    Re: You Misread It

    That’s right. As Ms. Perry is so very good about reminding us. And so, by the way, was Ancel Keys. I’ve never liked epidemiology, but today I see Wikipedia calls it “the cornerstone of public health.” Thank you for the discussion.

  8. Submitted by Susan Lesch on 01/22/2016 - 11:41 am.

    P.S. Back to original comment

    What was Dr. Nissen’s contribution to this discussion?

    Mr. Prescott, I would caution against saying the work done telling people to be careful of saturated fat is “one notch above junk science”. But my oldest textbook does indeed say that “much nutritional evidence derives from epidemiologic associations….” (Nestle, Marion. 1985. Nutrition in Clinical Practice. p. 2.) Nestle says diet is so complex and people’s needs vary so much that controlled trials are “difficult to design, to conduct, and to interpret.” I also seem to remember my first instructor, T. Colin Campbell, bemoaning nutrition’s lack of controlled trials; he wound up writing the Grand Prix of Epidemiology.

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