Health Care Professional Information

Scientific Name
Aspalathus linearis
Common Name

Redbush tea (South Africa), Rooibosch (Netherlands)

Clinical Summary

Prepared from the dried leaves of the rooibos plant native to South Africa, rooibos tea has grown popular in western countries because it is rich in antioxidants, especially the polyphenols aspalathin and nothofagin (1), and low in caffeine. It does not contain any catechins, the major flavonoids present in green and black teas (2).
In vitro and animal studies have shown that rooibos can modulate immune function (3) (4), exhibit anti-inflammatory effects (5), may prevent oxidative stress and play a role in alleviating symptoms associated with type-2 diabetes (7).
Animal studies also suggest that it may prevent chromosomal aberrations (8), and tumor mutagenesis (9) (10). Topically applied rooibos elicits a protective effect against microsomal lipid peroxidation and may help reduce chemical-induced tumor formation (1) (11). Rooibos also appears to protect against damage caused by radiation (12). However, these effects have not been confirmed in humans.
Rooibos was shown to inhibit angiotensin-converting enzyme in healthy volunteers (2), which may benefit cardiovascular health. Further research is needed.

Because compounds isolated from rooibos leaves demonstrated estrogenic activity (22), patients with hormone-sensitive cancers should use caution before taking rooibos.

Purported Uses
  • Acne
  • Allergy
  • Aging
  • Asthma
  • Cancer
  • Colic
  • Eczema
  • High blood pressure
  • Hypoglycemic control
  • Insomnia
Constituents
  • Volatile oils: Guaiacol, damascenone, geranylacetone, beta-phenylethyl alcohol, 6-methyl-5-hepten-2-one
  • Phenols: polyphenols, flavonoids, non-flavonoids
  • Protein and Minerals
    (9) (13) (14) (15)
Mechanism of Action

Rooibos was shown to enhance the activity of glutathione-S transferase and UDP-glucuronosyl transferase in rat liver (11) (16), allowing cells to protect against oxidative stress, and to reduce the effects of hepatocarcinogens. A study of oxidative stress in rats found that serum superoxide dismutase and urine 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations (as markers for DNA damage) were significantly reduced following administration of rooibos (17). Some studies have shown that the non-oxidized teas have greater antimutagenic effects compared to the oxidized forms. This is probably due to reduction in total polyphenol content with oxidization (11) (18) (19). The anti-inflammatory effects of rooibos are thought to be due to its inhibition of COX-2 enzyme (5).

Rooibos also modulates immune function: It induces higher IL6, IL10 and IFN-gamma levels and increases cell-mediated immunity (3); and increases IL2 levels while suppressing IL4 (4).

In other studies, rooibos significantly decreased glucocorticoid levels in rats and steroid metabolite ratios linked to metabolic disorders-cortisol:cortisone in humans and CORT:testosterone in rats (23).
Hot water-soluble solids from fermented rooibos inhibited adipogenesis and influenced adipocyte metabolism, suggesting a role in preventing obesity (24).

Pharmacokinetics

The major component of rooibos tea, aspalathin, is absorbed by the intestines as a C-glycoside. It is metabolized in the liver and is excreted in urine (20).

Adverse Reactions
  • Rooibos tea may cause hepatotoxicity (21).

A study done in male rats indicates that prolonged exposure rooibos might result in subtle structural changes in the reproductive system and may induce acrosome reaction, which can impair fertility. Intake of large amounts of rooibos may also harm liver and kidney function (25).

Herb-Drug Interactions

Rooibos tea has antioxidant effects and can interfere with the action of certain chemotherapeutic agents.

