SUMMARIES OF ROOIBOS HEALTH RESEARCH FINDINGS FROM PEER-REVIEWED SCIENTIFIC LITERATURE

• Rooibos as a source of antioxidants and cancer-fighting and anti-ageing agents
  

In 2003, the American Botanical Council published a comprehensive review of Rooibos research. It summarises the scientific evidence that Rooibos (scientific name = Aspalathus linearis) is a source of flavonoid antioxidants and protects against cancer, heart disease and stroke. The authors cite many studies showing that Rooibos contains antioxidants that have positive effects when tested as isolated substances and that the tea as a whole has good antioxidant activity in laboratory tests (in vitro). They list all the antioxidants found in Rooibos and confirm that Rooibos is the only known natural source of the antioxidant aspalathin, and that it also contains the rare antioxidant nothofagin. The review refers to several studies that have found that Rooibos contains polyphenol antioxidants that are potent free radical scavengers. [Free radicals (unstable molecules that have lost an electron) can damage the DNA in cells, leading to cancer, and they can oxidize cholesterol, leading to clogged blood vessels, heart attack, and stroke. Antioxidants can bind to free radicals before the free radicals cause harm.] The research captured in this review shows that fermented Rooibos reduces cancer-associated changes in animal cells exposed to the chemical mutagens (cancer-causing substances), and also reduces the cancerous transformation of mouse cells exposed to X-rays. Rats given free access to Rooibos over a period of 21 months also showed much lower age-related lipid peroxidation in the brain compared with rats that drank water. The review concludes that Rooibos appears to be safe and free of adverse side effects and "may help protect against free radical damage," which can lead to cancer, heart attack, and stroke. They add that more research is needed to confirm that these benefits observed in animal studies are also true in people. Reference for review article: Herbalgram, 59, 34 – 45 (2003)

Another extensive review of the history, cultivation and science of Rooibos and other South African herbal teas was published in the Journal of Ethnopharmacology in 2008. This comprehensive review was prepared by Professor Lizette Joubert of South Africa's Agricultural Research Council, in collaboration with other scientists. Reference for review article:  Journal of Ethnopharmacology 119 (2008) 376 - 412. 
 

Rooibos and cancer research  

 Several animal studies around the world have confirmed the cancer-fighting ability of Rooibos:

• In 2003 a team of South African researchers from several universities and research institutions published a comprehensive study confirming that Rooibos can protect the liver against oxidative damage and mutagenesis (a change in the cell that may lead to cancer).
  Reference for supporting scientific article: J Agric. Food Chem. 51, 8113 – 8119 (2003)


• Rooibos protects against some forms of chemically induced liver cancers in rats: This was the conclusion of a study published in 2003, based on a collaborative study between researchers at South Africa’s Medical Research Council and other research organisations.
  Reference for supporting scientific article: Mutation Research 558, 145 – 154 (2004)


• The ability of South African herbal teas (Rooibos and Honeybush extracts) to act as “chemopreventors” in skin cancer was also highlighted in an article published in 2005, once again as the result of the work of a South African research team. They showed that topical (external) application of the tea fractions significantly suppressed tumour growth in mice with skin cancer, when using processed and unprocessed tea.
  Reference for supporting scientific article: Cancer Lett 224, 193 – 202 (2005)


• In 2006 several South African researchers collaborated to compare the potential of different kinds of tea (Rooibos, honeybush, black oolong and green tea) to suppress mutations, and thereby prevent cancer. Their results confirmed that the phenolic compounds in herbal tea extracts have a strong anti-mutagenic effect.
  Reference for supporting scientific article: Mutation Research/Genetic Toxicology and Environmental Mutagenesis, Vol 611, 42 –53 (2006)


• Researchers at the Medical Research Council and Stellenbosch University worked together to try and understand which compounds in Rooibos are specifically responsible for its antimutagenic properties. They found that the antimutagenic potency of the flavonoids in Rooibos is reduced during fermentation (oxidation).
  Reference for supporting scientific article: Mutation Research  631, 111 – 123 (2007)


• The ability of Rooibos to scavenge free radicals was confirmed in collaborative study between researchers in South Africa (Stellenbosch University and the Agricultural Research Council) and the United States (University of Mississippi). They also investigated the relative potency of the different antioxidants in Rooibos and confirmed that fermentation (or the processing of green Rooibos) decreases its anti-radical capacity.
  Reference for supporting scientific article: Food Research International 37, 133–138 (2004)
  
  
• Rooibos as a treatment for stomach cramps and diarrhoea
  
Acknowledging that Rooibos is widely used to treat gastrointestinal upsets, researchers in Pakistan, Canada and Germany joined forces to explore the mechanism of this effect of Rooibos. Their results, published in 2006, explain the biochemistry of how the flavonoids and other active ingredients in Rooibos achieve this calming effect on the digestive system and concludes that it is justified to use Rooibos for the treatment of gastrointestinal disorders, such as gut spasms.
Reference for supporting scientific article: Basic and Clinical Pharmacology & Toxicology, 99, 365 – 373 (2006).


