The new dietary wisdom

Carbs are out.  Fats are in.  

We seem to be bombarded by messages these days warning of the evils of carbs, particularly sugar.  The recently released documentary, Fed Up, produced by Katie Couric presents one conspiratorial, over-wrought perspective on the issue.

In their indictment of farm policies, somehow the makers of Fed Up, failed to look at some of the best economic research on the topic, which shows that sugar import quotas, among other policies, make US sugar prices 2-3 times higher than the world price.  Moreover, ethanol policies have driven up the price of corn and have made high fructose corn syrup (HFCS) more expensive as well.  Here, for example, is USDA data on the price of HFCS over the past 14 years.  As you can see, prices have more than doubled since 2005.

Of course, that's just one example.  This week in the Sunday Review edition of the New York Times ran an editorial by David Ludwig and Mark Friedman, which a argued that over-eating is actually making us hungrier.  They seem to place the blame mainly on carbs, writing:

By this way of thinking, the increasing amount and processing of carbohydrates in the American diet has increased insulin levels, put fat cells into storage overdrive and elicited obesity-promoting biological responses in a large number of people. Like an infection that raises the body temperature set point, high consumption of refined carbohydrates — chips, crackers, cakes, soft drinks, sugary breakfast cereals and even white rice and bread — has increased body weights throughout the population.

One reason we consume so many refined carbohydrates today is because they have been added to processed foods in place of fats — which have been the main target of calorie reduction efforts since the 1970s. 

Last week, the Wall Street Journal also ran an editorial on the issue by Nina Teicholz, who has a recently released book, The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet.  In the editorial, she argues that past nutritional guidelines that emphasized carbs and demonized fat were a major cause of the rise in obesity, writing:

Seeing the U.S. population grow sicker and fatter while adhering to official dietary guidelines has put nutrition authorities in an awkward position. Recently, the response of many researchers has been to blame "Big Food" for bombarding Americans with sugar-laden products. No doubt these are bad for us, but it is also fair to say that the food industry has simply been responding to the dietary guidelines issued by the AHA and USDA, which have encouraged high-carbohydrate diets and until quite recently said next to nothing about the need to limit sugar.

Indeed, up until 1999, the AHA was still advising Americans to reach for "soft drinks," and in 2001, the group was still recommending snacks of "gum-drops" and "hard candies made primarily with sugar" to avoid fatty foods.

Teicholz does a good job describing how previous dietary guidelines were based on tenuous scientific evidence and largely represented group think and a desire to "do something."  

Here's my question: How can we be so sure we now know more?  It seems to me this history lesson would cause us to be much more cautious about what we know about nutritional science and about the ability of public policy to beneficially affect food choice, weight, and health.  Yet, the aforementioned writings, and others, often contain as much hubris as ever.  It is unhealthy to eat too many carbs (or too much fat for that matter), but do we really know enough to design policies that will have intended effects?  I'm skeptical.

One reason is that writings by medical doctors and nutritionists on carbs often narrowly focused and miss larger "macro" issues.  Here, for example, is USDA data on per capita sugar consumption.  I've added in the recent trend lines, which show a strong downward trend in consumption over the past decade.

I suspect some of the downward trend is due to increased public awareness of the dangers of over-consumption of sugars, but also because of market conditions and aforementioned government policies.   

Another factor that many of these writers seem to overlook is that we grow a lot of carb-producing grains not just because of nutritional guidelines but because of economic forces.  The reality is that, by far, the most cost efficient producers of calories and protein are crops like corn, wheat, soybeans, and rice.  Historically, the challenge has been (and it remains a current challenge in many parts of the world), producing enough food and calories to keep pace with a growing population.  Moreover, if you're concerned about environmental issues, you also want to get as many calories and nutrients using the least amount of land and other resources, and that's precisely why economic forces lead farmers choose to grow so much corn, wheat, soybeans, and rice (not to mention these can be stored and will not spoil and waste soon after harvest).  I'm not saying we shouldn't re-think how much of these types of grains we eat, often in processed food, but I think it is useful to have some perspective on why these crops are so prevalent on our farms and in our diet.

I'll conclude with this passage I recently read from Sara Hara, a nutritionist who was dismayed by what she saw in Fed Up.   

