A team of researchers with Inserm/INRA/Paris 13 University have concluded that a five-color nutrition label is the most effective nutritional information system for allowing consumers to recognize and compare the nutritional quality of foods. The results appear in the journal Nutrients.
The study was conducted from a sample of 14,230 participants of the NutriNet-Sante study, which compared the effect of different nutrition labels on the front of packs of various foods and how the participants were able to rank the foods appropriately.
Four simplified nutritional labeling systems were tested for their impact:
- The Guideline Daily Amounts (or Reference Intakes) system already used in France by some industrial companies
- The color-based 5-CNL system
- The Multiple Traffic Light system used in Great Britain
- The Green Tick - similar to that used in some Scandinavian countries and the Netherlands
A logo-free situation was also used as a reference. Five categories of foods were tested: frozen fish products, pizzas, dairy products, breakfast cereals and appetizers.
With the help of a web-based questionnaire specifically developed for this study, participants were asked to rank, on a relative basis ("less good," "moderate," "the best" or "I don't know") the nutritional quality of different series of three foods belonging to the same category. Each participant had to randomly test a combination of food products and nutrition labels from the five categories. For this, 25 different versions of the questionnaire were used. A statistical design (Latin Square) made it possible to ensure an equal number of participants for each labeling/product category combination.
The results concerning the comprehension of nutritional logos showed:
- The 5-CNL system performed better, including among individuals with a relatively "unfavorable" diet in terms of nutrition and health. In particular, the presence of 5-CNL strongly increased - over twenty-fold compared to the logo-free situation - the ability of individuals with no knowledge of nutrition to correctly rank the products compared with a logo-free situation.
- Of the nutrition labels tested, the 5-color nutritional labeling system (5-CNL) was also the most effective in terms of comprehension. It performed better than the Traffic Light, Reference Intakes, or Green Tick labeling systems.
- Individuals "at risk" of having a nutritionally poorer quality diet - older subjects, participants with a lower educational level, lower income, lower nutritional knowledge, and overweight or obese individuals - had greater difficulty in ranking food products according to their nutritional quality.
- The various nutrition labels significantly increased the ability of individuals, including those at risk, to rank three foods in order of their nutritional quality, compared with a logo-free setting.
- The nutrition labels had more impact than individual characteristics - education level, income, etc. - on increasing the ability of the individuals to correctly rank the foods by nutritional quality. The chance of correctly ranking the products was multiplied up to 12-fold with a logo, whereas individual characteristics enabled an increase in the chance by a factor of only 1.17.
The results of this study emphasize the interest of nutrition labels for helping consumers, particularly those at risk of making food choices that are relatively "unfavorable" to their health, to identify the products most conducive to a balanced diet. The 5-color logo (5-CNL) system turns out to be the best understood among individuals as a whole, and may therefore make it possible to inform consumers effectively and equitably on the nutritional quality of products, and thereby incorporate this information into determinants of their food choices.