• Rooibos recommended as a treatment for respiratory disease and to lower blood pressure
  
Based on a study published in 2006, researchers at the Aga Khan University Medical College in Pakistan found a sound basis for the wide medicinal use of Rooibos. They found that chrysoeriol, one of the bio-active components of Rooibos, acted effectively as a bronchodilator, with an associated effect on lowering blood pressure and relieving spasms. They also state in the article that chrysoeriol is already known for its antioxidant, anti-inflammatory, antitumor, antimicrobial, antiviral and free radical scavenging abilities.
Reference for supporting scientific article: Eur J Nutr, 45, 463 – 469 (2006)


• Rooibos protecting against liver disease
  
Researchers in Slovakia and Japan agreed that Rooibos is a safe and effective treatment to protect the liver (also known as a hepatoprotector) in patients with liver disease, mostly because Rooibos is such a rich source of natural antioxidants. They found that Rooibos offers specific protection when the liver is already damaged or experiencing oxidative stress. They published their results and made this recommendation, based on a study of the effect of Rooibos on the antioxidant status of the liver in a rat study.
Reference for supporting scientific article: Physiol. Res. 53, 515 – 521 (2004)


• Rooibos restoring immune function
  
Research teams at the Okyama University in Japan demonstrated that the active ingredients in a Rooibos extract restored immune-function in immune-suppressed rats.  These results hold significant potential for future research into the immune-boosting properties of Rooibos that could potentially benefit people living with HIV/AIDS.
References for supporting scientific article: Biosci. Biotechnol. Biochem. 65 (1), 2137 – 2145 (2001) and
Biosci. Biotechnol. Biochem 71 (2), 698 – 602 (2007)


• Rooibos as an anti-ageing agent
  
Fascinated by the wide range of beneficial properties of Rooibos, Japanese researchers have also studied to potencial of Rooibos to delay the effects of ageing. They recently demonstrated its anti-ageing effect in a study with Japanese quails. These birds were given Rooibos to drink and also had ground Rooibos added to their food. The hens on the Rooibos diet laid more eggs and kept on laying eggs as they were getting older, compared to quail hens on a standard diet.
Reference for supporting scientific article: British Poultry Science, 49 (1) 55 – 64 (2008)


• Rooibos protecting red blood cells
  
Rooibos inhibits free radicals in the blood stream and prevent them from destructing red blood cells. This was shown in a joint study between researchers in Japan and Slovakia, published in 2000.  They used Japanese quails for this in vivo study and found that a boiled water extract of Rooibos, fed to the quails, protected red blood cells against hemolysis (breaking up of red blood cells).
Reference for supporting scientific article: Gen. Physiol. Biophys. 19, 365 – 371 (2000)


• Rooibos may help to fight allergies
  
Japanese researchers at Showa University found that when Rooibos is consumed regularly as a beverage, it helps to improve allergy status, by boosting the production of Cytochrome P450, an important enzyme in the liver and many other tissues that helps to metabolise allergens.
Reference for supporting scientific article: J Pharmacol Sci 103, 214 – 221 (2007)


• Rooibos and honeybush: Protective partners
  
A review of the bioactivity of South African herbal teas, published by researchers at the USDA Human Nutrition Research Centre on Aging in Washington DC during 2003, confirms that Rooibos and Honeybush differ in composition, but share potentially beneficial activities in laboratory studies. Several animal model studies are quoted showing that both herbal teas possess potent antioxidant and immune-boosting components, and that both can protect against cancer-causing chemicals.
Reference for research review article: Phytother. Res. 21, 1 – 16 (2007)



FUTURE RESEARCH CHALLENGES

Extensive anecdotal evidence suggests that Rooibos has other beneficial effects not yet fully verified or understood by science. Some of the scientific challenges include:


• Demonstrating and understanding of the anti-allergic properties of Rooibos: Some claim that bathing the skin in lukewarm Rooibos is an effective way to treat conditions such as eczema, rashes and sunburn. In South Africa Rooibos is widely used as a drink for babies suffering from colic and allergies. These effects have not yet been fully researched.
  
• Exploring and understanding the immune-boosting effects of Rooibos: There is a huge future potential to investigate the potential of Rooibos to combat HIV.


• A more complete understanding of the active compounds in Rooibos, and exactly how they achieve their anti-cancer and anti-ageing effects.


• Searching for answers on optimal use of Rooibos in a healthy lifestyle, including its potential to prevent and treat several lifestyle diseases.