Image from Orhan’s FLickr photostream.

The supermarket is an increasingly baffling place. Walking round Sainsbury’s at the weekend, I realised that my internal monologue has shifted over the years. No longer do I approach a potato or bag of coffee and think ‘oo, that looks nice…and the price is right. I’ll buy it!’. Now I’m assailed by any number of variables.

Too many calories? Suitable for vegetarians? How much sugar? Shall I get the organic version? Can I recycle the packaging? Does this count towards my ‘five a day’? Was it ethically produced? How many reward points will I get? Has it been genetically modified? Was it grown locally? Thank goodness I don’t eat meat, am not allergic to peanuts, and have no religious stipulations on my diet.

To make things worse, few of the above are black and white decisions. There is still widespread disagreement about the benefits of organic food. What counts as a ‘portion’ of fruit and veg? And how long can I stand here pondering whether shrink-wrapped apples from the UK are better than loose ones from Italy before the person waiting behind me starts tutting?

It’s no wonder our foods require so much packaging. Pretty soon every packet of rice will come with a background essay and 20-page appendix of supporting information. No doubt written in 40 languages so as not to exclude anyone.

It’s a mess, and it just got messier. A story in the Guardian today suggests that ‘food mile’ labels, that latest encumbrance upon the ethical shopper’s conscience, are useless as a measure of carbon footprint. A potato might be grown locally, but the pesticides, equipment and packaging could be sourced from all over the world. The carbon impact of getting the food from farm to shop is only 2%.

So labelling something as ‘grown in the UK’ is meaningless. But then giving the consumer all the facts is only going to cause confusion over what matters.

Please can someone work out one of those wacky scientific formulas? One that pools all the ethical elements in my second paragraph and churns out an overall score? The Annals of Improbable Research are full of calculations that tell us how to make the perfect cup of tea, or find the ideal partner. So why not a formula that can absorb all these variables and compute an overall ‘goodness’ score?

I don’t want to weigh up 10 considerations, over 50 different products. I’m lazy. If the own-brand custard creams score 73% while the McVities version achieves 85% that makes my decision easy. And it would put pressure on producers to make their goods more ethical to boost that percentage.

So, amateur mathematicians, get your (Fair Trade) thinking caps on.