by Marion Nestle

Currently browsing posts about: Research

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.

May 24 2012

POM fights back with out-of-context ads

POM Wonderful has a full-page ad in today’s New York Times (how much do these things cost?) titled “FTC v. POM: You be the judge.”  The ad includes selected quotes from the judge’s decision (see yesterday’s post) and refers readers to its wonderfully named website, pomtruth.com, where you can see the quotes and the ads for yourself.

I couldn’t help doing some checking.

The POM ad quotes from Chief Administrative Law Judge’s decision:

Competent and reliable scientific evidence supports the conclusion that the consumption of pomegranate juice and pomegranate extract supports prostate health, including by prolonging PSA doubling time in men with rising PSA after primary treatment for prostate cancer (page 282).

I turned immediately to page 282.  The sentence before the one quoted would seem to support it:

The basic research, the Pantuck Study, and the Carducci Study, relied on by Respondents [POM Wonderful], support the conclusion that pomegranate juice has a beneficial effect on prostate health.

But what follows the quotation makes it clear that although the research claims to support the effect, it really doesn’t.  Here’s what immediately follows the quotation in the same paragraph:

However, the greater weight of the persuasive expert testimony shows that the evidence relied upon by Respondents is not adequate to substantiate claims that the POM Products treat, prevent, or reduce the risk of prostate cancer or that they are clinically proven to do do so.  Indeed, the authors of the Pantuck Study and the Carducci study each testified that their study did not conclude that POM juice treats, prevents, or reduces the risk of prostate cancer.  And, as Respondents’ expert conceded, no clinical studies, research and/or trials show definitely that the POM Products treat, prevent, or reduce the risk of prostate cancer.

I will just do one more of the quotes.  The ad says:

Competent and reliable scientific evidence shows that pomegranate juice provides a benefit to promoting erectile health and erectile function (page 198).

This is indeed on page 198 but is followed immediately by:

There is insufficient competent and reliable scientific evidence to show that pomegranate juice prevents or reduces the risk of erectile dysfunction or has been clinically proven to do so…There is insufficient competent and reliable scientific evidence to show that pomegranate juice treats erectile dysfunction in a clinical sense or has been clinically proven to do so.

Because these statements are attributed to the same expert witnesses, this must mean that while some studies show benefits, the experts do not believe that these studies (many of them sponsored by POM) are scientifically credible.

Pomegranate juice is a juice.  Fruit juices are healthy and especially delicious when fresh.  I happen to like the taste of pomegranate juice.

But does it have any special health benefits as compared to orange, grapefruit, grape, or any other fruit juice?

Would any fruit juice be likely to prevent heart disease or prostate problems on its own?

Despite POM’s out-of-context advertisement, the Administrative Law Judge did not think so, and neither do I.

Addition: I’m indebted to FoodNavigator.com for noticing some of the other ads.

The caption reads: “Natural Fruit Product with Health Promoting Characteristics–FTC Judge.”

May 23 2012

The FTC vs. POM Wonderful: the latest round

I’ve been following the legal battles between the Federal Trade Commission (FTC) and the makers of POM juice and other pomegranate juice products with avid interest, mainly because they deal with the credibility of sponsored scientific research.

This week, an administrative law judge ruled that POM violated federal law when it deceptively advertised  its products as able to “treat, prevent, or reduce the risk of heart disease, prostate cancer, and erectile dysfunction.”

The judge ruled that reasonable consumers would interpret the ads as making such claims but that the company had not produced convincing evidence to support them.

The judge’s decision makes entertaining reading for someone like me who enjoys debates about whether sponsorship of scientific studies influences results and interpretation—as evidence shows they most definitely do.

POM has invested more than $35 million in research to prove that pomegranate juice has health benefits.  It has sponsored about 100 studies at 44 different institutions.  At least 70 of these studies were published in peer-reviewed journals.

It is not difficult to design research studies to give sponsors the answers they want and to make sure they are conducted well.  POM is getting the best research that money can buy.

One such study, of the effects of drinking pomegranate juice on myocardial perfusion (MP, blood flow to the heart), was conducted by Dr. Dean Ornish, who runs a preventive medicine institute in California (the quotes come from pages 268-269 of the decision).

