Rooibos is a shrubby legume that is indigenous to the mountains of the Cape Province in South Africa. Rooibos grows in coarse, low-acid soil in areas where summers are hot and dry. The plant reaches 1½ to 5 feet in height and produces yellow flowers in the spring.
When cultivated commercially, the needle-like leaves and stems are usually harvested once a year in the summer. Local inhabitants of the mountainous regions of the Cape Province were the first to collect wild rooibos and use it to make tea. Rooibos became a cultivated crop in the late 1920’s, and it has been grown commercially since World War II. 1 Rooibos is now exported to countries worldwide, including Germany, Japan, the Netherlands, England, Malaysia, South Korea, Poland, China, and the United States. 2 The total domestic and international sales of rooibos in 1999 amounted to 6150 tons, of which 1800 tons were exported to 31 countries.2 The small towns of Clanwilliam and Wuppertal north of Cape Town in the Cedarberg region have a long history of rooibos cultivation; these towns are popular tourist stops because of their beautiful rural scenery and their role in the rooibos
Antioxidants in Rooibos
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. Rooibos tea contains many antioxidants that seem to be potent free radical scavengers in laboratory studies. A recently published analysis of fermented rooibos measured the levels of all the antioxidants (see Table 1).
Antioxidants in Aqueous Extract of Fermented Rooibos (mg/g +/- SD)
- isoorientin 0.833 +/- 0.007
- orientin 1.003 +/- 0.010
- aspalathin 1.234 +/- 0.010
- vitexin 0.330 +/- 0.002
- rutin 1.269 +/- 0.006
- isovitexin 0.265 +/- 0.002
- isoquercitrin and hyperoside 0.429 +/- 0.002
- luteolin 0.029 +/- 0.001
- quercetin 0.107 +/- 0.002
- chrysoeriol 0.022 +/- 0.001
- total 5.521 +/- 0.003
Elizabeth Joubert, PhD, specialist researcher at South Africa’s ARC Infruitec-Nietvoorbij and a rooibos expert, says that the
total antioxidants content of a cup of rooibos can be as much as 60 to 80 mg, depending on the brewing time and amount of leaves used. Similar antioxidants are found in many fruits and vegetables. Studies in the test tube have shown that these antioxidants can cause pancreatic cancer cells to commit suicide. In addition to causing death of cancer cells, antioxidants decreased primary tumor growth and prevented metastasis in a model of pancreatic cancer. Antioxidants are abundant in rooibos tea. Joubert says that her research group just recently developed a way to isolate pure antioxidants from rooibos.
The several studies show that rooibos tea contains antioxidants that have positive effects when tested as isolated substances. So, do all these antioxidants in rooibos tea lead to health benefits for tea drinkers? Laboratory studies have demonstrated beneficial effects of rooibos in the test tube and in live animals, but human studies have not been conducted. Much more research is needed, but the studies so far look intriguing.
Although rooibos does contain active antioxidants, many of the other health claims made for rooibos tea aren’t supported by science. For example, rooibos is not a source of vitamin C. Joubert says, “We have tested both the traditional rooibos and green rooibos, and vitamin C was not present.” Minerals are present in trace amounts, but not in enough quantity to be a meaningful dietary source. Distributors of rooibos tea often suggest it can help allergies, sleep problems, digestive problems, headache, and other ailments, but these claims have not been studied yet. South Africans use rooibos as a treatment for colic in babies; Joubert says the tea does seem to help infant colic, but no formal research has been done. Despite what is said in some promotional material, there’s no evidence that rooibos tea fights the HIV virus. This inaccurate claim probably arose because one study found
that a polysaccharide in rooibos leaves may have antiviral activity against the HIV virus, but the polysaccharide had to be chemically extracted from the leaves and is not found in tea made by steeping the leaves in water. An in vitro and in vivo study showed that
rooibos might enhance immune function, but very little research has been done on this topic.
The Bottom Line
Rooibos tea has become popular because of its fruity, sweet taste and its caffeine free, low tannin, antioxidant-rich status. Although more research is needed, rooibos seems to be safe and to have no side effects. The antioxidants in the tea help protect against free radical damage that can lead to cancer, heart attack, and stroke. Future research should reveal whether the antioxidant benefits of rooibos observed in test tube and in animals will translate into health benefits for humans.
I would like to thank Elizabeth Joubert, PhD, specialist researcher at South Africa’s ARC Infruitec-Nietvoorbij, and Jeanine L. Marnewick, senior research scientist at the Program on Mycotoxins and Experimental Carcinogenesis at the Medical Research
Council of South Africa, for their quotes and technical input. Their expertise on rooibos has contributed much valuable information to this article. They also provided copies of three research papers, which I greatly appreciate. I would also like to thank Lorenzo
Bramati, PhD, research scientist at the Instituto Tecnologie Biomediche CNR in Italy, for his helpful input and for providing copies of three research papers.
(PDF) Fact Sheet on Rooibos Tea. Available from: https://pdfs.semanticscholar.org/dbdc/3bbd9f6e1cc81888ff80c3e66546ef39a149.pdf [accessed Nov 24 2018].
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