The secret to preventing cancer, depression, Alzheimer's may be in our gut
The mysterious world of the human microbiome is revealing new secrets every month about how the tiny bugs in our guts may be the key to protecting us from all kinds of diseases, from cancer to depression. This previously underexplored concept is offering doctors and scientists new revelations about how our bodies work - and researchers at Stellenbosch University’s new African Microbiome Institute are perfectly poised to contribute.
The institute is headed by Professor Stephen O’Keefe, who has more than 40 years’ experience in nutritional gastroenterology and is a medical doctor and a researcher.
O’Keefe was born in Johannesburg, but grew up in Zambia, where his father was a doctor in rural areas.
“I had first-hand experience of the effects of malnutrition on health,” he said.
O’Keefe has become an internationally renowned expert on how nutrition affects our health - including a landmark study in 2015 which linked a low-fibre diet with a high risk of colon cancer.
Exploring the microscopic world inside our digestive systems was a natural next step.
“It’s like discovering another organ within the body,” he said. “It’s fascinating how much we’re learning about how the microbiome affects our health - both how it preserves health and also how it can cause disease.”
Earlier this year, researchers in Belgium identified two bacteria species that are depleted in people who suffer from depression.
“Both in depression and anxiety, the composition of the faecal microbiome is disturbed,” O’Keefe said. “There’s a lot of interest in autism as well - mice can develop autistic behaviour if they are colonised with specific types of microbiota. There are also associations with Alzheimer’s and Parkinson’s diseases.”
South Africa offers a unique landscape in which to study the gut microbiome because parts of our population eat according to rural African traditions, while the urban and upper-class population groups eat a completely different, Westernised diet.
This plays a key role in cancer risk, O’Keefe’s research found.
“Colon cancer is virtually unknown in rural Africans, whereas in all Westernised populations it’s very high and the second leading cause of cancer death,” he said.
Rural Africans typically eat a diet that is high in fibre from lots of complex carbohydrates and low in meat and fat. When these complex carbohydrates ferment in the gut, they produce short-chain fatty acids which are essential for maintaining a healthy colon. When you eat a lot of fibre, the resulting fatty acids can pass out of the digestive system, into your bloodstream and around different organ systems in the body.
“They are strongly anti-inflammatory and reduce cancer, not just in the colon. but also in the breast, lungs and several other different cancers,” O’Keefe said.
In sharp contrast, those who eat Western diets - including most urban Capetonians - are taking in very small amounts of complex carbs and fibre, and plenty of processed meats and fats.
“They had a microbiome that produced a lot of potential carcinogens,” he said.