The co-ingestion of caffeine and alcohol : influences and experiences - a qualitative study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, New Zealand

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Background: Caffeine is a mild psychoactive drug consumed daily by 80% of people worldwide and 71-96% of New Zealanders. Caffeine may be consumed in conjunction with alcohol. All beverages containing caffeine and alcohol, whether premixed or self-made, have different concentrations of caffeine and alcohol, hence the ratio is an important factor to consider as different ratios may impact an individual’s experience. Neurologically, caffeine is classified as a stimulant and alcohol as a depressant. When these substances are mixed together, caffeine’s stimulant effects masks alcohol’s sedation effects, resulting in the individual feeling less drunk. A caffeine consumption and habits questionnaire (CaffCo) has previously been developed to determine caffeine consumption in New Zealand. At present, it is unclear if CaffCo is suitable in assessing the co-ingestion of caffeine and alcohol. Currently there are significant gaps in understanding the patterns, habits and reasons for caffeine and alcohol co-ingestion (CAC). Aim: To gain an insight into caffeine and alcohol co-ingestion in New Zealand (NZ) and the potential modification of CaffCo to accurately evaluate CAC intake patterns, habits and influences on consumption and both positive and negative experiences across a range of beverage mixtures in NZ adults aged 18 years and older. Methods: A total of five focus groups were conducted. The focus group discussions were audio-recorded and facilitated by a moderator guide. The guide included seven topics (initial thoughts, product use, functional expectations, the context of use, product experiences, product perceptions and health perceptions). Data was transcribed and thematically analysed to identify the main themes derived from the discussions. This data was then manually compared to CaffCo to check CaffCo’s suitability in assessing the co-ingestion of caffeine and alcohol in New Zealand. Results: After conducting the focus groups, five main themes were identified. Firstly, the consumption of caffeine and alcohol were associated with having fun, although caution was highlighted around the potential for abuse (theme one). Taste, cost, alcohol percentage and setting were important factors in deciding whether to co-ingest caffeine and alcohol (theme two). Participants indicated that bright colours and lettering attracted them to beverages containing caffeine and alcohol (theme three). However, one participant observed that the advertisement of co-ingestion was embedded into our general culture. Participants found that co-ingestion caused the amplification of their emotions, regardless of the type of emotion (positive or negative) (theme four). The final theme highlighted the initial and delayed effects of co-ingesting significant amounts of these beverages. Initial effects included behavioural changes and/or loss of coordination, resulting in injuries as a direct outcome, whereas delayed effects included insomnia, agitation and grogginess. Comparing these themes to questions currently present in CaffCo, it was determined that it is important to provide a definition of what “beverages containing caffeine and alcohol” are before commencing data collection. CaffCo is currently able to obtain quantitative data on co-ingestion however; it is unable to effectively assess qualitative aspects of CAC, specifically around people’s personal experiences pre- and post-consumption. Several sample definitions and questions have been developed and piloted to amend CaffCo’s suitability. Conclusion: Co-ingestion is predominantly carried out by participants to experience the alcoholic effects of the beverage. The alcohol percentage is one of the main factors taken into consideration before consumption. Both initial and delayed effects of co-ingestion mimic the hangover effects of over-ingesting alcohol, leading to the conclusion that alcohol percentage is of higher importance to the public. CaffCo requires minor modifications to properly assess co-ingestion in New Zealand. More observational data is needed to observe people’s natural patterns of co-ingesting caffeine and alcohol. Additionally, our data suggests that the development of informative tools may be useful to explain the caution around the abuse of co-ingestion.
caffeine, alcohol, co-ingestion, New Zealand, CaffCo