Legislators potentially stall changes to dietary recommendations

An appropriations bill in the House of Representatives was passed out of the agricultural subcommittee last week.  It contained the following language:

“None of the funds made available by this Act may be used to release or implement the final version of the eighth edition of the Dietary Guidelines for Americans, revised pursuant to section 301 of the National Nutrition Monitoring and Related Research Act of 1990 (7 20 U.S.C. 5341), unless the Secretary of Agriculture and the Secretary of Health and Human Services comply with each of the following requirements:
(1) Each revision to any nutritional or dietary information or guideline contained in the 2010 edition of the Dietary Guidelines for Americans and any new nutritional or dietary information or guide line to be included in the eighth edition of the Dietary Guidelines for Americans—
(A) shall be based on scientific evidence that has been rated ‘‘Grade I: Strong’’ by the 6 grading rubric developed by the Nutrition Evidence Library of the Department of Agriculture; and
(B) shall be limited in scope to only matters of diet and nutrient intake. ”

Not surprisingly, the move has raised the ire of some nutritionists.  Here's one who pushes back by saying

“The type of studies that could produce “Grade 1: Strong” evidence is extremely difficult to do in nutrition science research, because of the realities of studying free-living human beings”

and

“It makes no sense to use different standards for existing recommendations than for new recommendations. ”

So, because it is too hard to get good evidence that goes beyond correlational analysis, we should be permitted to continue to use the voice of the government to promote weak evidence and advise millions of people how to eat?  And, because we've used weak science in the past, we should continue to to use it now?  

I'd ask many of these same people if drug companies should be able to get approval from the FDA for a new drug based on the same types of studies being used to make nutritional recommendations?  If the issue here is standards of scientific evidence, why the different bars of scientific scrutiny in one case vs. the other?

I'm sympathetic to the nutritionist's concerns about politics affecting science, and I don't have a position one way or the other on aforementioned language in the appropriations bill (which may or may not make into law).  Nonetheless, there is a presumption implicit in many arguments that support the recommendations that the scientists are relying on good, compelling scientific evidence.  But, they are people too, after all, as are our elected officials.  Moreover, as I've pointed out before with regard to these guidelines, there is as much value judgement going on here as there is science.  Another challenge is that the authors of the guidelines seem to presume that people will follow - precisely - the recommendations to a tee (rather than, say, substituting meat for more carbs) and will ignore cost implications, but this misses insights from behavioral research on how people will actually respond and substitute.  Most people won't follow the precise recommendations and that should be taken into consideration by the recommendation makers. The fact that we citizens are "free-living humans beings" not only makes the research hard, it should give us pause in expecting too much of high minded regulation.  

Environmental Impacts of Vegetarianism

Given the latest report from the new dietary guidelines committee that recommends less meat eating (see some of my previous discussion on that here), I found this study just published in Ecological Economics by Janina Grabs quite interesting.

Grabs ask an important question that is rarely asked.  If people stop spending money on meat, what will they spend their money on instead?  And, what are the environmental impacts of those other non-meat expenditures?  Using data based on Swedish consumers, she calculates that, at first blush, a vegetarian diet does indeed appear to have slightly smaller energy use and carbon impacts, BUT if you take into consideration what the vegetarians do with the extra money they used to spend on meat, those environmental gains become dramatically smaller.  She calls this the rebound effect.

