Models of dietary acculturation

Two main models have been proposed to explain the factors influencing dietary change in migrant populations^{(Reference Satia-Abouta, Patterson and Neuhouser9,Reference Kockturk-Runefors26)} . Their scope, strengths and weaknesses are discussed next.

The first dietary acculturation model was proposed by Kockturk-Runefors^{(Reference Kockturk-Runefors26)} and aimed to enhance the understanding of adaptation to new dietary patterns after migration. This model seeks to explain how food habits change depending on taste preferences and cultural identity. In this model, foods are grouped into staple foods, complementary foods and accessory foods. Staple foods are foods that form a dominant portion of the diet for a given population, and staple foods vary among different population groups. They usually are a source of carbohydrates and proteins. For most Africans, living within Africa or in HICs, popular staple foods are made from starchy carbohydrates such as cassava, yam, plantain and rice. Complementary foods are often protein-rich sources such as meat, fish, legumes and milk. Accessory foods are added to enhance the taste and presentation of the meal^{(Reference Kockturk-Runefors26)}.

According to the model, staple foods are likely to remain the same for several generations, however accessory foods change most easily on exposure to a new food environment, whereas complementary foods may remain unchanged over a long period. Kockturk-Runefors argues that if staple foods remain the same following migration, changing accessory foods is still perceived by migrant-origin groups to preserve the identity of the meal as the ‘traditional diet’ (Table 1).

Although the model developed by Kockturk-Runefors was based on observations of food habits of Turkish migrants in Sweden, studies in Europe have tested its usefulness^{(Reference Méjean, Traissac and Eymard-Duvernay17,Reference Osei-Kwasi, Boateng and Danquah24,Reference Nicolaou, Doak and van Dam27)} . An example is a study among Moroccans in the Netherlands that showed that Moroccan migrants tend to consume more sweets and snacks following migration^{(Reference Nicolaou, Doak and van Dam27)}. Another dietary change study, focusing on Ghanaian migrants, found a shift from a more traditional fish-based diet to a diet higher in dairy, red and processed meat, which can be seen as a more westernised dietary pattern following migration^{(Reference Osei-Kwasi, Boateng and Danquah24)}. In contrast to Kockturk-Runefors's model, the Ghanaian study also found a shift from traditional staples (plantain roots and tubers) to bread and cereals following migration, which suggests that staple foods are the last to change following migration. What this may mean is that when people migrate, foods perceived to be close to one's identity are still important in the sense that these foods are still consumed, but their relative importance to the food groups may change or be ‘diluted’ by other foods^{(Reference Osei-Kwasi, Boateng and Danquah24)}.

Additionally, Kockturk-Runefors purports that there is a similar differential change in meal patterns, i.e. breakfast, lunch, dinner and snacks, where initial changes are seen with snacking or grazing, because snacks are often not considered as real foods by migrant groups^{(Reference Mellin-Olsen and Wandel28)}, similar to the perception of accessory foods. This is followed by changes in breakfast, then lunch. The model further indicates that dinner, usually remains unchanged for so long because family members are more likely to come together at the end of the day. Therefore, there is more social, cultural and ethnic significance to eating dinner compared to lunch and breakfast. This could be compared to staple foods remaining unchanged for so long because of its strong ties with ethnicity. For instance, in a study of Ghanaian migrants, breakfast habits had shifted towards those of the majority ‘host’ population, which is consistent with the model, while the evening meal still had cultural importance, and family members were more likely to be around at the end of the day or during the weekends. Other studies have also found a similar process of change among migrants^{(Reference Mellin-Olsen and Wandel28,Reference Tuomainen29)} .

The second model of dietary acculturation, developed by Satia-Abouta and colleagues^{(Reference Satia-Abouta, Patterson and Neuhouser9)}, illustrates the complex relationship that exists between cultural factors (e.g. religion), socio-economic factors (e.g. employment), demographic factors (e.g. sex) and migration, and how this impacts different patterns of dietary intake. According to this model, change in dietary intake due to migration is not a simple or linear process where migrants make a discrete shift from traditional foods to the host diet or to westernised diets. Instead, change in dietary intake could take different pathways. It can be in the form of completely abandoning traditional diets or maintaining traditional diets, or to combining traditional diets with the host diet due to various reasons.

