The role of the home environment in sugar-sweetened beverage intake among northern Mexican adolescents: a qualitative study

To explore adolescents’ perceptions of how the home environment promotes the intake of sugar-sweetened beverages (SSBs) and to identify the potential environmental cues that trigger SSB intake at home. Twenty-nine semi-structured interviews were conducted among adolescents, aged 15–19 years, residing in an urban area in Northwest Mexico. Thematic analysis was used to analyse the data. Adolescents perceived that the availability of SSBs in the household increased their intake of SSBs. Availability of SSBs was facilitated mainly by taste preferences, ease of buying and beliefs that fruit-containing SSBs are healthy. Availability at home was considered important because SSBs were normally consumed with food during meals. Family influences and a lack of parental regulation were also regarded as factors promoting adolescents’ SSB intake at home. Drinking SSBs with food and having SSBs available at home were identified as habits that had been performed by participants’ families for many years. These findings provide insights into the role of the home and family environment in promoting SSB intake. Future interventions to reduce SSB intake in this sample of Mexican adolescents should address availability and facilitators of SSB intake at home, family influences and parental regulation.


Introduction
According to the latest Mexican National Health and Nutrition Survey 2016 (ENSANUT from its Spanish-language acronym), the combined prevalence of obesity and overweight among Mexican adolescents (aged 12-19 years) reached 36.3% in 2016 (Hernández Ávila et al. 2016). Evidence has suggested a positive association between a high intake of sugar-sweetened beverages (SSBs) and weight gain in adolescence (Jimenez-Aguilar et al. 2009;Malik et al. 2013). In 2012, per capita intake of SSBs among adolescents was approximately 497.8 ml/day (Stern et al. 2014)-two times higher than adolescents' average SSB intake in the UK (212 ml/day) (Bates et al. 2016). Despite the epidemiological research conducted in Mexico around the consumption patterns of SSBs (Barquera et al. 2008(Barquera et al. , 2010Jimenez-Aguilar et al. 2009;Stern et al. 2014;Sánchez-Pimienta et al. 2016), less evidence is available on the individual, social and physical environmental factors determining the intake of SSBs in Mexican youth. This is important because an understanding of these factors could not only reshape and redirect current fiscal policies (SSB tax) but also contribute to the design of complementary interventions to reduce SSB intake in this group.
Previous research on adolescents' proximal context, such as family, school and peers, has suggested a positive association between the home and school environments and SSB intake (van der Horst et al. 2008;Ezendam et al. 2010;Shi 2010;Tak et al. 2011;Bogart et al. 2017). Within the home environment, factors such as the availability and accessibility of SSBs, family meals, parental modelling, parenting practices and family food rules have been positively correlated with the intake of SSBs among children and adolescents living in developed countries (Grimm et al. 2004;van der Horst et al. 2007;Bere et al. 2008;Haerens et al. 2008;Ezendam et al. 2010;Verzeletti et al. 2010;Tak et al. 2011;Hebden et al. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10389-018-0993-6) contains supplementary material, which is available to authorized users. Van Lippevelde et al. 2013;Bogart et al. 2017). These findings provide an important insight into the factors that influence SSB intake at home in developed countries, mostly in Europe. However, less is known about the potential role of the home environment in the intake of SSBs among Mexican adolescents. Addressing this gap is important because cultural and family norms around food in Mexico are different from those in Europe.
Habit strength has also been associated, both directly and indirectly, with European adolescents' SSB intake van der Horst et al. 2007;Tak et al. 2011;van de Gaar et al. 2017), which suggests that SSB intake could be a habit-triggered behaviour. According to Gardener et al. (2014), habit is defined as Ba process whereby environmental cues automatically activate an unconscious impulse to perform a behaviour that has, through repetition, become associated with those cues^ (Gardner et al. 2014). Thus, if SSB intake is a habitual behaviour, it is likely that this habit has been formed through context-dependent repetition. However, less is known about in which contexts, or under which conditions, habits might be triggered (e.g. home, school, other places). Identifying the different circumstances in which the habit of drinking SSBs might be triggered would be useful in the design of future interventions that aim to reduce SSB intake in Mexican adolescents.
To bridge the aforementioned gaps in the evidence base, and in view of the fact that adolescents living in the North of Mexico consume a considerable amount of SSBs (Jimenez-Aguilar et al. 2009;Sánchez-Pimienta et al. 2016), this study used qualitative methods to explore in depth: (1) the context of consuming SSBs in the home environment and (2) the potential contextual cues or other stimuli that trigger SSB intake at home.

