Traditional Tanzanian diets based on grains, fruits and vegetables are associated with reduced inflammation and lower disease risk, but this is changing as cities shift to a more Western diet.Credit: Godfrey Temba, 2021
The increase in urbanization across sub-Saharan Africa has coincided with a rapid rise in non-communicable diseases, including cardiovascular and metabolic disorders. Now, researchers in Tanzania, the Netherland, and Germany have demonstrated how urban diets may cause a fundamental shift in the immune systems of healthy Tanzanians towards a pro-inflammatory state, which leaves them prone to diseases.
Traditional staple foods in rural Africa include grains, fruits, and vegetables rich in proteins and fibre. People living in urban environments often replace these foods with a more Western diet, high in processed foods and saturated fats.
A team led by Godfrey Temba at the Kilimanjaro Christian Medical University College, Moshi, Tanzania and Radboud University Medical Center, the Netherlands, examined how this dietary shift influences the overall health of Tanzanians. They analysed metabolites and RNA molecules circulating in the blood of 323 healthy Tanzanians from the city of Moshi and surrounding rural areas.
They found that food-derived metabolites changed the signature of urban dwellers’ immune systems by reprogramming their immune cells. The urban cohort had high levels of pro-inflammatory proteins and metabolites that are linked to cholesterol metabolism. In contrast, rural dwellers had more flavonoids and other anti-inflammatory molecules circulating in their blood, which worked to keep their immune systems better balanced.
There was also a seasonal element to their findings. The urban dwellers’ immune systems reverted to become similar to those of their rural counterparts during the dry season, which is harvest time in Tanzania.
“Our study highlights how urbanization and associated nutritional changes are creating a significant burden for our healthcare systems,” says Temba. “We’ve shown that Tanzania’s traditional diet reduces inflammation, and we hope our research will help raise public awareness of this issue.”
