Many industrial and agricultural sectors hostile to the Nutri-Score front-of-pack (FOP) nutrition label (only because it highlights the reality of the nutritional composition of the foods they produce), criticize – among others – the fact that its calculation is based on the composition per 100g of food and not “per serving”. The argument they usually use is that “we do not eat 100 g of Roquefort, 100 g of rillettes or 100 g of mayonnaise at once”. Of course we don’t, but in reality, the choice to use the reference of 100g of food (as for many other FOP nutritional labels used in the world), is based on both conceptual, pragmatic, scientific and public health arguments.
A simple, objective and standardized common denominator is therefore needed allowing to recognize at a glance the food which would have the most favourable nutritional composition compared to others. This is why public health authorities have proposed as a reference 100 g or 100 ml to allow the consumer to easily compare the nutritional quality of foods regardless of the quantity consumed; compare 100 ml of olive oil to 100 ml of maize or sunflower, soya, coconut oil; 100 g of Comté to 100g of Camembert or Roquefort or Mozzarella…; 100g of a type of breakfast cereals to 100g of other types of breakfast cereals, or for the same type of breakfast cereals, differences between brands (even with the same designation, they may have significant differences in nutritional composition).
One other reason for the choice of using 100g as a reference for the computation of Nutri-Score, is that the elements of the nutritional composition (calories, sugars, fats, saturated fatty acids, salt, proteins, etc.) that currently appear on food packaging (the mandatory “nutrition declaration” voted in Europe in 2011) are expressed per 100g or 100ml (Annex XV to the INCO Regulation, 2011) (2) as a mandatory requirement. These data, which are present in a table on the back of all food packages provide the basis for the calculation of the Nutri-Score. It is an accepted constraint for Nutri-Score to rely on data directly available on the packs of products. This allows a total transparency about the attribution of the colors/ letters of the Nutri-Score for a given product. So Nutri-Score doesn’t invent anything, but only takes into consideration the elements of composition contained in the nutrition declaration that are relevant from a public health point of view. And they are always expressed per 100g or 100ml of food. Under pressure from food manufacturers, the european regulation allowed them to also display, in the nutritional declaration, as a voluntary and complementary measure to the values per 100g or 100 ml, an expression per serving or per unit of consumption, but provided that the serving or unit of consumption is identifiable by the consumer. This last point raises many practical problems for consumers. Assessing a serving of any size, most often expressed in grams in the table of the nutritional declaration is really complex in real life. Various studies have shown that consumers have difficulty to accurately assess the amount corresponding to a serving (3,4): how to precisely estimate (without having to weigh with a scale what they eat) 30 g of Roquefort, 35 g of Mimolette, 30 g breakfast cereals, 40 g of rillettes or 175 g of pizza… In addition, the portion size is currently freely defined by the manufacturer and it can be confusing: a serving of a chocolate bar actually corresponds to only half of the package; the serving of breakfast cereals on packs vary from 25 to 45g, showing a great heterogeneity on how manufacturers define a serving size. Providing nutritional information and a FOP nutrition label based on a somewhat arbitrary definition of what a serving is, which would be different from one food to another and difficult for consumer to estimate is questionable and misleading. It is the interest of using universally the reference to 100g for all foods which avoid the problem of the definition and the variability of the servings and their difficulty of interpretation by the consumer.
Scientific and public health arguments
From a scientific and public health perspective, there is a high risk of confusion for consumers to interpret data per serving, as serving sizes may refer to two different concepts: “the amount of food to be consumed or usually consumed by an individual on a single occasion”, or “the quantity recommended for consumption on a single occasion as part of a qualitatively and quantitatively balanced diet”(5,6). These two concepts, which in English correspond to two different terms, «portion» and «serving», are often mixed (especially in the French-speaking world where the word «portion» is indifferently used for both concepts) can be particularly confusing for the consumer, both in terms of perception of use and level of consumption as well as interpretation of a nutrition label expressed per serving. Indicating on a can of 330 ml of soda that a serving (displayed on the nutrition facts table) is 330 ml may suggest that this is the recommended “official” amount to consume. But for the same soda of the same brand, but packaged in 1.5 L bottle, the serving displayed by the manufacturer is this time 250 ml ! Beyond its meaning and its vocation, one of the greatest difficulties for using the concept of portion/serving is the definition of its size.
Serving/portions sizes for foods are also very difficult to define because they vary widely according to individual energy requirements. To be relevant, they should be therefore defined specifically for men, women, adolescents, young children, active or sedentary subjects… So, it makes it difficult to calculate a universal FOP nutrition label based on the different portion sizes and displayed on the packaging.
