Most people don’t change their lifestyles or eating habits quickly. A few weeks ago a World Cancer Research Fund poll found only one in five consumers claimed to be following the five-a-day regime, virtually the same proportion as a decade ago. The reason isn’t hard to find. Some years ago IGD reported that most consumers only changed their diets when something happened to them as individuals - a fright or a warning.

So what are we to make of claims by Dr Sally Uren of Forum for the Future (Letters, 4 August) that public support for “fair” producer prices and the continuing growth of Fairtrade sales reflects a growing consumer interest in “reconnecting with their food”? Not a lot.

“Fairtrade sales may be growing but the volume is very small”VER6

Simply because one in five said they would change where they buy their milk to support farmers doesn’t mean they actually will. Claiming is easy - doing it is something else. Fairtrade sales may be growing but the total volume is still very small. Yes, there is a relatively small minority whose buying decisions are influenced by moral considerations but other factors - taste, consistency and branding - may push them in the same direction.

Then we get into the minefield of “fairness”. A profit margin at any stage of the supply chain is fair if the owner of the business thinks it is relative to what businesses elsewhere in the chain are thought to be making. Scale, efficiency, brand strength and bargaining power determine prices and margins in a competitive market. Any attempt to increase producer prices as a whole above their market level would not only require a consensus among retailers and processors but also collective action to deliver and sustain it - obviously impossible under competition law.

Nor is there much point in decrying the consumer’s demand for “cheap” food. What’s the alternative? Food prices that the moral minority can afford but most others can’t? And who says our food system isn’t sustainable? For centuries in this country, millions were under-nourished or starved. Now the vast majority eat well - even if they don’t manage five a day.