Nonprofit, nonpartisan journalism. Supported by readers.

UCare generously supports MinnPost’s Second Opinion coverage; learn why.

Historic guidelines about dietary fat and heart disease ‘should not have been introduced’

steak and fries

Researchers: “Two recent publications have questioned the alleged relationship between saturated fat and [coronary heart disease] and called for dietary guidelines to be reconsidered.”

When American and British health officials issued dietary fat guidelines back in the late 1970s and early 1980s, they did so without any good scientific evidence, according to new research published Monday in the online journal Open Heart.

The guidelines recommended that individuals limit their consumption of dietary fat to 30 percent of their total daily calories to lower their risk of heart disease. They also urged people to cut back their saturated fat intake to no more than 10 percent of daily calories.

The main reason for this warning, the officials said at the time, was because eating fatty foods raised the risk of artery-clogging plaques of cholesterol forming in the bloodstream.

Dietary fat has been generally demonized and feared ever since. In the United States, the recommendations became codified into what is now called the “Dietary Guidelines for Americans.” Tens of millions of people took the message to heart (more than metaphorically) and altered their eating patterns, cutting back on butter, cheese and fatty meats — or eliminating those foods from their diet altogether. “Low-fat” became many people’s dietary religion, and the multibillion-dollar-a-year low-fat food industry quickly sprang up to support it.

Tracking down the evidence

Yet when the two committees made those recommendations over three decades ago, even they acknowledged that the scientific evidence on the topic was inconclusive.

The committees didn’t actually cite any clinical trials when they issued their advice. The U.K. guidelines, did, however, refer to a large population study, called the Seven Countries Study, whose key author was University of Minnesota epidemiologist Ancel Keys. That study (controversial at the time and even more so now) had suggested — to much media fanfare — that heart disease “tended to be related” to cholesterol levels and that those levels in turn “tended to be related” to the amount of saturated fat in the diet. But even Keys admitted that his study could show only a correlation, not causation.

So what exactly was the evidence that the U.S. and U.K. committees had available to them 30 years ago? And just how conclusive (or not) was it?

To figure that out, a team of American and British researchers embarked on a database search. They found six relevant clinical trials involving seven different dietary interventions that had been published before 1983. Each had investigated the relationship between dietary fat, blood cholesterol levels and the development of heart disease. The studies spanned five years and involved almost 2,500 men.

An analysis of those six studies revealed a startling finding — one that calls into serious question just why the public was ever instructed to lower the percentage of their dietary fat intake.

The analysis found no statistically significant difference in the death rate between those in the “treatment” (low-fat) groups and those in the control groups.

Reducing dietary fat did reduce cholesterol levels, but the reduction did not result in any significant differences in the death rates.

What this means, say the authors of the meta-analysis, is that the American and British dietary committees had best-practice evidence available to them at the time they made their recommendations — evidence that “was not considered and should have been.”

Introduction of advice ‘seems incomprehensible’

In their conclusion, the researchers do not mince words:

From the literature available, it is clear that at the time dietary advice was introduced, 2,467 men had been observed in RCTs [randomized control trials]. No women had been studied; no primary prevention study had been undertaken; no RCT had tested the dietary fat recommendations; no RCT concluded that dietary guidelines should be introduced. It seems incomprehensible that dietary advice was introduced for 220 million Americans and 56 million UK citizens, given the contrary results from a small number of unhealthy men.

“Two recent publications have questioned the alleged relationship between saturated fat and [coronary heart disease] and called for dietary guidelines to be reconsidered,” the researchers add. “The present review concludes that dietary advice not merely needs review; it should have not been introduced.”

And as for why the guidelines were issued without any strong supportive evidence, the researchers place at least some of the blame on meddling politicians:

An exchange between Dr. Robert Olson of St. Louis University [a member of the U.S. committee that would eventually issue the new low-fat recommendations] and Senator George McGovern, chair of the Dietary Committee, was recorded in July 1977. Olson said, “I pleaded in my report and will plead again orally here for more research on the problem before we make announcements to the American public.” McGovern replied, “Senators don’t have the luxury that the research scientist does of waiting until every last shred of evidence is in.”

You can read the study in full on the Open Heart website.

Comments (6)

  1. Submitted by Steve Titterud on 02/10/2015 - 10:46 am.

    “dietary religion”

    Science and medicine have always pitched a good deal of religion, obeyed a political whitewash. They’ve just never admitted it, and probably never will.

