Tunisian migrants compared with non-migrant French and non-migrant Tunisians

Migrant health studies, beyond their importance for public health, help formulate hypotheses on the role of environmental vs. biological determinants of chronic diseases. The process of immigration is likely to influence food consumption and lifestyle and therefore to modify the risk of associated chronic diseases. Several studies have shown that immigrants usually have higher rates of mortality and morbidity linked to nutritionrelated noncommunicable diseases than the native population of their new host country, and also higher than the population of their home country. However this is not the case of Mediterranean migrant men living in Europe, an exception once called ‘the Mediterranean migrants paradox’. Among the possible explanations was the conservation of a traditional healthy diet. We therefore studied diet quality and its influence on nutritionrelated noncommunicable diseases in Tunisian migrant men living in the south of France compared with 2 nonmigrant male groups: local-born French of the same region and non-migrant Tunisians. The sampling was based on a quota of 150 men in each group related to age and place of residence. Native French men were matched for age and socio-professional category while the non-migrant Tunisian group was matched for age and geographical origin.

Components of the Diet Quality Index-International as mediators for effect of migration on disease

Using appropriate regression models, components of the Diet Quality Index-International (DQI-I) were tested as potential mediators for the effect of migration on overweight, hypertension, hypercholesterolemia, type-2 diabetes, and cardiovascular diseases. The total DQI-I score revealed good overall diet quality for all groups. Migrants scored higher than the French in variety (number of food groups, and varied sources of proteins), adequacy (level of agreement with various recommendations for preventing chronic diseases), and moderation (average level of lipids, saturated fatty acids, cholesterol, sodium or empty calories) and lower than Tunisians in overall balance (relative proportion of macronutrients, and of fatty acids). Migrants displayed a lower prevalence of overweight than French, lower prevalence of diabetes and CVD than non-migrant Tunisians, and lower prevalence of hypertension and hypercholesterolemia than the 2 non-migrant groups. A lower level of alcohol drinking was found as the main potential mediator for overweight between migrants and French.

Dietary adequacy, high consumption of fruits, and higher levels of vitamin C were mediators of the difference in hypercholesterolemia while the effect on hypertension was mediated by diet adequacy and fibre. Compared with non-migrant Tunisians, the effect of migration on hypercholesterolemia appeared mediated by saturated fat.

Healthcare utilisation, smoking and physical activity were mediators for the effect of migration on diabetes. The effect of migration on cardiovascular diseases was mediated by healthcare utilisation and energy intake. No obvious mediating effect was found for hypertension and hypercholesterolemia. Despite increasing levels of overweight, obesity and various related noncommunicable diseases in France, but also in Tunisia due to the advance of a fast growing nutrition transition, migrants appear to have conserved some healthy dietary characteristics. This partly explains their difference with local-born French, though other lifestyle factors also contribute to the favourable effect of migration.

Dietary differences between groups

Although the three diets did not appear strikingly different, as all three are of the ‘Mediterranean’ type, there were small differences which appear to have a significant impact on health. Tunisian migrants eat more pulses and less meat and dairy products than native French men. They also eat more fruits and vegetables, and as a consequence more fibre and vitamin C. They also kept the habit of a regular consumption of olive oil, which means a more favourable unsaturated to saturated fatty acid ratio, though their total lipid consumption was rather high.

Conversely, they avoided consuming too much sugar (including sodas) contrary to non-migrant Tunisians. Therefore, this study would indicate that small differences in saturated fat, sodium, fibre, vitamin C and sugar within a Mediterranean type diet, based on a fair share of fruits and vegetables, and associated to a slightly higher physical activity level, appear to have a significant and durable effect on various aspects of health. This observation can be of interest for the design of nutrition programmes based on small diet and physical activity changes.