A groundbreaking study published in Nature Medicine reveals the profound impact of dietary changes on the immune system and metabolism. Researchers discovered that a mere two-week switch from a customary African diet to a Western one can spark inflammation, weaken the immune response to pathogens, and initiate processes linked to lifestyle diseases. Conversely, adopting an African diet rich in vegetables, fiber, and fermented foods yields positive health effects.

This research highlights a growing concern: the rise of “welfare diseases” like cardiovascular disease, diabetes, and chronic inflammatory conditions in Africa. As economic growth and urbanization lead to increased adoption of Western dietary habits, understanding the health consequences becomes crucial.

The Study: A Tanzanian Dietary Exchange

The study, a collaboration between Radboudumc and KCMC University in tanzania, involved 77 healthy men from both urban and rural areas of Tanzania. Participants were divided into groups:

• One group transitioned from a traditional African diet, typical of the Kilimanjaro region, to a Western diet for two weeks.
• Another group switched from a Western diet to the traditional African diet for the same period.
• A third group consumed a fermented banana drink daily.
• A control group maintained their regular eating habits.

Researchers meticulously monitored the participants’ immune system function, inflammatory markers in the blood, and metabolic processes at the beginning of the study, after two weeks of dietary changes, and again four weeks later.

Key Findings: Inflammation and Immunity

The results were striking. Participants who consumed the Western diet for just two weeks exhibited elevated levels of inflammatory proteins in their blood. furthermore, the study revealed activation of biological processes associated wiht lifestyle diseases and a diminished immune response to pathogens.

Conversely, those who switched to the traditional African diet or consumed the fermented banana drink experienced a reduction in inflammatory substances. Notably, some of these effects persisted even four weeks after the dietary changes, suggesting that short-term dietary shifts can have lasting consequences.

These findings resonate with similar research conducted in the United States. For example, a 2023 study by the National Institutes of Health showed that processed foods, a staple of manny Western diets, can trigger an inflammatory response in the gut, potentially leading to chronic health issues.

Insights from the African Diet

According to internist Quirijn de Mast of the Radboudumc, “Research has previously been done into other traditional diets, such as the Japanese or Mediterranean diet, but we can also learn a lot from African food, especially now that the lifestyle there is changing quickly and welfare diseases are increasing sharply.Africa also has a wide variety of traditional dietary patterns, which offers unique opportunities to better understand how food influences our health.”

This study is the first to comprehensively map the health effects of a traditional African diet. De Mast emphasizes the rapid impact of dietary changes: “The African diet contains many vegetables,fruit,beans,grains and fermented products. We now show how favorable these traditional food products are for inflammation and metabolic processes in the body. Simultaneously occurring we show how unfavorable an unhealthy Western diet. This mainly contains processed and high -calorie products, such as fries and white bread, with lots of salt, fast sugars and saturated fat. Inflammation is at the basis of many chronic disorders and that is why this study is also vital for Western countries.”

These insights are notably relevant in the United States, where processed foods and fast food are prevalent. Understanding the inflammatory effects of these foods could empower Americans to make healthier dietary choices.

Dietary Details: A Closer Look

The study meticulously outlined the two diets used. The Western diet was characterized by a high intake of meat (daily),pizza,white rice,pasta,fries,eggs,white bread,and pancakes,with limited consumption of fruits and vegetables. In contrast, the traditional African diet of the Kilimanjaro region emphasized fruits, vegetables, beans, brown rice, limited meat (twice a week), and fermented products, including grains like millet and sorghum. The fermented drink, mbege, primarily consisted of bananas and millet.

For U.S. readers looking to incorporate aspects of the traditional African diet, consider incorporating more plant-based meals, substituting white rice and bread with whole grains, and exploring fermented foods like kimchi or sauerkraut, which offer similar probiotic benefits. Resources like the Oldways African Heritage Diet Pyramid provide guidance on building balanced meals based on traditional African ingredients.

Implications for the U.S. and Beyond

This study has significant implications for public health, particularly in the United States, where Western dietary patterns are widespread. The rapid inflammatory response triggered by a Western diet underscores the importance of promoting healthier eating habits to combat chronic diseases.

While the study focused on a specific African population, its findings are broadly applicable.Nonetheless of ethnicity, reducing processed food intake, increasing fruit and vegetable consumption, and incorporating fermented foods can contribute to better health outcomes.

Future research should explore the long-term effects of dietary changes on immune function and metabolic health, as well as investigate the specific components of the African diet that contribute to its beneficial effects. Further studies could also include more diverse participant groups to see if the results are the same around the world.

About the publication

This research was published in Nature Medicine: Immune and metabolic effects of African heritage diets versus Western diets in men: a randomized controlled trial. GS Tember, T Pecht, VI Cullia, N Vadaq, MV Mosha, T Ulas, S Canungo, L van Empst, L Bonaaguro, J Schult-Schrepping, E Mafuru, P Leonetti, MM Mhlan, AJ van der Ven, D Cavaliary, LAB Joosten, LRA Cvishe, B Mmbagaga, JLB Joosten, LRA Cvishe, B Mmbagaga, JLB Joosten, LRA Cvishe, B Mmbagaga, JLAB Joosten, LRA Cvishe, B Mmbagaga, JLMA Schultze, MG Netea, Q is Mast. DOI: 10.1038/s41591-025-03602-0.

The Radboudumc and KCMC University collaborated with international partners from Bonn and Florence for this study. Funding was provided by ZonMw/JPI-HDHL.