    To evaluate the work of the entire industry in this matter – NOT just Sen. McGovern – we might use a very down-to-earth scoring system a college professor of mine from days of yore would apply against each essay-style answer in a test:

    3 – demonstrated competence
    2 – suggested competence
    1 – suggested incompetence
    0 – demonstrated incompetence

    Wouldn’t you say they had EARNED a zero, or at the very best, a 1 on this scale ?? And that’s a score for the whole industry and its allies, not just a few researchers. If there were a true groundswell and uprising of opposition within the related professions, these guidelines couldn’t have stood all this time.

  2. Submitted by Susan Lesch on 02/10/2015 - 12:44 pm.

    2015 US Dietary Guidelines Advisory Committee

    Kindly review the work of the 2015 Dietary Guidelines Advisory Committee
    specifically listen to segment containing the Subcommittee 2 report by Frank Hu, starting at 0:36:19.

    At 1:05:50 Mary Story asks about recent media reports that we can eat as much butter as we want. Frank Hu replies that today we have hundreds of studies supporting low saturated fat (and that we have more evidence now than we had for the 2010 guidelines). At 1:08:54 Alice Lichtenstein adds that saturated fat meta-analysis didn’t distinguish between diets with replaced fat–for example, replacement with polyunsaturated fats would be an improvement. As far as I can see, that was the group’s only discussion of saturated fat.

    Yesterday’s Open Heart review says on page 6 that the amounts of “saturated, monounsaturated
    and polyunsaturated content of the control and intervention diets” were unknown except in the Woodhill study and the Leren study (intervention only). If the saturated fat theory is really wrong, then why didn’t someone stop this committee?

    • Submitted by Susan Lesch on 03/12/2015 - 07:13 pm.

      DCAG in September

      Sorry it took a month to follow up and answer my own question. The DCAG stopped itself.

      In September a subgroup on saturated fat and cardiovascular disease report was discussed. At 4:14 Frank Hu presents a literature search by the new subgroup.

      At 4:35 to 4:36 Alice Lichtenstein says the Dietary Guidelines changed in 2000 (from recommending low to recommending moderate fat). AHA changed in 2000 and NHLBI changed in 2000. She says it is this group’s consensus that low fat diets are “probably not a good idea” and says that we should be careful about perpetuating old wives tales in the field of nutrition.

      I’m not sure that the final guidelines stressed this discussion but maybe they did.

  3. Submitted by Malcolm Parker on 02/10/2015 - 02:44 pm.

    Dietary fat

    Well written, and on point. I have been arguing since 1980 that we do not know what we are doing with this unproven gospel. This argument has not gained currency until recent years. A study of change in medical consensus suggests that change requires 17 years. If your first column was 2 years ago, have we hope for 2030? M Bruce Parker MD FACEP

  4. Submitted by Ron Gotzman on 02/10/2015 - 03:45 pm.

    What was the motivation for these reports?

    Every time I hear the phrase “the science is settled” it causes me to doubt and question the motivation behind such claims.

    This is true when it concerns “health issues” as well as “global warming” issues. Especially when a politician – or a scientist who is funded by the Government, makes such claims.

  5. Submitted by Greg Kapphahn on 02/10/2015 - 05:08 pm.

    The Problem is NOT “Politicians funded by the government”

    It is politicians influenced and lobbied by industries that make massive profits or stand to make massive profits based on government recommendations and government policy.

    (Defense contracting has the same problem.)

    The largest opposition to casting aside the “low fat” gospel,…

    a gospel which, more and more is being held responsible for the obesity epidemic in the Western World (which has resulted from less satisfying highly-refined carbohydrates being substituted in countless foods for far MORE satisfying fats),…

    comes from the processed food industry which has made huge profits producing and marketing “low fat” foods (at a price premium of course),…

    and would bear substantial cost if the public turned away from such foods.

    It is the processed food industry which will lobby the politicians who will pressure government agencies NEVER to turn aside from the “low fat gospel.”

    Meanwhile those who love animals more than people will continue to come up with reasons why there is not a single type of meat or fish available that is safe to eat,…

    or which does not result from widespread and horrendous abuse of the animals slaughtered to provide it for us.

    Perhaps we can switch to “soylent green?”

Leave a Reply