Feb 12 (Reuters) – A nutritious diet that includes lots of
fruits and vegetables might be healthier for humans but not
necessarily healthier for the environment, according to a French
study.
After analyzing the eating habits of about 2,000 French
adults, and the greenhouse gas emissions generated by producing
the plants, fish, meat, fowl and other ingredients, researchers
concluded in The American Journal of Clinical Nutrition that
such a diet might not be the greenest in environmental impact.
“When you eat healthy, you have to eat a lot of food that
has a low content of energy. You have to eat a lot of fruits and
vegetables,” said Nicole Darmon, the study’s senior author from
the National Research Institute of Agronomy in Marseille,
France.
Growing fruits and vegetables doesn’t produce as much
greenhouse gas as raising cattle or livestock, but food
production – including the use of farming equipment and
transportation – is estimated to be responsible for 15 percent
to 30 percent of greenhouse gas emissions in development
countries, the authors said.
Scientists have long advised people to switch to a
plant-based diet to benefit the environment and their own
health.
To more closely examine that premise, Darmon and her
colleagues used food diaries from 1,918 French adults to compare
the nutritional quality of people’s real-world diets and how
much greenhouse gas they produced.
From the diaries that were kept for seven days between 2006
and 2007, the researchers identified the 400 most commonly
consumed foods. They then used a database to find out how much
greenhouse gas was emitted to produce each one, measured as the
grams of carbon dioxide equivalent per 100 grams of food.
All aspects of a food’s lifecycle were taken into account,
including how it was cooked, Darmon said.
“The only step that wasn’t taken into account was the
transport from the supermarket to the home,” she added.
Overall, about 1,600 grams of carbon dioxide were emitted
for every 100 grams of meat produced. That’s more than 15 times
the amount of greenhouse gas emitted during the production of
fruits, vegetables and starches and about 2.5 times as much
greenhouse gas as that from fish, pork, poultry and eggs.
That gap narrowed, however, when the researchers looked at
how many grams of carbon dioxide were emitted per 100
kilocalories (kcal) – a measure of energy in food.
The most greenhouse gas – 857 grams – was still emitted to
produce 100 kcal of meat, but only about three times the
emissions from a comparable amount of energy from fruit and
vegetables.
Greens also ended up emitting more gas for the calories than
starches, sweets, salty snacks, dairy and fats. It was also
about as much gas as pork, poultry and eggs.
When Darmon and her colleagues looked at what people
actually ate to get a certain amount of energy from food every
day, they found that the “highest-quality” diets in health terms
– those high in fruit, vegetables and fish – were linked to
about as much, if not more, greenhouse gas emissions as
low-quality diets that were high in sweets and salts.
Overall, the documented diets were responsible for around
5,000 grams of greenhouse gas emissions per day per person.
Darmon said that’s because people who eat a plant-based diet
need to eat more produce to get the amount of energy they’d have
in a piece of meat.
Roni Neff, the director of research and policy at Johns
Hopkins Bloomberg School of Public Health’s Center for a Livable
Future, cautioned against taking the findings too literally. For
example, according to the study’s calculations, people would
need to eat about four kilograms (nine pounds) of fruit and
vegetables to make up for a smaller serving of meat.
“I think they’re raising a lot of important questions that
need further investigation,” she said.
SOURCE: http://bit.ly/W1KW2y
(Reporting from New York by Andrew Seaman at Reuters Health;
editing by Elaine Lies)
