How Color-Coded Food Labels Are Changing How We Shop: The Traffic Light Effect

A study led by Jing Song at Queen Mary University of London, published in PLOS Medicine, reveals that color-coded nutrition labels, specifically those using the familiar red, yellow, and green of a traffic light, significantly sway consumers toward healthier food choices.

The Psychology of Color in Our Cart

We are biologically and culturally conditioned to react to color. In marketing, Red triggers appetite and urgency (think McDonald’s), while Blue suggests loyalty and precision (like Ford).

When applied to nutrition, these meanings become even more instinctive. The “Traffic Light” system works because its symbolism is nearly universal:

• 🔴 Red: Stop and think. This product is high in fats, sugars, or salt.

• 🟡 Yellow/Amber: Caution. This contains medium levels of these nutrients.

• 🟢 Green: Go. This is a healthier, lower-fat, or lower-sugar option.

Science-Backed Results: What the Research Says

Jing Song and her colleagues analyzed data from 134 studies spanning three decades (1990–2021). Their findings provide a clear “green light” for the effectiveness of color-coded labels:

• Positive Reinforcement: Color-coded labels, such as the UK’s Traffic Light system and the Nutri-Score (a color spectrum from A to E), are exceptionally effective at promoting the purchase of healthier products.

• Discouraging Risks: Warning labels—such as the black octagonal “High In” signs used in Chile—were more effective at discouraging the purchase of unhealthful options.

• Nutritional Impact: These labels nudged shoppers toward products with lower levels of sodium, saturated fat, and total energy (calories).

Why Does It Work?

The success of these labels isn’t just about information; it’s about emotion and perception.

1. Lowered Cognitive Load: Shoppers spend an average of only 10 seconds scanning a label. Colors provide an “at-a-glance” summary that doesn’t require calculating percentages or grams.

2. Emotional Nudging: Red labels can elicit a subtle “negative emotion” or a perception of risk, disrupting the habitual tendency to grab sugary or salty snacks.

3. Visual Clarity: Unlike complex “Nutrition Facts” tables on the back of packs, front-of-pack (FOP) labels are immediately visible during the decision-making process.

The Future of Food Labels in Indonesia

As Indonesia faces rising rates of non-communicable diseases like diabetes and obesity, the role of Food Science and clear labeling becomes vital. Integrating color-coded systems into local food technology could be a major step toward the 7th agenda of Nawacita—improving the country’s economic independence by fostering a healthier, more productive workforce.

By simplifying the choice at the grocery store, we move closer to a sustainable future where “healthy” is no longer a guessing game, but a color-coded reality.