The Nutri-Score Algorithm: Balancing the Good and the Bad
The Nutri-Score is a voluntary front-of-pack food labeling system that helps consumers quickly assess the nutritional quality of a product, particularly when comparing similar items. Developed by independent scientists, the system operates on a straightforward principle: balance. It weighs the content of nutrients and ingredients that should be limited (negative points) against those that should be encouraged (positive points). The final result is a single numerical score, which is then translated into a five-color, letter-coded logo (A to E). This calculation is always performed on the nutritional values per 100g or 100ml of the food product, allowing for standardized comparisons.
Scoring Unfavorable Nutrients (Component N)
Four components negatively impact a food's Nutri-Score, each assigned points based on the amount present per 100g or 100ml. The higher the amount of these elements, the more points the product receives. The maximum number of points for each negative component for general foods is typically 10, though more recent algorithm updates have adjusted this for certain categories like beverages. The components are:
- Energy Density: Measured in kilojoules (kJ).
- Saturated Fatty Acids: Measured in grams (g).
- Total Sugars: Measured in grams (g).
- Salt (Sodium): Measured in milligrams (mg).
Scoring Favorable Ingredients (Component P)
Conversely, three components earn a food product positive points, with higher amounts leading to a better score. These points are designed to compensate for the negative components. The maximum points for each of these can vary but typically range from 0 to 5 or higher depending on the specific algorithm for the product category. The favorable components are:
- Fruits, Vegetables, and Legumes: Calculated as a percentage of the total product. This includes pulses but excludes certain processed items and juices.
- Dietary Fibre: Measured in grams (g).
- Protein: Measured in grams (g).
The Calculation Process Step-by-Step
- Gather Nutritional Data: The manufacturer obtains the food's nutritional information from the mandatory nutritional declaration and ingredient list, based on a 100g or 100ml serving.
- Calculate Negative Points (N): Points (0–10 or higher) are assigned for energy, saturated fat, sugars, and salt based on predefined thresholds. The sum of these points is the product's total negative score.
- Calculate Positive Points (P): Points (0–5 or higher) are assigned for the percentage of fruits, vegetables, and legumes, plus the fiber and protein content. These points are summed for the total positive score.
- Subtract Positive from Negative: The final numerical Nutri-Score is determined by subtracting the total positive points from the total negative points (N - P).
- Determine the Final Grade: This numerical score is then compared against a set of predetermined thresholds to assign a final color and letter grade, from A (dark green) to E (dark orange).
Comparing Nutri-Score Grades
To illustrate how the Nutri-Score works, consider a comparison of two hypothetical breakfast cereals. The calculation method allows for a quick assessment of which product has a better overall nutritional composition.
| Feature | 'Healthy Start' Cereal (Nutri-Score B) | 'Chocolate Crunch' Cereal (Nutri-Score D) |
|---|---|---|
| Energy | Lower energy (e.g., 1400kJ/100g) contributes fewer negative points. | Higher energy (e.g., 1700kJ/100g) contributes more negative points. |
| Saturated Fat | Lower saturated fat content results in a lower negative score. | Higher saturated fat content adds more negative points. |
| Sugars | Very low sugar content minimizes negative points. | High sugar content significantly increases negative points. |
| Salt | Minimal salt content results in few or no negative points. | Higher salt content adds more negative points. |
| Fiber | High fiber content earns a high number of positive points. | Low fiber content earns few positive points. |
| Fruit, Vegetables, Legumes | Contains a percentage of dried fruit, earning positive points. | Contains none, earning zero positive points. |
| Protein | Moderate protein content adds some positive points. | Low protein content results in few positive points. |
Conclusion: Simplifying Nutritional Choices
The Nutri-Score provides an effective tool for consumers to make more informed choices, especially when comparing processed products within the same category. The color-coded system distills complex nutritional information into an easily understandable format, even for those with limited nutritional knowledge. While it is a voluntary label in most countries, its adoption by manufacturers allows for greater transparency and encourages product reformulation towards healthier profiles. It is important to remember that Nutri-Score is a comparative tool, not an absolute measure of healthiness; for example, a high-scoring cereal does not replace the benefits of whole fruits and vegetables. For more detailed information on the official guidelines, consumers can refer to resources from public health agencies like Santé publique France.