The Ornish MP study was originally designed to last 12 months, with measurements at baseline, 3 months, and 12 months.  [The FTC] charges that the study was cut short when the three-month data came in favorably and Dr. Ornish faced cost overruns.

Dr. [Frank] Sacks [expert witness for the FTC] opined that the shortened study period and failure to report the planned duration are inconsistent with widely accepted standards for conduct of clinical trials and undermine any confidence in the findings.

Dr. Ornish testified that the Ornish MP Study was terminated after three months only because the Resnicks did not provide the funding that they had previously committed to this study….[he said the study]constitutes credible and reliable science showing that pomegranate juice lessens the risk of cardiovascular problems.

The judge found evidence on this study and many others conflicting.  He ruled that this level of disagreement about the quality of the research means that the scientific evidence is not good enough to substantiate the claims.

I was interviewed for a story in Business Week about this decision.

This makes it clear why everyone should be suspicious of the results of sponsored studies…POM-sponsored studies produce results favorable to POM.

POM’s owners have their own spin on the decision.

It says the ALJ’s ruling affirms the scientific validity behind the general health benefits of pomegranates and “completely exonerates” POM regarding its claims in broadcast or print interviews.

Let’s be clear what’s at stake here.  According to the decision document, the owners of POM control 18,000 acres of pomegranate orchards.

From September 2002 through November 2010, sales of POM juice alone totaled nearly $248 million (the supplements and other products add more).

The owners must believe that nobody will buy pomegranate juice and supplements for any reason other than health benefits.

Health claims are about marketing, not health.

Let’s hope the FTC can make the decision stick.

Nov 11 2011

Oh no! USDA cutting back on research.

A couple of days ago, William Neuman wrote about an announcement by the USDA’s statistical research unit that under pressures to cut budget, it would eliminate or cut back on its ongoing research reports.

This is alarming.

As USDA explained:

The decision to eliminate or reduce these reports was not made lightly, but it was nevertheless necessary, given the funding situation. Because of the timing of the agency’s survey work during the coming year, these decisions are necessary now.

The affected reports include these, among others:

  • Annual Reports on Farm Numbers, Land in Farms and Livestock Operations – Eliminate
  • Catfish and Trout Reports – Eliminate all
  • Annual Floriculture Report – Eliminate
  • Chemical Use Reports – Reduce frequency of commodity coverage
  • Annual Bee and Honey Report – Eliminate
  • Fruit and Vegetable in-season forecast and estimates– Reduce from monthly and quarterly to annual report
  • Nursery Report – Eliminate

This decision, Neuman reports, “reflects a cold-blooded assessment of the economic usefulness”—translation: lack of political clout in the affected industry—of the 500 or so reports issued by the National Agriculture Statistics Service each year.  The reports will still be issued on the big commodities: corn, soybeans, cattle, and pigs, for example.

Why do I find this alarming?  If these reports can be eliminated, so can the ones that I personally care about and depend on for my research.

I am particularly worried about the invaluable data produced by USDA’s Economic Research Service on the composition of foods, their availability (production less exports plus imports), and per capita nutrient availability in the American diet.

I have plenty of reason to be worried.

For decades, USDA has converted information about food availability to nutrient availability in a continuous series dating back to 1909.  This is the data set I use to explain how calories in the food supply have increased to today’s 3,900 per person per day from 3200 in 1980—an increase of 700 calories per day exactly in parallel with rising rates of obesity.

USDA stopped this series in 2006.

I wrote USDA to ask whether more recent data were available.  Here is the response in its entirety:

Because of other project priorities the Food Supply project has been curtailed.  There are programming issues to which we haven’t been able to devote available resources.

Neuman quoted a former USDA official who argues that pressures to continue the statistical reports are an example of

how hard it was to eliminate a government program, no matter how small the constituency….These congressmen up on the Hill say, “$50,000 is not much, let’s give it to them.”   [The reports apparently cost about $50,000 to produce]

I have a different reaction.  Isn’t it a responsibility of government to produce research that nobody else has the resources to produce?   This argument reminds me of similar ones I hear that if a book hasn’t been taken out of a library in ten years, the library ought to dump it.

