Rooibos is a plant native to South Africa, scientifically known as Aspalathus linearis. Its infusion, often referred to as rooibos tea, is cherished for its sweet and slightly nutty flavor.

Industrial Production Process

• Harvesting. Rooibos leaves are manually harvested in the mountainous regions of South Africa, where the plant naturally grows. Harvesting typically occurs during the summer.
• Fermentation and Drying. After harvesting, the fresh Rooibos leaves undergo a natural fermentation process, which enhances their flavor and color. Subsequently, the leaves are sun-dried to stop the fermentation process.
• Extraction. The dried leaves are then ground and subjected to an extraction process to separate the bioactive compounds. Extraction can be performed using hot water or solvents such as ethanol, depending on the desired type of extract and its final use.
• Purification. The obtained liquid extract is concentrated under vacuum and purified to remove impurities and residual solvents, thus obtaining a concentrated and high-quality Rooibos extract.
• Quality Control. The Rooibos extract undergoes quality control checks to verify the concentration of antioxidants, purity, and the absence of contaminants. These tests can include spectroscopic, chromatographic, and microbiological analyses.

Commercial Applications

Beverages. Rooibos is most commonly known as the base for infusions and teas, valued for their unique taste and lack of caffeine, making them suitable for evening consumption or as alternatives to traditional tea for those avoiding caffeine.

Cosmetic Products. Due to its antioxidant, anti-inflammatory (1) and antimicrobial properties due to the presence of polyphenols (2), Aspalathus linearis finds application in various cosmetic products, including skin creams, lotions and hair care products, to help protect and regenerate the skin.

Dietary Supplements. Rooibos is used in supplements for its health-promoting effects, such as aiding digestion, improving cardiovascular health, and its antioxidant action, which helps to combat free radical damage. Beyond its internal benefits, rooibos is used in products aimed at relieving conditions such as eczema, allergies, and skin irritations, thanks to its soothing properties.

Safety

Rooibos is generally considered safe, but its efficacy is highly dependent on the processing and purity of the raw materials (3), and cases of liver toxicity have also been reported (4) so it would be a good idea not to overdo the intake.

In particular, it should be noted that Aspalathus linearis is sensitive to environmental contamination, so caution should be used in patients receiving treatment with allopathic medicines to avoid undesirable alterations in the drug's plasma concentration (5).

References_____________________________________________________________________

(1) Baba, H., Ohtsuka, Y., Haruna, H., Lee, T., Nagata, S., Maeda, M., ... & Shimizu, T. (2009). Studies of anti‐inflammatory effects of Rooibos tea in rats. Pediatrics International, 51(5), 700-704.

Abstract. Background: Rooibos tea is known to be caffeine free with abundant flavonoids. Aspalathin and nothofagin, the main flavonoids contained in Rooibos tea, have stronger anti-oxidative activity than other flavonoids. As oxidative stress can induce inflammation, the anti-inflammatory effects of Rooibos tea were investigated using a rat colitis model. Conclusion: Rooibos tea may prevent DNA damage and inflammation by its anti-oxidative activity in vivo. As Rooibos tea is free from caffeine, routine intake may be safe and useful in reducing oxidative stress in children.

(2) Krafczyk, Nicole, and Marcus A. Glomb. Characterization of phenolic compounds in rooibos tea. Journal of Agricultural and Food Chemistry 56.9 (2008): 3368-3376.

Abstract. Polyphenols present in rooibos, a popular herbal tea from Aspalathus linearis, were isolated in two steps. First, phenolic ingredients were separated by multilayer countercurrent chromatography (MLCCC). Preparative high-performance liquid chromatography (HPLC) was then applied to obtain pure flavonoids. The purity and identity of isolated compounds was confirmed by different NMR experiments, HPLC-diode array detector (DAD), or gas chromatography−mass spectrometry (GC-MS) analysis. This strategy proved to be valid to isolate material in up to gram quantities and to verify known and previously not published polyphenol structures. In addition the chemistry of dihydrochalcones and related intermediates was studied. The dihydrochalcone aspalathin was oxidized to the corresponding flavanone-C-glycosides ((R)/(S)-eriodictyol-6-C-β-d-glucopyranoside and (R)/(S)-eriodictyol-8-C-β-d-glucopyranoside). Flavanone-6-C-β-d-glucopyranosides were further degraded to flavones isoorientin and orientin.

