Risks associated with consumption of herbal teas

Exploring the ancient roots and modern global brews of tea and herbal beverages: A comprehensive review of origins, types, health benefits, market dynamics, and future trends

Tea, a culturally significant beverage, originated around 2700 B.C. in ancient Chinese civilization, with a profound understanding of its therapeutic properties. Herbal medicines from diverse plant sources have been esteemed for their phytochemical content. Today, tea's appeal spans the globe, with various processing techniques creating distinct tea varieties. This review article comprehensively explores tea and herbal teas, encompassing their origins, types, trade history, health benefits, chemical composition, and market and future dynamics. This review examines tea's evolution from ancient China to its global significance and analyzes the impact of tea trade routes on cultural exchanges and trade dynamics. The review covers conventional teas (black, green, and oolong), blended teas, and herbal teas. It primarily focuses on herbal beverages' chemical composition and active components derived from diverse plants and botanicals, highlighting their traditional uses and health-promoting applications. The review provides valuable insights into the dynamic herbal tea market, growth, consumer preferences, industry trends, and future aspects of the herbal beverage. Additionally, it explores the proper classification and preparation of herbal drinks for maximum benefits, shedding light on tea manufacturing and preparation processes. This review is a valuable resource for tea enthusiasts, health-conscious individuals, and industry stakeholders, offering profound insights into teas and their multifaceted allure.

Functional Properties and Acceptability of Potentially Medicinal Tea Infusions Based on Equisetum arvense, Desmodium molliculum, and Mentha piperita

Natural herbal teas are one of the three most consumed beverages in the world, and despite their frequent use in the cosmetic, food, and pharmaceutical industries, there is still much to about them. This study aimed to determine the functional properties of tea infusions made from dried Equisetum arvense (EA), Desmodium molliculum (DM), and Mentha piperita (M) grown in the Peruvian Andes. Next, using a simplex design with unrestricted centroid amplified centroid, 12 combinations were obtained for the combination of dried leaves with EA: 0∼100%, DM: 0∼100%, and M: 0∼100% optimal combination of EA: 6.59%, DM: 84.62%, and M: 8.79% maximizes functional components for total polyphenols (2,831.18 mg EAG/100 g), flavonoids (37.73 mg CAT/g), and antioxidant capacity (145.99 μmol Trolox/g). It can be confirmed that dried mixtures of these plants made into tea are a significant source of bioactive molecules, have a tolerable flavor, and can be used for therapeutic purposes when consumed.

Ethnobotanical study on herbal tea drinks in Guangxi, China

BACKGROUND

Herbal tea drinks, different from classical Camellia beverages, are a wide variety of herbal drinks consumed for therapeutic purposes or health promotion. Herbal tea is widely consumed in Guangxi. However, the documentation on the plants for herbal tea and their related health benefits is still limited.

METHODS

An ethnobotanical survey was conducted in 52 villages and 21 traditional markets in Guangxi from 2016 to 2021. Semi-structured interviews, key informant interviews, and structured questionnaires were applied to obtain ethnobotanical information of herbal tea, in which 463 informants had participated. Relative frequency of citation (RFC) and cultural food significance index (CFSI) were used to evaluate the most culturally significant herbal tea plants, and informant consensus factor (ICF) was applied to assess the agreement among informants.

RESULTS

This study recorded 155 herbal tea species belonging to 49 families. The most commonly used parts included leaf (27.61%), whole plant (22.09%), branch and leaf (19.02%), and flower (13.50%). The most frequent preparation method of herbal tea was decoction. Herbal tea was very popular in Guangxi, attributing to its therapeutic value, special odor, and good taste. There are 41 health benefits classified into eight categories. Among them, clearing heat was the most medicinal effects. Local people had high consistency in tonic, removing cold and cough, improving blood circulation, and clearing heat away. Based on CFSI values of each species, the most culturally significant herbal tea species were Siraitia grosvenorii (Swingle) C. Jeffrey ex A. M. Lu & Zhi Y. Zhang, Plantago asiatica L., Gynostemma pentaphyllum (Thunb.) Makino, Zingiber officinale Roscoe, Pholidota chinensis Lindl., and Morus alba L.