Participants
Semi-structured interviews were conducted in the city of Hermosillo, Mexico, between April and May 2016. The study was approved by the Univeristy of Bristol, School for Policy Studies Research Ethics Committee (SPS REC 14-15. A16). Detailed information on the design, recruitment and data collection can be found elsewhere (Ortega-Avila et al. 2018). In brief, 391 adolescents who had taken part in a previous crosssectional study assessing SSB intake (unpublished results) were contacted again, this time in order to participate in an interview. Purposive sampling was used, where inclusion criteria were: adolescents, males and females between 15 and 19 years who consumed at least one portion (240 ml) of SSBs per day. SSB intake had been previously assessed through an online survey (unpublished results), using an adapted beverage intake questionnaire (BEVQ) comprising 16 beverage items (Hedrick et al. 2012). A pragmatic approach was followed with the objective of achieving an initial medium-sized subject pool of 30 SSB consumers (Baker and Edwards 2012). Participants provided written informed consent prior to the interview and received $100 Mexican pesos (approximately $5, £4) at the end of the interview.

Data collection
A total of 29 interviews were conducted at participants' homes or in public spaces. They were conducted in Spanish by the lead author, who is a native of the city and trained and experienced in conducting qualitative research. Interviews lasted an average of 35 min (range: 27-50 min). Different topics regarding SSB intake were discussed, including SSB intake in different contexts, such as home and out-of-home, as well as perceptions of the current SSB taxation (Ortega-Avila et al. 2018). The semi-structured interview guide (translated into English) is presented in Table 1, and the Spanish version is presented in Supplementary Material online, Appendix 1. The present study reports findings on adolescents' perceptions of SSB intake in the home environment.
For the purpose of recruitment, interviews and data analysis, the definition of SSBs comprised any carbonated and non-carbonated drinks containing added sugars (sugars added during the production process or home preparation) (Erickson and Slavin 2015). This included sodas, fruit juices (excluding 100% fruit juices), fruitflavoured drinks, sports and energy drinks and sweetened coffee/tea. Traditional Mexican beverages called aguas frescas were also included, as they are prepared with water, fresh fruit and sugar. Aguas frescas can be prepared at home or purchased at restaurants and markets and from street vendors. Notes were taken, and at the end of each interview the interviewer summarised the discussion points to confirm the accuracy of the recorded statements with the participants. All interviews were recorded, anonymised and transcribed verbatim. As this was an exploratory study, the 29 interviews conducted were sufficient to capture a range of participant perceptions and responses regarding SSB intake in the home environment and to reach code saturation, with no new themes emerging from the analysis.

Data analysis
Using data collected via an online survey completed during our earlier cross-sectional work (unpublished results), descriptive statistics (means and standard deviations) were used to describe personal and socio-demographic characteristics as well as daily SSB intake of participants. These analyses were performed using Stata 14 (Statacorp, College Station, TX).
Data collection and analysis proceeded in parallel. To prevent misinterpretation of participant statements, it is recommended to conduct qualitative analysis in the original language (Birbili 2000;van Nes et al. 2010;Al-Amer et al. 2015). Therefore, the analysis of the interview transcripts was conducted in Spanish. Only themes titles and theme-relevant quotes were translated into English by the researcher who conducted the interviews and who was a native Spanish speaker. They were back-translated into Spanish by an independent bilingual researcher to check for accuracy (Birbili 2000;Esposito 2001). Relevant quotes are presented in English in this article and in Spanish in the Supplementary Material online (Appendix 2) (Lincoln et al. 2016). Each quote was allocated a quote number (Q1-Q52) for identification purposes in the Spanish version in the Supplementary Material online, as well as a participant number (P1-P29), and was supplemented in the current report by gender (male/female) and age.
Thematic analysis of the interview transcripts, using the framework approach, was used to evaluate the data. This method allowed descriptive and exploratory themes that facilitated an understanding of the intake of SSBs within the home environment to be extracted, while retaining a clear audit trail to the original data (Smith and Firth 2011;Gale et al. 2013). The framework approach followed five stages: (1) familiarisation, (2) coding, (3) development of analytical framework, (4) indexing and (5) charting. The detailed steps followed during the analysis are described in Table 2. The qualitative analysis was carried out using NVivo (version 10, QRS International Pty Ltd., UK).

