by Marion Nestle

Currently browsing posts about: Fats-and-oils

Dec 4 2018

Where are we on dietary fat?

The endless arguments about dietary fats and dietary fat versus carbohydrate make no sense to me, because we mostly eat these as components of food, and foods as components of diets of massive complexity.

But scientists do like to debate such issues so it comes as a breath of fresh air to read a consensus statement from people who do not necessarily agree about such issues.

Looks good to me.  I’m glad they did this.

 

Nov 12 2018

Another industry-funded study for your amusement

As I discuss in my latest book, Unsavory Truth: How Food Companies Skew the Science of What We Eatfood industry funding of nutrition research produces highly predictable results and, therefore, is not good for science, public health, or trust.

Industry-funded studies are easily recognizable by their titles.  When I see a title like this one, I immediately wonder why anyone would do a study to example this particular question.  And then I look to see who funded it.

Title: Corn Oil Lowers Plasma Cholesterol Compared with Coconut Oil in Adults with Above-Desirable Levels of Cholesterol in a Randomized Crossover TrialJ Nutr 2018 148(10):1556-63.

Conclusion: “When incorporated into the habitual diet, consumption of foods providing ∼54 g of corn oil/d produced a more favorable plasma lipid profile than did coconut oil in adults with elevated cholesterol.”

Sponsor: “Supported by ACH Food Companies, Inc., Oakbrook Terrace, IL,” and all of the authors either received research funding from ACH Food Companies, Inc., or are employees of that company.

Comment: So what is this about?  ACH is the maker of Mazola oil, which must be losing market share to coconut oil.

Which oil is better for you and does it really matter?

I sure would like some independent researchers to weigh in on this.

Jul 12 2018

Food Navigator’s collection of articles on “healthy fats”

Fat remains in the news.  Which ones are health, and which not?  FoodNavigator-USA collects its articles on the topic.  My thoughts:  Beyond that, food fats are mixtures of monounsaturated, polyunsaturated, and saturated fatty acids, of the omega-3, -6, and -9 varieties.  And then there are the hydrogenated trans-fats.  These variations make fats complicated.

One attribute of fats is not complicated: fat has 9 calories/gram compared to 4 for protein and carbohydrate.  A tablespoon of oil, butter, lard, or tallow has about 100 calories.  If you are concerned about energy balance, watch out for fat calories (and the other ones count too).

FoodNavigator’s Special Edition: Healthy fats
Fat – we are told – is back. But what kind of fat, and can you have too much of a good thing? Is the science changing on saturated fats? Is whole milk a better choice, or should we stick to low fat dairy? Is coconut oil as healthy as some marketers make out, and is the pressure off to reduce fat now all eyes are on added sugar?  Get the lowdown on fat in this special edition…

May 14 2018

WHO seeks comments on saturated fat and trans fat

The World Health Organization (WHO) is collecting comments until June 4 on its recent “consultation” (committee report) on saturated fat and trans fat.

The consultation recommends:

  • Saturated fat: no more than 10% of calories
  • Trans fat: no more than 1% of calories

These recommendations are consistent with

I wish that dietary recommendations would refer to foods, not nutrients.

We don’t eat specific fatty acids.  We eat foods containing mixtures of saturated, unsaturated, and polyunsaturated fatty acids; some foods have more than one kind than another.

Trans fats appear in highly processed foods.  Therefore, they are a euphemism for snack and other foods containing them.

As for saturated fats: the Dietary Guidelines give their main sources:

The guidelines use two layers of euphemisms.

  • Saturated fat is a euphemism for meat and dairy foods; these have higher proportions of saturated fatty acids.
  • “Mixed dishes” and “protein foods” are also euphemisms for meat and dairy foods.

But saying so is politically impossible.

Do comment on the WHO guidelines.  It may help clarify the recommendations.

Dec 12 2017

Oops. Fat replacing sugar in US diets.

In the late 1980s, nutrition scientists identified fat and saturated fat as key nutrients that needed to be reduced in US diets.

One result was the Snackwell’s phenomenon in the early 1990s—“no-fat” cookies with just as many calories as the ones with fat.  They flew off the shelves.

