Our results indicate that after immigration to Canada, the majority of Chinese immigrants tended to consume more healthy foods like fruits and vegetables, and showed a decrease in less healthy food habits such as deep-frying as a way of preparing foods. Furthermore, as a whole, Chinese immigrants reported a higher awareness of healthy food choices and increased knowledge of nutritional information on food tables and food products after immigration, however, there was no association between these variables and length of residence. Length of residence did show a positive correlation to potentially less healthy food habits such as portion size, restaurant meals/dining out and convenience foods after immigration of Chinese immigrants to Canada. Taking into account that CVD risks are higher among Chinese immigrants after immigration [7, 8], this trend could partially be explained by the increase in portion sizes, more frequent dining out after immigration and higher consumption of convenience foods.
Our findings are consistent with other studies that reported an increase in consumption of fruits and vegetables after immigration in Chinese immigrants [18, 19, 24]. This is supported by our study population reporting an increased awareness of healthy foods, and greater than 50% reporting availability of fruits and vegetables. An earlier study reported a greater year-round availability of fresh fruits and vegetables in supermarkets in Canada as opposed to China . In addition, an increased consumption of fruits and vegetables could also be related to how these products are displayed in supermarkets. Research shows that with more shelf-space for fruits and vegetables the purchase and consumption increases . It is possible that fruits and vegetables are displayed differently in shops in Western countries compared to China.
While our results are in line with those of Kwok et al. who reported a decrease in fat intake by reducing the consumption of fried foods among Chinese immigrants , others reported an increase in the consumption of fatty foods in Chinese immigrants after immigration to a Western country [18, 19]. This dissimilarity in outcome could be related to differences in the investigated populations. According to Osypuk et al. neighbourhoods with a higher proportion of Chinese immigrants tended to have a diet lower in fat , suggesting that Chinese immigrants preserve their traditionally healthier food practices better when living in these neighbourhoods, whereas neighbourhoods with a lower proportion of people of Chinese background may be less likely to have foods available familiar to the Chinese immigrants. This study was conducted in Vancouver and its surrounding areas, where throughout the city, neighborhoods can be found with a high proportions of Chinese immigrants, which may have resulted in a greater availability of familiar foods. However, the previous cited studies also were conducted in neighbourhoods of predominantly Chinese immigrants. It is possible that our different findings may be due to how the data were collected. Previous studies used food frequency questionnaires [18–20], while our questionnaire was based on participant perceptions of change.
The suggested increase in portion size after immigration to Canada described in our study has, to our knowledge, not been investigated in previous research. In Canada, as well as in China, nutrition guidelines are used to recommend people about healthy amounts of food consumed daily. Although the nutrition guidelines are presented differently in the two countries, similar amounts of food are recommended . Therefore it is not likely that differences in nutritional guidelines has an influence on the change in portion size among Chinese immigrants after immigrating to Canada. A possible explanation for the larger portion sizes could be that larger portion sizes are offered in shops and restaurants. Additionally, Whalqvist reported that when new foods are included along with the availability of traditional foods, this increase in variety can result in an increase in food consumption .
Consistent with previous research , our study revealed a higher awareness of healthy food habits among Chinese immigrants after immigration. Food labels were reported to be read more often by Chinese immigrants after immigration, and were understood better. However, this change was not found to be related to length of residence. One explanation could be that these changes occur soon after immigration to Canada. As for better understanding and more frequent reading of food labels, a possible explanation could lie in the different requirements concerning regulation of food labelling in China versus Canada. Chinese regulations only require a list of ingredients, and the net weight (the weight of the product alone) to be present on pre-packaged food products . Canadian regulations require the same information on a food label, along with a table of nutrition facts given per serving . Moreover, four diet-related health claims are allowed to be shown on Canadian pre-packaged foods suitable for diets that reduce risk factors for chronic diseases or conditions. Research has shown that these health claims improve the quality of dietary choices .
Our research indicates that Chinese immigrants increased their portion size, dining out and consumption of convenience foods after immigration to Canada. As we did not examine the actual composition of the foods which were eaten as part of the portion sizes, dining-out meals and convenience foods, we cannot say if this is a healthy or unhealthy change. An increase in portion size may be interpreted as an unhealthy change for it increases the risk of obesity [31, 32]. However, portion sizes of fruits and vegetables could also have increased, which would be beneficial for the risk of CVD . We also found that more than 50% of the Chinese immigrants reported that it was easier to choose healthy foods when dining out after immigration. In an earlier investigation we reported that length of residence was related to household income  and this may in part explain the greater reported frequency of dining out with increased length of residence as those people with greater income may have more financial freedom to eat in restaurants. Lastly, more than 60% of Chinese immigrants reported hearing more about healthy food choices through the media after immigration which may relate to eating more healthy foods. However, in these same participants, we reported that length of residence was positively associated with increased thickness of the carotid artery, a known precursor to CVD, and this was also greater than non-immigrants of the same age . It is possible that despite a number of reported favourable changes in dietary patterns in this group, these benefits may be outweighed by the negative health effects of increased portion sizes as well as increased consumption of convenience foods and restaurant meals.
Several limitations should be considered when interpreting our results. Our study participants tended to have a high level post-secondary education and household income which has been found to be associated with a greater health outcomes and knowledge . In addition, the M-CHAT study purposely recruited participants across a range of BMI values and therefore oversampled for Chinese people who were obese. The greater number of people with obesity in our study population may be reflected in our findings that portion sizes increase with length of residence in Canada, as portion sizes tend to be higher in people with higher BMI. However, our earlier study did not find a relationship between increasing BMI and length of residence . As we did not assess dietary intake but rather perception of dietary changes with immigration, we cannot be certain of the exact changes in diet, and actual changes in dietary behaviours with immigration should be explored in future research. We must also acknowledge that recall of previous dietary patterns has been found to be less accurate than the recall of current dietary patterns . Finally, as this was a cross-sectional study, longitudinal data are needed to explore whether there is a causal relationship between the change in dietary patterns and CVD risk among Chinese immigrants.