Food Fads and Fears

I've been reading the book Fear of Food by Harvey Levenstein.  It is a fascinating read, chronicling the history of food fears and fads that hit Americans in the 19th and 20th centuries.  I have a few quibbles with some of the material in the chapter on "Bacteria and Beef", but overall, good stuff.

One passage showed how at least one version of the Paleo diet had been advanced since the early 1900s for many of the same reasons it is advocated today, almost 100 years later:

“In 1920 Fleischmann’s urged eating its yeast cakes because ‘the process of manufacture or preparation’ removed from many foods the ‘life giving vitamine’ that provided the energy people needed. ‘Primitive man,’ it claimed, ‘secured an abundance of vitamines from his raw, uncooked foods and green, leafy vegetables. But the modern diet - constantly refined and modified - is too often badly deficient in vital elements.’”

Levenstein also chronicles the emergence of food scientists and nutritionists who often had significant effects on dietary fads and public policies.  It is remarkable the hubris with which many of these men made dietary advice and public policy, particularly because we now know they were often quite wrong in their scientific knowledge.  Whether it was Metchnikoff and Kellogg and their views on autointoxication and the merits of yogurt, or Horace Fletcher's method of chewing to "Fletcherize" food,  or Harvey Wiley and his war on benzoate of soda, or Elmer McCollum and his promotion of acidosis, or Russell  Wilder's belief that thiamine deficiencies would cause the nation to loose their will to fight the Nazis - there seems to be a continual stream of people willing to use scant evidence to promote their favored cause to promote public health.  Not just idly promote - but with often with righteous indignation and certitude of belief.  I have no doubt many of these men passionately believed the diets they promoted but that didn't ultimately make them right.  

Levenstein writes, in the midst of concern of lack of vitamin consumption in 1941, that

“The New York Times said, ‘The discovery that tables may groan with food and that we nevertheless face a kind of starvation has driven home the fact that we have applied science and technology none too wisely in the preparation of food.””

Unfortunately, something similar could be said about how applied science and technology have often been used none too wisely to promote various public policies and best selling books.   

It is true that science has progressed and we know more than we used to.  One of the things we've hopefully learned is that we often need to exercise a bit of humility.

How should food policy issues be decided?

Not only is it the case that people are likely to differ in their opinions about the desirability of mandatory GMO labeling or soda taxes, but they are also likely to differ in how they think such issues should be decided.  

A while back, I ran across this paper by Gaskell and colleagues published in Science.  They sought to categorized citizens in terms of their attitudes about how technology should be governed by asking two questions relating to whether decisions about technology should be made by 1) experts vs. average Americans and 2) moral and ethical issues vs. scientific evidence on benefits/costs.  

In the latest edition of the Food Demand Survey (FooDS), I applied these questions to five food policy issues.  Unlike Gaskell's work I also allowed respondents to have different answers for different issues.  

The first question asked: “Decisions about food policy should be based mainly on the views and advice of experts OR decisions about food policy should be based mainly on the views of the average American.”  The second question asked: “Decisions about food policy should be based mainly on the moral and ethical issues involved OR decisions about food policy should be based mainly on the scientific evidence of risk and benefit.”  Then five food policy issues were listed in random order: labeling of genetically modified food, use of growth hormones, legality of selling raw, unpasteurized milk, use of the term "natural" on packaging, and the tax charged on sugar sodas.

Here's what we found.

More than 70% of respondents wanted policy decisions related to GMO labeling and use of growth hormones to be based on expert advice rather than the views of the average American. I find that result rather striking in light of the fact that opinion polls show large numbers of people saying they want GMO labeling.  Here, we see that a large majority thinks this sort of issue should NOT be decided by the views of the average American.  That would seem to imply that folks do not think GMO labeling should be settled by ballot initiative.  

In stark contrast to the other food policy issues, almost 70% wanted decisions about soda taxes to be based on the views of the average American rather than the "elites".  

Recall that we also asked about whether decisions should be based on morals and ethics or based on scientific evidence on risk and benefit.

For three issues, milk pasteurization, hormones, and GMO labeling, the majority thought decisions should be based on science.  There was a split on natural labeling.  For soda taxes, the majority thought moral issues should be the deciding factor.

As with the prior research, we used the answers to categorized people into one of four categories for each of the five food policy issues.  “Scientific elitists” wanted policy decisions made by experts on the basis of scientific evidence, “moral elitists” wanted policy decisions based made by experts on the basis of moral issues, “scientific populists” wanted the average American to make decisions on the basis of scientific evidence, and “moral populists” wanted the average American to make decisions on the basis of moral issues.

A plurality of respondents were "scientific elitists" for GMO labeling, use of growth hormones, and legality of selling raw milk.  The same was true for use of the term "natural" on labeling, but there was a larger share of "moral elitists" in regard to this issue than for others.  Finally, for soda taxes, "moral populists" described the largest share of respondents.

