Table 1. Characteristics of Included Studies.
| Author reference and country | Design | Study setting | Population | Product category | Label type (i.e., text-only, image-and-text) | Content of label | Comparisons included in the review | Outcome measures | Duration | Results (primary outcomes) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Acton and Hammond (2018) Canada |
Between-subjects RCT | Laboratory | Young adults 16 + | Non-alcoholic drinks (SSBs) | Text-only | ‘WARNING: Drinking beverages with added sugar (s) contributes to obesity, diabetes and tooth decay.’ | No label vs. text-only HWL | Primary: Selection (selection of SSB with purchase) | Immediate (≤ one day) | No significant effect of text-only HWL on outcomes compared to control condition | |
| Ang et al. (2019) Singapore |
Between-subjects RCT | Online | Adults 21+ | Food and non-alcoholic drinks (SSBs and high-in-sugar food) | Text-only | ‘HEALTH WARNING: Consuming products with added sugar(s) contributes to obesity, diabetes, and tooth decay.’ | No label vs. text-only HWL | Primary: Selection (proportion of high in sugar products selected, with purchase) | Immediate (≤ one day) | The proportion of high in sugar products selected was lower in the text-only HWL group compared to the control arm | |
| Billich et al. (2018) Australia |
Between-subjects RCT | Online | Adults 18–35 | Non-alcoholic drinks (SSBs) | Text-only and image-and-text | Text-only HWL: ‘Warning: Drinking drinks with added sugar contributes to obesity, type 2 diabetes and tooth decay’. Image-and-text HWL: The addition of an image showing rotting teeth. |
No label vs. text-only HWL vs. image-and-text HWL | Primary: Selection (proportion of participants selecting sugary drink) | Immediate (≤ one day) | Compared to the control group, the image-and-text HWL, text-only HWL, sugar information and HSR labels all significantly reduced selection of a SSB in the choice scenario. The magnitude of effect was greatest for the image-and-text HWL | |
| Bollard et al. (2016) New Zealand |
Between-subjects RCT | Online | Adolescents and young adults 13–24 | Non-alcoholic drinks (SSBs) | Text-only and image-and-text | Text-only HWL: ‘WARNING: Drinking beverages with added sugar(s) contributes to obesity, diabetes, and tooth decay’ Image & text HWL: The addition of an image showing tooth decay. |
No label vs. text-only HWL vs. image-and-text HWL | Secondary: Intention to purchase SSB | - | ||
| Clarke et al. (2020a) UK |
Between-subjects RCT | Online | Adults 18+ | Alcoholic drinks (beer and wine) | Text-only and image-and-text | Text-only HWL: ‘Excess calories cause [liver cancer, bowel cancer, breast cancer]’ Image-and-text HWL: the addition of an image showing bowel cancer, liver cancer, breast cancer (diseased organs or surgery scar) |
No label vs. text-only HWL vs. image-and-text HWL | Primary: Selection (proportion of participants selecting alcoholic beverage) Secondary: Negative emotional arousal, acceptability |
Immediate (≤ one day) | Text-only and image-and-text HWLs significantly reduced selection of alcoholic drinks compared to no label | |
| Clarke et al. (2020b) UK |
Between-subjects RCT | Online | Adults 18+ | Food (energy-dense snacks) | Text-only and image-and-text | Text-only HWL: ‘Excess calories cause obesity, which causes [heart disease, bowel cancer, type 2 diabetes]’ Image-and-text HWL: the addition of an image showing bowel cancer, heart disease, type 2 diabetes (diseased organs and blinded eye) |
No label vs. text-only HWL vs. image-and-text HWL | Primary: Selection (proportion of participants selecting energy-dense snack) Secondary: Negative emotional arousal, acceptability |
Immediate (≤ one day) | Text-only and image-and-text HWLs significantly reduced selection of energy-dense snacks compared to no label | |
| Grummon et al. (2019) USA |
Between-subjects RCT | Laboratory | Adults 18+ | Non-alcoholic drinks (SSBs) | Text-only | ‘WARNING. Beverages with added sugar contribute to tooth decay, diabetes, and obesity’ | Barcode label vs. text-only HWL | Primary: Selection (selection of SSB with purchase) Secondary: Negative emotional arousal, intentions to limit consumption, acceptability |
Immediate (≤ one day) | Text-only HWLs reduced SSB purchases | |
| Mantzari et al. (2018) UK |