These different outcomes of dietary acculturation are in line with Berry and Sam's classification of acculturation strategies^{(Reference Berry, Sam, Berry, Segall and Kagitcibasi30)}. For instance, maintaining some traditional dietary behaviours and adopting new ones from the host country could be described as a sign of integration. The departure from traditional diets has been reported in some studies in the UK and France, especially among younger generations of migrant-origin groups^{(Reference Gilbert and Khokhar31)}. On the contrary, studies among Afro-Caribbeans living in Manchester^{(Reference Mennen, Jackson and Sharma32)} and Ghanaians living in London, Amsterdam and Berlin showed the maintenance of traditional diets, even after several years of living in the UK^{(Reference Osei-Kwasi, Boateng and Danquah24,Reference Galbete, Nicolaou and Meeks33)} . This is supported by another study conducted among Ghanaian migrants living in Greater Manchester who were described as having bi-cultural dietary patterns, indicating that they neither completely changed traditional dietary practices to that of the host country or completely maintained traditional dietary practices^{(Reference Osei-Kwasi, Powell and Nicolaou34)}. In this study, three typologies were identified similar to the three patterns demonstrated in the model of dietary acculturation^{(Reference Satia-Abouta, Patterson and Neuhouser9)}, namely the maintenance of traditional eating patterns; the adoption of host country eating patterns and bicultural eating patterns. However, Satia-Abouta's model implies a strict division within the three patterns, whereas this study found evidence of an overlap between dietary typologies and nuances in bicultural dietary practices. This finding is consistent with those from previous studies of Ghanaians in the UK^{(Reference Tuomainen29)} and female migrants from different African and Asian countries living in Norway^{(Reference Garnweidner, Terragni and Pettersen35)}.

Most dietary acculturation studies have investigated the process of change from traditional to new patterns of diet (i.e. westernised diet), suggesting a change from healthy to less healthy diets^{(Reference Gilbert and Khokhar31)}. However, recent studies among Ghanaian migrants propose that migration may contribute to healthier or unhealthy dietary changes^{(Reference Osei-Kwasi, Powell and Nicolaou34)}. A study conducted among international students in Belgium also reported increases in the consumption of healthy foods following migration^{(Reference Perez-Cueto, Verbeke and Lachat36)}. Exposure to host food culture through the media, friendships and the work environment were hypothesised to result in increased nutrition knowledge, which in turn led some migrants to adopt healthier diets. This contradiction in the influence of migration on dietary practices confirms the idea that dietary acculturation is a complex process that depends on several factors. The operant model of acculturation and ethnic minority health behaviour^{(Reference Landrine and Klonoff37)} may go some way to explaining these seemingly contradictory findings. An implication of the varying perceptions regarding a change in dietary practices resulting in healthy/unhealthy dietary practices is that it is possible that within the Ghanaian population not everyone will require the same kind of intervention^{(Reference Osei-Kwasi, Boateng and Danquah24)}.

While Satia-Abouta's model of dietary acculturation discussed earlier is useful for nutritionists to understand dietary acculturation, its limited inclusiveness and lack of accounting for the many other factors that influence dietary practices following migration have been criticised^{(Reference Abraído-Lanza, Armbrister and Flórez38,Reference Antin and Hunt39)} . It is largely based on traditional migration models and considers dietary change from the perspective of relatively disadvantaged communities. Migration is often assumed to be from an underprivileged situation to a more prosperous country, and that the resultant dietary change is therefore from an implied healthy, traditional diet, to a more westernised and less healthy one. This limits its relevance to more recent voluntary migrant groups or migrants from a high SES background before migration^{(Reference Thomas40)}, thus it may not be relevant for future migrant generations, i.e. second-, third- or fourth-generation migrants. Once again this emphasises the importance of considering the heterogeneity of migrant populations.

One limitation of Satia-Abouta's model^{(Reference Satia-Abouta, Patterson and Neuhouser9)} is the separation of factors into socio-economic, demographic and cultural factors, which tends to present a simplistic view of the process of dietary change that is more complex than the model suggests. Other factors that have been shown to influence dietary practices such as contemporary migration patterns and those of the globalisation of the food system are not included, for example^{(Reference Fanzo, Haddad and McLaren1,Reference Thomas40)} .