This is short-sighted.

Yes, $50,000 seems like a lot of money to you and me, but it is peanuts in comparison to the billions the USDA spends every year on support payments to people who aren’t even farmers.

Hence: alarming.

Oct 13 2011

Alas, vitamin supplements

Two studies released this week provide additional evidence that vitamin supplements are potentially harmful and, at the very least, do no good.

This depressing news comes from the Iowa Women’s Health Study.  Older women in the study who took supplements ranging from multivitamins to high doses of single nutrients had a greater risk of dying than those who did not.

Equally depressing are the results of a trial of high-dose vitamin E and selenium versus prostate cancer.  It found higher rates of the cancer among men taking vitamin E (selenium was somewhat protective).   In this trial, it was so obvious that the supplements did not protect against prostate cancer that the investigators ended it before its scheduled date of completion.

USA Today interviewed me and Dr. Jeffrey Blumberg (Tufts University) about our interpretations of these trials.

I think that the main conclusion to be drawn from this research is that supplements do not make healthy people healthier.   They may not cause harm at high doses, but they appear not to do good.

I don’t take them and I don’t recommend them—except to people who have diagnosed nutrient deficiencies or other problems handling nutrients.

Dr. Blumberg, in contrast, thinks multivitamins constitute a useful nutrition insurance policy and everybody should be taking them.

Supplements are a good example of how scientists can interpret research in different ways, depending on point of view.  I illustrate this point in Food Politics in a table in which I compare what I call “belief-based” (for lack of a better term) and “science-based” approaches to deciding whether supplements are needed, effective, or safe (see table 29, page 232).

For example, on the need for supplements, a belief-based approach rests on:

  • Diets do not always follow dietary recommendations.
  • Foods grown on depleted soils lack essential nutrients.
  • Pollution and stressful living conditions increase nutrient requirements.
  • Cooking destroys essential nutrients.
  • Nutrient-related physiological functions decline with age.

A science-based approach considers:

  • Food is sufficient to meet nutrient needs.
  • Foods provide nutrients and other valuable substances not present in supplements.
  • People who take supplements are better educated and wealthier: they are healthier whether or not they take supplements.

The statements in both approaches are true.

This is why point of view is such an important consideration in interpretation of nutrition research.

Aug 23 2011

New study: healthy diets produce health benefits

The latest issue of JAMA has a paper on a “portfolio” of dietary means to reduce blood cholesterol levels.

The paper is likely to get lots of press because it concludes that consuming the “portfolio”—a combination of plant sterols, soy protein, viscous fibers, and nuts—does a better job of lowering LDL-cholesterol (the “bad” kind) than does dietary advice to reduce saturated fat.

The paper is unusually difficult to read  (see the Abstract, for example).  But besides that, I interpret the study in part as a drug trial.

One look at the Abstract and I immediately suspected that this study must have been sponsored by a maker of plant sterol margarines.

Bingo!

Plant sterols are well established to reduce blood cholesterol levels.  Unilever, which makes Take Control margarines, is one of the sponsors.

As I interpret it, the study shows:

  • Advising people who weigh an average of 76 kg (167 pounds) to consume a healthy diet doesn’t work.  Study subjects did not change their diets by much during the six months of the trial.  No news here.
  • Advising people to add things to their diets has a better chance of succeeding than advising taking things away (like saturated fat).
  • All of the portfolio items have been established to lower blood cholesterol in clinical trials, although the evidence for soy protein seems a bit iffy these days.
  • The study does not distinguish between the relative effects of soy protein, fiber, or cholesterol lowering margarines. If soy is eliminated, that leaves fiber and margarines. I’m guessing the margarines were the critical factor. Hence: a partial drug trial.

And because my book on calories is coming out next March, I must point out that the study groups reported losing  losing small amounts of weight, which means they must also have reduced their calorie intake.  Weight loss alone should help with blood cholesterol.

The take-home message: if you really do substitute nuts, sources of fiber, and healthy foods for whatever less healthful foods you used to eat, you ought to get some health benefit, with or without plant sterol margarines.

QED: Healthy diets produce health benefits.

It’s always nice to see that confirmed.