Results
In total, 29 adolescents [13 males, 16 females, ranging in age between 15 and 19 years (mean = 17.0; SD = 1.4)] participated in the interviews. Detailed personal characteristics are presented in Table 3. On average, participants had a normal body mass index (BMI) and came from a middle socio-economic status (SES) background. The mean SSB intake was 1020 ml/ day. The final framework consisted of 17 subthemes clustered into five themes (Table 4).

Context of SSB availability at home
The presence of SSBs was something common in adolescents' households, as nearly all participants mentioned that different SSBs were available at home. Very few participants mentioned not having SSBs in their homes and referred only to the accessibility of other beverages, such as water, milk and non-caloric powdered beverages: BThere is always iced tea in my house; also, there are always juices.^(Q1/P16/female/16 years) BWe always have juice at home, soda and iced tea.^(Q2/ P18/male/17 years) The availability of SSBs at the household level varied across participants and was either through purchase or home preparation. SSB purchases were generally made at the supermarket during the weekly grocery shopping or every day in shops near home: BBeverages are normally bought in the shop near the house, because it's the fastest.^(Q3/P13/male/19 years) BWe buy beverages when we buy the groceries.^(Q4/ P27/female/16 years) The role of parents, especially mothers, was of key importance since they were commonly in charge of buying or preparing SSBs on a daily or weekly basis: BMy mom is the one who takes care of it; normally when she goes to the supermarket she buys them [SSBs].^(Q5/P24/male/17 years) BMy mom is the one who goes to the supermarket and makes the beverages.^(Q6/P15/female/19 years) To a lesser degree, fathers also played a role in the availability of SSBs at home: BMy dad, it's like he says: 'Mm…a soda' or 'We need iced tea'. It's because he likes sweet things.^(Q7/P28/ female/17 years) BSometimes my dad arrives home with sodas and it causes chaos.^(Q8/P15/female/19 years) In a few cases, purchasing of SSBs was split between all family members: (1) Familiarisation Familiarisation started with the verbatim transcription of the data, followed by reading the transcripts repeatedly (2) Coding Two trained Mexican researchers independently coded an initial number of transcripts (n = 3) to validate the coding process (3) Development of an analytical framework Coding was discussed in several meetings until both coders agreed on a set for forming the analytical framework. This was then independently applied to three more interviews, where new codes, themes and nuances were considered to refine it (4) Indexing The analytical framework was systematically applied to the rest of the transcripts (5) Charting Codes and interview data were organized into a chart to facilitate interpretation Decision-making processes about beverage availability mostly involved all household members, but the parents were normally the ones responsible for purchasing them. This indicates that agreements regarding what beverages are available at home did not necessarily depend on one family member and that the different beverage preferences were considered by the parents prior to purchase: BWell, we all decide, but they [parents] are the ones who buy the groceries right now and we get what they buy. But if I say: 'I would like this to drink', they will buy it.( Q10/P11/female/19 years). BIt's decided by a majority of votes.^(Q11/P25/female/ 17 years) However, some adolescents thought that their parents were the ones who decided what types of beverages would be available to them in the household: BIndirectly, it's their [the parents'] decision, because they buy three types of drinks for the house; each of us chooses what we are going to drink, but they are the ones who buy them [SSBs].^(Q12/P13/male/19 years) BIt's almost always my dad who decides.^(Q13/P17/ female/15 years) BMy parents decide together what is going to be available to drink…they never ask.^(Q14/P1/male/15 years)

