Bread is important. It's not just important for the nutrition and energy it gives us, which can vary depending on the ingredients in the bread. It's symbolically important.

When we eat with others, we call it "breaking bread." The word companion means "one with whom bread is shared" from the Latin "com" (with or together) and "pani" (bread). In the Bible, Jesus refers to himself as the "bread of life," and the use of that phrase in the ancient book shows that culturally bread was considered essential to life thousands of years ago.

But a new study shows that bread is damaging something else important to us: the environment.

Published in the journal Nature, a study by researchers at England's University of Sheffield looked at the entire supply chain of a loaf of bread, from seed to store shelf, to find out how much each step in the chain affected the environment.

If you think the creation and disposal of the plastic bags bread is wrapped in is the biggest problem, you're wrong. The studied showed that "more than half of the environmental impact of producing the loaf of bread arises directly from wheat cultivation, with the use of ammonium nitrate fertilizer alone accounting for around 40 percent."

The fertilizer used to grow wheat is contributing to global warming, the researchers concluded. quotes one of the researchers, Dr. Liam Goucher, a research fellow from the University of Sheffield:

"We found in every loaf there is embodied global warming resulting from the fertiliser applied to farmers' fields to increase their wheat harvest. This arises from the large amount of energy needed to make the fertilizer and from nitrous oxide gas released when it is degraded in the soil."

The synthetic fertilizers used on the wheat consist of "substances and chemicals such as methane, carbon dioxide, ammonia and nitrogen." The fertilizers are used to produce higher yields from the wheat crop so that bread is inexpensive for consumers while still creating a profit for farmers.

There are over 100 million tons of this fertilizer used globally each year on all crops, not just wheat, and the emissions from the creation of the fertilizer and the release of these fertilizers into the environment are a huge contributor to greenhouse gases.

What can consumers do?

Sliced loaf of bread To reduce your environmental impact, opt for organic bread or find a local bakery that uses locally produced wheat. (Photo: Charoenkrung.Studio99/Shutterstock)

On the personal level, buying bread that's been made from wheat that wasn't grown with these chemical fertilizers is a start. Organic bread is one option, but finding a local bread maker that uses locally produced wheat that's grown organically and naturally is an even better option, if you can find one.

On a global level, it's a much more complicated matter.

Achieving sustainable food security is both a technical and political economic question, researcher and professor Peter Horton told He said it requires interdisciplinary research, which is what the team at Sheffield does.

The research has concluded that this problem is solvable, though. It won't be easy to solve, but there are those out there doing the hard work to do it.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.

What's the environmental cost of a loaf of bread?
If you thought the plastic bag waste from a loaf was a big problem, wait till you find out what's even more damaging.