CONCLUSION

Herbal tea is a valuable heritage that carries the local people's traditional knowledge, like health care and religious belief. The recorded herbal tea species in this study possess tremendous potential for local economic development in the future. Further research on efficacy evaluation and product development of herbal tea species is necessary.

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

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.

Hypericum lanceolatum Lam. Medicinal Plant: Potential Toxicity and Therapeutic Effects Based on a Zebrafish Model

Hypericum lanceolatum Lam. (H. lanceolatum) is a traditional medicinal plant from Reunion Island used for its pleiotropic effects mainly related to its antioxidant activity. The present work aimed to 1) determine the potential toxicity of the plant aqueous extract in vivo and 2) investigate its putative biological properties using several zebrafish models of oxidative stress, regeneration, estrogenicity, neurogenesis and metabolic disorders. First, we characterized the polyphenolic composition by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and identified chlorogenic acid isomers, quercetin and kaempferol derivatives as the major compounds. We then evaluated for the first time the toxicity of an aqueous extract of H. lanceolatum and determined a maximum non-toxic concentration (MNTC) in zebrafish eleutheroembryos from 0 to 96 hpf following OECD (Organization for Economic Cooperation and Development) guidelines. This MNTC test was also determined on hatched eleutheroembryos after 2 days of treatment (from 3 to 5 dpf). In our study, the anti-estrogenic effects of H. lanceolatum are supported by the data from the EASZY assay. In a tail amputation model, we showed that H. lanceolatum at its MNTC displays antioxidant properties, favors immune cell recruitment and tissue regeneration. Our results also highlighted its beneficial effects in metabolic disorders. Indeed, H. lanceolatum efficiently reduces lipid accumulation and body mass index in overfed larva- and adult-models, respectively. In addition, we show that H. lanceolatum did not improve fasting blood glucose levels in a hyperglycemic zebrafish model but surprisingly inhibited neurogenesis impairment observed in diabetic conditions. In conclusion, our study highlights the antioxidant, pro-regenerative, anti-lipid accumulation and pro-neurogenic effects of H. lanceolatum in vivo and supports the use of this traditional medicinal plant as a potential alternative in the prevention and/or treatment of metabolic disorders.

Inhibition of Angiotensin Converting Enzyme, Angiotensin II Receptor Blocking, and Blood Pressure Lowering Bioactivity across Plant Families

Hypertension is a major risk factor for coronary heart disease, kidney disease, and stroke. Interest in medicinal or nutraceutical plant bioactives to reduce hypertension has increased dramatically. The main biological regulation of mammalian blood pressure is via the renin-angiotensin-aldosterone system. The key enzyme is angiotensin converting enzyme (ACE) that converts angiotensin I into the powerful vasoconstrictor, angiotensin II. Angiotensin II binds to its receptors (AT1) on smooth muscle cells of the arteriole vasculature causing vasoconstriction and elevation of blood pressure. This review focuses on the in vitro and in vivo reports of plant-derived extracts that inhibit ACE activity, block angiotensin II receptor binding and demonstrate hypotensive activity in animal or human studies. We describe 74 families of plants that exhibited significant ACE inhibitory activity and 16 plant families with potential AT1 receptor blocking activity, according to in vitro studies. From 43 plant families including some of those with in vitro bioactivity, the extracts from 73 plant species lowered blood pressure in various normotensive or hypertensive in vivo models by the oral route. Of these, 19 species from 15 families lowered human BP when administered orally. Some of the active plant extracts, isolated bioactives and BP-lowering mechanisms are discussed.

Evaluation of antioxidant activities of extracts from 19 Chinese edible flowers

Extracts of 19 selected edible flowers were investigated for their free radical scavenging activity (FRSA), polyphenolic contents and flavonoid contents in the paper. The results showed the extracts of Paeonia suffruticosa Andr., Paeonia lactiflora Pall., and Rosa rugosa Thunb. possessed obviously stronger DPPH FRSA (94.221 ± 0.102; 93.739 ± 0.424 and 94.244 ± 0.163%, respectively), superoxide FRSA (55.818 ± 1.518; 52.142 ± 1.374 and 57.321 ± 0.608%, respectively), hydroxyl FRSA (85.872 ± 0.873; 89.307 ± 0.803 and 88.560 ± 0.277%, respectively) and polyphenolic contents (96.208 ± 0.689; 87.938 ± 1.187 and 92.164 ± 0.799 mg CE/g, respectively) that were superior or comparable to black and green teas. Polyphenolic contents did correlate well with DPPH FRSA (r = 0.943, P < 0.01), superoxide FRSA (r = 0.833, P < 0.01), and hydroxyl FRSA (r = 0.500, P < 0.05). It indicated that this potent FRSA may be attributed to its phenolic compounds. These findings showed that the tested flowers could be considered as new sources of safe natural antioxidants and preservatives of food industry.