Here's the abstract:

“Sustainable diets, in particular vegetarianism, are often promoted as effective measures to reduce our environmental footprint. Yet, few conclusions take full-scale behavioral changes into consideration. This can be achieved by calculating the indirect environmental rebound effect related to the re-spending of expenditure saved during the initial behavioral shift. This study aims to quantify the potential energy use and greenhouse gas emission savings, and most likely rebound effects, related to an average Swedish consumer’s shift to vegetarianism. Using household budget survey data, it estimates Engel curves of 117 consumption goods, derives marginal expenditure shares, and links these values to environmental intensity indicators. Results indicate that switching to vegetarianism could save consumers 16% of the energy use and 20% of the greenhouse gas emissions related to their dietary consumption. However, if they re-spend the saved income according to their current preferences, they would forego 96% of potential energy savings and 49% of greenhouse gas emission savings. These rebound effects are even higher for lower-income consumers who tend to re-spend on more environmentally intensive goods. Yet, the adverse effect could be tempered by purchasing organic goods or re-spending the money on services. In order to reduce the environmental impact of consumption, it could thus be recommended to not only focus on dietary shifts, but rather on the full range of consumer expenditure.”

A couple caveats.  First, it is important to notice an important clause to sentence claiming a 16% reduction in energy use and 20% reduction in greenhouse gas emissions - this is the reduction related only to their diet.  In terms of overall impact, I believe these only translate to 1.8% and 4.15% reductions, quite simply because food only makes up a small part of the consumers overall energy use and carbon impact.  Of course, all this relates to the "first round" impacts and ignores the rebound effect, which is the main point of this study.

Second, the later part of the abstract, which suggests that the, "adverse effect could be tempered by purchasing organic goods" is mainly due (if I'm understanding the study correctly) to an income effect NOT because organics have substantively less energy/carbon impacts.  Because organics cost more, that leaves less money for the consumer to spend on other things that would require energy.  You could create the exact same kind of result by simulating a person who bought and ate less food, and then took all the dollar bills that were saved, and burned them.  This little thought experiment ought to reveal that the goal in life is not to minimize energy use per se, only to reduce it to the extent that you're not taking into account the impacts on others that are not already reflected in the market price.

None of that should distract from the overall important message of this study: that we need to look at all the effects (even unintended ones) when trying to look at policies that encourage people to change dietary habits.  

A comedian's take on contract poultry farming

On the HBO show Last Week Tonight, comedian John Oliver (formerly with the Daily Show on Comedy Central) weights in on the issue of contract poultry farming.  His piece is a take-off of the themes in Christopher Leonard's book, The Meat Racket (which I critically reviewed here).  

Here's the episode, which already seems to be garnering quite a bit of attention. 

Update on Meat Prices

It's been a little less than a year since I last weighed in on the change in  meat prices.  So, what's been happening?  

Below is a graph of retail prices from the  Bureau of Labor Statistics over approximately the last five years (from January 2010 to February 2015).

Beef prices (ground beef and steak) have continued their rise, while pork products (pork chops and ham) have come down a bit off their highs in the summer/fall.  Chicken prices have remained relatively steady.  

It is a little easier to focus in on changes by looking at the following graph, where I've plotted the changes in each meat's price relative to its price in January 2010 (and multiplied by 100).

Compared to five years ago, ground beef prices are 54% higher (an annual increase of over 10%) and steak prices are 43% higher (an annual increase of 8.6%).  Pork chop and ham prices are 30% and 39% higher than they were five years ago despite the recent declines.  Chicken prices today are only about 10% higher than 5 years ago (experiencing annual increases of only 1-2%).  

On at least a couple of occasions (here and here), I've discussed the driving factors behind these price changes, and none of that has really changed.  The fact that pork prices are now falling and beef isn't is likely due to the shorter life-cycle of pork relative to beef.  A sow can produce two litters per year (with about 9-12 pigs/litter) and those baby pigs are big enough for our dinner plates in about half a year.  By contrast, a cow will typically have one calf in a year, and it takes a little less than 2 years before that calf becomes our hamburger.  Both hog and beef producers want to produce more animals to take advantage of the higher prices (a move that will eventually bring down prices), but biological lags mean pork producers will be able to respond more quickly.  

So, when will beef prices begin to come down?  If biological lags are the answer, I'd say wait about a year and a half.    