Facilitators of SSB availability in the house
Home availability of different SSBs seemed to be affected by three different factors. One that facilitated the availability of fruit-containing beverages or fruit-flavoured drinks, independent of sugar content, was the perception that these were healthier than artificially flavoured drinks, and thus they were considered an acceptable beverage to have at home. This seemed to favour the intake of aguas frescas and sweetened juices. Preferring aguas frescas over other beverages, including water, was reported as a way to improve diet, and this was achieved through a shift from industrialised to home-made SSBs: BIt's not natural juice but it's better than the soda.^(Q15/ P18/male/17 years) BIf we drink Jamaica [hibiscus water] it's with brown sugar; my family try to make beverages healthy, and it's like 'Let's not drink soda.'^(Q16/P2/female/15 years) BI drink a beverage that does not contain gas, and according to me it's not as harmful as [soda brand].^(Q17/ P4/male/16 years) Second, the availability of bottled SSBs at home was facilitated by the ease of buying them rather than preparing beverages (mostly aguas frescas). Buying bottled SSBs was perceived as a good alternative when there was no time to make Bhealthier^beverages: BIt is faster to buy soda than to prepare a beverage.( Q18/P19/male/18 years) BIf they don't have time to make lemonade they buy something…if there is nothing to drink we go to the [mini-market name] and buy flavoured sodas. That's what we buy when we don't have time.^(Q19/P29/female/16 years) Third, taste preferences for SSBs also appeared to promote their availability at home. Adolescents perceived that they and their family members had a strong preference for SSBs, thereby facilitating availability due to their high acceptance: BI say they [the family] drink soda because they like the taste of it, because they drink [soda brand] they like its BI'm the one who gives priority to that [SSBs] because of the taste, because I like the sweetness.^(Q23/P20/ male/17 years) BSometimes when I'm craving something sweet, I drink juice.^(Q24/P6/male/16 years) Nonetheless, the most prevalent reason was that SSBs complemented food intake. Nearly all participants emphasized the importance of accompanying food with sweet drinks rather than plain water: BDrinks [SSBs] are to accompany food, we never drink water with food.^(Q25/P13/male/19 years) BWell, yes, I mean with sweet beverages you can better accompany food and they are tastier.^(Q26/P19/male/ 18 years) Carbonated beverage intake was particularly linked with Mexican dishes (e.g., tacos) and fast food (e.g., pizza or hamburgers), whereas iced tea and aguas frescas were associated with salads or dishes considered to be Bhealthier^: BWell, if it is junk food, like maybe pizza or something like that, it's generally with soda.^(Q27/P23/male/16 years) The role of family in SSB intake at home All adolescents in this sample lived with their parents and/or other family members. It was therefore essential to explore adolescents' perceptions of how their families' preferences and behaviours regarding SSBs might play a role in their own intake of SSBs at home. First, as mentioned previously, preferences for SSBs were evident among parents and family members: BMy dad likes to drink root beer…I associate [soda brand] with my mom because it's the only thing she drinks.^(Q33/P26/female/17 years) BMy dad likes to drink coffee or Jamaica [hibiscus water]; she [mom] drinks water or soda, but she also drinks Jamaica [hibiscus water].^(Q34/P22/male/17 years) Participants also indicated that one or more of their siblings also had certain preferences towards drinking SSBs: BMy brother does not like water, and, for example, if there is Jamaica [hibiscus water] he will have a bottle of iced tea; he buys it and he drinks it all the time.^(Q35/ P29/female/16 years) BMy sister likes iced tea a lot, she likes [iced tea brand], either the peach or lemon one, it doesn't matter which.( Q36/P21/male/18 years) Some participants also mentioned other family members, such as grandparents, aunts and uncles, and their preferences towards SSBs. They cohabited in the same house, lived close or visited their homes often. This indicates that relatives other than parents and siblings can also influence the consumption of SSBs: BMy grandparents are coffee drinkers and whenever I go to their home they make iced tea for lunch; then I started to drink sweetened tea and then coffee with sugar when I was there and then I started to do the same in my house.

Parental regulation and SSB intake at home
Within the 'Role of family in SSB intake at home' theme, parental regulation seemed to be an important factor. Most participants expressed that they were free to drink SSBs at home and that there was no rule preventing them from doing so: BThey have never banned any beverage or said: 'Drink this'.^(Q44/P28/female/17 years) BMy mom doesn't restrict them [SSBs]; well, I can't remember her ever saying: 'Don't drink that!'.^(Q45/ P9/male/17 years) Others mentioned that some rules on SSBs and their availability at home existed. These restrictions seemed to be influenced by the level of health consciousness among the parents: BMy dad gets worried that I drink a lot of sugar and he always tells me '[participant's name], you drink a lot of sugar', so when I go to his house he won't allow me to drink anything with sugar.^(Q46/P27/female/18 years) In some cases, limiting the home availability of SSBs was the result of parents trying to lose weight or having a health condition, such as diabetes: BBefore, we used to drink a lot of [soda brand]; we did not buy many juices, but then my dad came out diabetic and we stopped buying; well, we stopped buying so much [soda brand]. Before, it was like three litres of soda a day, but since my dad has been sick we have stopped drinking so much [soda brand].^(Q47/P17/female/15 years) BWell, my mom has always been on a diet eating salads and all that, and she tries to never buy [SSBs].^(Q48/ P8/male/19 years) In households where there were efforts to reduce SSB intake, some inconsistencies in maintaining healthy beverage habits over time were nevertheless highlighted by adolescents: BMmm, they used to say that [SSBs] are very bad, and in my family, they stopped drinking it, but then they would drink it again.^(Q49/P13/male/19 years) BMy mom says: 'We already drink lots of soda; we are going to drink lemonade or Jamaica [hibiscus water], because we already drink a lot of soda and we have to stop', and then we stopped for like two weeks only.( Q50/P22/male/17 years)

