A recent consultation by the UK Department of Health about food labelling has drawn attention to two long-standing issues, both relating to food energy and the calorie.
In May 2012, the Department of Health (DoH) launched a UK wide consultation about front of pack (FoP) food labelling. The consultation is now closed, but details may be found on the DoH web site, FoP consultation.
UK health ministers want to see all food manufacturers and retailers using the same system to show – on the front of packs – how much fat, salt, sugar, and how many calories (the ministers’ words, not mine) is in the products. Readers will be familiar with both the ‘traffic light’ system used by, for example, Sainsbury’s, Waitrose and the Co-op, and with the rather more obscure GDA system used by other supermarkets and certain brands such as Kellogg’s.
UKMA responded to the consultation, supporting consistency of FoP labelling as valuable aid for consumers wishing to compare food products at the supermarket, nationally, across the EU and internationally. However, we suggested that two other issues relating to food labelling deserve attention:
1. The use of the word ‘calorie’ to mean food energy. After all, we don’t say we are going to the DIY superstore to buy square metres when we mean flooring, or to the street market to buy kilos when we mean potatoes.
2. The continuing use of calories, kilocalories (kcals) or Calories to measure food energy, in preference to the SI unit, the joule.
The unsatisfactory nature of the calorie to measure food energy has been recognised for some time. The calorie was developed by the British Association for the Advancement of Science and introduced in 1873 as part of the centimetre-gram-second (cgs) system of measurements. However, it was soon realised that these units were too small for most practical purposes. One of the specific problems with the original calorie was its inconsistency across a range of temperatures – a calorie at a low temperature was larger than a calorie at a higher temperature.
When further development of the cgs system of units was considered in 1889 (yes 1889!), the calorie was replaced by the joule as the single unit of energy for all activities. Unfortunately, the calorie had by then become well established in the fields of diet and nutrition.
Hitherto, UKMA has taken the view that the use of the calorie should be avoided, and that internationally agreed standards and best practice should be used whenever possible. However, at this stage in the UK’s prolonged metric transition there may be something to be said for seeing the calorie as a friend not an enemy:
• It is certainly metric, if not SI.
• It has no Imperial rival – no one would dream of measuring food energy in foot-pounds or in British thermal units.
• It is still widely used around the world, particularly in countries which formerly used the cgs system and in the USA, but also in some newly metricated countries too.
One the other hand, the joule has been successfully adopted for measuring food energy to the exclusion of the calorie in, for example, Australia and New Zealand, and the continuing use of the calorie by the British public while scientists use the SI alternative is likely to add to the divide between the two.
Clearly issues relating to the calorie are unlikely to be resolved any time soon. UKMA’s measurement units style guide suggests ways of dealing with them in the mean time.