by Marion Nestle

Currently browsing posts about: Research

Sep 30 2019

Eat as much meat as you like? Really?

The press release from the Annals of Internal Medicine arrived last week under embargo, sent to me by several reporters: “New guidelines: No need to reduce red or processed meat consumption for good health.”

The press announcement was accompanied by 5 review papers, a sixth with this recommendation, and an editorial.  These are posted on the website of their publisher, the American College of Physicians, implying this organization’s endorsement of this guideline.

Collectively, these papers challenge dietary advice to eat less processed meat and red meat on the grounds of inadequate science.

These papers argue:

  • Eliminating processed and red meat from the diet may reduce disease risks but the effects are small and evidence for them is of low quality and low certainty.
  • Omnivores are unwilling to eat less meat.
  • If you continue to think eating meat is bad for you in the face of this evidence, you are a victim of the “the less you know, the more you hold to your beliefs” syndrome.
  • You can ignore dietary guidelines (regardless of source) and continuing eating meat as you always have.

This is a good example of what I call nutritional nihilism, an approach that insists that because observational studies are based on self-reported information and necessarily flawed, their conclusions are unscientific and should be discounted.  Therefore, because we can’t do more rigorous studies, we should not advise the public about diets best for health or the environment.

I have several concerns about all this:

  • Yes, the effects are small but that is true of nutrition studies in general.  The small effects show benefits from eating less meat.  The authors could easily have interpreted their work as suggesting that eating less meat might be useful.  This is an example of interpretation bias.
  • The authors took a strictly science-based approach to a problem strongly affected by social, economic, and political factors and values.
  • The studies look at previous studies that compared people who eat meat to those who eat less. The authors excluded studies of vegetarians compared to meat-eaters.
  • They look at meat outside its context of calories.
  • The authors did not look at the totality of the evidence; they excluded laboratory and animal studies that can be more closely controlled.
  • They excluded studies of environmental impact, which has a significant bearing on human dietary practices (meat production adds more greenhouse gases than vegetable production).
  • The conclusions fall into the category of “everything you thought you knew about nutrition is wrong.”  This rarely happens.  Science usually works incrementally, not in one enormous reversal like this.

Do the authors really believe that all those other committees and commissions urging less meat were wrong and continue to be wrong?   Their strictly science-based approach seems unrealistic.

The papers come across to me as a concerted attack on dietary guidelines (national and international), on nutrition science in general, and on nutritional epidemiology in particular.

The meat industry and its supporters will love them.

Attacks on the quality of nutrition research have been coming from many sources lately: the food industry, of course, but also statisticians (John Ioannidis at Stanford is making a career of this), and some scientists (usually with ties to food companies).  The criticisms themselves are not new.

What is new is the vehemence and level of effort to discredit observational studies, particularly those based on self-reports of dietary intake.  Yes, nutritional epidemiology has flaws, but the methods have been useful in many instances, as argued convincingly by two of its leading practitioners.

In looking at nutrition research, I think it is essential to evaluate the totality of information available: laboratory, animal, human epidemiology and clinical studies—and to do this in the context of what people actually eat and the number of calories they consume, as well as adding in a hefty dose of common sense.

Common sense is what’s missing in these studies.  Do the authors really believe that:

  • Meat eaters are healthier than vegetarians?
  • Eating more meat is better for health?
  • Meat eaters are less obese and have less heart disease and cancer than those who eat less?

If not, the conclusions make no sense.

Most of the authors report no financial ties to the food industry.  I would love to know the back story about why they chose to do these studies and to interpret them in this way.

Reactions (I will be adding to this list as they come in)

Mar 19 2019

Trump budget double-speak: USDA/ERS budget cuts

The Trump administration released more details on its proposed budget, in language straight out of George Orwell’s 1984.

Framed as “savings and reform,” the proposal is to move the USDA’s Economic Research Service out of Washington DC.   Although this proposal says the purpose is to bring the ERS closer to rural America, its real purpose is to put the ERS out of business.

Why do I say this?  Because this proposal comes with a $26 million budget cut.   I also hear rumors that ERS research staff are being offered retirement options.

ERS is the jewel in USDA’s crown, nothing less than a national treasure, not only worth preserving but worth extolling for its truly important contributions to society.

