Trade Talk

The Dispatches programme, aired on Channel 4 on January 10, accused processors of understating salt and fat levels in foods. Ready meals were a chosen example. If the producer had ever done any cooking, they would know it's impossible to ensure every portion of a stew, say, has precisely the same amount of every ingredient. One spoonful may have 10 beans, another may have two. As for fat, have they tried to mix the stew very quickly and serve it out before the fat separates out? It can't be done. Each portion will be different. But, if you eat the same meal regularly, ingredient levels should even out over time. Accurate nutrition labelling is extremely difficult for many foods.

In the 1980s, when voluntary nutrition labelling first came in, Marks & Spencer was challenged by local trading standards for having more fat in an egg mayonnaise sandwich than the label stated. The retailer got very cross, threatening to opt out of nutrition labelling if it was convicted under the law for over-filling sandwiches. It won.

This all raises the question: is it more helpful to consumers to have some nutrition labelling rather than none? It seems the manufacturer can't win. It's better to have some idea about what's in your food than no idea, even though what the manufacturer puts in the mixing bowl isn't necessarily what comes out in every portion. If salt is being reduced, you obviously want people to notice, so there's little incentive to mislead.

Bacon or canned fish are other examples of foods where salt levels can vary substantially. When bacon is cured, the salt penetrates to different levels throughout the lump of dense meat muscle. A rasher cut from the centre may contain less salt than one from the outside. Similarly, the outer parts of tuna - frozen at sea in brine - are saltier than the inner core.

Premium muesli may well contain more fat and sugar than economy brands, because it contains more fruit and nuts. That's why GI diets recommend making your own muesli rather than buying ready-made. You can count the nuts in the former, but life's too short to divide shop-bought muesli's constituent parts into equal portions.

We should also ask which analysts Dispatches used for its sampling. Different analysts' results can vary as much as the food. When you heap variability on top of variability, the chances of an accurate result are significantly impaired.

Clare Cheney​​ is director general at the Provision Trade Federation​