New evidence proving that people can absorb the active compounds in Rooibos tea

A new collaborative study between researchers at two German universities (Leibniz University and Braunschweig Technical University) confirmed that the active compounds in Rooibos tea can be absorbed and broken down by the human body. These new findings about the bioavailability of Rooibos help scientists to understand and explain the multitude of health benefits that Rooibos tea offers, including protection against heart disease and cancer.

The researchers took blood and urine samples of 12 healthy male volunteers before and after drinking Rooibos. They found several metabolites (breakdown products) of the key antioxidants in rooibos – aspalathin and nothofagin. They also found intact aspalathin, proving that humans can absorb aspalathin into the bloodstream, even if only at low levels. Aspalathin is the major flavonoid in rooibos. It is a novel compound (found only in Rooibos), but also the most active antioxidant in Rooibos in many cases.

Scientific reference: Breiter, T., Laue, C., Kressel, G., Groll, S., Engelhardt, U.H., Hahn, A., Bioavailability and antioxidant potential of rooibos flavonoids in humans following the consumption of different rooibos formulations, Food Chemistry (2011), in press.

Available online at ScienceDirect.com

Local study examines rooibos anti-ageing potential

The pharmaceutical and cosmetic industries have long sought to restore and reverse the effects of ageing, now local scientists are investigating whether rooibos may hold some answers.

The contention that this indigenous plant could beneficial in countering the effects of time is not that far-fetched. The most accepted theory of ageing is the free-radical hypothesis. Rooibos is rich in antioxidants, which bind with free-radicals and prevent them from damaging cells.

Numerous local and international studies have proved that the antioxidants in rooibos slow down and prevent various forms of cancer, reduce the risk of heart attack and stroke and provide a plethora of other health benefits. There is, however, little published research on its precise molecular and cellular involvement against ageing.

Professor Maryna van de Venter of the Department of Biochemistry and Microbiology and her colleague, Dr Trevor Koekemoer, at the Nelson Mandela Metropolitan University are seeking to rectify this.

Prof Van de Venter explains that one of the characteristics associated with ageing is the progressive redistribution of body fat. This results in a decrease in the subcutaneous fat (the layer just under the skin) and an expansion in abdominal fat.

Subcutaneous fat loss leads to cosmetic changes such as wrinkles, sunken eyes and skin folds. The accumulation of body fat is potentially more harmful. Visceral fat is associated with increased risk of many age-related diseases, including insulin resistance, diabetes and heart disease.

“In layman’s terms there’s less fat in the places where it should be and more in the places it shouldn’t, with substantial clinical consequences,” she explains.

Preadipocytes, the cells from which fat cells develop, may be the reason this happens. These represent between 15% and 50% of the cells in adipose (fat) tissue and consequently are likely to have a significant influence on its growth and function.

Recent studies have shown that over time preadipocytes lose their ability to multiply and develop into mature fat cells. Although scientists are not yet sure why this happens, they believe inflammation of the fatty tissue, oxidative stress and the introduction of factors which prevent the cells from dividing may contribute.

Prof Van de Venter’s research will investigate the potential influence that the antioxidants contained in rooibos may have on these molecular mechanisms thought to cause preadipocyte dysfunction. Preventing this may slow or even reverse age-related adipose redistribution and associated cosmetic changes and health risks.

The findings will contribute to our understanding of the health benefits of rooibos and provide much-needed scientific evidence to substantiate its anti-ageing properties, beyond what is already known about its antioxidant capacity.

 

Enjoy Rooibos – red or green – as both offer health benefits

Green Rooibos tea has higher levels of antioxidants than traditional Rooibos, but recent studies are proving that both kinds of Rooibos protect against a range of diseases, and that drinking green Rooibos is not necessarily better.


Prof Jeanine Marnewick has been involved in Rooibos research for more than 15 years

Prof Jeanine Marnewick has been involved in Rooibos research for more than 15 years.

“People should drink the kind of Rooibos they enjoy most, since we now know that Rooibos with a higher-antioxidant content does not always provide the best benefits,” recommends Professor Jeanine Marnewick, manager of the Oxidative Stress Research Centre in the Faculty of Health and Wellness Sciences at Cape Peninsula University of Technology.