I’ve long said that ERS was the best kept secret in government.  Its researchers worked tirelessly to provide real data on America’s food production and what it means for health.

Here, for example, is its latest report on how the U.S. food dollar is spent.

The best thing I can say about this budget is that it is unlikely to pass.  Members of Congress have been trying to put a stop to this move.  Let’s hope they succeed.

This may be a small piece of what’s happening, but in my field it is essential.

Please tell your congressional representatives to restore ERS’s budget and keep it in Washington, DC.

How?

Addition

The Office of Management and Budget’s analysis

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Jun 1 2018

Weekend reading: Declining US investment in agricultural research

The USDA reports that investment in agricultural research is declining (since 2009) in high-income countries, particularly in the U.S.

The U.S. share of total agricultural investment in research was 35% in 1960; it fell to 25% in 2013.

What with global problems of hunger, chronic disease, and climate change, shouldn’t we be doing more agricultural research, not less?

The documents

Jun 23 2017

Healthy Food America’s Policy and Research Briefs: Diet Drinks

Healthy Food America is a relatively new organization.  Based in Seattle, it

Acts on science to drive change in policy and industry practice so that all people can live in places where nutritious food is easy to obtain and exposure to unhealthy products is limited..  We are coordinating with other advocates to energize a national movement to roll back added sugars in food and beverages to healthful levels.​

It runs a blog, publishes a newsletter, and produces useful information.  I was particularly interested in its information on diet drinks.

It’s Policy Brief discusses whether or not artificially sweetened beverages should be included in soda tax initiatives.

Sugary drink taxes were conceived of as a strategy to prevent chronic health conditions by reducing consumption of sugar. Recently, however, some jurisdictions have included artificially sweetened, or “diet”, beverages. There is strong scientific evidence associating sugary drinks with higher rates of chronic diseases such as type 2 diabetes, heart disease, high blood pressure, liver disease and dental disease. The evidence of harm from diet drinks is less certain.  Therefore, we recommend not including diet drinks in beverage taxes.

Its Research Brief summarizes the evidence linking artificially sweetened beverages to disease risk.

This research brief summarizes:

1) reviews or meta-analyses of prospective cohort studies that analyzed the association between ASB consumption and disease risk,

2) randomized trials that studied the metabolic and health effects of ASB consumption, and

3) randomized trials that studied the effect of ASB consumption on weight loss.

Reviews and meta-analyses were restricted to those published in the last 5 years, to ensure that this brief reflected the latest science. All studies were obtained through PubMed searches.

It helps to have all this.

May 23 2017

What ag schools really need to teach: a report

The Association of Public Land-Grant Universities has just released a report titled “Challenge of Change” about how the USDA can do a better job of funding research to solve important problems in food and agriculture.

The challenge:

 

Traditionally, the effort to achieve food security has been largely focused on the need to increase yields in order to produce more food. There is now broad recognition that production alone will not solve the grand challenge. All aspects of our food systems must be considered: nutrition, food safety, food loss, economic costs, individual behaviors, incentive structures, and societal factors affect not only production, but also access and utilization. There is also now an understanding that production increases must be achieved in the context of water availability, energy limitations, and environmental impact.

The report concludes that universities will need to change, so as to:

  • Elevate Food and Nutrition Security to a Top Priority
  • Align University Resources and Structures for Transdisciplinary Approaches
  • Enhance and Build University-Community Partnerships
  • Educate a New Generation of Students to be Transdisciplinary Problem Solvers

To achieve food security, food and agriculture will need to change to:

  • Broaden the Focus Beyond Yields
  • Change the Food System’s Incentive Structure
  • Develop the Capacity of Universities in Low-Income Countries
  • Leverage Technology, Big Data, and Information Science Information

This is an important report because it comes from land-grant universities .  These are currently responsible for supporting industrial agricultural systems and virtually ignoring—or firmly opposing—sustainable agricultural production methods.

A challenge for change indeed.  I hope land-grant universities listen hard.

 

Jun 3 2016

Weekend reading: Science & Nutrition Research

I’ve just started getting a new Science and Research newsletter from William Reed: Informing Business Growth.

Some of the listings focus on dietary patterns or emerging microbiome research:

But most of them focus on single nutrients, ingredients, or foods—suggesting that they are about marketing those ingredients, not necessary health (people don’t eat single foods exclusively; we eat meals and mixtures).