(3) Areo, O. M., & Njobeh, P. B. (2021). Risk assessment of heavy metals in rooibos (Aspalathus linearis) tea consumed in South Africa. Environmental Science and Pollution Research, 28(42), 59687-59695.

Abstract. A total of 80 rooibos tea samples from a range of brands were purchased from various registered retail shops in South Africa. The samples were bought during 2019 winter (40) and summer (40) period which are classified as 6 natural rooibos, 18 herbal rooibos samples, and 16 flavor rooibos samples and subjected for heavy metal analysis such as chromium (Cr), iron (Fe), arsenic (As), cadmium (Cd), and lead (Pb) using inductively coupled plasma mass spectrometer (ICP-MS). Human health risks were determined by estimating the daily intake non-cancer hazard quotient (THQ) and hazard index (HI) via oral exposure to toxic elements based on daily tea consumption. The concentration range of the determined heavy metals in rooibos tea samples were as follows: Cr (0.17–11.98 mg/kg), Fe (31–450 mg/kg), As (ND–0.51 mg/kg), Cd (0.09–0.17 mg/kg), and Pb (0.06–2.73 mg/kg). Cr was found in higher amount when compared to the World Health Organization (WHO) permissive limit (1.3 mg/kg). The concentrations of all studied heavy metals during winter and summer period were compared using two-way Anova, and no significant differences (p = 0.832) were observed for the two seasons. Both the target risk quotient (THQ) and the hazard index (HI) levels in all analyzed tea were well below 1, implying that intake of rooibos tea with analyzed heavy metals should not cause a threat to human health. On the other hand, the continuous intake due to the high concentrations of trace metals such as Cr may pose a serious chronic health risk due to accumulation in body tissues over time. The study, therefore, suggests constant monitoring of these heavy metals in teas in order to limit the risk of exceeding the permissive limits.

(4) Carrier P, Debette-Gratien M, Jacques J, Grau M, Loustaud-Ratti V. Rooibos, a fake friend. Clin Res Hepatol Gastroenterol. 2021 Mar;45(2):101499. doi: 10.1016/j.clinre.2020.06.020. Epub 2020 Aug 20. PMID: 32828746.

Abstract. Rooibos is consumed worldwide and its use considered safe. It contains scavengers of free radicals and is so is deemed to be a liver protector. Nevertheless, hepatic toxicity exists even if rare. It is probably underdiagnosed and clinicians should think about it in case of acute hepatitis. We report a case of liver injury attributed to Rooibos.

(5) Pyrzanowska J. The toxic contaminants of Aspalathus linearis plant material as well as herb-drug interactions may constitute the health risk factors in daily rooibos tea consumers. Int J Environ Health Res. 2023 Feb;33(2):129-142. doi: 10.1080/09603123.2021.2009780. Epub 2021 Nov 25. PMID: 34823434.

Abstract. Rooibos tea is brewed using Aspalathus linearis plant material sensitive to environmental contamination. This review covers the safety data from preclinical experiments as well as human studies and delivers a report on its hepatic activity. In vitro tea investigation reveals antioxidative and anti-mutagenic features and ability to modulate microsomal enzymes. In rodent research, it exerts protective or neutral impact on liver functions and morphology, yet several human case reports suggest possible acute hepatic damage. Summarizing rooibos consumption seems to be safe in terms of hepatotoxicity; however, there may be designated a group of consumers with higher risk of liver irritation. The contamination of plant material may contribute to herb-induced liver injury. Due to the impact on CYPs, there is a possible risk of herb-drug interactions affecting bioavailability of some co-administered medicines. Caution should be exercised in patients receiving the treatment with allopathic medicines to avoid untoward alteration of drug plasma concentration.