Japanese and German studies validate rooibos’ health properties

Important scientific evidence that supports some of the health benefits associated with rooibos tea has emerged from studies in Japan and Germany.

A study carried out at the Tokyo University of Agriculture and Technology confirmed that aspalathin – the unique flavonoid in rooibos tea – is able to help lower raised blood sugar levels and improve the metabolism of glucose. The Japanese research team investigated the anti-diabetic action of aspalathin in living muscle cells and a diabetic mouse model which was able to shed light on the specific mechanisms involved at molecular and cellular level. Its results have been published in the December 2012 issue of the European Journal of Nutrition. (The abstract is available online at http://www.ncbi.nlm.nih.gov/pubmed/23238530.)

The team in Japan currently collaborates with South African rooibos researchers at the Medical Research Council and the Agricultural Research Council (ARC) as part of a scientific co-operation agreement between Japan and South Africa.

These latest results add further weight to a previous study by them, published in 2009, and a 2012 study by the South Africa researchers. The latter study found that an aspalathin-enriched extract of green Rooibos is able to lower raised glucose levels in the blood of diabetic rats. Further work to elucidate the mechanism(s) whereby the chemical constituents present in Rooibos can affect the metabolism is on-going.

In another study, this time at Heidelberg University in Germany, scientists demonstrated that rooibos tea has the potential to promote longevity in living organisms. Using roundworms (Caenorhabditis elegans) as a model, they produced evidence that rooibos decreased oxidative damage in their cells. They were also able to show that aspalathin played a major role in their survival rate by targeting stress and ageing related genes. Local researchers from the ARC and the University of Johannesburg are co-authors on the research paper published in the December 2012 issue of the scientific journal Phytomedicine. (The abstract is available online at http://www.ncbi.nlm.nih.gov/pubmed/23218401.)

“It is encouraging that international researchers are taking such an interest in South Africa’s herbal teas and that their findings help to improve our understanding of the health properties of rooibos tea,” says Professor Lizette Joubert, herbal tea expert at the Agricultural Research Council. “This should provide further impetus to our efforts to understand the chemistry and biological properties of rooibos and other herbal teas so that we will be able to advise people how to get the maximum health benefit from these unique South African teas.”

Rooibos may deter fat cell development

A new in vitro study in mouse cells suggests that Rooibos could inhibit the development of fat cells, or adipocytes, if the active compounds are able to reach pre-adipocytes (immature fat cells). The study, which was a collaboration between the Medical Research Council (MRC) and the Agricultural Research Council (ARC), has been accepted for publication and is currently in press in Phytomedicine
(http://www.sciencedirect.com/science/article/pii/S0944711313003140)

Dr Micheline Sanderson
Dr Micheline Sanderson, first author of a recent paper about the effects of Rooibos on adipogenesis (or the development of fat cells), preparing a cell culture used in Rooibos research at South Africa’s Medical Research Council.
A new in vitro study in mouse cells suggests that Rooibos could inhibit the development of fat cells, or adipocytes, if the active compounds are able to reach pre-adipocytes (immature fat cells). The study, which was a collaboration between the Medical Research Council (MRC) and the Agricultural Research Council (ARC), has been accepted for publication and is currently in press in Phytomedicine
(http://www.sciencedirect.com/science/article/pii/S0944711313003140)

Fatty tissue develops when pre-adipocytes grow into mature, lipid-accumulating adipocytes during a process known as adipogenesis. After previous Rooibos studies hinted at the anti-obesity potential of Rooibos, researchers decided to investigate the effect of hot water-soluble matter from traditional Rooibos on the differentiation of mouse embryonic fibroblasts (a pre-adipocyte) into adipocytes.

“Every cup of tea is different,” says the MRC’s Dr Christo Muller, “but the ‘standard’ infusion process we used to obtain the soluble matter of Rooibos is a starting point for investigating the possible health benefits of this South African household favourite.”

“Standard” in this case refers to a 5-minute infusion of 2,5 g “normal” (fermented in the traditional was) Rooibos tea leaves in 200 ml of boiling water.

After filtering and freeze-drying the infusion, Muller and his team re-dissolved the product into the mouse cells’ nutritional liquid environment. They prepared a fresh batch of this Rooibos-supplemented media every day for nine days, in order to achieve “chronic” exposure of the cells to the tea.

