Cardiovascular disease (CVD) is a group of disorders that involve the heart and blood vessels. With an estimated 17.7 million people dying from CVDs in 2015—representing 31% of all global deaths—CVD is now the leading cause of mortality worldwide [1
]. While “non modifiable” risk factors such as age, gender, and family history cannot be changed, other risk factors such as hypertension (high blood pressure), diabetes, smoking, being overweight/obese, being inactive, and bad diet can be changed. The World Health Organization (WHO) reported that high blood pressure resulted in 13% of CVD deaths, while tobacco resulted in 9%, diabetes 6%, lack of exercise 6%, and obesity 5% [2
]. Other than these risk factors, scholars have also identified immigration as a predictor of cardiovascular risk through the theory known as the “healthy immigrant effect” where it has been proven that newly arrived immigrants have lower rates of cardiovascular risk factors than nonimmigrants [3
]. As new immigrants arrive in the host country, they go through a cultural transition called acculturation.
Acculturation is the process of adapting to the traditions, values and practices of a host country [5
]. The length of residence, the most commonly used proxy measure of acculturation, is associated with increased prevalence of CVD risk factors among immigrants in Western countries [1
]. Little is known about the association between the length of residence of immigrants and CVD risks among new immigrants in the Republic of Korea (Korea) as most research has mainly focused on the acculturation of Hispanic, European, and Asian immigrants in Western societies [8
]. Korea was mostly known for its large-scale emigration, however it has recently emerged as a popular destination for immigrants [10
]. For the first time, it is estimated that three out of every 100 individuals in Korea originated from a foreign nation [12
]. The country is consequently transitioning from a homogenous society to a multicultural country” [11
]. Until very recently, Korea has had little or no experience with large-volume immigration [8
]. As a tool for advancement or survival [15
], the Korean government welcomes a great number of English teachers mainly from seven countries: Canada, USA, UK, Australia, New Zealand, and South Africa.
Given the rapid increase in English teachers mainly from Canada and the US (around 5000 in public schools), this study aimed to examine the association between the duration of residence and CVD risk factors mediated by gender and the dietary acculturation of English teachers in Korea. To my knowledge, this is first research studying acculturation and CVD risk factors in Korea. The preliminary conceptualized model of the relationship between the duration of residence in Korea, dietary acculturation, and CVD risk factors is shown in Figure 1
Many studies have found a correlation between acculturation and CVD risk factors in Western countries [1
]. This was the first study to examine the association between duration of residence and CVD risks factors mediated by gender and dietary acculturation of English teachers in Korea. Given the small sample used (n
= 385), the fact that more than 11% reported as currently smoking and having hypertension should raise alarms about the health status of this growing population in Korea. Furthermore, overweight/obesity (47.4%) and the lack of physical activity (63.3%) are two known risk factors of cardiovascular disease [24
Gender is a “non-modifiable” risk factor and cannot be changed. Although CVD remains the leading killer of both women and men worldwide, there are substantial gender differences in the prevalence of different CVDs [26
]. Even though more women than men die from CVD every year, this group of diseases has often been viewed as a man’s disease [26
]. When it comes to CVD risk factors, the results are inconsistent as race is often a factor. In the U.S., for example, the highest rate of hypertension is among black women when compared to other races [26
]. Our study did not differentiate race; however, the findings of this study were consistent with other studies showing that men had higher levels of hypertension [29
]. Observed gender differences in hypertension could be behavioral [30
]; with BMI [30
], smoking [30
], and physical inactivity [30
] as risk factors. The examination of Table 2
shows that CVD risk factors were predominant in men with 16.5% of men who were current smokers when compared to 6.9% for women. In addition, 47.4% of men were overweight/obese when compared to women (41.7%).
This study was in agreement with several lines of evidence that have shown that the prevalence of obesity and hypertension increased with duration of residence in the host country [7
]. Obesity is a serious public health epidemic that this century has known; there are approximately 2 billion adults that are overweight or obese. Prior studies have found that immigrants from low- to medium-income countries who have migrated to and reside in high-income countries are more susceptible to overweight and obesity than their local counterparts [35
]. This study showed that the phenomenon was the same from high-income countries (USA, Canada, UK, and Ireland) to another high-income country (Korea). Furthermore, among the US and Australian based migrant groups, people born in Italy, Greece or Cyprus, the former Yugoslavia, Germany, the Netherlands, Poland and other Eastern European countries recorded a higher likelihood of overweight and obesity than people born in Malaysia, Vietnam or Cambodia, the Philippines, or China [37
Although studies have suggested that longer residence is associated with diabetes and smoking, an increasing length of residence in Korea was not significantly associated with diabetes and smoking. Only three English teachers were reported to have diabetes. This number is not sufficient to determine a correlation. Furthermore, even though two of the three reported cases of diabetes were from participants living in Korea for over five years, the lower reporting of diabetes as a CVD risk factor could be associated to the “healthy immigrant effect” [3
A decrease in physical inactivity with increasing length of residence in Korea was also observed. There are two possible reasons for this inverse association. First, the English teachers may have been aware of their health condition and consequently decided to exercise more. Second, as stated by Koya, this may have been part of a “positive acculturation effect” [6
]. As immigrants reside longer in the host country and acculturate to their new environment, they are more likely to adopt healthy beliefs on the benefits of exercise.
After stratification for the length of residence in Korea to <than 5 years and >5 years, the odds of smoking became 1.5 greater for participants residing in Korea for over five years (Table 4
). However, it is possible that the habit could have been acquired during teenage years before migrating to Korea and not necessary attributed to acculturation. The average age of English teachers in this study was 33.23 years (SD 8.50). Out of the 43 people who reported to be smokers, twenty had lived in Korea for less than five years when compared to the 23 said to be in Korea for over five years. Nevertheless, smoking is a modifiable CVD risk factor and awareness programs aimed at English teachers in Korea are necessary.
Finally, typical Korean food was not associated with CVD risk factors as over 95% of English teachers in Korea easily went through a nutrition transition. Nutritional transition relates to the tendency in decreased consumption of healthy and nutritional foods in favor of fatty and processed foods [38
]. The weight gain observed among English teachers was likely to be associated to poor diet choice. Korean food is generally regarded as healthy although the country has been going through a diet transition [40
]. Concurrent changes in lifestyle include the rapid introduction of elements of what may be termed a Western lifestyle despite national efforts to retain elements of a traditional diet. It is therefore possible that English teachers in Korea will choose Korean food with more familiar elements as food habits are likely to be the last to change when people become acculturated.
This study had some limitations. The majority of participants were well educated (Table 1
), which limits generalization. Data on hypertension and diabetes were self-reported, which may be subject to recall bias or prone to misclassification. However, self-reported data of hypertension have been shown to be highly correlated with medical records. The results may have also been influenced by a potential cohort effect since the study did not distinguish between pre- and post-migration diagnosis of hypertension or diabetes by a medical doctor. Since self-reported hypertension was associated with duration of residence in Korea, measuring pre- and post-migration hypertension by a medical doctor would provide a more accurate association. On the other hand, the fact that the findings of this study were consistent with previous studies [7
] lends evidence to the face validity of this study. The length of residence and eating Korean ethnic food were used as proxy indicators for acculturation. Other measures of acculturation such as language proficiency, participating in ethno-cultural networks, and celebrating holidays and cultural events were not examined. Future studies with larger samples and race specifications are needed since there might be heterogeneity within English teachers in Korea. This will provide a better understanding of how acculturation influences cardiovascular risk factors among immigrants in Korea.