Ethnobotanical survey of cooling herbal drinks from southern China

BACKGROUND

Liáng chá ("cooling tea", "herbal tea" or "cool tisane" in Chinese) are herbal drinks widely produced in southern China and consumed by billions of people worldwide to prevent and treat internal heat as well as a range of associated health conditions. Globalization and renewed interest in botanical remedies has attracted growing attention in cooling herbal drinks by industry, scientists and consumers. However, there is a knowledge gap on the plant species used and commercialized for cooling herbal drinks in southern China and their associated ethnobotanical use, habitat and conservation status. This is the first study to document plant species used and commercialized as liáng chá in southern China's Lingnan region and associated ethnomedical function, preparation methods, habitat and conservation status.

METHODS

Three hundred market surveys were conducted between 2010-2012 in the largest herbal drink producing region of China to record plants used for liáng chá and to document knowledge on their medicinal function, habitat and conservation status. Product samples and voucher specimens were collected for taxonomic identification.

RESULTS

All informants harvest and cultivate plants for preparing herbal drinks for their medicinal, cultural and economic values. A total of 222 ethnotaxa corresponded to 238 botanical taxa (species, varieties or subspecies) belonging to 86 families and 209 genera were recorded as liáng chá to treat health conditions in the study area. Recorded remedies consisted of one or several plant species to treat conditions classified into 27 major health conditions with clearing internal heat being the most common medicinal function. The habitat types of plants documented for use as liáng chá include 112 wild harvested species, 51 species that are either wild harvested or cultivated, 57 cultivated species, and 2 naturalized species. According to China's Red List and CITES on conservation status, one of these species is endangered, one species is critically endangered, eight species are vulnerable, one is listed in CITES II, three are listed in Regional Red Data Book and the remaining 224 species are in the least concerned conservation category.

CONCLUSIONS

The liáng chá industry of southern China reflects the plant species richness and cultural diversity of the region. Future research on safety and efficacy of herbal drinks as well as ecological and cultural conservation efforts are needed for the sustainable growth of China's botanical industry.

Evaluation of metal concentrations in mentha herbal teas (Mentha piperita, Mentha pulegium and Mentha species) by inductively coupled plasma spectrometry

Phytopharmaceuticals are gaining popularity worldwide; however, cases of adverse effects and drug interactions have also increased. One reason is in the high metal content both as ingredients but also as contaminants. Metal monitoring in food, like herbal teas, provides basic information on safety aspects in regulatory processes as well as nutritional values. In the present work, Cd, Pb, K, Na, Ca, Mg, Al, B, Ba, Co, Cr, Cu, Fe, Mn, Zn, Li, Ni, and Mo were determined by inductively coupled plasma spectrometry (ICPS) in 36 samples of Mentha sp. Mint tea bags and loose leaves were randomly obtained from supermarkets, traditional markets, herbal stores, and pharmacies in Tenerife (Canary Islands, Spain). Metal contents varied significantly, dependent on the stores the products were purchased in and on tea packaging (loose leaves versus tea bags). Pb analyses revealed levels (0.65±0.71mg/kg) below legal limits. The maximum permissible limit for Cd, 0.3mg/kg, set by the WHO for medicinal plants, was exceeded by 19.44% of the samples (0.22±0.13mg/kg), but all values were below the limit given in the European Pharmacopoeia for this metal (4mg/kg). We observed high Al (151.24±162.73mg/kg) and Li (5.46±3.94mg/kg) levels. B, Ba, Co, Cr, Cu, Fe, Mn, Ni, Zn, and Mo mean levels were 20.51, 14.15, 0.26, 1.65, 10.65, 406.00, 55.05, 1.72, 33.67, and 0.73mg/kg, respectively. Mean Ca, Mg, K, and Na were detected in concentrations of 10.32, 3.83, 7.23 and 1.17g/kg, respectively. In conclusion, metal exposure through herbal mint teas does not seem to be of health concern, as to most of the studied metals, but regulatory limits for Al contents should be imposed.

