Rooibos takes the fight to diabetes

World Diabetes Day, held annually in November, aims to raise global awareness of the disease and what can be done, in many cases, to prevent it. A team of South African researchers has released results of a promising study that involves the beneficial effect of rooibos on blood sugar levels.

The rooibos plant (Aspalathus linearis), a member of the legume family and indigenous to South Africa, is known for its health-boosting properties. Rooibos is usually made into a tea – or more correctly, a tisane, as it is a non-caffeinated beverage – that has various healthful effects ranging from antioxidant properties to a calming effect and a good night’s sleep.

Scientific studies with animals and to a lesser degree, with humans, have shown that rooibos can also restore immune function and generally improve the immune system. In a UK study, rare poison dart frogs that were reared from tadpoles in a rooibos-infused liquid became resistant to fungal infection. This is because the antioxidants in rooibos have anti-fungal properties as well, according to the frog research team.

Now new evidence has emerged that rooibos can combat diabetes in rats and, with more research, possibly humans. Results of the study were published on 19 October in the online version of Phytomedicine journal, under the title Acute assessment of an aspalathin-enriched green rooibos extract with hypoglycemic potential.

The study was a joint effort between the Diabetes Discovery Platform from South Africa’s Medical Research Council (MRC) and the Agricultural Research Council’s (ARC) Infruitec-Nietvoorbij Institute, with the help of the National Research Foundation.

“Although we have started off with small animals,” says team leader Dr Johan Louw of the MRC, “the next step is to take our research to human patients – provided we can secure funding.”

Louw explains that, as the research models are designed to simulate what is seen in humans, he is confident that the team will be able to duplicate the rat results. He clarifies that people with diabetes type one, which is controlled with insulin, won’t see a benefit but that type two patients, who control their condition largely through diet, will.

“Our focus as scientists is the promotion of healthy lifestyles and a healthier population, not just in South Africa but all over the world – so don’t hesitate to drink that cup of rooibos as part of a good diet,” he says. “Obviously you can’t do anything about your age or your family history, but there are certain factors that you have control over, such as your eating habits or your level of activity.”

World Diabetes Day is an initiative of the International Diabetes Federation and the World Health Organisation. The date, 14 November, celebrates the birthday of Canadian Nobel laureate Frederick Banting, who is credited with the life-saving discovery of insulin, along with his colleague Charles Best.

Rooibos health benefits

The diabetes study was carried out with extracts of green rooibos, prepared by Prof Lizette Joubert of the ARC and analysed by the MRC. Green rooibos is the unoxidised version of the amber-coloured tea available widely in South African shops and increasingly around the world.

“Rooibos has many compounds, which have different effects at different concentrations, but the two we are interested in for this study are aspalathin, which is found exclusively in rooibos, and rutin,” says Louw. “The extracts were enriched with the two compounds. On its own, rutin has no effect while aspalathin has a slight effect, but when they are combined the results are remarkable.”

The South African Rooibos Council reports that green rooibos has higher levels of antioxidants – one of which is aspalathin – than normal rooibos, but that both are proven to be beneficial.

Monitored over a period of six hours, the two test compounds together succeeded in lowering the blood glucose level of the rats. In humans this could have the same effect as drugs that are currently available.

“We are the first in the world to show this effect from rooibos extract,” said Louw.” Rooibos has no side effects for most people and drinking it can only have a positive effect.”

For the millions of South Africans who have the condition, this is good news.

The Rooibos Council is involved with several MRC projects as a funder. They include the impact of rooibos on weight loss; the role of rooibos in preventing tissue damage during exercise; the influence of rooibos on the biosynthesis of cortisol, known as the stress hormone; and an investigation into the cancer prevention properties of the plant.

Raising awareness

Diabetes will affect 439-million people around the world by 2030, according to the World Health Organisation. Currently some 6.5-million South Africans have diabetes, although experts feel that number may be under-reported.

The disease develops when the body does not produce enough insulin, a hormone that enables cells to absorb glucose from the blood and convert it into energy.

Insulin is produced in the pancreas, and diabetes arises when production is halted or is slowed, or the body becomes resistant to the insulin that is produced. The condition falls into two main categories – types one and two – although there are other smaller categories such as gestational diabetes which can sometimes occur during pregnancy.

