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Study Claims Lettuce Causes More Greenhouse Gases Than Bacon

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Study Claims Lettuce Causes More Greenhouse Gases Than Bacon

In a new study that’s sure to cause some controversy and lots of debate, Carnegie Mellon University (CMU) have found that eating a vegetarian led diet could actually be just as harmful for the environment as eating some meats.

In a shocking claim, the study - published in the Environment Systems and Decisions journal, says that eating an ingredient like lettuce is “over three times worse in greenhouse gas emissions than eating bacon”.

The study looked at specific ingredient calories and how their overall life cycle, from growing in the field to eventually being stored in the home, impacts on the environment.

They focused on healthier foods that were recently recommended by the US Department of Agriculture (USDA) and Paul Fischbeck, co-author of the study, said: “Lots of common vegetables require more resources per calorie than you would think. Eggplant, celery and cucumbers look particularly bad when compared to pork or chicken.”

The research modelled three different styles of diet: one with less calories consumed, one by maintaining normal calorie intake and eating only the healthy foods on the USDA’s recommended list and the final diet involved cutting meat entirely and reducing calories.

The Results

Calorie Reduction - this diet would cut combined emissions and also cut energy and water use by around 9 per cent.

Just Healthy Foods - this increases energy use by 43 per cent, water use by 16 per cent and emissions by 11 per cent.

Cutting Meat and Calories - increases energy use by 38 per cent, water by 10 per cent and emissions by 6 per cent.


The study shows the complex relationship there is between making healthy eating choices and the effect that these choices eventually have on the environment.

It stands against the argument that switching to the new healthy diet recommended by the USDA would actually increase a person’s impact on the environment.

What it doesn’t seem to consider are different production methods for vegetable, new tech that can massively reduce the impact of farming or local social growing initiatives that reduce the impact of transportation, packaging and storage in the supple chain. It also doesn’t look at the massive emissions experts say would be lost if meat production was stopped all together - a business that many say contributes some of the largest emissions in any industry.

The Independent spoke with Anthony Froggatt at Chatham House, an independent think-tank that is currently working on research on the link between meat consumption and emission impact and he highlighted just how different the study results could look depending on how foods are actually raised and grown. He also highlighted that this type of research normally focuses on proteins produced, while the CMU study looked at calorie production. He also said that if you study protein and look at replacing meat based proteins with plant based proteins - emissions are reduced.

Whatever way you look at the results, they certainly point towards just how complex it is to make the right choices for your own health and the health of the planet.

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