Image result for snackwell's no fat cookies

Now the push is to get rid of carbs, especially sugars.  The result?  Fat is back, along with its calories (fat has more than twice the calories per gram as carbohydrates, 9 as opposed to 4).

A tweet from Kevin Bass tells the story:

The USDA tells the same story, but with respect to specific products:

These products may be more satiating, but watch the calories!

Also watch out for the saturated fat:

 

Sep 5 2017

The PURE study warrants some skepticism

I love getting notes like this one from a reader:

Why aren’t you saying anything about the PURE study.  Doesn’t it prove that everything you’ve been saying about eating more fruits and vegetables and about saturated fat is wrong, wrong, wrong.  Admit it.

Not this time.  Whenever I hear the claim that “everything you thought about nutrition is wrong,” I know that skepticism is in order.  Science rarely works that way; it usually progresses incrementally.

What the PURE study is about: The PURE (Prospective Urban Rural Epidemiology) study was designed to examine, among other things, the effects of lifestyle behaviors on the health of about 135,000 people in 18 countries over up to 10 years.  Its results have just been published in Lancet journals.

What the headlines say: “Study challenges conventional wisdom on fats, fruits and vegetables.”

What the studies say:  Three papers report results: 

1,  Fruit, vegetable, and legumes vs. cardiovascular disease and death

Higher fruit, vegetable, and legume consumption was associated with a lower risk of non-cardiovascular, and total mortality. Benefits appear to be maximum for both non-cardiovascular mortality and total mortality at three to four servings per day (equivalent to 375–500 g/day).

2.  Fat and carbohydrate vs. cardiovascular disease and death

High carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.  [Note: the data do not distinguish types of carbohydrate.]

3.  Association of nutrients with blood lipids and blood pressure

Our data are at odds with current recommendations to reduce total fat and saturated fats. Reducing saturated fatty acid intake and replacing it with carbohydrate has an adverse effect on blood lipids. Substituting saturated fatty acids with unsaturated fats might improve some risk markers, but might worsen others.

Why the need for skepticism:

I like the way James Hamblin explains the problem in The Atlantic:

The practically important findings were that the healthiest people in the world had diets that are full of fruits, beans, seeds, vegetables, and whole grains, and low in refined carbohydrates and sugar.

As a writer and a reader, though, this is very boring. If I pitched that to my editor, he would laugh at me. What is new here? Why is this interesting? You know what would be novel? You getting fired! Now get out there and find me a story, dammit!

Why did they do this study?  

I looked immediately to see who paid for it.  The list of funders is very long (it must have been extremely expensive).  The list begins:

The PURE Study is an investigator initiated study funded by the Population Health Research Institute, the Canadian Institutes of Health Research (CIHR), Heart and Stroke Foundation of Ontario, support from CIHR’s Strategy for Patient Oriented Research (SPOR) through the Ontario SPOR Support Unit, as well as the Ontario Ministry of Health and Long­Term Care and through unrestricted grants from several pharmaceutical companies, with major contributions from AstraZeneca (Canada), Sanofi­Aventis (France and Canada), Boehringer Ingelheim (Germany and Canada), Servier, and GlaxoSmithkline, and additional contributions from Novartis and King Pharma and from various national or local organisations in participating countries [the funders that follow are mainly government and private research bodies along with a sugar trade association and more drug companies—the list takes up more than half a column].

Drug companies have a big interest in this topic, especially if dietary approaches to heart disease prevention aren’t proven.

What the PURE study really tells us: For this, I am going to quote from David Katz’s lengthy analysis:

On the basis of all of the details in these published papers, the conclusion, and attendant headlines, might have been: “very poor people with barely anything to eat get sick and die more often than affluent people with access to both ample diets, and hospitals.” One certainly understands why the media did NOT choose that! It is, however, true- and entirely consistent with the data.

Also, by way of reminder: the HIGHEST levels of both total fat, and saturated fat intake observed in the PURE data were still LOWER then prevailing levels in the U.S. and much of Europe, providing no basis whatsoever for headlines encouraging people already exceeding these levels to add yet more meat, butter, and cheese to their diets. Absolutely none.

