How far does your food have to travel to hit your dinner plate? Not so long ago for most of humanity, the majority of our food came from areas we could walk to or at least from within our own countries. These days, our food is increasingly from many thousands of miles away.

It's amazing that we can enjoy many foods out of season and at relatively low cost; but the price paid in terms of environmental damage can be very high.

The environmental impact is mainly related to freight and shipping - more trucks, more planes, more ships, more consumption of oil and more greenhouse gas emissions. Also, food imported from some countries may have been grown in very unsustainable ways; for instance, rainforests may have been cleared, toxic processing effluent released into the environment, inappropriate use of pesticides and herbicides applied to crops.

The food mile problem is an increasing one in the western world. In a report from the UK Department for the Environment, Food and Rural Affairs, it was stated that food miles increased by 15% cent between 1992 and 2002. 95% of fruit and 50% of the vegetables in the UK are imported.

According to a report on the Australian Conservation Foundation web site, the energy used to import food often outweighs the energy value of the food itself. The ACF states that it takes around 1,000 kilojoules of energy to ship 170 kilojoules worth of strawberries from Chile to the United States. The food for an average meal for a North American has travelled well over a thousand miles and possibly many times higher if the meal contains out of season fruits or vegetables. It's simply not a sustainable approach to our diets.

Take a look in your cupboard and freezer and you may be surprised as to how many food items you think are locally grown aren't sourced from within your own country. For example, while preparing a pizza the other day, I noticed the anchovies were from Morocco and the prawns from Thailand. We have sustainable anchovy and prawn industries here in Australia.

Cost is a major factor for many people when buying food, and I'm very much a cost conscious shopper, but I've been increasingly examining my purchasing habits and trying to make some changes to a more sustainable diet. A recent change has been coffee; not just because of the environmental food miles aspect, but also related to fair trade.

My previous brand of coffee was grown in Brazil. That's a distance of nearly 9,000 miles (over 14,000 kilometers) as the crow flies. I switched to a fair trade brand from East Timor - under 2,000 miles - around 3,200 kilometers. Just to illustrate the difference:

Distance comparision between the origins of my old brand of  coffee
 (Brazil) and new brand of fair trade coffee (East Timor)

I may even take it a step further and only buy locally grown coffee in the future.

For years now in my country, trade associations have been encouraging to buy local. The reasons they usually give relate to quality or supporting local industry - a very strong patriotic approach. An important aspect they tend to leave out in their marketing campaigns are the environmental, sustainability and food mile aspects mentioned above. The introduction of these issues could be enough to get many more people buying more local products. If you're a local producer, introduce these elements into the marketing of your own goods.

Try to buy local where you can - even if it's just one or two more products that you regularly use. Read labels on cans and learn more about what foods are in season within your country and try to utilize those more as there will be less chance of you accidentally purchasing imported foods. Bear in mind also that out of season foods grown locally may require huge amounts of resources for production e.g. the heating of greenhouses.

Better still, consider starting a vegetable garden for your back yard; greatly reducing your food miles from thousands of miles to a few feet - plus saving you money!

Every little bit helps!