Controversy over the new dietary guidelines

Yesterday I filmed a piece on Fox Business about the new dietary recommendations and the call to reduce meat consumption to improve health and the environment (I couldn't get the video to embed, but you can view it here).  I suppose I had at least a couple good points to make because the clip was featured for most of yesterday on the main web page for Fox News.  

One of the hosts mentioned a Cambridge study showing that vegetarians and vegans have substantially lower environmental impacts than meat-eating diets.  A written piece at foxnews.com about the recommendations also mentions the same study.  I'm not sure how representative that cited study is.  My own analysis suggests that vegetarians spend about the same amount on food as do meat eaters.  To the extent prices reflect resource use, that stat would suggest both diets are "using up" similar levels of "stuff."  I've also written on the argument that the grain fed to livestock is "wasted."

But, perhaps more importantly, what evidence is cited in the new report of the dietary guidelines committee?  The papers they cite seem to suggest small improvements in greenhouse gas (GHG) emissions and improved health outcomes (but more on that in a minute) from a move to vegetarian diet.  Here are some selected quotes of the review in Chapter 5 part D where quantitative impacts on environment were mentioned (note: there are many other cited studies, some of which suggest higher impacts).

“Peters et al. examined 42 different dietary patterns and land use in New York, with patterns ranging from low-fat, lacto-ovo vegetarian diets to high fat, meat-rich omnivorous diets . . . although meat increased land requirements, diets including meat could feed more people than some higher fat vegetarian-style diets”

and

“Aston et al. assessed a pattern that was modeled on a feasible UK population in which the proportion of vegetarians in the survey was doubled, and the remainder adopted a diet pattern consistent with the lowest category of red and processed meat (RPM) consumers. They found . . . the expected reduction in GHG for this diet was ~3 percent of current total carbon dioxide (CO2) emissions for agriculture. De Carvalho et al. also examined a high RPM dietary pattern with diet quality assessed using the Brazilian Healthy Eating Index.They found . . . that excessive meat intake was associated not only with poorer diet quality but also with increased projected GHG emissions (~ 4 percent total CO2 emitted by agriculture). ”

This one is most interesting references:

“a report from Heller and Keoleian suggests that an isocaloric shift from the average U.S. diet (at current U.S. per capita intake of 2,534 kcals/day from Loss-Adjusted Food Availability (LAFA) data) to a pattern that adheres to the 2010 Dietary Guidelines for Americans would result in a 12 percent increase in diet-related GHG emissions. This result was modified, however, by their finding that if Americans consumed the recommended pattern within the recommended calorie intake level of 2,000 kcal/day, there would be a 1 percent decrease in GHG emissions. ”

My take?  Eating too many calories likely has as much an impact on GHG as eating meat.  Reducing meat consumption would lower GHG emissions, but I would characterize the effects as "small" (3 to 4% of the GHG emissions from agriculture, or likely less than 1% of the total of all GHG emissions), particularly if people move toward pork and poultry, which have far fewer GHG emissions than ruminants like cattle.  Moreover, if we want to improve environmental impacts of livestock production, I think we're likely to get a bigger bang for our buck by improving productivity and researching new ways to reduce impacts than we will be cajoling people to eat less meat (see this paper on the reduction in environmental impact of beef production brought about over the past 40 years due to technological advancement).

What about the health impacts of meat consumption?  It is true that many observational, epidemiological studies show a correlation between red meat eating and adverse health outcomes (interestingly there is a fair amount of overlap on the authors of the dietary studies and the environmental studies on meat eating).  But, this is a pretty weak form of evidence, and much of this work reminds of the kinds of regression analyses done in the 1980s and 90s in economics before the so-called "credibility revolution." 

There have been many, many books written on the topic of whether meat eating is good or bad for you, and I won't try to adjudicate them all here.  However, I will point you to this really interesting exchange (see the comments section) on Marion Nestle's website where she mentions the new guidelines and takes a swipe at Nina Teicholz's book, Big Fat Surprise.  Nina responds, as do her critics.