SSB intake as habitual behaviour in the home environment
For some adolescents, drinking SSBs at home was regarded as habitual behaviour. For instance, some participants explained that drinking SSBs was a family habit, something they were used to doing or something that was common because their families had done it for many years, or for as long as they could remember: BSoda is a habit of my parents, they got me used to it; it's innate…I do not know how this happened. I remember there was always soda or some type of sugary drink.( Q51/P12/female/18 years) BIt could be a habit because it's what we have always drunk.^(Q52/P19/male/18 years) Also, some adolescents thought that the constant home availability of SSBs throughout the years had led them to form a habit of consuming SSBs: BIt's always the same, so it's like we got used to drinking the same.^(Q53/P16/female/16 years) BSoda has always been available.^(Q54/P12/female/18 years) One of the components of habit is automaticity (Verplanken and Orbell 2003). Automatic processes are unconscious, that is, no mental effort is applied and therefore they tend to be fast (Moors and Houwer 2006;Orbell and Verplanken 2010). According to some participants the decision to drink SSBs at home was quick, possibly indicating some degree of automaticity. Participants also mentioned that the speed of their choice would depend on what types of drinks were available:

Discussion
This study qualitatively explores the factors surrounding SSB intake in the home environment among a sample of adolescents living in an urban area in Northwest Mexico. Five emerging themes help to describe the role of the home environment in adolescents' intake of SSBs: (1) context of SSB availability at home; (2) facilitators of SSB availability at home; (3) perceived importance of having SSBs at home; (4) role of family in SSB intake at home; (5) SSB intake as habitual behaviour in the home environment. These findings highlight a number of barriers for current policies, but also present a number of opportunities for future interventions directed to the reduction of SSB intake among Mexican adolescents.
Previous evidence has suggested that home availability of SSBs is associated with the intake of SSBs in adolescents (Grimm et al. 2004;Ezendam et al. 2010;Tak et al. 2011;Hebden et al. 2013;Van Lippevelde et al. 2013). Our findings explain more profoundly how this correlation might occur because of potential facilitators of home availability in Mexican households. For instance, the belief that fruitcontaining beverages, such as fruit beverages and aguas frescas, are healthy and therefore good to drink, was prominent among this sample of adolescents. Block et al. (2013) first introduced the term Bhealth halo^to refer to young adults' beliefs with regard to the health benefits of juice. Earlier qualitative studies among Mexican children and Latino adolescents and their parents also emphasized the notion of the Bhealthfulness^of aguas frescas because of their fruit content and natural ingredients (Theodore et al. 2011;Bogart et al. 2013). Although the preparation of aguas frescas is more Bnatural^compared with other industrialised beverages, this Bhealth halo^is likely to hinder adolescents' capacity to question what they drink and therefore requires attention. For example, the sugar content of aguas frescas is sometimes not acknowledged, as the amount of sugar in these beverages is subjective and based on an individual's taste during preparation. This suggests that looking at the sugar content of these beverages and identifying ways to reduce the amount of sugar added to homemade drinks could be a viable public health intervention. It is also important to recognise that the amount of sugar in these home beverages would not have been affected by the recent changes in SSB prices in Mexico, as the taxation only applies to bottled SSBs and not to homemade SSBs. Moreover, as suggested by Theodore et al. (2011), beverage marketing in Mexico has also contributed to the belief that fruit juices or other industrialised fruit-flavoured and fruitcontaining beverages are Bhealthier^. Educational strategies are therefore needed, not just for adolescents, but also for family gatekeepers, in order to inform the public about the sugar content of fruit beverages, as well as healthier preparation of homemade beverages, and to promote water as the healthiest beverage of all.
Food intake, especially during lunchtime, seemed to be a facilitator of SSB consumption. This shows how embedded in routine and family practices SSB intake can be and is also consistent with previous findings from a qualitative study conducted among children in Mexico City, where a Mexican culinary rule of accompanying savoury food with sweet beverages was also identified (Theodore et al. 2011). Cultural norms play an important role in individual food choices, shaping personal eating patterns and food preferences, as well as defining what foods are eaten, when food is eaten and how it is prepared (Larson and Story 2009). By considering that accompanying food with SSBs is a cultural behaviour in Mexico, we could assume that it is learnt early in life through an enculturation process (when culture is transmitted from one generation to the next), so the phenomenon is deeply rooted (Larson and Story 2009). This could represent an obstacle when trying to reduce SSB intake in Mexican households as cultural beliefs and traditions might be difficult to change. It might also be the case that accompanying meals with SSBs is influenced by the marketing and globalization of the western diet, where accompanying certain (fast) foods with SSBs is presented as common practice (Larson and Story 2009;Reisch et al. 2013). Future interventions need to consider these factors in their design and identify ways to modify cultural norms and practices to reduce the intake of SSBs in adolescents.