These are a lot of fun.  They raise the possibility of magic bullets (if only).

But watch out for the weasel words “may,” “could,” “might”.  These mean “may or may not,” “could or could not,” “might or might not.”

Wouldn’t you rather eat chocolate than beets?  That’s what such studies are about.  And I wonder how many of them are funded by the makers of the products.  Want to take a look?

Sep 19 2014

Do artificial sweeteners cause–not cure–glucose intolerance?

The big nutrition scare last week was the study in Nature finding that in mice and, maybe, humans, artificial sweeteners mess up the microbiome and make some people even more intolerant of glucose.

The authors conclude that their results call for a reassessment of massive use of artificial sweeteners.

The study is complicated and difficult to read but the Wall Street Journal has a nice summary.  It explains why the study is getting so much attention:

The new Nature study marks a significant advance because it brings together two separate areas of research—the role of sweeteners in raising blood sugar levels, and the complex workings of the vast colonies of bacteria that inhabit the gut. Individuals can have differing bacterial colonies in their gut, meaning people respond differently to what they consume.

The study involved several experiments.  These found:

  • Mice fed saccharin, sucralose, or aspartame had significantly higher blood-glucose levels than mice whose diet included sugar, or just water.
  • Mice with sterilized digestive tracts, who were given bacterial transplants from artificial-sweetener-fed mice, displayed higher blood sugar levels than those receiving bacterial transplants from sugar-fed mice.
  • People who typically use artificial sweeteners have different kinds of bacteria in their intestines than those who do not.  They also are more glucose intolerant.
  • Seven volunteers fed artificial sweeteners for four days displayed higher blood-sugar levels as well as altered populations of bacteria in their gut.

The Wall Street Journal quotes the Calorie Control Council (the trade association of makers of artificial sweeteners).  The CCC said:

The results from the mouse experiments may not apply to humans, while the human experiments had a small sample size. It said further research was needed.

Despite my lack of enthusiasm for artificial sweeteners, I think the Calorie Control Council has a point.

The excellent report by Kenneth Chang in the New York Times explains why.

At present, the scientists cannot explain how the sweeteners affect the bacteria or why the three different molecules of saccharin, aspartame and sucralose result in similar changes in the glucose metabolism.

Chang ends with this:

Dr. Frank Hu, a professor of nutrition and immunology at the Harvard School of Public Health who did not take part in the study, called it interesting but far from conclusive and added that given the number of participants, “I think the validity of the human study is questionable.”

Here’s why I’m not fond of artificial sweeteners:

  • They taste bad (to me)
  • They have no demonstrated effectiveness in helping people lose or maintain weight.
  • They are artificial, and violate my rule to “never eat anything artificial.”

Do they mess up the microbiome and cause glucose intolerance, insulin resistance, and metabolic syndrome?

That would be fascinating, but I’m reserving judgment pending further research.

In the meantime, I’ll take sugar—in moderation, of course.

Aug 11 2014

Dan Glickman heads board of Foundation for Food and Agriculture Research

Former USDA Secretary Dan Glickman has just been named chairman of the board of the Foundation for Food and Agriculture Research (FFAR).

Research on agriculture has long been the underfunded stepchild of the federal research enterprise.  The 2014 budget gave USDA under $3 billion in total to fund all of its in-house research units and their granting operations: Agricultural Research Service, National Institute of Food and Agriculture, Economic Research Service, and Agricultural Statistics Service.

This may seem like a lot, but NIH gets $30 billion a year.

The 2014 farm bill contained a provision aimed at raising money for agricultural research.  It provided $200 million (peanuts in federal dollars) to establish FFAR, which will operate as a non-profit corporation to obtain matching funds from private industry.

The members of the board were announced a couple of weeks ago.

It should be no surprise that many of the board members represent industry.  Industry nominated 7 of the members.  The other 8 were selected from a list provided by the National Academy of Sciences.

Now the board has to raise at least $200 million from industry, presumably with no strings attached.

Here’s the foundation’s dilemma: if industry funding has no strings—earmarks for certain research projects, for example—why would industry want to contribute?  But if the contributions do come with strings, they create conflicts of interest.

This will be fun to watch.  Stay tuned.