Switching from a traditional African diet to Western food for just two weeks triggered inflammation, weakened immune responses, and activated disease-related processes in healthy men, according to groundbreaking research published in Nature Medicine. Conversely, urban dwellers who adopted a traditional plant-based African diet saw remarkable anti-inflammatory benefits.
The study, conducted by researchers from Radboud University Medical Center and KCMC University in Tanzania, provides the first comprehensive look at how quickly dietary changes can impact our immune system and metabolism, with potential long-term consequences for chronic disease risk.
“A switch of just two weeks from a traditional African diet to a Western diet causes inflammation, reduces the immune response to pathogens, and activates processes associated with lifestyle diseases,” noted the research team in their findings, published Thursday in Nature Medicine.
This dietary investigation comes as lifestyle diseases like cardiovascular conditions, diabetes, and chronic inflammatory disorders surge across Africa. As economic development, urbanization, and wider availability of processed foods accelerate the adoption of Western eating habits, health researchers sought to document the impact of these changes.
The researchers recruited 77 healthy Tanzanian men from both rural and urban areas. Some participants who traditionally ate an African diet switched to a Western diet for two weeks, while others who consumed a Western diet adopted a traditional African diet. A third group consumed a traditional fermented banana drink called “Mbege” daily. Blood samples were analyzed before, immediately after, and four weeks following the dietary interventions.
The results were striking. Men who switched to a Western diet gained weight and showed increased inflammatory proteins in their blood. Their immune cells also responded less effectively to pathogens. Some participants gained as much as 2.6 kg (5.7 pounds) during the two-week Western diet intervention.
Perhaps most concerning was that some negative changes persisted even four weeks after returning to their normal eating patterns, suggesting that even short-term dietary changes can have lasting effects.
The traditional African diet in the study was predominantly plant-based, rich in vegetables, fruits, beans, whole grains, and fermented foods. In contrast, the Western diet consisted of processed and high-calorie foods like French fries, white bread, fried chicken, and foods high in salt, refined sugars, and saturated fats.
“The African diet includes plenty of vegetables, fruits, beans, whole grains, and fermented foods. Our study highlights the benefits of these traditional food products for inflammation and metabolic processes in the body,” said internist Quirijn de Mast from Radboudumc. “At the same time, we show how harmful an unhealthy Western diet can be.”
The fermented banana beverage group also showed positive effects, with reduced inflammatory markers. The traditional drink, which undergoes fermentation with finger millet, contains beneficial microbes and bioactive compounds.
De Mast finds it remarkable how significant the effects were after such a short intervention. “Inflammation is at the root of many chronic conditions, which makes this study highly relevant for Western countries as well.”
The research demonstrated that diet-induced molecular and cellular changes affected multiple biological systems. Western diet consumption increased white blood cell counts and activated immune cells, potentially setting the stage for chronic inflammation. Such inflammation has been linked to heart disease, diabetes, and other chronic illnesses.
Participants who switched to the African diet or consumed the fermented beverage showed decreases in inflammatory markers and positive changes in metabolic pathways linked to health protection.
The findings come amid growing scientific interest in traditional diets worldwide. While Mediterranean and Japanese diets have been extensively studied, this research represents the first comprehensive mapping of a traditional African diet’s health effects.
“There is just as much to learn from traditional African diets, especially now, as lifestyles in many African regions are rapidly changing and lifestyle diseases are increasing,” noted de Mast. “Africa’s rich diversity in traditional diets offers unique opportunities to gain valuable insights into how food influences health.”
As Western-style eating habits continue to spread globally, this research underscores the potential value of preserving and promoting indigenous dietary practices. The researchers suggest that incorporating elements of traditional diets could help combat the rising tide of chronic diseases, not just in Africa but worldwide.
The study represents a collaborative effort between Radboudumc and KCMC University, with additional international partners from Bonn and Florence. The research was funded by ZonMw/JPI-HDHL.
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