A new approach for simultaneous screening and quantification of toxic pyrrolizidine alkaloids in some potential pyrrolizidine alkaloid-containing plants by using ultra performance liquid chromatography-tandem quadrupole mass spectrometry

A rapid, but sensitive and selective method for simultaneous screening and quantification of toxic pyrrolizidine alkaloids (PAs) by ultra performance liquid-chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS) on a tandem quadrupole mass spectrometer (TQ-MS) is described. This was accomplished by incorporating the precursor ion scan (PIS) acquisition and multiple reaction monitoring (MRM) acquisition in the same UPLC-MS/MS run. Notably, the developed PIS approach for detecting two pairs of characteristic product ions at m/z 120/138 or 168/150, allowed specific identification of toxic retronecine and otonecine types PAs. This PIS method is highly sensitive with over 10-fold sensitivity improvement upon previously published LC-MS method. Moreover, this new approach is suitable for high sample throughput and was applied to the screening and quantifying toxic PAs in 22 samples collected from seven Parasenecio species and four Senecio species. In addition, coupling the MRM with PIS approach generated quantitative results equivalent to those obtained by conventional MRM-only approach. This coupled MRM with PIS approach could provide both qualitative and quantitative results without the need of repetitive analyses.

Herbal products: behaviors and beliefs among Italian women

PURPOSE

The use of phytotherapy is growing worldwide, but the popular perception is that this kind of approach is natural and therefore safer than traditional medicine; for this reason the use is frequently not communicated to the doctor. Instead, even if many herbal remedies are benign in nature, some of these therapies have potentially harmful side effects or adverse interactions with other medications. So, the purpose of our study was to analyze the behavior patterns and decision-making modalities about herbal remedy use among a sample of Italian women.

METHODS

During a 5-month period, interviews to women attending the outpatient ambulatory of an urban university general hospital were made on the basis of a pre-structured 25-item questionnaire.

RESULTS

Among a random study population of 1,044 subsequent patients, 491 women (47.03%) reported to have been taking one or more herbal products in the last year, sometimes used during pregnancy or given to their children (35.23%). The 10 most frequently used herbal products reported were propolis, aloe, valerian root, blueberry, fennel, dandelion, mallow, arnica, thyme, and Echinacea. The major purposes for using these products were to stimulate the immune system and to cure respiratory problems. 47/491 (9.57%) women reported side effects, but only 36% referred to the doctor. In most of the cases, herbal products were taken in combination with drugs (44.61%) or homeopathic treatments (11.81%). The majority of our women did not obtain information about this kind of therapy from a health care provider (72.71%).

CONCLUSIONS

The present survey highlights the general use of phytomedicines by a sample of Italian women, the potential risk of their confidence with the 'natural world,' and the lack of discussion on this argument with doctors and pharmacists. This suggests the importance of training for health care providers and the need of informational programs for consumers.

Screening for pyrrolizidine alkaloids in plant materials by electron ionization RP-HPLC-MS with thermabeam interface