 

 

Aug 8 2011

It’s time for some Q and A’s

I’ve just turned in the copy-edited manuscript of Why Calories Count: From Science to Politics (pub date March 2012) and now have time to catch up on some questions:

Q. I was recently given to read a book titled “The China Study” which is based on research conducted in 1970’s in China by Dr. Colin Campbell. His main conclusion is that eating dairy and meat causes cancer. His resolution is that a plant-based diet (i.e. vegan) is the (only?) healthy diet for humans. This book has made strong enough of a point to convince several of my friends to “convert” to a vegan diet in order to save their health. Could you share some comments on the validity of the research and conclusions this book presents with regards to detrimental effects of dairy and meat on human health?

A. Campbell makes a forceful argument based on his interpretation of the research and on case studies of people whose diseases resolved when they became vegans. And yes I’ve seen Dr. Campbell’s new movie, Forks over Knives. The first half is a terrific introduction to how the current food environment promotes unhealthy eating.  The second half promotes Dr. Campbell’s ideas about the hazards of meat and dairy foods.

Whether you agree with these ideas or not, the film is well done and worth a look.

Some scientists, however, interpret the research as demonstrating that people are healthier when they eat dairy foods.  For example, the enormous consensus report on diet and cancer risk from the American Institute for Cancer Research and the World Cancer Research Fund concluded in 2007 that eating lots of red meat and processed meat is convincingly associated with an increased risk of colorectal cancer (but no others).

On the other hand, they found dairy foods to be associated with a decrease in the risk of colorectal cancer.  They found limited and less convincing evidence that dairy foods might decrease the risk of bladder cancer but increase the risk of prostate cancer.

How to make sense of this?  These are two food groups in the diets of people who consume many kinds of foods and who do many things that might increase or decrease cancer risk.  Given this complexity, one food or food group seems unlikely to have that much influence on cancer when considered in the context of everything else people eat and do.

Nutrition research, as I am fond of saying, is difficult to do and requires interpretation. Intelligent people can interpret the studies differently depending on their point of view.

The new Dietary Guidelines say to cut down on saturated fats. Those are most plentiful in meat and dairy foods (plant foods have them, but in smaller amounts). Pretty much everyone agrees that plant-based diets promote health/  But whether they have to be 100% plant-based is highly debatable.

The new USDA MyPlate food guide suggests piling plant foods—fruit, vegetables, and grains—on 75% of your plate so the argument is really about what goes on the remaining 25%, what USDA calls the  “Protein” section. You can put beans in that quarter if you don’t want to eat red meat, poultry, or fish.

Q. I’d love to hear your take on the recent walnut flap [accusations that the FDA now considers walnuts to be drugs].  I suspect walnuts got caught with such offenders as Pom, Froot Loops, and Juicy-Juice, but I’d love to find out what the FDA actually said about this. For some odd reason I don’t believe the article is presenting the whole truth.

A. This is a health claims issue. The FDA is not saying walnuts are drugs. It is saying that Diamond Walnut is claiming walnuts as drugs on package labels. How so?

The labels say the omega-3 fatty acids in walnuts may help lower cholesterol; protect against heart disease, stroke and some cancers (e.g. breast cancer); inhibit tumor growth; ease arthritis and other inflammatory diseases; and even fight depression and other mental illnesses. These are disease claims for which the FDA requires scientific substantiation.

The company’s petition did not provide that substantiation so the FDA issued a warning letter. In general, you should be skeptical any time you see a nutritional factor advertised for its ability to prevent or treat such a broad range of problems.

Q. A question about sugar and how it is counted: My books say: 4 g = 1 teaspoon = 15 calories. My Illy Caffe says 10 g of sugar, but 50 calories. Ingredients: coffee, sugar, potassium bicarbonate, potassium citrate. If the drink is 50 calories, shouldn’t it say 12 g or more for the sugar listing?

A. Sugar should be the only ingredient that has calories in this coffee but I’ve seen calorie lists that say 5 calories per gram for sugars. Food companies have some leeway in the way they compute calories. Illy may be using a method that gives 5 rather than 4. But the difference between 40 and 50 is hardly measurable and I wouldn’t worry about amounts this small, annoying as imprecise figures may seem.

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