African indigenous food groups present an exciting area to explore when it comes to taste and nutrition. They may even offer potential as nutritional therapy for people with health problems.
Foods like jute mallow, pearl and finger millet, wild medlar, caterpillars and bambara nuts all have nutritional properties that could be useful in managing inflammation.
Inflammation is the body's natural response to injury or infection. It helps us fight off infections and begins the healing process. However, problems arise when inflammation continues. It can start to damage healthy tissues and blood vessels, interfere with how the body uses sugar and fat, and weaken the immune system. Over time, this ongoing inflammation can lead to diseases such as diabetes.
Type 2 diabetes is a long-term health condition affecting many adults. It causes serious health problems and a high risk of death.
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The worldwide number of people living with diabetes rose from 200 million in 1990 to 830 million in 2022. Prevalence has been rising more rapidly in low- and middle-income countries than in high-income countries. In 2021, diabetes and kidney disease due to diabetes caused over 2 million deaths.
Read more: Diabetes is a ticking time bomb in sub-Saharan Africa
As public health and nutrition researchers, we focus on functional foods - foods with special health benefits. Our research experience in nutrition and health, and plant metabolomics helps us identify bioactive compounds in food that can help reduce the impact of chronic diseases.
We conducted a review of 46 research articles on the role of indigenous African food groups in preventing and managing type 2 diabetes mellitus. It examined the anti-inflammatory properties of African food groups in relation to this disease.
We found that many African food groups significantly reduce oxidative stress linked to type 2 diabetes. Oxidative stress occurs when the body produces more harmful oxygen-related molecules than it can neutralise with its natural antioxidant defences. This overproduction of oxidants disrupts the normal cellular control systems. We found several phenolic compounds in these African food groups that confer anti-inflammatory properties.
Our findings provide useful information for the development of African traditional therapeutic meals tailored for patients with type 2 diabetes in Africa.
Food groups and type 2 diabetes
The traditional African diet primarily consists of cereals, legumes, fruits, vegetables, milk and poultry, with a notable emphasis on edible insects and low red meat consumption. Many indigenous foods such as okra leaves, nightshade, amaranth and cowpeas are underutilised in modern cooking and farming. They are also often viewed as "food for poor people".
Over time, many Africans have shifted from traditional African diets, which are rich in fibre, polyphenols and antioxidants, to a western diet high in sugar, salt and unhealthy fats. This change has significantly increased the risk of type 2 diabetes.
Our analysis covered 46 studies conducted between 2010 and 2023. The selection of these studies enabled a comprehensive evaluation of how African food groups may influence inflammation associated with type 2 diabetes mellitus. The review highlights the potential mechanisms and outcomes relevant to public health nutrition.
Our findings show that these food groups could be beneficial in mitigating chronic inflammation if included in diets.
Read more: Lessons from a diabetes clinic in Malawi: why everyone should follow a healthy diet
Edible insects
Our review shows that edible insects like ants, caterpillars, crickets and locusts release substances called angiotensin-converting enzyme and antioxidant hydrolysates/peptides.
Particularly, locust peptides can block certain enzymes which are involved in breaking down sugars and fats. Breaking down excessive amounts of sugar and fat can lead to risks such as fatty liver disease, diabetes, heart disease and chronic inflammation.
Our review also found common beneficial components in insects include chitin, polyphenols, antimicrobials and peptides/proteins. These components can help reduce oxidative stress in people with diabetes.
Caterpillars have two to five times more antioxidant capacity than orange juice or olive oil. Similarly, locusts have high levels of antioxidants and lipoxygenase. Antioxidants are essential for protecting cells and food quality. Lipoxygenase helps produce anti-inflammatory compounds that support cellular health and modulate inflammation. Together, they play a vital role in overall well-being.
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Vegetables
We found that African leaf vegetables such as cowpea, nightshade, amaranth and okra leaves can help lower blood sugar levels. In one study, patients with type 2 diabetes who consumed blackjack (Bidens pilosa) saw their fasting blood sugar drop after treatment. Blackjack is a traditional vegetable in southern Africa. The leaves can be cooked or they can be used to brew tea.
Similarly, pigweed helps reduce total protein levels linked to kidney problems in diabetes.
Vegetables like cowpea leaves, jute mallow and wild bitter gourd have important anti-inflammatory properties. Jute mallow helps reduce inflammation in diabetic patients by stopping the formation of nitric acid and increasing nitric oxide production. Wild bitter gourd helps by lowering the levels of pro-inflammatory cytokines.
Cereals/grains
Indigenous African small grains naturally contain fibre, which helps lower glucose levels.
For instance, African finger millet has a high fibre content that thickens stomach contents and reduces glucose absorption. An experiment on the effects of finger millet on diabetic rats showed that rats given finger millet had lower fasting blood sugar levels compared to untreated diabetic rats. Similar results were found with sorghum, which improved insulin sensitivity and reduced type 2 diabetes in mice.
Our review found that sorghum contains anti-oxidant compounds like luteolin and quercetin, which may help reduce inflammation in diabetic patients. Red pericarp sorghum in Africa has been shown to lower inflammation levels in diabetic rats. This suggests its valuable medical role.
Read more: Amazing ting: South Africa must reinvigorate sorghum as a key food before it's lost
Fruits
Our review found that prickly pear can help manage blood sugar by blocking certain enzymes.
Another study found that baobab fruit powder can lower blood sugar. Similarly, wild medlar blocks unwanted enzyme activity. Both offer potentially more affordable solutions for diabetic patients.
Read more: Africa indigenous fruit trees offer major benefits. But they're being ignored
Roots and tubers
Cassava contains a substance that prevents dietary starches from being effectively broken down and absorbed in the gastrointestinal tract. This mechanism can contribute to the management of obesity and the regulation of blood sugar levels.
Research indicates that consuming yams or their extracts can enhance important blood glucose parameters. These benefits include lowering fasting blood glucose levels and reducing insulin levels.
Additionally, yams and their extracts may help reduce body fat and lower blood lipid levels. These improvements can lower the risk of developing diabetes. Furthermore, if fermented, yams could be very useful in enhancing the antioxidant defence system and modulating inflammatory mediators in diabetic patients.
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Livingstone potatoes also show similar effects by improving kidney and liver health in diabetic patients. Laboratory studies suggest that these roots can help regulate glucose metabolism, enhance insulin secretion, reduce insulin resistance, improve blood vessel function and manage oxidative stress levels.
Legumes
The most common legumes in the African diet include cowpea, bambara nuts, soybean and mung bean.
We found that cowpea helps produce insulin, which is important for managing glucose. Both bambara nuts and cowpea contain soluble and insoluble fibre, which help reduce blood sugar spikes and cholesterol, making them useful for managing type 2 diabetes.
Soybeans also improve glucose tolerance and insulin production.
We also discovered that mung beans can lower cholesterol while boosting insulin secretion. In terms of antioxidants, many legumes can fight free radicals, which cause inflammation in diabetes patients.
Specifically, bambara nuts have a higher antioxidant capacity than orange peels.
Way forward
As healthcare costs rise, many people, particularly in marginalised communities, face financial struggles. Incorporating African indigenous food groups in medically tailored meals can reduce health costs and improve well-being.
Utilising local agricultural resources to cultivate these food groups enhances community health, preserves cultural traditions and promotes sustainable diets.
Tendaiishe Berejena, Public Health Nutrition Researcher, University of South Africa
Florence Malongane, Senior lecturer, University of South Africa