Food supply chain

As shown in Fig. 3, the food supply chain comprises food production, food storage and distribution, and food marketing. These activities and associated actors are responsible for production, consumption and disposal of its waste^{(Reference Hawkes and Ruel46)}. Unlike other food supply chains, that for traditional foods of African migrants is more complicated, given that most of these are imported into Europe. It is well known that the level of food production influences food availability and affordability, which also in turn influences diet quality and diversity^{(Reference Lartey, Hemrich and Amoroso47–Reference Legg50)}. The availability of these foods is therefore, not only dependent on the production of African foods but controlled by all the elements of the trade and export arrangements in place by the importing HIC and the country where the food is exported from. Hence, any disruption to the international market affects the availability and prices of these traditional foods.

Food environments (food availability and affordability)

Beyond the issues of international trade, the availability and affordability of traditional African foods is largely driven by demand. In areas of super-diversity (refers to the unprecedented collection of different nationalities, faiths, languages, cultures and ethnicities in a society)^{(Reference Vertovec51)}, such as in London, Birmingham and Manchester in the UK, traditional African foods are readily available and prices are cheaper compared to areas of less diversity. In these areas of diversity, there are a number of local traditional shops, thus offering competitive prices to attract consumers.

Studies on African migrant origins in Greater Manchester^{(Reference Osei-Kwasi, Nicolaou and Powell52)} and Birmingham^{(Reference Asamane, Greig and Aunger53)} have confirmed that the availability and affordability of traditional foods directly shape eating behaviours of both older and younger African migrants in the UK^{(Reference Osei-Kwasi, Nicolaou and Powell13,Reference Osei-Kwasi, Powell and Nicolaou34,Reference Asamane, Greig and Aunger53)} . In the study conducted in Greater Manchester, participants compared the food environment in the UK with the context before migration, where food was unavailable during certain times of the year and indicated the abundance of foods including traditional foods in the UK^{(Reference Osei-Kwasi, Nicolaou and Powell52,Reference Asamane, Greig and Aunger53)} . This was attributed not only to the high number of ethnic shops that sold traditional foods in areas of super-diversity, but also because large UK-wide supermarkets such as Tesco, Asda and Sainsburys in super-diverse areas also have aisles stocked with ethnic foods which are described as ‘world foods’ (Table 1). This perception could be because the food environment was compared with that before migration, in which participants reported food scarcity during certain times of the year^{(Reference Watson and Hiscock54)}. This could be due to lack of food processing and storage facilities in most farming areas, but also because in many communities food production is dependent on subsistence agriculture and rainfall^{(Reference Watson and Hiscock54)}. In a recent scoping review exploring the interactions of factors in the food environment of migrants using the Analysis Grid for Environments Linked to Obesity (ANGELO) framework, it was found that time constraints, availability of transport services and the opportunity to be sign posted to traditional food markets by close networks were essential overarching themes that influenced the choice of migrants accessing different food options^{(Reference Berggreen-Clausen, Pha and Alvesson55)}.

Several studies have also cited how environmental factors change following migration^{(Reference Satia-Abouta, Patterson and Neuhouser9,Reference Osei-Kwasi, Nicolaou and Powell13,Reference Agyemang, Addo and Bhopal56)} . For instance, exposure to a new food supply can result in changes in procuring and preparation of food and the unavailability of traditional foods that can lead to an increased intake of foods found in the host country^{(Reference Satia-Abouta, Patterson and Neuhouser9)}.

In more recent times, especially during the COVID-19 pandemic, a number of ethnic food shops started trading online and advertising using social media and other ethnic minority-specific communication channels, such as local UK-based African radio stations. These shops offer access to traditional foods even for those living in areas of less diversity. However, the quality and prices of these foods purchased online can differ from foods purchased from physical shops.

Individual level factors

Individual level factors include a person's SES, situational factors^{(Reference Fanzo, Arabi and Burlingame57)}, cultural identity, age and ageing, medical condition and body image.

Consumer behaviours

Consumer behaviours in this context refers to food-related decisions or choices that African migrants make regarding what foods to buy, where to buy, how to prepare and consume food and how to store it. Taste, socio-cultural context, age and medical conditions (as discussed earlier) have been found to strongly influence consumer behaviours of African migrants in the UK^{(Reference Osei-Kwasi, Powell and Nicolaou34,Reference Asamane, Greig and Aunger53)} .