Plant samples from leaves of Cerinthe minor, Cynoglossum clandestinum, Echium tuberculatum (as well roots), Eritrichium rupestre, Lithospermum purpureo-coerulem, Nonnea lutea, Nonnea setosa, Onosma stellulatum and Cynoglossum amabile were screened for toxic pyrrolizidine alkaloids (PAs) with a newly elaborated procedure comprising gradient HPLC with diode array (DAD) and thermabeam electron impact mass spectrometry (EI-MS). Dried plant material was extracted with boiling 1% tartaric acid in methanol for 2 h on an electric basket and crude extracts purified with cation-exchange solid phase extraction (CE-SPE). Purified extracts containing alkaloids were separated on Zorbax SB RP18 stationary phase in gradient of 0.1% formic acid in methanol. The flow rate was 0.25 mL/min and was suitable both for DAD and EI MS detections. Applied gradient procedure permitted quite sufficient separation of PAs in various plant extracts. On the basis of EI MS spectra, toxic PAs with unsaturated 1,2-double bond in the necine moiety were found in all plant materials and in nine of them (excluding only Cynoglossum amabile) for the fi rst time. They included the following types of structures: 9- and 7-viridifloryl-retronecine monoesters, 9-angeloyl-7-viridifloryl-retronecine, 9-angeloyl-retronecine diester, 9-viridifloryl-retronecine saturated ester, 7-angeloyl-9-viridifloryl-retronecine, 7-angeloyl-9-echimidinyl-retronecine, trachelanthamine and others. Selected ion monitoring (SIM) chromatograms at m/z 119, 120 and 136 together with analysis of UV spectra from DAD detector can be applied in rapid screening for toxic PAs in new plant extracts but to obtain detailed structural information (molecular weight and stereochemistry) more expensive hyphenation is required. Consumption of all analysed plants should be avoided as carcinogenic and hepatotoxic properties of the alkaloids detected are expected.

Inhibition of liver carcinogenesis in Wistar rats by consumption of an aqueous extract from leaves of Ardisia compressa

This study evaluates the chemopreventive effect of an aqueous extract of dried leaves of Ardisia compressa against liver cancer. A rat liver assay that mimics progressive forms of human disease was used as a carcinogenesis model. Forty-five male Wistar rats (180-200 g body weight) were injected intraperitoneally on day 1 with a single dose (100 mg/kg) of diethylnitrosamine (DEN), and also received via gavage 20 mg/kg acetylaminofluorene (2-AAF), on days 7, 8 and 9. The rats were randomly divided into four groups (n=15). Control groups (Group 1 and Group 2) had free access to water. Group 3 received 0.5% (w/v) of A. compressa tea for 10 days before treatment and during the study as the sole source of fluid until the rats were killed. A fourth group of 15 rats received no carcinogen or promoter but did receive 0.5%, (w/v) of A. compressa tea. All animals had 70% partial hepatectomy at day 10. The incidences of hepatocellular foci, nodules and carcinoma were significantly smaller in Group 3 than in Group 2 (P<0.01). A. compressa tea consumption alone (Group 4) did not induce the development of foci, nodules or carcinomas (P<0.01). The striking observation of this study was that consumption of A. compressa tea resulted in complete inhibition of the chemically-induced hepatocarcinogenesis in Wistar rats.

Pyrrolizidine Alkaloids—Genotoxicity, Metabolism Enzymes, Metabolic Activation, and Mechanisms

Pyrrolizidine alkaloid-containing plants are widely distributed in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Because of their abundance and potent toxicities, the mechanisms by which pyrrolizidine alkaloids induce genotoxicities, particularly carcinogenicity, were extensively studied for several decades but not exclusively elucidated until recently. To date, the pyrrolizidine alkaloid-induced genotoxicities were revealed to be elicited by the hepatic metabolism of these naturally occurring toxins. In this review, we present updated information on the metabolism, metabolizing enzymes, and the mechanisms by which pyrrolizidine alkaloids exert genotoxicity and tumorigenicity.

Leaf extract from Ardisia compressa protects against 1-nitropyrene-induced cytotoxicity and its antioxidant defense disruption in cultured rat hepatocytes

Herbal tea preparations of Ardisia compressa (AC) have been used in folk medicine against liver disorders. The objective of this study was to evaluate the in vitro protective effect of an aqueous extract of dry leaves of AC on 1-nitropyrene (1-NP) induced cytotoxicity on rat hepatocytes. Lipid peroxidation (malondialdehyde), antioxidant enzyme activities (glutathione reductase, glutathione peroxidase, superoxide dismutase) and glutathione levels were studied. After 2 h of incubation, 0.25 microg/ml of 1-NP had an approximately 50% cytotoxic effect on hepatocytes. This environmental toxicant also increased malondialdehyde (77%), and glutathione peroxidase (46%), producing a significant consumption of endogenous antioxidant glutathione. (-)Epigallocatechin 3-gallato (EGCG) and AC decreased the viability of hepatocytes after 2 h of incubation at concentrations above 3 microg/ml and 2.52 microg, equivalents of (+)catechin/ml, respectively. A 100% hepatocyte protection was observed when cells were first exposed to AC (2.52 microg, equivalents of (+)catechin/ml), and then followed by 1-NP (0.25 microg/ml). Cells incubated with AC, either simultaneously or before treatment with 1-NP, were protected 75 and 84%, respectively. Cell protection of AC was superior to EGCG. Addition of AC to 1-NP (1:10) modulated superoxide dismutase and glutathione reductase activities (P<0.005), as well as the cellular level of GSH. The results indicate that AC has an antioxidant protective effect on rat hepatocytes when exposed to 1-NP.