Even though tap water is potable in this part of Mexico, our findings also suggest that water was not commonly used to accompany meals in this sample of adolescents. Participants often referred to the ease of purchasing SSBs compared with preparing beverages themselves or drinking water at lunchtime. Although serving a glass of water requires less effort than going out to purchase SSBs, this was not a frequent occurrence within the adolescents' home environment and further highlights the need to identify feasible and acceptable ways to promote water intake, particularly as an accompaniment to meals, as the beverage option of choice.
Parents appeared to influence adolescents' intake of SSBs, which could be explained by parental modelling and a lack of home rules regarding SSB intake at home. This is consistent with previous studies in European adolescents, where parental modelling (Grimm et al. 2004;van der Horst et al. 2007;Bere et al. 2008;Tak et al. 2011;Van Lippevelde et al. 2013) and permissive parenting practices in relation to food intake were associated with higher SSB intake Verzeletti et al. 2010). Interestingly, our findings also suggest that siblings, grandparents and aunts/uncles can serve as role models and contribute to SSB availability at home, which adds to the limited evidence on the role of other family members in adolescent SSB intake. Thus, our research provides important insights into how wider family members' SSB intake patterns can influence adolescents' SSB consumption by shaping the range of drinks available at home and making SSB drinking a common practice, integral to the family's identity. Therefore, the adolescents' capacity for reflecting on what they drink at home seems to be either neutralized or attenuated by their families' dietary practices. Future research should consider the role of parents and other family members in the intake of SSBs in Mexican youth by gathering more objective information from parents, or other close family members, to explore this association in depth. These findings could then be used to inform future behaviour change efforts.
Our findings with regard to exploring potential environmental cues that might promote habitual intake of SSBs suggest that availability seemed to trigger SSB intake. The presence of SSBs appeared to be consistent at home (i.e. always or almost always available) over the years, which prompted the behaviour and its repetition, eventually causing the automaticity of consuming SSBs, a characteristic of habitual behaviours. This is consistent with the findings of Tak et al. (2011), who also suggested that the availability and accessibility of SSBs at home may induce habit strength and automatic behavioural responses. The present study suggests that home eating occasions, together with the perceived importance of accompanying food with SSBs, also prompted repetition of the behaviour, making it a less cognitive decision and therefore more difficult for adolescents to have control over. This needs to be considered in future interventions, since modifying availability patterns could attenuate the context-behaviour association and therefore reduce the intake of SSBs among adolescents.
The current study provides in-depth information about how different home environmental factors shape and trigger the intake of SSBs in a sample of adolescents living in Northwest Mexico. To our knowledge, this is the first qualitative study to explore factors related to adolescents' SSB intake in the Mexican home context. However, the study is limited in terms of generalisability as the interviews were conducted in a single city in Northwest Mexico. Moreover, we had a homogeneous sample in terms of socio-economic status, as participants were mostly from middle and high socioeconomic backgrounds. Therefore, we cannot know if the participant discourse would be different among low-income adolescents. Similarly, most of the participants were of normal weight, thus overweight and obese adolescents were underrepresented, so it is not known if their perceptions of the home environment in relation to SSB intake differ from those presented in this study. In our earlier cross-sectional work in this sample, we only collected data on the daily intake of SSBs, but we did not assess SSB intake separately for different eating occasions (e.g. at home, at school or other out-of-home activities). In addition to total daily intake, future studies should assess SSB intake in each individual context, as this will help the development of targeted interventions to reduce SSB consumption.

Conclusion
Our findings in this sample of Mexican adolescents support the notion that the home environment, including availability, perceived importance and family influences, contributes to adolescents' SSB intake. Results also highlighted the significance of habitual behaviours and cultural and family norms in influencing the intake of SSBs in Mexican youth. These factors need to be considered when designing interventions intended to modify SSB intake among Mexican adolescents and their families. Such schemes could complement the national SSB taxation policy currently in force (Colchero et al. 2017) by directly addressing availability and facilitators of SSB intake at home, family influences and parental regulation.