Professor Marnewick, who has been actively involved in Rooibos research over the last 15 years, explains that it is not only the level of antioxidants, but also the specific combinations of bio-active compounds in Rooibos that are important. “The health benefits from drinking Rooibos tea will also be different for every person – depending on your overall health status,” she adds.

Scientists are still busy unravelling the complex pathways whereby the active compounds in Rooibos can play a role in disease prevention, but several studies done on skin, liver, heart and oesophagus models, researchers have shown that traditional rooibos offers similar (and sometimes even better) health properties compared to green Rooibos.

Researchers at the Cape Peninsula University of Technology found that both traditional and green Rooibos were able to protect and aid recovery of hearts tissue in rats following damage of the heart .

A recent study at South Africa’s Medical Research Council showed that green and traditional Rooibos could play a significant role in preventing or slowing done cancer of the oesophagus .

A collaborative study in Europe showed that both green and fermented Rooibos significantly increases the antioxidant capacity in human blood, thereby boosting the body’s natural defences.

In an earlier study on skin cancer in mice researchers at South Africa’s Medical Research Council Found that traditional rooibos was even more effective than green rooibos at inhibiting cancer.

Much like making wine, making a good quality Rooibos tea is both a science and an art. The characteristic colour and flavour of Rooibos tea develops when enzymes that occur naturally in the plant turns the shredded green tea leaves reddish brown. This happens on the tea court while the moist tea is slowly dried in the sun. When making green Rooibos, this step is skipped and the tea is dried as soon as possible in order to inactivate the enzymes in the plant and retain the green colour in the dried leaves.

Researchers optimistic about anti-diabetic potential of rooibos

Cape Town, South Africa – With World Diabetes Day in sight on 14 November, new evidence of the anti-diabetic potential of Rooibos has emerged …

Cape Town, South Africa – With World Diabetes Day in sight on 14 November, new evidence of the anti-diabetic potential of Rooibos has emerged from a study conducted jointly at the Diabetes Discovery Platform from South Africa’s Medical Research Council (MRC) and the Agricultural Research Council’s (ARC) Infruitec-Nietvoorbij Institute. Researchers found that an aspalathin-enriched extract of green Rooibos is able to lower raised glucose levels in the blood of diabetic rats. Aspalathin is a unique antioxidant found in nature only in the Rooibos plant (Aspalathus linearis). When combined with rutin, another key compound in Rooibos tea, the glucose-lowering action was further enhanced.

Working with diabetic rats, the researchers were able to show that the Rooibos extract could achieve a glucose lowering effect comparable to known diabetic drugs.

“Our work confirms the constituents present in Rooibos could prove beneficial in the fight against diabetes,” says Doctor Johan Louw of the MRC who led the study. “We believe that Rooibos can provide a basis to develop a standardised anti-diabetic product and in a country like South Africa, where a large section of the population relies on herbal medicines, such a product could be of huge value.”

“We have also confirmed that the polyphenols in complex mixtures, such as Rooibos tea, work synergistically to achieve favourable health effects,” Louw explains. “This points to the value of drinking the ‘whole’ tea containing the required amount of these beneficial constituents, rather than a tablet containing just one of the compounds.

“Our Rooibos research to date focused mostly on the antioxidant activity of Rooibos, but this evidence of its ability to lower blood glucose levels opens up new and exciting possibilities for this unique South African herb” says Prof Lizette Joubert of the ARC who collaborated on this project. “We now need to dig deeper to determine the optimal combination and ratio of the active compounds such as aspalathin and rutin in controlling blood glucose levels, and also to understand the exact mechanisms involved.” Follow-up studies indicated that other compounds are also important.

The study has been published online on 19 October 2012 in the Journal of Phytomedicine. (http://www.phytomedicinejournal.com/article/S0944-7113(12)00320-0/abstract)

This Rooibos and diabetes study was funded jointly by the National Research Foundation of South Africa, the Medical Research Council and the Agricultural Research Council, with contributions to post-doctoral fellowships from the Department of Science and Technology. Prof Stephen Fey from the University of Southern Denmark also collaborated on the study.

Notes for editors

The World Health Organization (WHO) estimates that 439 million people will have diabetes by 2030, with the major increase occurring in developing countries.

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 http://www.virologyj.com/content/9/1/137.

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; karen.knipping@danone.com

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