Rooibos shows potential for reducing Alzheimer's risk, say South African scientists

Research indicates Rooibos extracts have the potential to reduce the risk and onset of neurodegenerative diseases. Picture: Supplied

Research indicates Rooibos extracts have the potential to reduce the risk and onset of neurodegenerative diseases. Picture: Supplied

Published Sep 7, 2023


World Alzheimer’s Month, which is in September, is set aside to raise awareness and encourage discussion around the disease and the worldwide necessity of finding new potential disease-modifying therapies.

To date, only symptomatic treatments exist – all trying to counterbalance the neurotransmitter disturbance.

Currently, there is no cure for Alzheimer’s. Preliminary studies with rooibos extracts have shown that tisane may be able to reduce the risk and onset of neurodegenerative diseases.

Alzheimer’s disease is a progressive illness that destroys memory and other important mental functions, and affects an estimated 55 million people worldwide.

It not only affects individuals diagnosed with the disease, but also has a profound emotional impact on their families.

In recent decades, there has been a significant rise in Alzheimer’s cases globally and in South Africa – largely due to unhealthy lifestyles, which often lead to chronic illnesses like diabetes, hypertension and cardiovascular disease.

Another risk is old age. As life expectancy increases, more people are reaching the age where neurodegenerative diseases are becoming more common, necessitating the development of new, more effective therapies.

Enter rooibos tea, a popular South African tisane that has caught the attention of scientists studying brain health.

Two prominent South African scientists, who have been studying rooibos and brain health for several years, attribute the tisane’s neuroprotective effect to its unique combination of polyphenolic compounds, including other rare antioxidants, that help the body detoxify and rid itself of harmful free radicals caused by oxidative stress.

Over time, oxidative stress leads to inflammation and many pathophysiological (abnormal) conditions in the body. Some of these include Parkinson’s disease, chronic fatigue syndrome, heart disease and Alzheimer’s.

Free radicals are unstable molecules that can cause damage to our cells. They are formed when our bodies break down food or when we are exposed to things like pollution or UV radiation.

These molecules have an unpaired electron, which makes them highly reactive and eager to steal electrons from other molecules in our body.

This can lead to a chain reaction of damage to our cells and DNA. Antioxidants, commonly found in fruits and vegetables, help neutralise free radicals and protect our cells from harm.

While animal studies have shown promising results in improving memory and cognitive function, further research is needed to draw definitive conclusions.

Cape Peninsula University of Technology's Dr Taskeen Fathima Docrat is conducting research into rooibos's possible ability to prevent Alzheimer's disease.

Dr Docrat's research delves into the field of epigenetics, which explores how behaviours and the environment can influence gene function without altering DNA make-up.

Dr Taskeen Fathima Docrat working with her Alzheimer’s in vitro model within a controlled cell culture environment. Picture: Supplied

Her work focuses on mitochondrial dysfunction, a condition where the powerhouses of cells, known as mitochondria, fail to generate energy properly. Mitochondrial dysfunction is linked to various conditions, including Alzheimer's disease.

Docrat wants to study how rooibos can affect certain things in Alzheimer's disease. She will look at markers in the body that show oxidative stress (which is like damage to our cells), and how genes and tiny molecules called microRNAs are involved.

The goal is to see if rooibos can help with problems in the mitochondria, which are important for energy in our cells, in people with Alzheimer's.

To fully understand the potential benefits of rooibos, she compared the effects of fermented (red) and unfermented (green) rooibos.

This study not only offers information on the anti-Alzheimer's features of different rooibos types, but also on how processing differences affect their bioactive properties.

“Although we are still busy with these studies, preliminary findings look promising, suggesting that rooibos could positively impact these factors.”

She believes the insights they are gathering will guide the design of future human clinical trials to explore rooibos's effects in real-world scenarios.

“Currently we are laying the foundation for potentially developing supplements that could act preventively,” she said.

Renowned molecular physiology professor, Ben Loos, from Stellenbosch University, has dedicated the past 12 years to studying Alzheimer's disease, neuronal ageing, malignant brain tumours, and neuronal injury and trauma.

His groundbreaking research has homed in on autophagy activity, an intracellular degradation process that enables cells to recycle damaged components, generate energy, and create new cellular structures.

Simply put, autophagy serves as a cellular housekeeping mechanism, swiftly digesting and eliminating damaged cell parts.

According to Loos's extensive research, autophagy function defects associated with ageing are closely linked to cancer and Alzheimer's disease development. In layman's terms, autophagy can be understood as your body’s process of reusing old and damaged cell parts in order to regenerate newer, healthier cells.

His primary objective is to prevent or delay cell death. He brings to attention that the greatest risk factor for Alzheimer's disease is ageing itself.

"We all age differently," he says.

Living neurons are captured using 3D image acquisition on this confocal/super-resolution microscope. From left: Catherine Smit (MSc student), Sholto de Wet (PhD student) and Prof Ben Loos. Picture: Supplied

"Some age poorly due to unhealthy lifestyle choices, while others age gracefully. This led us to explore the molecular hallmarks of ageing, such as mitochondrial dysfunction, oxidative damage, and the accumulation of toxic protein aggregates.

“During this investigation, we stumbled upon the potential health benefits of rooibos and became curious about its impact on these markers. If rooibos positively affects these parameters, we hypothesise it could potentially reduce the risk of neurodegeneration."

Loos and his team are currently researching to assess the impact of rooibos extract on damaged or diseased mitochondria, mimicking conditions seen in Alzheimer's disease.

Their findings indicate that treating neurons with the extract leads to an increase in mitochondrial volume, suggesting that rooibos plays a crucial role in controlling cell energetics and health. Initial research also suggests that rooibos extract preserves cell membrane integrity.

“The cells are all treated with an equivalent amount of either three or six cups of rooibos so that a low and high concentration can be compared. We also use fermented and non-fermented rooibos.

“Our results show that at both low and high concentrations of fermented and non-fermented rooibos extract, mitochondrial function was improved.”

He adds: “If we can show that rooibos extracts increase the cell’s ability to remove toxic protein cargo, such as amyloid beta, by enhancing autophagy, this would be a massive finding. Autophagy, which increases upon fasting or exercise, has been shown to directly rescue diseased Alzheimer’s neurons.

“Such a finding would be very direct evidence of the effect of rooibos on cell health and healthy ageing. We would also want to introduce an even better model for Alzheimer’s disease, where we can switch on the production of these toxic proteins and measure whether the presence of rooibos can decrease the toxic burden.

“In the future, we would like to measure the effect of rooibos on the mitochondria and autophagy in human blood cells to have an even better translational value,” said Loos.

Both Docrat’s and Loos's research approaches offer multifaceted insights into rooibos's potential benefits against Alzheimer's, covering cellular and molecular aspects.