References
  1. Marnewick J, Joubert E, Joseph S, et al. Inhibition of tumour promotion in mouse skin by extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), unique South African herbal teas. Cancer Lett. 2005 Jun 28;224(2):193-202.
  2. Persson IA, Persson K, Hägg S, Andersson RG. Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers. Public Health Nutr. 2010 May;13(5):730-7.
  3. Hendricks R, Pool EJ. The in vitro effects of Rooibos and Black tea on immune pathways. J Immunoassay Immunochem. 2010 Apr;31(2):169-80.
  4. Kunishiro K, Tai A, Yamamoto I. Effects of rooibos tea extract on antigen-specific antibody production and cytokine generation in vitro and in vivo. Biosci Biotechnol Biochem. 2001 Oct;65(10):2137-45.
  5. Na HK, Mossanda KS, Lee JY, Surh YJ. Inhibition of phorbol ester-induced COX-2 expression by some edible African plants. Biofactors. 2004;21(1-4):149-53.
  6. Darvesh AS, Carroll RT, Bishayee A, Geldenhuys WJ, Van der Schyf CJ. Oxidative stress and Alzheimer's disease: dietary polyphenols as potential therapeutic agents. Expert Rev Neurother. 2010 May;10(5):729-45.
  7. Kawano A, Nakamura H, Hata S, et al. Hypoglycemic effect of aspalathin, a rooibos tea component from Aspalathus linearis, in type 2 diabetic model db/db mice. Phytomedicine. 2009 May;16(5):437-43.
  8. Sasaki YF, Yamada H, Shimoi K, Kator K, Kinae N. The clastogen-suppressing effects of green tea, Po-lei tea and Rooibos tea in CHO cells and mice. Mutat Res. 1993 Apr;286(2):221-32.
  9. Marnewick JL, Gelderblom WC, Joubert E. An investigation on the antimutagenic properties of South African herbal teas. Mutat Res. 2000 Nov 20;471(1-2):157-66.
  10. Marnewick JL, Batenburg W, Swart P, et al. Ex vivo modulation of chemical-induced mutagenesis by subcellular liver fractions of rats treated with rooibos (Aspalathus linearis) tea, honeybush (Cyclopia intermedia) tea, as well as green and black (Camellia sinensis) teas. Mutat Res. 2004 Mar 14;558(1-2):145-54.
  11. Marnewick JL, van der Westhuizen FH, Joubert E, et al. Chemoprotective properties of rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia) herbal and green and black (Camellia sinensis) teas against cancer promotion induced by fumonisin B1 in rat liver. Food Chem Toxicol. Jan 2009;47(1):220-229.
  12. Komatsu K, Kator K, Mitsuda Y, Mine M, Okumura Y. Inhibitory effects of Rooibos tea, Aspalathus linealis, on X-ray-induced C3H10T1/2 cell transformation. Cancer Lett. 1994 Feb 28;77(1):33-8.
  13. Erickson, L. Rooibos Tea: Research into Antioxidant and Antimutagenic Properties, HerbalGram. 2003;59:34-45.
  14. Habu RAF, Mon TR, Morton JF. Volatile components of Rooibos J. Agric. Food Chem. March 1985;33(2):249-254.
  15. McKay DL, Blumberg JB. A review of the bioactivity of South African herbal teas: rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia). Phytother Res. 2007 Jan;21(1):1-16.
  16. Marnewick JL, Joubert E, Swart P, Van Der Westhuizen F, Gelderblom WC. Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and Honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats. J Agric Food Chem. 2003 Dec 31;51(27):8113-9.
  17. Baba H, Ohtsuka Y, Haruna H, et al. Studies of anti-inflammatory effects of Rooibos tea in rats. Pediatr Int. 2009 Oct;51(5):700-4.
  18. Standley L, Winterton P, Marnewick JL, et al. Influence of processing stages on antimutagenic and antioxidant potentials of rooibos tea. J Agric Food Chem. Jan 2001;49(1):114-117.
  19. Van der Merwe JD, Joubert E, Richards ES, et al. A comparative study on the antimutagenic properties of aqueous extracts of Aspalathus linearis (rooibos), different Cyclopia spp. (honeybush) and Camellia sinensis teas. Mutat Res. Dec 10 2006;611(1-2):42-53.
  20. Kreuz S, Joubert E, Waldmann KH, Ternes W. Aspalathin, a flavonoid in Aspalathus linearis (rooibos), is absorbed by pig intestine as a C-glycoside. Nutr Res. 2008, Oct; 28(10):690-701.
  21. Sinisalo M, Enkovaara AL, Kivistö KT. Possible hepatotoxic effect of rooibos tea: a case report. Eur J Clin Pharmacol. 2010 Apr;66(4):427-8.
  22. Shimamura N, Miyase T, Umehara K, Warashina T, Fujii S. Phytoestrogens from Aspalathus linearis. Biol Pharm Bull. 2006 Jun;29(6):1271-4.
  23. Schloms L, Smith C, Storbeck KH, et al. Rooibos influences glucocorticoid levels and steroid ratios in vivo and in vitro: A natural approach in the management of stress and metabolic disorders? Mol Nutr Food Res. 2013 Sep 11. doi: 10.1002/mnfr.201300463. [Epub ahead of print]
  24. Sanderson M, Mazibuko SE, Joubert E, et al. Effects of fermented rooibos (Aspalathus linearis) on adipocyte differentiation. Phytomedicine. 2013 Sep 20. doi:pii: S0944-7113(13)00314-0. 10.1016/j.phymed.2013.08.011. [Epub ahead of print]
  25. Opuwari CS, Monsees TK. In vivo effects of Aspalathus linearis (rooibos) on male rat reproductive functions. Andrologia. 2013 Sep 6. doi: 10.1111/and.12158. [Epub ahead of print]

Consumer Information

How It Works

Bottom Line: Rooibos tea is rich in antioxidants which may protect against cancer and other diseases. However, these effects have not been shown in humans.

Rooibos tea contains compounds that may prevent tumor growth and aging processes. But the specific mechanisms are not known. Further studies are needed.
Some compounds isolated from rooibos leaves showed estrogenic activity. Patients with hormone-sensitive cancers should use caution before taking rooibos.

Purported Uses
  • To treat acne, eczema and wrinkles
    Rooibos is used to treat acne, eczema, and to prevent wrinkles. Clinical evidence is lacking.
  • To prevent cancer
    Rooibos may inhibit tumor growth. Human studies are needed.
Side Effects

Rooibos tea may cause liver damage.

A study done in male rats indicates that prolonged exposure to rooibos might result in subtle structural changes in the reproductive system and may impair fertility. Intake of large amounts of rooibos may also harm liver and kidney function.

Special Point

Rooibos tea has antioxidant effects and can interfere with the action of certain chemotherapeutic agents.

E-mail your questions and comments to aboutherbs@mskcc.org.