Food stores such as Tesco and Marks & Spencer have said that they will label products that have been transported by air. But according to the researchers, only around 2% of the environmental impact of food comes from transporting it from farm to shop. The vast majority of its ecological footprint comes from food processing, storage, packaging and growing conditions. So food grown locally could have a considerably bigger footprint than food flown halfway around the world, and consumers who make their choices on air miles alone may be doing more environmental harm, according to the scientists.
"I'm a bit worried about the food miles [debate] because it is educating the consumer in the wrong way. It is such an insignificant point," said Ruth Fairchild at the University of Wales Institute in Cardiff. "Those [foods] could have been produced using pesticides that have travelled all the way around the world. If you just take food miles, it is the tiny bit on the end."A better system, she argues, would be one that considers all environmental impacts from farm to dinner plate. One option is ecological footprint analysis, which takes into account the amount of land needed to provide the resources to produce food, both directly on the farm and indirectly from the energy that goes into growing, harvesting, processing, packaging and transporting it. A food's impact is measured in "global hectares", the notional land area needed to produce it. But she thinks that consumers are not yet ready for ecological footprint labelling and the science behind it is not yet watertight.
To help confused consumers, Dr Fairchild and colleague Andrea Collins at Cardiff University have used the ecological footprint concept to develop a set of eco-diets designed to minimise the impact of food consumption on the planet. Sticking to the diets does not mean eating lentils all day, but the most eco-friendly diet excludes wine, spirits, chocolate, ice cream and most meat. The study is published in the journal Sustainable Food Consumption.
The diets are based on an analysis of the ecological footprint associated with the food consumed by the average Cardiff resident in a week. The three diets are progressively more austere in their ecological footprint, with the most ascetic allowing only foods with a footprint of less than 0.002 global hectares per kilogramme. This meant replacing around one in six food items with less eco-profligate fare which had a similar nutritional makeup . This diet has a 40% lower ecological footprint than the typical Cardiff diet.
Most meat is pushed out of the super-eco-diet because feeding livestock is energy intensive. Cheese is also out because of the large amounts of energy that go into processing it and refrigerating it in storage. The footprint for wine is just too high, while sprits and chocolate have a per kilogramme footprint which is around double the cut-off point. Bread, vegetables, cakes, biscuits, eggs, pork, ham, bacon and milk are all acceptable.
A typical day on the diet
Breakfast: Cereal and milk, tea/coffee (from weekly allowance half as large as normal diet)
or
Toast and jam (or marmalade)
Lunch: Avocado and poached egg with toast
or
Black-eye bean, rocket and pinenut salad
Dinner: Spinach, leek and pinenut risotto with yoghurt.
Fruit salad
or
Pork cassoulet with mustard, honey and cinnamon, served with green salad. Sweet pancakes with jam, honey, tahini, chocolate sauce or yoghurt
Drinks/Treats: Two glasses of beer, pack of fruit pastilles, two Jaffa Cakes
or
One can cola and nine boiled sweets
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