My translation: This study confirms that the single most important risk factor for poor health is poverty.  The study results are consistent with the idea that largely plant-based diets are good for health.  No single study can settle the fat vs. carbohydrate debate because people eat complicated combinations of foods and diets containing those nutrients.  What we really need are well designed studies of dietary patterns—the ones done to date suggest that largely plant-based diets are associated with excellent health and longevity.  

Aug 30 2017

Another ongoing saga: the legacy of Ancel Keys

I cannot understand the revisionist attack on the work of Ancel Keys, who died at the age of 100 in 2004.  Most scientists are lucky to have made important contributions in one area.  Keys produced outstanding work in several:

  • High altitude physiology
  • The physiology of starvation (for this alone, he should be honored)
  • Mediterranean diet benefits
  • Heart disease epidemiology

The fuss, of course, is over this last one, particularly his role in the Seven Countries Study.  The arguments falls right into today’s absurd debate about sugar vs. fat as a cause of disease (absurd, because we don’t eat sugar or fat; we eat foods and diets that provide energy measured as calories).

What started off this most recent fuss is Ian Leslie’s The Sugar Conspiracy, which begins with the question “How did the world’s top nutrition scientists get it so wrong for so long?”  This alone is a red flag.  “Everything you thought you knew about nutrition is wrong” is a sure signal for caution; that’s not how science works.

The attack on Keys’ work induced the True Health Initiative to develop a ​White Paper in defense (here’s its press release).  Its authors: Katherine Pett (who had written a blog post in defense), Joel Kahn (who also wrote a blog post) Walter Willet (long a champion of Mediterranean diets), and David Katz (who wrote about it in his own blog post).

In response, Michael Joyner pointed out that R.A. Stallones (a professor of mine at the School of Public Health at Berkeley) had made the same arguments years ago.

Another defense of Keys’ work comes from Kevin Klatt, a nutrition biochemistry PhD student at Cornell.

Sarah Tracy, a science historian at the University of Oklahoma, has been working on a biography of Ancel Keys for years.  I can’t wait for it to come out.  We need to have Keys’ life and work put in reasonable perspective.

While waiting for the fat v. sugar debate to resolve (I’m predicting it won’t), eat a healthy diet, enjoy what you eat, and be skeptical when writers write about nutrients, not food.

Sep 12 2016

Sugar industry funding of research, 1967 style (with many lessons for today)

I wrote a commentary for a study published this morning in JAMA Internal Medicine: “Food industry funding of nutrition research: The relevance of history for current debates.”

The study, by UCSF investigators Cristin Kearns, Laura Schmidt and Stanton Glantz, is based on their archival research.  They found documentary evidence of shocking manipulation by the sugar industry of a Harvard review of studies on dietary factors and heart disease published in the New England Journal of Medicine in 1967.

Kearns et al. discovered that the sugar industry trade association paid investigators at Harvard an impressive amount of money ($48,000 in today’s dollars) to produce research demonstrating that saturated fat—not sugar—raises the risk of heart disease.

In my commentary, I reproduced a figure from the sugar-funded 1967 reviews.  This summarizes the epidemiology showing that both sugar and saturated fat intake were then indistinguishably associated with increased mortality in 14 countries.

Nevertheless, the reviews exonerated sugars and blamed saturated fat.

Yes, I know that association does not necessarily mean causation, but I’m guessing that the epidemiology still shows that both sugars and saturated fats are associated with increased heart disease risk.

My interpretation: We would all be healthier eating less of sugary foods and fatty meats.

Here are the relevant documents for your reading pleasure:

The Sugar Association issued a response to today’s article by Kearns et al.:

We acknowledge that the Sugar Research Foundation should have exercised greater transparency in all of its research activities…Generally speaking, it is not only unfortunate but a disservice that industry-funded research is branded as tainted…We question this author’s continued attempts to reframe historical occurrences to conveniently align with the currently trending anti-sugar narrative, particularly when the last several decades of research have concluded that sugar does not have a unique role in heart disease.  Most concerning is the growing use of headline-baiting articles to trump quality scientific research—we’re disappointed to see a journal of JAMA’s stature being drawn into this trend.

I will post press accounts as they appear (I’m quoted in most of these):