Simultaneous determination of N-oxides and free bases of pyrrolizidine alkaloids by cation-exchange solid-phase extraction and ion-pair high-performance liquid chromatography

Cation-exchange solid-phase extraction using LiChrolut SCX (Merck, Darmstadt) cartridges filled with polymeric strong cation-exchanger enabled efficient isolation of both N-oxides and free bases of pyrrolizidine alkaloids (PAs). The recoveries were about 80% for retrorsine-N-oxide, 90% for retrorsine and 100% for senkirkine and were assessed both by TLC-densitometry and ion-pair high-performance liquid chromatography (HPIPC) on Hypersil BDS C8 stationary phase and hexane-l-sulfonic acid as ion-pairing agent. The applied HPIPC gradient procedure was suitable for separation of PAs with various types of structures (N-oxides, free bases, otonecine-PAs). The method limits of detection and quantitation, respectively, ranged from 0.06 ng/microl (senecionine) and 0.2 ng/microl (senkirkine) to 0.1 and 0.35 ng/microl for retrorsine-N-oxide. For each component calibrated by linear regression method, correlation coefficients were higher than 0.9995 (six-point calibration from 4 to 100 microg/ml). The elaborated procedure was used in searching for PAs in plant derived samples from Symphytum sp. (comfrey), Petasites hybridus and Petasites albus (butterbur), Tussilago farfara (coltsfoot), Emilia coccinea (tassel flower) and Doronicum columnae (leopard's bane). For the last three samples macrocyclic PAs (senecionine, senecionine-N-oxide. senkirkine) have been detected for the first time. Details of precision of the analyses are also included.

An investigation on the antimutagenic properties of South African herbal teas

The antimutagenic properties of South African herbal teas were investigated using the Salmonella typhimurium mutagenicity assay. Aqueous extracts of fermented and unfermented rooibos tea (Aspalathus linearis) and honeybush tea (Cyclopia intermedia) both possess antimutagenic activity against 2-acetylaminofluorene (2-AAF) and aflatoxin B(1) (AFB(1))-induced mutagenesis using tester strains TA98 and TA100 in the presence of metabolic activation. A far less inhibitory effect was noticed against the direct acting mutagens, methyl methanesulfonate (MMS), cumolhydroperoxide (CHP), and hydrogen peroxide (H(2)O(2)) using TA102, a strain designed to detect oxidative mutagens and carcinogens. Depending on the mutagen used, the unfermented tea exhibited the highest protective effect. A similar response regarding the protection against mutagenesis was obtained when utilising different variations of the double layer Salmonella assay. The double layer technique proved to be more effective to detect the protective effect of the different tea preparations against the direct acting mutagens. With respect to indirect mutagens, the highest protection was noticed when the carcinogen was metabolically activated in the presence of the tea extract as compared with when the tea extract was incubated in a separate layer with the bacteria. The current data suggest that two mechanisms seem to be involved in the antimutagenicity of the tea extracts towards carcinogens that require metabolic activation: (i) the tea components may interfere with cytochrome P450-mediated metabolism of these mutagens and (ii) the direct interaction between the tea constituents, presumably the polyphenolic compounds, with the promutagens and/or the active mutagenic metabolites. However, the mild and/or lack of protection and in some cases even enhancement of mutagenesis induced by direct acting or oxidative mutagens, provide new perspectives regarding the role of the polyphenolic compounds known to exhibit antioxidant properties, in the protection against mutagenesis in the Salmonella assay. The present study provides the first evidence on the antimutagenic activity of honeybush tea and further evidence on the antimutagenicity of rooibos tea.