Original article
The immigration effect on obesity and overweight in Israeli Jewish male adolescents born 1970–1993

https://doi.org/10.1016/j.annepidem.2014.02.012Get rights and content

Abstract

Purpose

The aim of the study was to assess the relationship between age of arrival of male pediatric immigrant populations in Israel and their risk for subsequent high-weight morbidity at adolescence.

Methods

The study analyzed a pooled cross section of 89,744 foreign-born male Jewish study participants, who were born in the former Soviet Union or Ethiopia (1970–1993) and immigrated in childhood to Israel. Each participant's body mass index was measured at approximately 17 years of age. Odds ratios were calculated for obesity and overweight according to age on arrival to Israel. A total of 52,503 Israel-born participants with origins in those same countries were measured at the same age and used as references. A total of 52,258 native Israelis without known immigrating ancestry were also used for comparison. The risk stratification accounted for possible socio-demographic confounders and birth year.

Results

Foreign-born immigrants had decreased risk for obesity and overweight relative to Israeli-born immigrants when measured at the age of 17 years. However, those who arrived in Israel during infancy and early childhood (before the age of 3 years) had greater risk for high weight compared with those immigrating during late childhood and adolescence.

Conclusions

Although generally protective against obesity and overweight relative to native, these beneficial effects of immigration are diminished for those arriving in early childhood rather than later in adolescence.

Introduction

Body weight has been studied extensively in the past regarding its effect over morbidity and mortality, especially in the cardiovascular spectrum [1]. There is evidence in existing research that among other factors, immigration also modifies risk for cardiovascular diseases, including coronary heart disease and diabetes mellitus [2], [3]. The body mass index (BMI) profile of some immigrant populations, including adolescents [2], [4], [5], [6], was found to change after residence in the host society. A “healthy immigrant effect” has been described in immigration across countries, in which newly arrived immigrants enjoy better health than the native population but lose this advantage with the duration of stay. In the United States, for example, a pooled analysis showed that longer residence of immigrants resulted in higher prevalence of hyperlipidemia and obesity with ethnicity as a risk modifier for such trajectories [7], [8], [9], [10]. The same effect has also been observed in children and adolescents [11], [12]. This so-called “acculturation” of immigration populations is considered obscure by researchers as to its precise socio-biological mechanisms and degree of relevance among different ethnic-immigrant populations.

Israel has gathered throughout its history several populations from different origins across the globe. This includes survivors of the Holocaust from Europe in the 1940s and 1950s, Asian and African populations that immigrated mainly during the 1950s and 1960s, people from the former Soviet Union (USSR) and Eastern Bloc who came in large numbers beginning in the 1970s, and population from Ethiopia beginning in the 1980s. Healthwise there is evidence that some of these populations have modified their morbidity profile. The Jewish population that originated in Yemen increased its rate of diabetes mellitus from almost nonexistence to approximately 12% in a follow-up of 25 years [13], [14], [15]. The same cohort also showed increased blood lipids on follow-up versus time of arrival even in nondiabetics [15]. Studies showed a sharp rise in the prevalence of diabetes in members of the Israeli Jewish Ethiopian community as well [15], [16]. Apart from these specific trends in discrete communities, a general surge of obesity and overweight is evident in Israeli youth with estimates of 6% obesity and 17% overweight for 17-year-old males born in 1993 [17].

The goal of present study, as part of continuing research conducted previously by our group about population-based trends in obesity [17], was to explore the association of age at immigration with high-weight status in immigrant populations that arrived in Israel in childhood. This was achieved through a multiyear pooled cross-section of boys who were measured for weight and height by professionals at the age of approximately 17 years. Foreign-born immigrants were compared with Israeli-born reference groups, all born between 1970 and 1993. The study was meant to augment existing research in the question of acculturation, “healthy immigrant effect,” and the influence of environmental changes at young age on weight. We compared two Jewish Israeli immigrant populations from the USSR and Ethiopia, which formed the bulk of immigration to Israel in the 1970s, 1980s, and 1990s. We included these specific populations because for the most part they arrived in a time period when obesity was (and still is) increasing in prevalence in Israel [17] relative to earlier periods. Presumably, this would produce the greatest environmental pressure on newly arriving immigrants in the context of “healthy immigrant effect.”

Section snippets

Data collection

In Israel, all Jewish Israeli citizens are obligated by law to serve as conscripts at the age of 18 years in the Israeli Defense Forces (IDF). The draft process includes preliminary medical examinations at the age of approximately 17 years, in which the candidates are measured for weight and height and also provide socio-demographic data such as country of birth, year of birth, and year of immigration (when applicable).

The study population includes male adolescents grossly divided into three

Results

Table 1 shows the characteristics of our study population. We extracted data for 89,744 foreign-born male immigrants from the USSR and Ethiopia and 52,503 Israeli-born participants with ancestry from those countries. Data were also extracted for 52,258 native Israelis without paternal or grandpaternal immigration. All participants had complete records for weight, height, municipality of residence, and age at immigration. Mean age at examination by the IDF was 17.24–17.75 (SD 0.36–0.61)

Discussion

This study explores the influence of immigration over prevalence of obesity at the age of 17 years. Immigration at a young age across countries poses abrupt and potentially substantial changes to the environment in which a young child or adolescent lives. Such alterations may include nutritional, recreational, and cultural shifts from the original country, along with psychosocial implications inherent in the act of immigration itself. Taken together, these form a multidimensional array of

Conclusions

This study was conducted in continuum to our previous studies in the field of cardiovascular risk factors in Israeli Jewish adolescents, which demonstrated a general rise in obesity and overweight in recent decades with various socio-demographic risk factors associated with these outcomes including socio-economic score, level of education, and country of origin [17], [21], [22]. Moreover, obesity in Israeli adolescents was associated with obesity-related morbidity in adulthood and specifically

Acknowledgment

Authors' contributions: C.M., G.T., and E.D. designed the study, analyzed the results and formulated the study's discussion. E.D. and D.T. conducted data collection efforts and statistical analysis of the results. B.G. participated in conceptualization of the study. A.A. and A.S. were the study's facilitators. All authors took part in reviewing the article for publication.

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  • Conflicts of interest: The authors report no conflict of interest regarding the study.

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