Dietary Guidelines

On March 12, 2012, for instance, there was a profusion of especially scary headlines, including one in the New York Times: “Risks: More Red Meat, More Mortality.” This story referred to a research finding that just three additional ounces of red meat a day were associated with a 12 percent greater risk of dying overall, including a 16 percent greater risk of cardiovascular death and a 10 percent greater risk of cancer death. The study’s announcement echoed around the world, with news reports in virtually every country.

The data for that report came from the so-called Nurses’ Health Study II, which has followed more than 116,000 nurses for more than twenty years and is among the longest and largest epidemiological studies ever undertaken. For the red meat analysis, researchers at the Harvard School of Public Health, which directs the study, combined the nurses’ data with a similar, smaller data set on male physicians from another epidemiological study they oversee. In the questionnaires answered by these doctors and nurses, the investigators discovered an association between eating red meat and reduced mortality. However, an association, as we know, can be merely coincidental—it does not demonstrate cause and effect, and this association, it turned out, was tiny.

The actual numbers underlying the 12 percent finding (percentages often look more dramatic when they are calculated from small numbers) show that the increase in the risk of dying was only one person per hundred over the twenty-one years of the study. Moreover, the risk did not rise in lockstep with meat eating (meaning that eating a certain amount more red meat didn’t translate smoothly to a certain amount of increased risk, which is that “dose-response” relationship that epidemiologists consider crucial for establishing the reliability of an association). Indeed, the risk associated with red meat eating in the Harvard study dropped steadily as meat consumption grew, and then only worsened in the group of biggest meat eaters—an odd finding that suggested there might be no real association after all.

But what about that group of biggest meat eaters? Could they not be seen as a cautionary tale? Many other observational studies have shown an association between eating a great deal of red meat and negative health outcomes. Possibly a high consumption of red meat triggers an effect only seen at a very high threshold? Or, more likely, maybe this effect is seen because people consuming a lot of red meat today are living less healthy lifestyles overall for reasons that have nothing to do with meat. In choosing to eat a lot of red meat, most of these people have consistently ignored the linchpin of dietary advice from doctors, nurses, and health officials for decades. It’s quite likely, therefore, that these people are failing to prioritize their health in other ways: they probably don’t visit their doctors regularly, don’t take medications, don’t exercise frequently, attend cultural events, or embed themselves in meaningful ways in their communities—all factors that have been shown to be associated with good health. It is therefore not surprising that in the Harvard study, the top meat eaters were also found to be less physically active, more obese, and more likely to smoke.

By the same token, it is also true that people eating a lot of fruits and vegetables over the past few decades are healthier in ways that have nothing to do with diet. People who make a conscientious effort to follow doctor’s orders, whether to take a pill or exercise more regularly, have long been found by researchers to be healthier than people who don’t. This effect, called the “compliance” or “adherer” effect, was discovered during the Coronary Drug Project in the 1970s, when researchers found that the men who took the intervention drug most faithfully cut their heart disease risk by half. But surprisingly, men taking the placebo most faithfully also cut their risk by half. The objective value of the intervention mattered less than the willingness to follow the doctor’s orders. It turns out that people who dutifully follow advice are somehow quite different from the sort of people who don’t; maybe they take better care of themselves in general. Maybe they’re richer. But whatever the reason, statisticians generally agree that this compliance effect is quite large.

Therefore, any associations found between meat eating and disease, in order to be meaningful, must be big enough to overcome this compliance effect as well as other confounding variables. Yet, like the small association that Harvard researchers found in their 2012 study, the associations seen between red meat consumption and heart disease have generally been minimal, a scientific detail that study leaders tend not to emphasize and that the mainstream media have also, on the whole, overlooked.

Dietary Fat Recommendations

2013:

• Advise adults who would benefit from lowering LDL cholesterol to aim for a healthy dietary pattern* that achieves 5-6% of calories from SFA. Replace with MUFA & PUFA.

• Reduce % of calories from TFA.

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For example, based on a 2,000 calorie per day diet, a heart-healthy eating pattern that is consistent with a DASH (Dietary Approaches to Stop Hypertension)-type eating plan could include:

 Fruits: 4-5 servings a day

 Vegetables: 4-5 servings a day

 Whole grains, preferably high fiber: 6-8 servings a day

 Fat-free or low-fat milk and milk products: 2-3 servings a day

 Lean meats, poultry and fish: 6 or fewer ounces a day

 Nuts, legumes and seeds: 4-5 servings a week

 Fats and oils: 2-3 servings of healthy oils per day, limit trans and saturated fat

 Limit sweets, sodium, and added sugars

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The same DRI publication also issued recommendations for saturated fat intake. Saturated fatty acids have physiologic and structural functions and our bodies produce them in adequate amounts to meet these needs. Because they have no known role in preventing chronic disease, there is not an Adequate Intake or Recommended Dietary Allowance for these fats. In addition, there is a positive linear relationship between saturated fat intake and LDL cholesterol, which increases risk of CHD. Thus, increasing saturated fat intake increases CHD risk. However, it is not feasible or even recommended to achieve 0% of energy from saturated fats because all dietary fats contain mixtures of fatty acids. Of note is that some fats, principally liquid vegetable oils, are low in saturated fats and high in healthy unsaturated fats. This is why current dietary guidance recommends replacing food sources of saturated fat with foods containing unsaturated fat.

