Japan has the lowest food self-sufficiency of any industrialised country and therefore pays a huge cost, financially and environmentally, just to get the food it eats to the table. But the government has committed itself to addressing the situation. Michael Fitzpatrick reports.

Again this year, the Japanese government has called for urgent measures to increase the country's self-sufficiency in food production. Some commentators suggested the move was a patriotic gesture by a right leaning government that doesn't believe Japan can boost its self-sufficiency beyond even 50%, from its current level of 40%, the lowest of any industrialised nation.

However, the policy shift is not just about placating the nationalists or the legions of farmers the ruling party relies on to stay in power. Japan seriously needs to curtail its food imports for other reasons than simply the fear of dependency. For Japan, the far more pressing concern is the cost of its food in energy usage, energy that resource-poor Japan simply doesn't have.

A shift to self-sufficiency would be bad news for the countless food producers who export to Japan but good news for environmentalists and a strapped government too reliant on imported energy.

With only 40% food self-sufficiency, compared to 74% in the UK, Japan is a massive net food importer, which means it spends a colossal amount on getting the 60m tons of food it imports annually to its shores. The environmental impact has been equally great. In fact, the country enjoys the dubious honour of being placed at the top of the 'food mileage' list year after year.

"Food mileages" are calculated by multiplying the transportation distance with the volume of food shipped, giving a figure in ton-kilometres. A country's food mileage can also be calculated and compared on a per capita basis. In these terms, Japanese food consumption is more than twice that in the UK, at 7,093 ton-kilometres per capita against 3,195 ton-kilometres per capita. The average food item sold in the US travels about 2,000 kilometres, but in Japan the same item travels six times as far.

Japan is therefore 'eating' more oil along with its meals than any other OECD member - an untenable position for a country that likes to pride itself on its energy efficiency and green credentials. It is, after all, the home of the Kyoto Accord.

Nevertheless, the average Japanese family of four creates about 16 tonnes of CO2 a year from the production, processing, packaging and distribution of the food they eat. That's the same amount produced by the family's home and transport added together.

So as top of the charts in terms of energy use for food and possible global warming in CO2 output, news of cuts in Japan's food imports should be good for the planet, good for the Japanese government's bottom line, and good sense.

Unfortunately, the Japanese government is less forthcoming on how it will achieve its goal of reduced import dependence. Japanese consumers already pay some the highest prices for food in the world, and its protected rice market means high prices for Japanese rice farmers, but an agricultural economy that is too geared to producing one crop.

Cutting its food miles will be Japan's biggest trade challenge to date. Yet if it does succeed in implementing this overvaulting ambition towards greater food independence there could be lessons for other countries in how to go about it. The world will be watching to see if the greatest polluter when it comes to getting dinner on the table can really turn the tide.