The very worthy proposal of the Food Standards Agency (FSA) that menus should state energy values is undermined by its failure to use proper measurement units.  UKMA has responded by advocating joules rather than so-called “calories” (whatever they may be).

Consultation closes today on the FSA’s proposal that restaurants (including fast food bars) should state the energy value of the food on their menus.  The purpose of this proposal would be to enable customers to relate their energy intake to their daily energy requirement – an important factor in leading a healthy lifestyle.  (In principle, if your energy intake exceeds your energy use you will gain weight – and vice versa.)

The catering industry has been wary of this proposal (not least because many fast food outlets rely on people eating unhealthily!) and the FSA’s proposal is for a voluntary rather than a statutory scheme.  It would be difficult if not impossible to enforce against the thousands of individual fish and chip shops and Chinese or Indian takeaways, so it is mainly targeted at the chains of fast food restaurants that populate every High Street, shopping mall, and motorway service station.

In its submission to the FSA, UKMA has not commented in detail on the (obviously laudable) principle of including energy values on menus, but has recommended that any scheme that is agreed with the industry should use proper measurement units that are compatible with those used in nutritional science.  In particular it has advocated the use of the joule (J) as the primary (or preferably the only) measurement unit rather than the obsolete and unsatisfactory “calorie” – or “kilocalorie” – or “Calorie”.

Unfortunately, the FSA consultation paper set a very poor example by equating the physical concept of “energy” with the misused word “calorie” – for example, writing “calorie intake” rather than “energy intake”.   This is in direct contradiction to the recommendation of the Royal Society – as long ago as 1972 – that “calories” should be discontinued – including in the media.

We give below an extract from UKMA’s submission (text in blue):

“The use of the kilojoule (kJ) vs. the use of the calorie (cal), Calorie (Cal), and kilocalorie (kcal)

We applaud the principle of giving consumers the ability to make purchasing decisions based on the energy content in food. However the consultation document’s proposed continued use of obsolete measurement units presents several issues:

The “calorie” is often confused with, or used in equivalence to, the “kilocalorie”.

A convention is sometimes applied which attempts to avoid the inevitable misunderstanding that this causes. This involves the use of a capital letter ‘C’ when “calories” are to read as “kilocalories”, such that:

1000 calories = 1 kilocalorie = 1 Calorie

Indeed, the consultation document itself is a good illustration of this issue as it uses the word “calorie” erroneously in several instances where the word “kilocalorie” or “Calorie” is intended. e.g. Annex H, 7.3 (text in green):

“Note: “kcal” is used in these statements but “calories” should be substituted if        “calories” are declared as the energy information at point of choice.”

The consultation document acknowledges that …

“36. To aid consumer understanding and contribute to consistency of labelling only one        form of expression (either kcal or calories) should be used in an outlet. “

However, this stipulation will not prevent inconsistency of labelling across different establishments.

In their 1972 report on nutritional sciences, the Royal Society identified the problem of the continued use of calories to describe energy content of food. Its conclusions remain valid nearly 40 years later (text in dark red):

“We are very much aware of the problems that arise because as a result of 30 years of education the public has an awareness of the term ‘calorie’. We cannot see any easy solution to the problem of substituting the concept that man has a requirement for the energy-yielding constituents derived from food, and this is measured in joules, …”

“We recommend that editors of journals should not allow the use of the word ‘calorie’ and list below some obvious alternatives :

calorie intake                                  energy intake

calorie requirement                         energy requirement …”

The Units Of Measurements Regulations, which implements Directive 80/181/EEC, requires that energy should be measured using the SI derived unit, the joule. The fact that the calorie is not an SI unit, and is not listed in the Directive, means that calories can only be authorised for use as supplementary indications, and should not appear more prominently than the primary measurement, in joules (J) or kilojoules (kJ).

Many packaged foods are already labelled in kilojoules (kJ).

Progressive countries such as Australia, have already adopted the kilojoule as the primary unit of energy to indicate energy content of food.

Conclusion

A single unit, the joule, used for all purposes regarding energy (not just food), will both benefit the consumer, and increase the general public’s understanding of the concept of energy in general.

It is for these reasons that we strongly recommend that the opportunity that this consultation presents should be taken to begin the phasing out of the obsolete unit “calorie” in favour of the “joule” (which incidentally is named after the British scientist, James Prescott Joule).

References:

REPORT OF THE ROYAL SOCIETY’S BRITISH NATIONAL COMMITTEE FOR NUTRITIONAL SCIENCES

METRIC UNITS, CONVERSION FACTORS AND NOMENCLATURE IN NUTRITIONAL AND FOOD SCIENCES

Report of the Subcommittee on Metrication of the British National Committee for Nutritional Science

Proc Nutr Soc. 1972 Sep;31(2):239-47.

http://journals.cambridge.org/action/displayFulltext?type=1&fid=980848&jid=PNS&volumeId=31&issueId=02&aid=655296 “

[UKMA submission ends]

Further comment

Some have argued that the general public is familiar with “calories”, and to replace them with joules would be confusing and would reduce the effectiveness of the proposal to include energy values on menus.  This is to patronise the general public and underestimate their intelligence.  It is not difficult, for example,  to remember that the average daily energy requirement of an adult male is approximately 10 megajoules (10 MJ) and hence to relate that to a meal of, say, 4 MJ, or a bottle of wine at 2 MJ.  Moreover, to continue the dumbing down of energy information by using non-scientific units helps to maintain the gulf between the educated scientific community and people who have to rely on the popular media for their information.

The question of how best to measure energy (and also power) is a theme to which we shall return in a forthcoming article.

Technical footnote:

What the above Royal Society quotation does not explain is the reason why the joule is a better unit than the “calorie” (in all its variations).  This is because, whereas the value of the “calorie” is determined experimentally (by heating water), the joule is defined in terms of other SI units.  Thus, since energy = force x distance, a joule is a newton times a metre, or in other words the quantity of energy needed to accelerate a mass of one kilogram at a rate of one metre per second squared over a distance of one metre.  Similarly, a joule can be directly related to the watt (1 W = 1 J/s).  By contrast  the “calorie” is simply an unrelated anomaly that – unfortunately – has gained some currency in the popular media and some parts of the weight-watching industry.  It should be phased out as soon as possible, and the FSA should be helping in this – rather than prolonging its life.