Why are there ethnic differences in cardio-metabolic risk factors and cardiovascular diseases?

By Elisa Dal Canto, Bushra Farukh and Dr Luca Faconti

The population of Europe has become increasingly more ethnically diverse with an estimated 55% of residents in urban London originating from non-White British backgrounds. Studies investigating populations of various ethnic backgrounds have found the risk of developing heart disease, diabetes, or having a stroke as significantly different for people even living in the same area.

Ethnic minorities in Europe tend to be affected more by cardiovascular risk factors such as high blood pressure, high sugar level (diabetes), and abnormal blood lipids (dyslipidaemia). Although the precise mechanisms for such differences is still unknown, it is, however, likely to be a combination of the complex interactions between the environment (i.e. diet, smoking) and genetics (i.e. factors that we are born with) that influence the pathophysiology. In our study, we focussed on T2DM (Type II diabetes mellitus) and dyslipidaemia in people from different ethnic backgrounds living in the Netherlands and the United Kingdom.

Genetic background studies highlight the disproportion in the incidence and prevalence of T2DM in migrant populations of Europe. This excessive risk cannot be fully explained by measures of body composition (i.e. body mass index, fat percentage and waist circumference) and thus suggest other factors, such as migration history or the environmental effects of the host country, are likely to be involved. For example, the higher prevalence of T2DM in some ethnic minorities residing in the Netherlands seem to be attributed to their socio-economic status but this finding is still debated. Compared to Europeans, individuals from South East Asian backgrounds (SA) are found to be approximately 3-5 times more likely to develop T2DM whereas Black African (BA) population demonstrated a 2-3fold increased risk of T2DM.

Similarly, there is an increased prevalence of dyslipidemia in ethnic minorities, although data investigating this disproportion is sparse. SA individuals exhibit higher levels of dyslipidemia and T2DM at comparatively lowers levels of BMI and body fat than Caucasian individuals, leading to an increased risk of cardiovascular morbidities. Whereas the BA population, with its high incidence of hypertension and T2DM, depicts a favourable lipid profile which may be a result of genetic differences found in the enzyme hepatic lipase. Interestingly, even with this favourable antiatherogenic lipid profile, BA individuals have a disproportionately high risk of developing cardiovascular disease (CVD) when compared to their white peers, a phenomenon well characterized as the Insulin Resistance-Lipid Paradox in People of African Ancestry.

With the increase of various ethnicities in Europe, it has become important to understand why migrant populations have a higher risk of developing CVD. Ethnic variations in cardio-metabolic risk factors partially contribute to this increased risk, but the precise underlying mechanisms still remain elusive. The rising epidemiological figures will inevitably impact the National Health Service as the disease profile of migrant populations differs to that of the residents. Therefore, further randomized control trials should be conducted in order to identify and create prevention and treatment options tailored specifically to these ‘high risk groups’.