Between-subjects RCT | Online | Parents selecting for children age 11–16 | Non-alcoholic drinks (SSBs) | Image-and-text | An image of rotting teeth alongside the caption ‘Excess sugar intake causes dental decay’ | No label vs. image-and-text HWL | Primary: Selection (selection of SSB) Secondary: Negative emotional arousal, acceptability |
Immediate (≤ one day) | Image-and-text HWLs significantly reduced selection of SSBs compared to control labels | |
| Mantzari et al. (2020) UK |
Between-subjects RCT | Laboratory | Adults | Non-alcoholic drinks (SSBs) | Image-and-text | An image of rotting teeth alongside the caption ‘Excess sugar consumption causes dental decay’ | No label vs. image-and-text HWL | Primary: Selection (selection of SSB) | Immediate (≤ one day) | Addition of an image-and-text HWL or calorie information label on SSB packaging did not reduce selection of SSBs | |
| Roberto et al. (2016) USA |
Between-subjects RCT | Online | Primary caregiver of child age 6–11 | Non-alcoholic drinks (SSBs) | Text-only | 4 HWL conditions: California label: 'drinking beverages with added sugar (s) contributes to obesity, diabetes and tooth decay'; Weight gain label: 'drinking beverages with added sugar (s) contributes to weight gain, diabetes and tooth decay' Preventable label: 'drinking beverages with added sugar (s) contributes to preventable diseases like obesity, diabetes and tooth decay' Type 2 diabetes label: 'drinking beverages with added sugar (s) contributes to obesity, type 2 diabetes and tooth decay' |
No label vs. 4 text-only HWLs combined | Primary: Selection (selection of SSB) Secondary: Acceptability, intentions to purchase |
Immediate (≤ one day) | Caregivers who saw SSBs with text-only HWLs were significantly less likely to choose an SSB relative to those who saw calorie or no labels on beverages | |
| Stafford and Salmon (2017) UK |
Between-subjects RCT | Laboratory | Adults (students) | Alcoholic drinks (alcopops) | Text-only and image-and-text | Text-only HWL: 'alcohol causes fatal liver cancer' Image-and-text HWL: The addition of an image showing a diseased liver. |
No label vs. text-only HWL vs. image-and-text HWL | Primary: Consumption (consumption speed) Secondary: Acceptability |
Immediate (≤ one day) | Alcohol was consumed at a faster rate for those in the control condition compared to both the image-and-text HWL and text-only conditions | |
| Temple (2016) USA |
Within-subjects RCT | Laboratory | Young adults 15–30 | Non-alcoholic drinks (caffeinated energy drinks) | Text-only | Caffeine HWL: 'high levels of caffeine intake can cause headache, nausea, anxiety, irregular heartbeat, vomiting, and, in extreme cases, death. Use caution when consuming caffeine' | No label vs. text-only HWL | Primary: Selection (selection of ED with purchase) | Immediate (≤ one day) | The adolescent population may be sensitive to labelling, but labelling would not have an impact among adult ED consumers | |
| VanEpps and Roberto (2016) USA |
Between-subjects RCT | Online | Adolescents 12–18 | Non-alcoholic drinks (SSBs) | Text-only | 4 HWL conditions: California label: 'drinking beverages with added sugar (s) contributes to obesity, diabetes and tooth decay' Weight gain label: 'drinking beverages with added sugar (s) contributes to weight gain, diabetes and tooth decay' Preventable label: 'drinking beverages with added sugar (s) contributes to preventable diseases like obesity, diabetes and tooth decay' Type 2 diabetes label: 'drinking beverages with added sugar (s) contributes to obesity, type 2 diabetes and tooth decay' |
No label vs. 4 text-only HWLs combined | Primary: Selection (selection of SSB) Secondary: Intentions to purchase, acceptability |
Immediate (≤ one day) | Participants who saw SSBs with text-only HWLs were less likely to hypothetically purchase an SSB relative to those who saw no labels, an effect that was statistically significant for three of four label conditions | |
| Wigg and Stafford (2016) UK |
Between-subjects RCT | Laboratory | Adults (students) | Alcoholic drinks (beer and wine) | Text-only and image-and-text | Text-only HWL: 'alcohol causes fatal liver cancer' Image-and-text HWL: The addition of an image showing a diseased liver. |
No label vs. text-only HWL vs. image-and-text HWL | Secondary: Intention to quit; negative emotional arousal (fear) | Immediate (≤ one day) | - | |
SSBs = sugar-sweetened beverages; HWL = health warning label; RCT = randomised controlled trial.