This Traditional African Diet Appears to Boost The Immune System

Africa's numerous cultures have long enjoyed a heritage of diets based on items known to be good for gut and metabolic health, including a range of vegetables, grains, fruit, and fermented goods.

While the impacts of adopting a diet rich in heavily processed and high-calorie foods have been studied around the world, African populations have been underrepresented in the data.

"Previous research has focused on other traditional diets, such as the Japanese or Mediterranean diet," says infectious disease specialist Quirijn de Mast from Radboud University Medical Center in the Netherlands.

"However, 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. Africa's rich diversity in traditional diets offers unique opportunities to gain valuable insights into how food influences health."

A study led by de Mast investigated the health effects of switching between a Kilimanjaro heritage-style diet and one considered more Western among northern Tanzanians.

The changes were both rapid and profound, with notable impacts on immune and metabolic profiles detectable within weeks of replacing traditional food items of various porridges, okra, sour milk, and fermented grains, with a menu featuring sausages and white bread, jams, pancakes, ketchup, and french fries, or vice versa.

The team recruited 77 healthy men from urban and rural parts of Northern Tanzania, who either habitually ate Western foods or tended to stick to a more traditional fare such as 'kiburu' – boiled green plantain with kidney beans – washed down with a bowl of fermented banana and millet called 'mbege'.

After a week of their usual daily rotation of meals, a selection of volunteers were instructed to swap for two weeks. Some urban recruits were asked to instead enjoy a serving of low-alcohol mbege with their usual Western meal for one week, before reverting back to their old habits.

At key points throughout the investigation the researchers took blood samples to analyze cell types, the production of immune signals called cytokines, and the production of numerous metabolic compounds.

Those who switched from Kilimanjaro cuisine to items like bread and sausages showed elevated levels of inflammatory proteins and markers of metabolic dysregulation, with a significant drop in immune response to a number of fungal and bacterial pathogens.

They also experienced slight weight gain, which can't be ruled out as a potential contributing factor to other metabolic changes.

Conversely, moving from Western foods to more fruits, fermented foods, vegetables, and whole grains increased anti-inflammatory responses, giving the immune system a boost.

Even a week of drinking the traditional fermented beverage improved activation of critical defense cells called neutrophils and boosted chemical responses to fungal pathogens like Candida.

Surprisingly, the influence of the diet swaps were still detectable four weeks later, making it clear that health changes were not only swift but could also be long-lasting.

Not only are Western diets being adopted across the African continent, supplementing if not replacing meals based on healthier items, but emigrants from African cultures moving into Westernized communities face an even greater challenge retaining a heritage that might be healthier for them.

By better understanding the risks of limiting food options not just in regions like Tanzania but around the globe, more of us can make healthier choices about our own diets, while enjoying a diverse banquet of exotic new food items.

"Our study highlights the benefits of these traditional food products for inflammation and metabolic processes in the body. At the same time, we show how harmful an unhealthy Western diet can be," says de Mast.

This study was published in Nature Medicine.