Use Rooibos To Make Tea at Home

Rooibos Research

Cancer prevention. Although preliminary studies suggest that drinking rooibos tea may help prevent malignant mutations, the number of investigations remains small, and most of them have been conducted in Japan. Here’s a summary of the research.

• Research conducted in 1993 in Japan shows that rooibos suppressed malignant cell changes in mice when added to drinking water; it also suppressed malignant cell changes in cell cultures when added to the culture medium.

In several experiments, rooibos and green tea did comparably well. In one study, green tea did nothing while rooibos showed strong inhibitory activity. Because rooibos contains only a small amount of catechins (the compounds primarily responsible for green tea’s antioxidant capacity), it seems likely that rooibos gets its antimutagenic potential from a different set of molecules.

• Research published in Mutation

Research found that rooibos tea inhibited premalignant changes in tissue-cultured mouse cells that were exposed to X-rays. The inhibiting action took place when cells were treated with as little as a 2 percent rooibos solution (roughly equivalent to 2/3 cup a day for humans) and peaked when cells were treated with a 10 percent solution (a little more than 3 cups). At the higher concentration, the rate of transformation was no greater than that of normal, non-irradiated cells.

• Rooibos also protects mice against gamma radiation. Mice treated with 1 ml of rooibos tea two hours before irradiation experienced less DNA damage than untreated mice. (For a human, this equals about 4 liters of double-strength tea.) One molecule, luteolin, appears to be responsible for the greatest inhibition.

Antioxidant content. Rooibos is richly endowed with a wide spectrum of antioxidant phenolic acids and flavonoids. Although several of these (such as quercitin, rutin, luteolin, and caffeic acid) occur in other vegetables and fruits, one is unique to rooibos. Called aspalathin, its antioxidant activity is comparable to that of vitamin E and occurs in high concentration. Aspalathin constitutes roughly 1.5 percent of dry rooibos leaves.

Brain benefits. Scientists working in another Japanese laboratory discovered that rooibos suppresses age-related brain deterioration. Rats who drank nothing but rooibos tea from ages 3 to 24 months showed little change in several classes of brain function when compared to three-month-old rats. The relevance to human brain function remains to be determined.

Anti-HIV activity. Two further studies in Japan indicate that rooibos contains at least one substance that inhibits binding of HIV-1 to MT-4 lymphocytes, the cells that the virus targets. To date, the active molecule is not fully described. Scientists do know that it’s a polysaccharide containing uronic acid and various sugars, and that it is soluble in sodium hydroxide or sodium carbonate but not in hot water. This means that normal brewing conditions will not release the active compound into tea.

Cornelia Carlson holds a doctorate in biochemistry and is an avid grower and user of herbs. She writes frequently for Herbs for Health and is the author of The Practically Meatless Gourmet (Berkley, 1996). She writes from her home in Tucson, Arizona. 

References

Inanami, O., et al. “The suppression of age-related accumulation of lipid peroxides in rat brain by administration of rooibos tea (Aspalathus linearis).” Neuroscience Letters 1995, 196:85–88.

Komatsu, K., et al. “Inhibitory effects of rooibos tea, Aspalathus linearis, on X-ray-induced C3H10T1/2 cell transformation.” Cancer Letters 1994, 77:33–38.

Nakano, M., et al. “Anti-human immunodeficiency virus activity of oligosaccharides from rooibos tea (Aspalathus linearis) extracts in vitro.” Leukemia 1997, 11, supplement 3:128–130.

——— “Polysaccharide from Aspalathus linearis with strong anti-HIV activity.” Bioscience, Biotechnology and Biochemistry 1997, 61: 267–271.

Sasaki, Y., et al. “The clastogen-suppressing effects of green tea, Po-lei tea, and rooibos tea in CHO cells and mice.” Mutation Research 1993, 286:221–232.

Shimoi, K. et al. “Radioprotective effects of antioxidative plant flavonoids in mice.” Mutation Research 1996, 350:153–161.

Von Gadow, A. et al. “Comparison of the antioxidant activity of aspalathin with that of other plant phenols of rooibos tea (Aspalathus linearis), alpha tocopherol, BHT, and BHA.” Journal of Agricultural and Food Chemistry 1997, 45:632–638.

———. “Effect of extraction time and additional heating on the antioxidant activity of rooibos tea (Aspalathus linearis) extracts.” Journal of Agricultural and Food Chemistry 1997, 45:1370–1374.