An important note for those who are earnestly trying to sort through the abundance of the information and misinformation about "good foods" and "bad foods" in search of the truth: know the source of the information being promoted and the difference between a real nutrition expert and a self-proclaimed "expert". Most medical doctors are well trained in medicine, but have less than a semester of nutrition education in the entirety of their training (there are a few rare exceptions). Medical doctors are smart, but are not typically experts in nutrition. Investigative journalists are also a talented lot, but rarely have formal education in nutrition.Registered Dietitians/Nutritionists (RD or RDN) have at least a 4 year degree in nutrition (many have an additional 2 year master's degree), have completed a clinical nutrition internship, and maintain continuing education requirements to retain their credential. THESE are the nutrition experts... along with researchers and other professionals who have advanced degrees in Nutrition. I was struck by the fact that the new film Fed Up has a list of "experts" that includes medical doctors, a psychologist, politicians and journalists...all very intelligent and respected professionals, but none with extensive training in nutrition. There are no RDN's among their "experts"... and for good reason. Most true nutrition experts do not agree with the propaganda being promoted by this film. The RDN experts know that the issue is multi-faceted and cannot be reasonably blamed on a single factor. Nutrition needs to be viewed in context of lifestyle habits, genetics, personal preferences, and so much more. Sensationalism sells... but healthy living and common sense are what will fix our nation's failing health.

FooDS May 2014

The latest edition of the Food Demand Survey (FooDS) is now out.

Because we've been conducting the survey for over a year now, we are not only able to report changes relative to the previous month but also changes relative to the same month last year.

This month's survey reveals willingness-to-pay (WTP) for meat products is down in May relative to April and relative to May 2013. Consumers expect higher meat prices this month and report spending more on food at home and away from home.    

Some of the biggest changes witnessed this month relate to a spike in how much consumers said they heard, and how concerned they said they were, about greenhouse gasses.  The result is likely a consequence of the widely publicized release of a report on climate change by the White House on May 6 (the National Climate Assessment update).  

We also added some ad hoc questions to gauge public support/opposition for the controversial laws that seek to prohibit release of undercover reporting at animal production facilitates (these are derogatorily known as "ag gag" laws).

We randomly allocated participants to one of two groups.  The first group was told and asked the following:

Several state legislatures have considered bills to outlaw certain activities on livestock facilities.  The laws would prohibit a person entering an animal or research facility to take pictures by photograph, video camera, or other means with the intent to commit criminal activities or defame the facility or its owner.  the laws would also charge a person with a crime if he or she willfully obtains access to an agricultural production facility by false pretenses or knowingly makes a false statement or misrepresentation as part of an application for employment at an agricultural production facility with the intent to commit an act no authorized by the owner. Would you support or oppose such legislation?  

The second group was asked the same question except the first sentence was altered to provide some context for the laws and give some insight as to why the laws are coming about.  The first sentence for this group read:

In response to the release of undercover videos revealing cases of animal cruelty by animal activist organizations, agricultural groups have lobbied legislatures in several states to introduce bills to outlaw certain activities on livestock facilities.  

Here's what we found:

Regardless of which group a participant was randomly assigned, more people supported than opposed such laws.  Unexpectedly, adding contextual information increased the level of support for the laws.  Interestingly, providing contextual information also increased opposition as well.  This means that it moved people out of the "undecided" category.  Given that there are about 500 people in each group, the margin of error (or sampling error) on these questions is plus or minus 4.4%.  With the 1st group, we can be pretty confident there are more supporters than opponents, but with contextual information, there is a statistical dead heat.  

Cost of Calories and Protein from Meat

Yesterday I gave a talk for some of the world's largest pork producers as part of an event put on by PIC, the world's largest supplier of pork genetics. 

In my presentation, I touched briefly on the environmental impacts of meat production, and showed the following slide, which made the rounds on Twitter yesterday.

I thought a few points of clarification and expansion were in order.  

First, note that Bailey Norwood and I published a paper a few years ago comparing the costs of producing different meats to producing corn, soybeans, wheat, and peanuts (also note that there was a calculation error in the tables; the corrected tables are here). As we show there, it is generally less expensive to get calories or protein from corn or soybeans or wheat than it is from cattle or hogs.   That's one reason we grow such much corn, wheat, and soy - they are incredibly efficient generators of calories and protein.  

I will also note that there have been many attempt to calculate the retail cost of eating "healthy vs. unhealthy" food.  Here, for example, is a paper by the USDA-ERS.  Adam Drewnowski also has several papers on this subject.  This work often shows that meat is relatively  (relative to many fruits and vegetables) inexpensive on a per calorie or per gram of protein basis, although meat looks more expensive when placed on a per pound basis.   If you want really inexpensive calories eat vegetable oil or crackers or sugar; if you want real expensive calories, eat zucchini or lettuce or tomatoes.

The reason I picked lettuce as an example is to make the point that people often do not reason consistently when they argue we should unduly focus on costs of calories.  I have never once heard anyone say how "inefficient" production of lettuce or tomatoes or peppers are, and yet I have repeatedly heard this argument about meat.  

