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.
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, USA, 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."
The same research shows that the African Ghanaians are well off with a slightly higher bodyweight. Obesity is a possible sign of an unhealthy lifestyle in the 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 a ‘healthy’ bodyweight. 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.