LOS ANGELES, July 18 (UPI) -- In a ranking of foods by environmental impact, lamb, beef and cheese generate the most greenhouse gases, a study says.

The Meat Eater's Guide, based on research by the Environmental Working Group, ranked 20 popular meat, fish, dairy and vegetable proteins, using a cradle-to-grave, life-cycle assessment that includes the amount of fertilizer used to grow animal feed, as well as information on processing, transportation and disposal of each food, the Los Angeles Times reported Sunday.


"There's been a lot of information out there about all the various impacts of meat production and consumption," EWG senior analyst Kari Hamerschlag said. "We wanted to consolidate and highlight the most important things consumers need to know to make better choices."

Livestock such as sheep and cows "release substantial amounts of methane," a greenhouse gas 25 times more powerful than carbon dioxide, the study said.

The study measured the carbon footprint of each food, equating it to equivalent car miles driven.

Eating a 4-ounce serving of beef, for example, generates the same amount of greenhouse gas emissions as driving a car 6 miles, the guide said.

While the study acknowledges the healthy proteins and other nutrients provided by meat when consumed in moderation, it cited a 2009 National Cancer Institute study that found people who ate the most red meat were 27 percent more likely to die of heart disease than those who ate the least.

"Most people in the U.S. eat way more meat than is good for them or the planet," TV chef Mario Batali said in endorsing the guide.