Another important point is that efficiency or cost isn't everything.  What do we get in return?  Who cares if lettuce is really expensive on a $/kcal basis?  A nice salad is tasty.  And healthy.  The trouble is that many of our most efficient producers of calories or protein (field corn, soybeans, wheat) are not that tasty by themselves.  Given the choice to eat a raw soybean or a raw carrot, I'll take he latter any day despite the fact that the latter is "less efficient."  

This discussion reveals another point that Bailey and I discussed in our paper.  To get corn and soy and wheat into foods we like to eat requires processing, which takes energy and is costly.  Thus, one needs to look at the costs of the foods as we eat them not as they're grown.  And, there is generally much less cost wrapped up in the processing of meat and animal products than there is for grain-based products (based on the farm-to-retail price spreads reported by the USDA).

Finally, note that one of the ways we process corn and soybeans into something we like to eat is by feeding them to animals.  Animals convert relatively untasty grains into tasty milk, eggs, and meat.   And even if some energy is "lost" or "wasted" in that process, we're getting something in return.  Here's what I previously had to say about that:

Almost no one looks at their iPad and asks, "how much more energy went into producing this than my old Apple II." The iPad is so much better than the Apple II.  We'd be willing to accept more energy use to have a better computer.  Likewise a nice T-bone is so much better than a head of broccoli.  I'm willing to accept more energy use to have a T-bone than a head of broccoli.    

Pollan and Bittman on GMOs

A good passage by Keith Kloor on the subtle shift by some in the "food movement" on GMOs:

As I have said to Lynas, this kind of turnabout owes not so much to discovering science but more to unshackling oneself from a fixed ideological and political mindset. You can’t discover science–or honestly assess it–until you are open to it. The problem for celebrity food writers like Bittman and Michael Pollan, who is also struggling to reconcile the actual science on biotechnology with his worldview, is that their personal brands are closely identified with a food movement that has gone off the rails on GMOs. The labeling campaign is driven by manufactured fear of genetically modified foods, a fear that both Pollan and Bittman and like-minded allies have enabled.

Kloor argues that 

Now that this train has left the station, there is no calling it back, as Bittman seems to be suggesting in his NYT column.

There may be no calling it back but I suppose we should at least celebrate the fact that celebrity foodies aren't actively at the engine anymore.  Now if I can just persuade Bittman and Pollan on the science and economics that conflict with some of their other pet food causes (including some of the nonsense Bittman spread about organics in the same column where he admits the safety of GMOs) . . .

Do USDA Quality Grades Mislead Consumers?

If you've ever seen the words "Choice" or "Prime" advertising a cut of beef, then you've been influenced by the federal beef quality grading system, which is administered by the Agricultural Marketing Service of the USDA.  From "best" to "worst" the grades are Prime, Choice, Select, and Standard.  

In a paper forthcoming the Journal of Animal Science, Eric and Megan Devuyst and I report the results of a study revealing that the USDA beef quality grading system likely sends confusing and misleading signals to final consumers (which is exactly the opposite of the purpose of the grading system).

The key determinant of quality in current grading system is "intramuscular fat" - the amount of fat inside the muscle of the steak.  Steaks with more fat get higher grades, primarily because of the large amount of research showing that consumers prefer the taste of steaks with more intramuscular fat.

But, do consumers know this?  And do they understand the information communicated by the grade names? Based on results of two nationwide surveys (both with over 1,000 people), we believe the answers are clearly: "No".

Most people thought the grade name "Prime" was the leannest, while also expecting it to be juiciest.  When looking just at the pictures (the same ones shown above but without the names), most people thought the picture of the Prime steak would be the cheapest, and they were most likely to associate the picture of the Prime steak with the name "Select."  

Only 14% of respondents correctly ranked the grade names according to leanness, and only 14% correctly matched the pictures with the respective grade names.  That's worse than random guessing (16.67% would be correct just by pure chance given that people had to match three items).   

We conclude the paper with the following:

if the current grading system fails to adequately inform consumers of the relative quality of grades, there remains the likelihood that consumers’ expectations will be unmet. There are three potential methods for addressing this lack of understanding. First, the current quality grading system could be dropped in lieu of private or third-party systems. . . .Second, an educational program could be  developed to promote knowledge of the link between higher marbled beef and taste. . . . The costs of such an effort, however, are likely to be large, and it is unclear what effects they may have particularly when one realizes the existence of many prior educational efforts that have been undertaken in the 70 year existence of the Prime-Choice quality grade nomenclature. . . . Finally, consumers could likely benefit from more descriptive nomenclature. . . . for example, “USDA Prime—Higher Fat, Most Juicy,” “USDA Choice—Juicy,” and “USDA Select—Less Fat, Less Juicy.” 

You can read the whole thing here.