As serving sizes cannot be standardized on a scientific basis and defined according to different relevant consumer groups (with specific nutritional needs), when they are proposed on packs of some foods, it is currently in the form of a single quantity fixed by the manufacturer itself and which is often largely below the servings actually consumed (as observed in food consumption studies). If they are so underestimated by manufacturers, it is because they are the ones providing the values for calories, fat, saturated fats, sugar, salt, etc. included, on a voluntary basis, on the table of the nutritional declaration displayed on the back of packs, next to the values given for 100g (which are mandatory). It is common for breakfast cereals, that manufacturers suggest a serving size of 30g while the majority of teens, for example, consume portions of 60 or 80g or more. The consequence is to artificially reduce the theoretical amounts of nutrients present in the foods considered to be nutritionally unfavourable (sugar, fatty acids, salt) in a serving of the product. Similarly, some manufacturers sell individual bags containing two servings of 25g chocolate bars. But the nutritional values are presented per serving, and they use 25g as the reference, which corresponds to only one of the two bars contained in the bag, while the majority of consumers would consume both bars once the bag is opened…
Finally, since servings are usually set by manufacturers, this allows potential manipulation of the information: manufacturers have just to define smaller portion sizes on their packs to artificially reduce the amounts of fat, sugar or salt in the serving of their products indicated to consumers. And, if this serving size is used for the computation of FOP nutritional labels (as requested by some food companies and agricultural sectors), it would allow them to ”launder’ the colors of the label at their advantage. It is what was proposed, a few years ago, by the conglomerate of multinational food companies named Big6 (Nestlé, Mars, Mondelez, Coca-Cola, Pepsi-Cola, Unilever) through the label they had developed (Evolved Nutrition Label, ENL) as an alternative to Nutri-Score, which was expressed per serving. Thus this labelling appeared more favourable for certain products of low nutritional quality, resulting in the display of an orange and not a red – as it would have appeared using 100g as reference. This has been shown to distort consumer judgment. A study (7) demonstrated that, unlike Nutri-Score (which refers to 100g of food) the use of ENL (calculated per serving) had a very limited effect in reducing the serving sizes of low-quality products and would even tend to increase the serving size for certain foods such as spreads, by falsely reassuring consumers on their nutritional values… Fortunately this misleading label was abandoned in 2019.
Given the limitations in using servings, the lack of consensus and international standards to define their size in the European market, and their possible manipulations by manufacturers, it is not possible to use the servings as reference for the calculation of a nutritional label that would be useful for the consumers. On the other hand, using of a standard amount, such as 100g for solid foods and 100ml for liquid foods, is a reasonable choice, allowing a valid comparison between foods without inducing an estimation error. This is the goal of a nutrition label, such as Nutri-Score, which aims to inform consumers about the nutritional quality of foods and enable them, by comparing comparable foods, to direct their choices towards a healthier diet.
- Hercberg S, Touvier M, Salas-Salvado J, On Behalf Of The Group Of European Scientists Supporting The Implementation Of Nutri-Score In Europe. The Nutri-Score label. Int J Vitam Nutr Res. 2021 Jul 27. doi: 10.1024/0300-9831/a000722.
- Règlement (UE) n o 1169/2011 du Parlement européen et du Conseil du 25 octobre 2011 concernant l’information des consommateurs sur les denrées alimentaireshttps://eur-lex.europa.eu/legal-content/FR/TXT/?uri=celex%3A32011R1169
- Faulkner, G. P. et al. Serving size guidance for consumers: is it effective? Proc. Nutr. Soc. 2012, 71, 610–621.
- Van der Horst, K., Bucher, T., Duncanson, K., Murawski, B. & Labbe, D. Consumer Understanding, Perception and Interpretation of Serving Size Information on Food Labels: A Scoping Review. Nutrients 20129, 11.
- Faulkner G.P., Pourshahidi L.K., Wallace J.M.W., Kerr M.A., McCrorie T.A., Livingstone M.B.E. Serving size guidance for consumers: Is it effective? Proc. Nutr. Soc. 2012;71:610–621.
- Steenhuis I.H.M., Vermeer W.M. Portion size: Review and framework for interventions. Int. J. Behav. Nutr. Phys. Act. 2009;6:58.
- Egnell M, Kesse-Guyot E, Galan P, Touvier M, Rayner M, Jewell J, Breda J, Hercberg S, Julia C. Impact of Front-of-Pack Nutrition Labels on Portion Size Selection : An Experimental Study in a French Cohort. Nutrients. 2018 ; 10 (9): 1268.
Serge Hercberg, Pilar Galan, Emmanuelle Kesse-Guyot, Mathilde Touvier, Chantal Julia
Université Sorbonne Paris Nord. Equipe de Recherche en Epidémiologie Nutritionnelle U1153 (Institut National de la Santé et de al la Recherche Médicale / Institut National de la Recherche Agronomique/CNAM/Université Sorbonne Paris Nord), Bobigny, France.
Unité de Nutrition et Santé Publique, Dép. de Santé Publique, Hôpital Avicenne, Bobigny, France.