19 May Why African migrants live longer than those who stay behind

In a recent publication titled, Epigenetic-age acceleration in the emerging burden of cardiometabolic diseases among migrant and non-migrant African populations: a population-based cross-sectional RODAM substudy, PhD Student at AIGHD Dr. Felix Chilunga and colleagues explore the role of biological ageing in the emerging burden of cardiometabolic diseases among migrant and non-migrant Africans. Felix is working on projects about epidemiology and epigenetics of cardiovascular risk factors under the supervision of Professor Charles Agyemang.

Migrants from Africa face many health problems. Yet their life expectancy is better than that of Africans who stay in Africa. Research by Amsterdam University Medical Centers shows that a possible explanation can be found in the epigenetic age. This way of judging the health of a person is better for emigrants than for those who stayed behind.

This study, published this week in The Lancet Healthy Longevity, compares the epigenetic age of Ghanaians living in Ghana to that of their compatriots who have emigrated to the Netherlands, England or Germany. The epigenetic age is a measure of the age of cells. A healthy man of 40 has cells that are also 40 years old. In some cases, if the person lives unhealthily, the cells age faster. For example, an unhealthy man of 40 years old may have cells that are already 60 years old. Faster ageing of cells is linked to a lower life expectancy.

EPIGENETIC AGE

The age of the cells can be read by analyzing the “environment” of the DNA, hence the name epigenetic age. The environment of the DNA is influenced by many factors such as diet, lifestyle, environment. The DNA itself is not affected by such factors. The environment of the DNA is also important because it affects how the DNA is read.

The study is done by the RODAM team in which Dr. Felix Chilunga, and Prof. Charles Agyemang amongst others work together with colleagues from Europe, Africa, the United States, and India. They studied the difference in the epigenetic age of Ghanaian residents in Europe and their countrymen living in Ghana. In the European Ghanaians, the cells were ageing less rapidly than in the home-based Ghanaians. Dr. Chilunga notes: “This is remarkable because there are many health problems in Ghanaian migrants such as diabetes, obesity and cardiovascular disease as has been observed in other migrant populations. We now know that this is not due to faster ageing of the cells.”

OVERWEIGHT

The same research shows that the African Ghanaians are good off with slightly higher body weight. Obesity is a possible sign of an unhealthy lifestyle in high and middle-income countries and leads to a greater chance of all kinds of diseases. This does not appear to be the case in countries with low incomes. Ghanaians living in Ghana who are slightly overweight have a better life expectancy than Ghanaians with “healthy” body weight.

Chilunga: “We compared this with studies from South Africa and India and the results were the same.” One explanation for this is that people who are slightly overweight have a better buffer against chronic inflammation in the body.

According to Charles Agyemang, professor of Global Migration, Ethnicity & Health, another remarkable outcome of the study is that migrants have a better life expectancy than those left behind despite the diseases of affluence they contract here. In fact, migrants, in general, live longer than their European compatriots in Europe – the so-called ‘healthy migrant effect.’ Agyemang: “This study opens a new horizon to learn more about the role of epigenetic ageing and its impact on longevity and chronic diseases.”

This study was funded by the European Commission and the European Research Council.

This story was originally written by Marc van den Broek and published on the Amsterdam UMC website.