lettuce bacon


Is lettuce really worse for the environment than bacon? That’s what the latest headlines say, based on findings from new research at Carnegie Mellon University in Pittsburgh.

Allegedly, lettuce produces more greenhouse gas (GHG) emissions than unhealthy foods like bacon. The media have gleefully proclaimed, based on this study, that vegetarian diets are bad for the environment.

But that’s not what the study showed. It’s not even what the study looked at. It looked at what happens when people eating a usual American diet shift towards a healthier eating pattern as defined by the USDA. And what happens is that the environmental benefits of eating less red meat are offset by the greater GHG emissions associated with dairy, seafood, fruits and vegetables—all foods recommended as part of this healthier eating pattern.

The researchers said this:

 Dairy, by far, has the greatest impact on increased GHG emissions because it has the third highest emissions intensity value, which is then compounded by USDA recommendations for substantial increases in dairy. Fish/seafood is the second most driving force behind increased GHG emissions. While recommended intake of fish/seafood is low relative to fruits and vegetables, the emission intensity of fish/seafood is significantly higher.”

In short, replacing red meat with dairy and fish is not good for the environment. The study didn’t look at what happens if people replace red meat with grains, beans and soyfoods. Nor did it look at vegetarian diets. The investigators did, however, acknowledge that other research shows that adopting a vegetarian diet reduces water footprint and GHG emissions. In fact, they noted that a vegetarian diet is more effective than usual healthy eating patterns in this regard.

So what about the lettuce versus bacon comparison? It’s pointless. Even if lettuce is associated with greater GHG emissions than bacon on a per calorie basis, this isn’t relevant to vegetarian diets or any other kind of diet since nobody is packing in calories from lettuce. You would have to eat 16 cups of iceberg lettuce to match the number of calories in three strips of bacon.

But there is a little bit of a problem here for animal activists. Because vegans sometimes play the exact same game. How often have you seen infographics and memes showing that broccoli, spinach and even parsley are more protein dense on a caloric basis than beef?

Parsley? Seriously? Yes, it has a fair amount of protein per calorie, but you’d need to eat 16 cups of raw chopped parsley or 8 cups of cooked broccoli to get the amount of protein in three ounces of steak. That doesn’t sound like a very useful comparison to me. In fact, it sounds about as useful as comparing GHG emissions between lettuce and bacon.

And while we might rightfully complain about the way in which the media misrepresented findings from this study, it’s not as though vegans never do the same thing. Just last month my Facebook feed was packed with memes and links suggesting that processed meats are as carcinogenic as cigarettes, an assertion that misrepresented a report from the World Health Organization.

I know that many vegans are not doing this intentionally. It’s hard to evaluate all of the health information that flies around the internet, and to determine what is accurate and what isn’t. But in the face of that difficulty, we do need to use some care in how and what we share regarding vegan diet and health. Because vegans cannot challenge biased interpretations and misinterpretations of research or irrational conclusions about nutrition if we do the same things ourselves.

We can’t speak out against bad science that hurts the image of veganism if we use bad science to promote veganism. We need to approach the research on diet and health—and on the environment—with the utmost integrity. Then, when the media and others make ludicrous claims that hurt the image of veganism, we can respond from a position of strength.