A natural question is whether these categories explain people's attitudes about the food policies.  Gaskell et al. showed that "scientific elitists" in regard to general technology were the majority citizen type in their surveys and this type had more favorable attitudes toward biotechnology and nanotechnology than other consumer types - particularly moral populists.

I find something similar here as well.  Take for example, the 4-category breakdown on GMO labeling.  I find that "scientific elitists" on GMO labeling express the lowest level of concern about eating GMOs (an average score of 3.06 on a 1 to 5 scale of concern), whereas "moral elitists" and "scientific populists" had scores of 3.41 and 3.43.  Moral populists averaged 3.34.  There also seems to be a political dimension to people's views about how these food policy issues should be decided.  For example, scientific elitists and scientific populists were slightly more conservative (about 3.05 on a 1 to 5 scale of liberal to conservative) than were those who focus more on moral/ethical issues (score of about 2.9 on the scale).  Those identifying with the Democratic party were more heavily represented in the "moral elitist" category than they were in other categories.  

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.

More on Soda Taxes

The Huffington Post just ran a piece I wrote in response to prior post in the same outlet by a doctor advocating for soda taxes.  Here are some excerpts: 

Jeff Ritterman, Vice Present of the Board of Directors for his local chapter of the Physicians for Social Responsibility recently wrote on The Huffington Post that we should "Tax a Cola, Save the Planet."

I've read lots of editorials advocating soda taxes, but this one beats them all in promising what a soda tax will deliver. He argues that:

"A simple policy change like the Soda Tax can help us waste less water, lower our GHG production, and lessen the pollution of our air, water and soil. At the same time, it can fund vital programs in our schools, parks and neighborhoods to improve nutrition and physical education opportunities for our children. It's a win-win-win: a win for the environment, a win for our children, and a win for our communities."

Wow, one tax will do all that! H.L. Mencken reportedly said that "for every complex problem there is an answer that is clear, simple, and wrong."

After discussing the literature showing how price changes and soda taxes cause people substitute toward other beverages and foods, I argued:

Ritterman argues that a soda tax will results in less soda being consumed, and he's probably right. But does that mean that there will be less water and less aluminum consumed? Well, it depends what consumers drink and eat instead of soda. If people instead drink more milk or more beer, as previous studies have suggested, will water consumption really be cut? If more cows are needed to produce more milk due to the increased demand caused by soda taxes, will greenhouse gases really fall?

Ritterman is right to suggest that enacting a soda tax can raise revenue for the government. But, that hardly makes it an economically efficient thing do. A tax is akin to reducing in one's income. No one likes having less income. Using taxes to direct people to buy goods they didn't purchase before the tax cannot make people better off. 

Real-world effect of soda taxes

A new study in the journal Health Economics by Jason Fletcher and coauthors examines whether variation in soda tax policies across states leads to differences in weight and obesity.  

First, the authors note previous work on the issue:

studies using data on individual-level consumption and within-state variation in actual tax rates have found no net measureable effects on population weight. For example, Fletcher et al. (2010a) find that increases in soft drink tax rates decrease soda consumption among children, but do not influence total caloric intake, as children increase their consumption of other high-calorie beverages. This finding is consistent with a similar lack of effects for adults (Fletcher et al., 2010b). Other research taking this approach finds mixed results, demonstrating that average weight in some high risk populations may be more susceptible to soda taxes (Sturm et al., 2010).

Then, they point out a potential problem with this line of research: the variation in tax rates across locations isn't large enough to tell us what will happen if a state passed a "large" soda tax - or whether there are "non-linear" effects:

one concern with the ability of the results from some previous studies to predict the consumption response to large taxes, such as the 18% tax proposed in New York in 2008, and a potential reason for the differences in the results from the various strands of literature is that the existing soda tax rates are too low to be meaningful to most consumers because the average tax rate in 2006 was approximately 5% (Sturm et al., 2010; Todd and Zhen, 2010). Implicit in this argument is that substitution effects would also exhibit a threshold effect, where at high enough soda tax rates, individuals would substitute towards no beverages or low-calorie alternatives (e.g., water).

What did they find?

First, we examine whether there is any evidence of non-linear effects of current soda tax rates, with the idea that if very large taxes could have relatively larger effects, then we should see evidence consistent with this hypothesis based on the larger tax rates in our data, which reach 12%. However, using a variety of specifications, we find no evidence of effects on use or weight for a nationally representative sample of adults.

Our second approach uses a new comparative case-study method that leverages the sudden and large tax increase found in Ohio in the early 1990s. This method creates a ‘synthetic Ohio’ based on a weighted average of states that are most similar to Ohio’s population BMI before the tax was raised. Outside of simulation methods, this is the most informative approach to understanding the potential impact of recently proposed taxes, and it suggests very little evidence that the large tax imposed in Ohio had any detectable effect on population weight. Together, our results cast serious doubt on the assumptions that proponents of large soda taxes make on its likely impacts on population weight.