Dietary Fat Recommendations

2015

Dietary Guidelines Advisory Committee report:

• <10% of calories from SFA. Replace with unsaturated fat, particularly PUFA.

• Partially hydrogenated oils containing TFA should be avoided

NEW YORK (AP) — Mars Inc., the maker of Skittles and M&M’s, is breaking ranks with other food companies and denouncing an industry-funded paper that says global recommendations on limiting sugar are based on weak evidence.

The paper drew criticism this week because it was paid for by a group whose members include Coca-Cola, Hershey, Red Bull and Oreo cookie maker Mondelez.

Mars — which is also a member of the group, the International Life Sciences Institute — said Wednesday the paper undermines the work of public health officials and makes all industry-funded research look bad.

Company spokesman Matthias Berninger said the study, published by the Annals of Internal Medicine, creates more doubt for consumers rather than helping them make better choices.

Emails obtained by The Associated Press show two Mars executives were copied on discussions about the research project last year. But Berninger said Mars was not a driving force for the paper and would make clear to ILSI from now on that it does not support such work.

The situation highlights the potential for conflicts of interest in nutrition science. Critics say the nature of nutrition research leaves the door open for companies to cherry-pick projects that make their products seem healthy, or cast doubt on science that suggests they fuel obesity.

Eric Hentges, ILSI’s executive director, said the group devised the concept for examining inconsistencies in sugar guidelines around the world. The paper clearly disclosed how it was funded, but said the authors “wrote the protocol and conducted the study independently from ILSI.” On Wednesday, the journal published a corrected version of the disclosure to state ILSI “reviewed and approved” the scope of the protocol, after the AP provided it with emails showing the group sent the authors “requested revisions” on the proposal last year.

Berninger said it was difficult to identify a universal recommended limit on sugar intake, or directly link sugar to specific health consequences. But he said even Mars realizes people consume too much sugar, and wants to help them understand how to cut back.

Despite the criticism, the paper’s underlying point takes note of a recognized issue about evidence for dietary recommendations. The U.S. government’s guidelines, for instance, have evolved over the years with science.

Bradley Johnston, a professor at the University of Toronto and co-author of the paper, said he studies how researchers come to their conclusions, and the quality of the evidence they use. He noted that the type of causal inferences that can be made between smoking and lung cancer cannot be made with sugar, and that methodologies for developing sugar guidelines could be stronger.

“We think there’s room for improvement,” he said.

Notably, one of the paper’s criticisms was the lack of transparency about possible conflicts of interest by those developing sugar guidelines. That’s even though one of the paper’s co-authors previously received funding that was not disclosed.

Joanne Slavin, a professor at University of Minnesota who helped write the study proposal, did not list that she received a $25,000 grant from Coca-Cola in 2014. When contacted by the AP, the Annals of Internal Medicine said it was looking into publishing a correction.

Christine Laine, editor-in-chief of the journal, said that grant should have been disclosed, especially since the author disclosed a grant from the Mushroom Council. Laine said she always tells researchers to err toward providing too much information, since it could otherwise “look like you’re trying to hide something.”

Slavin told The Associated Press she did not disclose some of her funders for reasons including differences in how money can be allocated. She said the Coca-Cola grant came through the university’s foundation and such funding is not typically subject to disclosure.

She said she planned to file a new disclosure including the Coca-Cola grant and funding from Quaker Oats owner PepsiCo for an oatmeal study.

“What I’m going to do is list everybody who’s funded our research in the last five years in any way, and I hope people aren’t mad,” Slavin said.

Slavin had also worked on a paper on sugar guidelines in 2012 funded by ILSI. That paper was co-authored by an employee of the group, with feedback from a Coca-Cola executive and others, according to emails obtained by the AP through a public records request. Slavin said she would list the grant for the first ILSI paper in her new filing.

Also in 2012, Slavin presented a session for dietitians sponsored by Coke and Pepsi called “The Confusing World of Dietary Sugars” at an event held by the Academy of Nutrition and Dietetics. A slide for the presentation concluded that efforts to “micromanage” diets by imposing strict dietary rules are difficult to support with science.

Slavin said she did not collaborate with the companies on the talk or receive compensation other than travel reimbursement. Emails obtained by the AP show she inquired afterward about an honorarium, apart from travel expenses, and was told the usual amount was $2,000. But Slavin told the AP she did not have a record of the money being paid.