• In Tanzania, it was observed that switching from an African diet to a Western one, characterised by the consumption of ultra-processed foods and an excess of calories, increases the pro-inflammatory state and reduces the effectiveness of the immune system.
• Switching from a Western diet to an African diet has, conversely, an anti-inflammatory effect.
• The results highlight the importance of preserving indigenous diets for health, as well as how harmful the Western diet can be.

How much does diet influence the immune and metabolic system? And what is the impact of the globalisation of food? The journal Nature has published a study by the Kilimanjaro Christian Medical University College in Tanzania, carried out with the participation of the Università degli Studi di Firenze and other European universities, which investigated the immune and metabolic effects of the traditional African diet compared to the Western diet on a sample of the Tanzanian population.

According to the results, abandoning a traditional African diet — rich in fruit and vegetables, cereals, legumes and fermented foods — and adopting a diet typical of the globalised Western world, characterised by the consumption of ultra-processed foods and an excess of calories, causes inflammation and reduces the immune response to pathogens. The reverse path, on the other hand, brings positive effects.

Western diet vs traditional African diet: the effects on the body in a study

The study started from the premise that traditional African diets are increasingly being replaced by Western-style dietary patterns due to urbanisation, economic development, greater access to processed foods, globalisation and changing social norms. The aim was to investigate the health consequences of this nutritional transition.

The researchers conducted a randomised controlled clinical trial in the Kilimanjaro region of northern Tanzania, involving 77 men, young and in good health, living in both urban and rural areas. One group of participants who were following an African diet switched to a Western diet. Another group did the opposite. A third group consumed a fermented banana drink every day.

The researchers analysed immune system function, blood inflammatory markers and metabolic processes at the start of the trial, after two weeks and after four weeks. The switch from the traditional diet to the Western one affected several metabolic pathways associated with non-communicable diseases (such as cardiovascular conditions and diabetes) and promoted a pro-inflammatory state, along with a less effective immune response to pathogens. Conversely, switching from a Western-style diet to a traditional African one and consuming fermented drinks had a predominantly anti-inflammatory effect. Some of the changes observed in the immune and metabolic profiles persisted even beyond the four weeks, suggesting a lasting impact of the short-term dietary intervention.

The need to preserve indigenous food practices to counter disease

According to the researchers, the results underscore the importance of preserving indigenous food practices to mitigate risk factors for non-communicable diseases in sub-Saharan Africa. For researchers Duccio Cavalieri and Paolo Lionetti of the Università degli Studi di Firenze, the study also shows how harmful a diet consisting mostly of processed and high-calorie foods can be for Westerners.