Microscopic and gene expression analyses were then used to determine the effect of Rooibos on the cells: fat accumulation, as well as the expression of key genes involved in adipogenesis (the process whereby fat cells develop), decreased significantly.

“The results suggest that if the active compounds in a regular cup of fermented Rooibos tea was able to reach pre-adipocytes after ingestion, it could curb adipogenesis,” says Muller. But, he cautions that this does not mean Rooibos can prevent or reverse obesity.

“No medication or dietary supplement can replace exercise and a healthy, energy-controlled diet as a treatment for obesity. Our findings merely suggest that Rooibos could help people maintain a healthy weight,” he says.

Muller also made it clear that this preliminary study does not give an indication of how many cups of Rooibos one would need to drink to observe anti-adipogenic effects. “Studies like these give us insights into the effects of Rooibos at a cellular level, and thus about the potential for investigating these effects further in rodents, and eventually in humans.”

Since these early results are positive, research into this area will continue. For example, researchers still need to discover the precise molecular mechanism behind the observed anti-adipogenic effects. They also need to look at which active compounds are absorbed by the body after drinking a cup of tea (bioavailability), in high enough concentrations to exert the positive effects that have been observed in cellular studies.

The study was supported by the South African Rooibos Council, as well as the MRC and ARC.

MEDIA ENQUIRIES

Dr Christo Muller, Medical Research Council
Tel: (021) 938 0894
Email: christo.muller@mrc.ac.za

Rooibos helps protect against skin cancer

People who spend a lot of time in the sun should consider using a skin care product containing rooibos extracts to prevent the development of skin cancer and to delay the onset of malignant tumours.

People who spend a lot of time in the sun should consider using a skin care product containing rooibos extracts to prevent the development of skin cancer and to delay the onset of malignant tumours.

This is one of the findings of a recent study in which normal and cancerous skin cells were analysed to determine how exactly rooibos extracts in skin care products such as soaps, sun creams and lotions help stop the development of skin cancer.

“Lower concentrations of rooibos extracts may be able to prevent the development of skin cancer by stopping the multiplication of cancerous cells and removing these cells by prompting them to commit ‘suicide’,” says Dr Tandeka Magcwebeba, who conducted the study as part of her doctorate in Biochemistry at Stellenbosch University.

“Once the skin has been exposed to the sun’s ultra violet (UV) rays, rooibos extracts will remove precancerous damaged cells and also block the onset of inflammation – the latter being one of the processes that promote the formation of tumours in skin.”

According to Magcwebeba, it is better to use rooibos extracts during the early stages of cancer development when they are more effective in prolonging the progression of cancerous cells into a tumour.

She says one of the major reasons why rooibos extracts are incorporated into skin care products is because “they contain certain natural compounds (polyphenols) which give them their anti-oxidant properties”.​

Magcwebeba adds that these compounds, which are found in most plants, are linked with the prevention of various chronic disorders, including cancer.

She says the presence of these compounds in an extract may also help to predict its activity and may thus serve as a measure of quality control to ensure that rooibos extracts are biologically active before being used in cosmetic products.

Magcwebeba is quick to point out that her study focused on promoting the use of rooibos extracts in an ointment rather than consuming it as a beverage to protect the skin.

“Studies on well-researched skin products have shown that topical application is more effective as the product is easily absorbed when it is directly applied on the skin.”

Her research will provide knowledge towards the development of topical products that would be less invasive and cheaper to prevent cancer development, says Magcwebeba.

“South Africa has one of highest rates of skin cancer, and one of the factors contributing this problem is attributed to non-compliance to prevention strategies and the treatment is reported to be highly invasive, expensive and tends to have a high recurrence rate.”

Magcwebeba mentions that rooibos not only helps to prevent the development of skin cancer but is also used to treat eczema, acne, nappy rash, colic in babies, nausea, heartburn, cramps, hay fever and asthma in folk medicine. It is also known to improve appetite, reduces nervous tension, promotes sleep and boosts the immune system, she adds.

Magcwebeba says she now focuses on how a different plant (Gannabos) can help fight cancer and inflammation, but will definitely go back to rooibos in future.

Dr Tandeka Magcwebeba is currently a postdoctoral fellow in SU’s Department of Biochemistry. She recently spoke about her research at SU’s annual New Voices in Science colloquium held at the Stellenbosch Institute for Advance Study (STIAS).

​Photo: Tandeka with one of the apparatuses she used as part of her research.

​Photographer: Justin Alberts