Saturday, May 3, 2008

Does Food Choice Trump Food Miles?

An upcoming article to be published in Environmental Science & Technology Journal will present data that show the choice of food eaten can significantly reduce or increase a family's household impact on climate change. Carnegie Mellon researchers Christopher L. Weber and H. Scott Matthews article expands the perspective of the question asking if reducing "food miles", i.e., consuming locally grown foods versus those transported in from afar, decreases greenhouse gas emissions and thus reduces an individual's and/or family's food-related contributions to global warming.

Their analysis shows that the transportation involved with the distance that food travels produces only around 11% of the average American household's food-related greenhouse gas emissions. They do agree that fruit, vegetables, meat and milk produced closer to home require fewer petroleum-based transport miles than foods brought cross country (or from the other side of the world!) to your table, however, their analysis demonstrates that the large amount of greenhouse gas emissions involved with producing the food matters more than the distance traveled.

The authors also agree with other reports that eating less red meat and/or dairy products will lower food-related climate impacts. They give some examples to put these recommendations into perspective by estimating that a shift to eating an entirely locally grown diet would reduce the equivalent greenhouse gas emissions as much as reducing your driving by 1,000 miles per year, while changing only one day per week's meat and dairy-based calories to chicken, fish, or vegetables would have about the same impact. However, shifting entirely from an average American diet to a vegetable-based one would reduce the same emissions the equivalent of driving 8,000 fewer miles per year. (Wow, I no longer feel like I need to purchase a hybrid car to significantly reduce my personal impact on climate change.)

"Where you get your food from (i.e., where it is grown) is a relevant factor in family food decisions, but what you are eating - and the greenhouse gas emitting processes needed to grow it - is much more important from a climate change perspective,'' said Matthews, associate professor of civil and environmental engineering and engineering and public policy at Carnegie Mellon.

My recommendations would be to buy locally grown and organic food when possible and eat a plant-based diet every day of the week with no more than 2 ounces of meat per day (or equivalent animal protein - see my previous posting for examples). Making a commitment to these food choices (1) supports our local small farmers, local economy, and community, (2) reduces our impact on climate change, and (3) optimizes both our stewardship of the planet and personal health. This sounds like a win-win-win (or more!) situation to me. :-)

The beautiful graphic I used here came from the blog called A Veggie Venture, which has compiled a seemingly endless number of delicious and exciting vegetable recipes (yes, I really do get excited looking at and eating beautiful vegetables!).

One more final thought to consider. A colleague recently reminded me of this Japanese phrase concerning both healthy eating habits and lifestyle.

"Hara hachi bu",

It means to eat until only 80% full to allow space in one's life.

Hmmmmm, I like thinking about the space in my life image. :-) Is this more physical space, i.e., in my stomach or getting those closets and rooms finally cleaned out, space within each day (i.e. time), more days in my life span, or what? What does more space in your life mean to you?

Diana Dyer, MS, RD


Anonymous said...

Hi Diana,

Thanks for featuring the graphic!

I'm curious: If the report suggest that what we eat is more important than where it's grown/raised, why then do you go on to recommend buying local food?

I don't mean this in an antagonistic way, am just curious why. There are so many people who've jumped on the locavore wagon -- it 'feels' good, 'feels' right', for sure -- but doesn't this research suggest that it's not particularly effective (at least for the purpose of affecting climate change)?

Diana Dyer said...


Thank you for the use of your beautiful Local Foods graphics.

Thank you also for your curiosity and question asking me to clarify my thoughts about recommending locally grown foods in spite of the relatively small reduction of greenhouse gas emissions that results from that decision.

Buying locally grown organic foods when possible (i.e., available and affordable) does help reduce greenhouse gas emissions, even if the reduction is much smaller than completely changing what foods one eats irregardless of where they are grown. Additionally, buying locally grown foods has many economic and social benefits for my local community, which I am passionate about promoting.

Using an example from another area of my life, many cancer patients are often asked to choose a treatment regimen from a variety of possible options by balancing potential benefit (i.e. the pros such as long-term survival, short-term survival, improved quality of life, etc, etc) versus risk (i.e., the cons like difficult side effects, costs, distance and frequency of travel to a treatment site, etc, etc.). In many situations, these treatment options may offer potential benefit that is only a few percentage points higher than another. After thoughtful information gathering and consideration, cancer patients may choose a treatment regimen that permits them to "give it their all" even if that regimen only increases the odds a few percentage points and is in spite of the potential side effects or other hardships associated with that treatment as they work to give themselves the best chance possible for long-term survival.

I have used this same thought process as I think about how my personal lifestyle options may affect the long-term health of our planet, the global community (I have not even touched on how our personal food choices in this country are impacting world hunger in this posting), my local community, and my personal health. I feel deeply committed to "doing all I can". Every person will have a different level of commitment, and I respect that, but I do hope everyone will care enough about the impacts of their food choices to find a way that they can do more than they are currently doing to reduce greenhouse gas emissions.

I suspect that I have even more to say about this topic :-), so I do encourage questions. I cannot promise to respond to all of them directly, but I will think about them and try to incorporate my thoughts into future blog postings.

I will sign off this lengthy comment with the "sign off" that a colleague uses on his posts to the listserv for the Hunger and Environmental Nutrition Dietetic Practice Group of The American Dietetic Association:

Unless someone like You cares a whole awful lot, nothing is going to get better. It's not.
-Dr. Seuss

Thanks again for caring enough to ask your question!

Diana Dyer, MS, RD

Anonymous said...

Somehow I just knew there'd be a long and much-thoughtful answer. Many thanks!