Diabetes type one is a result of non- or under-production of insulin, while type two occurs when the body becomes resistant to the hormone. The first type can only be treated with insulin administration while the second can be managed through diet and exercise, and with extra medication when necessary.

Symptoms include weight loss, thirst, frequent urination and fatigue coupled with blurry vision, numbness or tingling in hands and feet, recurring infections of the skin, mouth and bladder, and wounds that are slow to heal.

Testing can be done on blood or urine samples at a clinic, doctor or pharmacy. However, healthy living can prevent a multitude of conditions, such as high cholesterol and blood pressure, obesity, and diabetes type two.


Dutch Researchers Show The Potential Of Rooibos To Inhibit Rotavirus

A group of Dutch researchers has demonstrated, for the first time, that Rooibos tea has strong antiviral activity against rotaviruses that cause serious infections, often with fatal consequences.

The research was carried out at the Danone Research Centre for Specialised Nutrition in Wageningen, the Utrecht Institute for Pharmaceutical Sciences and the Wilhelmina Children’s Hospital in Utrecht. The study was published in the Virology Journal and the full text is available online at

The research team investigated 150 extracts with known nutritional uses to test its effect on rotaviruses. They found 11 extracts able to inhibit rotavirus, but only three, including Rooibos, were found to have strong and significant antiviral activity. They have concluded that these plant extracts, including Rooibos, are potentially useful in the treatment of rotavirus infections. Worldwide, rotaviruses are a leading cause of severe dehydrating diarrhoea in children under the age of five and cause the deaths of nearly half a million children younger than 5 every year. It is therefore important to find potent, accessible and widely affordable ways to restrain rotavirus and to treat patients.

Scientific enquiries: Dr Karen Knipping;

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

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

“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

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

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.


Dr Christo Muller, Medical Research Council
Tel: (021) 938 0894

Protection of rooibos could boost economic growth

4 August 2014
The recent ruling to protect the rooibos trademark under Geographical Indicators (GI) framework of South Africa’s intellectual property (IP) laws is a major step in protecting South African products and promoting economic growth and competitiveness.

The reciprocal agreement between South Africa and the European Union sees South Africa’s rooibos and the EU’s feta cheese get GI protection and gives rooibos producers ownership and authority over the name.

Dawie de Villiers, chairman of the SA Rooibos Council says: “Obviously we’re delighted that this iconic South African product now enjoys international protection under a robust regulatory framework.

“Governments have an obligation to protect their nations’ assets and the Department of Trade and Industry’s (Dti) efforts in securing GI for rooibos could provide real impetus for other intrinsically local products, says De Villiers. “By rights, a GI for rooibos should be a fairly simple undertaking. It’s grown in a very specific and limited part of the Western Cape and nowhere else in the world.

“So an attempt, for example, by the French company Compagnie de Trucy to register rooibos as French was mischievous, to say the least.

We were delighted that the Trade and Industry Minister, Mr Rob Davies scrutinised the issue from all angles and then acted boldly.”

Gazetting a proposal to protect rooibos and names such as Rooibosch, Rooibostee, Rooitee and Red Bush under the Merchandise Marks Act now protects this globally unique product under domestic law. This enables the Dti to seek international protection usiWIPO (World Intellectual Property Organisation), explains De Villiers.

“This could help set a precedent for the protection of other products from a specific, localised area, such as tea and Karoo lamb.

GI’s are used to protect products specific to a region, which is why champagne may only be labelled as such if it comes from the Champagne area of France, and Darjeeling tea from a specific area of India, and Colombian Coffee from Colombia.

De Villiers adds: “Achieving this protection for rooibos was partly the result of eight years of intensive research, collation of fact and some intensive lobbying. The GI allows a number of important steps. From the perspective of growing the rooibos sector, quality control is crucial, as it enables us to ensure the authenticity of products containing rooibos tea blends. A minimum of 80% rooibos content is required for it to be described as an official rooibos product.”

Other crucial benefits include rooibos’ use as a powerful tool for promoting regional tourism and for protecting the biodiversity of the area, which is especially important considering the fynbos region’s fragile ecosystem.

All these benefits will in turn contribute to the socioeconomic development of the area and the livelihoods and dignity that sustainable development will yield.

It means, in short, that SA’s rooibos tea producer can take ownership of the rooibos name and that name may only be used on products they produce and which are endorsed by them, concludes De Villiers.