Healthy adults, aged 18-65 years old and able to provide informed consent, were recruited from the south coast of England, through University contacts, community groups and flyers distributed in coffee shops and other public places. No further inclusion criteria were utilised. Minimal inclusion criteria and many recruitment strategies aimed to allow inclusion of volunteers from a range of backgrounds, providing a wide range of attitudes. Ethical approval for the study was granted by the Research Ethics Committee of Bournemouth University (ID: 29215) prior to commencement. All participants provided informed consent before participation and were compensated for their time.
The study used a combination of focus groups, dyadic interviews and solo interviews to generate a wide range of perspectives and understandings. Topics for discussion were considered by the researchers to be non-sensitive, hence suitable for discussion in focus groups and dyadic interviews, and focus groups were used to elicit collective as well as personal opinions. Interviews were conducted only where participants were unable to attend a focus group session. Data collection was undertaken from Jan. 2018 to March 2020. During this time (April 2018), a nationwide tax on soft drinks that contain at least five grams of sugar per 100 millilitres, the ‘Soft Drinks Industry Levy’ (SDIL) was implemented across the UK [33]. Some focus groups were conducted prior to the implementation of the SDIL, while others were conducted following different time periods after this implementation, allowing collection of a wide range of attitudes. The specific time periods aimed to provide attitudes in both the short- and long-term following implementation of the SDIL.
A moderator guide was used to structure all focus groups and interviews. Questions focused on participants’ beliefs about sugar and sweeteners, their preferences and rationales for consumption or avoidance, their attitudes towards different sweetener terms or categories, attitudes towards sugar intake versus sweet-tasting food intake, and their opinions on current and potential strategies to reduce free sugar intakes. The open-ended question moderator guide was piloted prior to use in six interviews, and refined to ensure the clarity, relevance and value of each question. The refined guide was then used for all focus groups and interviews. Visual materials were presented at various time-points during each session, with the purpose of generating more discussion. These included: pictures of the sugar content of several commercial beverages in sugar cubes, in relation to current Public Health England recommendations [8,9]; examples of different categories of sweeteners [24-26]; examples of packaging using graphic imaging similar to that that has been used for cigarettes under The Standardised Packaging of Tobacco Products Regulations 2015 [34]; and a BBC news article on the SDIL illustrated as a newspaper clipping. All visual materials are provided in the Supplementary Materials.
Focus groups and interviews were conducted using established methods [35-37]. All sessions were conducted in a semi-structured manner to encourage both personal and collective opinions. All sessions were audio-recorded for transcription and analysis. Each session lasted not more than an hour. All sessions began with an introduction and explanation on the study procedure, audio recording, confidentiality and anonymity. Three trained researchers moderated the various focus group sessions, using the piloted refined question moderator guide, but the sequence and use of each question depended on the flow of each session. Towards the end of each session, moderators asked if participants had any more thoughts on the topic that were not yet discussed. The session then continued until there was no further input from participants. By the last focus group, no new attitudes or reasons were generated and data collection for the study was concluded.