• Traditional eating habits can boost immune system

Plantains, cassava and fermented banana drink should be added to global healthy eating guidelines alongside the olive oil and tomatoes of the Mediterranean diet, say researchers who found that the traditional diet of people living in Tanzania’s Kilimanjaro region had a positive impact on the body’s immune system.

Traditional foods enjoyed in rural villages also had a positive impact on markers of inflammation, the researchers found in a study published this month in the journal Nature Medicine.

One of the paper’s authors, who holds positions at the KCMC University in Moshi, Tanzania, and the Radboud University Medical Centre in the Netherlands, Dr. Quirijn de Mast said that they were now in a race against time to record and study the potential benefits of African heritage diets before they disappear as people move to cities and adopt Western-style eating habits. “Time is ticking because you see that these heritage diets are being replaced more and more by Western diets,” he said. “We will lose so much interesting information (from which) we can learn – and not only for Africa.”

In previous research, the team had established that people following the traditional way of life in rural areas had a different immune-system profile to urban dwellers, with more anti-inflammatory proteins. Chronic inflammation is a key driver of many non-communicable diseases (NCDs), including rheumatoid arthritis and Alzheimer’s disease.

The new study set out to establish whether diet played a role. For a fortnight, 77 young men in their 20s and 30s were switched from heritage to Western-style diets, or the reverse – with blood samples taken at the start and end, and again four weeks later. Meals on the heritage diet menu included green plantain mixed with kidney beans, boiled chicken served with green vegetables and brown rice and beans. On the Western-style menu, they included pizza, fried chicken and French fries and spaghetti served with beef stew.

Those newly adopting a Western-style diet saw inflammatory markers in their blood increase and tests suggested that their immune systems did not respond as well to infections. They also gained weight. By contrast, switching from a Western diet to a heritage diet had a largely anti-inflammatory effect, and blood markers linked to metabolic problems fell.

In a third arm of the trial, participants following a Western-style diet were asked to drink the local fermented banana beverage, known as mbege, for one week. That group also saw improvements in markers of inflammation.

For the first author of the paper and a lecturer at the KCMC University, Dr. Godfrey Temba, the findings were not a surprise. “When we are in most of the villages, talking to elderly people (of) 80 or 90 years, they are very healthy. They don’t have any health complications (and) they tell you about consuming this type of diet and this beverage since they were 25.”

However, the diet and its benefits have not been explored and documented – unlike the traditional diets of the Mediterranean and Nordic countries, which are promoted by the World Health Organisation for their beneficial effects.

Temba said: “African heritage diets can be also included in the global guidelines of diets, because they really have a health benefit – but because it’s not studied extensively, it’s not easy to convince (people) that they are healthy, because you don’t have enough data.”

The diet’s components, such as flavonoids and other polyphenols, and its impact on the gut microbiome were likely to play a part in the observed effects, De Mast said.

The study was conducted only in men for logistical reasons, but the researchers said that they would expect similar findings in women, and for the benefits to be maintained over time if the people continued the diets.

Many countries are facing rising rates of NCDs such as diabetes, obesity and heart disease.

“I think you should have really region-specific recommendations based on scientific data,” De Mast said. 

“There’s so much diversity in dietary patterns,” said De Mast. “Thirty kilometres down the road in the Kilimanjaro region, there is the Maasai tribe and their diet is entirely different. It’s mainly animal protein based – still, traditionally, cardiovascular disease was almost absent.”

(The Guardian)