Rooibos Tea and Health: A Systematic Review of the Evidence from the Last Two Decades

Abstract

An expanse of research has investigated the effects of black and green teas in relation to aspects of health. Rooibos tea, also known as Red bush is derived from the South African Cape fynbos plant, Aspalathus linearis, and is caffeine free, naturally sweet and abundant in polyphenols. Evidence related to the health aspects of drinking Rooibos tea is advancing, but does not appear to have been collated. Therefore, we aimed to examine the health effects of Rooibos tea through a systematic review of the literature. A PUBMED search was undertaken (2000 up to June 2020) for human and laboratory studies investigating the efficacy of Rooibos in relation to health. Seven human studies and 49 laboratory studies were identified. Overall Rooibos tea consumption seems to benefit the lipid and redox profiles of those at risk of cardiovascular disease. It also appears to possess other promising ‘general’ effects on glycaemic control, bone, liver, cognitive and respiratory health. Ongoing research using standardised interventions is now needed to help formulate congruent conclusions that are relevant to public health.

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Nutrion and Food Technology: Open Access
ISSN 2470-6086 | Open Access
Nutr Food Technol Open Access | NFTOA
1
REVIEW ARTICLE
Rooibos Tea and Health: A Systemac Review of the Evidence from the Last
Two Decades
Timothy Bond J1, and Emma Derbyshire J2*
1Tea Advisory Panel; Tea and Herbal Soluons, Bedford, United Kingdom
2Nutrional Insight, Epsom, Surrey, United Kingdom
Received: 08 May, 2020 | Accepted: 29 May, 2020 | Published: 05 Jun, 2020
Volume 6 - Issue 1
e health properties of rooibos tea have been ascribed to it being
caeine free and its abundant phenolic composition [9,10]. Rooibos
tea has a divergent polyphenol prole and is a rare dietary source of
dihydrochalcones-aspalathin and nothofagin which possess potent
antioxidant actions [11-13]. Aspalathin and nothofagin are the
main avonoids in Rooibos tea and have a particularly strong anti-
oxidative activity, though aspalathin tends to be lower in fermented
than unfermented foods [10,12,14]. is is relevant to health as the
antioxidants present in rooibos may help to protect against oxidative
stress which is known to induce inammation and other health
conditions [10,15].
Rooibos tea is naturally slightly sweet with caramel, oral, honey
and woody undertones [16]. It has been used both as a tisane, as
well as consumed traditionally for medicinal purposes and has been
popular in South Africa for generations [5,11]. Traditionally, rooibos
has been used for its medicinal properties in South Africa to help
alleviate allergies, asthma, dermatological conditions and infantile
colic [17]. Both the leaves and ne stems can be used as herbal tea,
predominantly in the traditional ‘fermented’ (oxidised/aerated) red-
brown form but also in its ‘unfermented’ (unoxidized/aerated) green
form [18]. Rooibos tea can also be extracted and dried, spray-dried/
freeze-dried to form powdered rooibos tea extract (RTE) which is also
abundant in polyphenols [5]. Traditionally fermented beverages such
as Kombucha have been produced eectively using rooibos leaves [19].
*Corresponding author: Emma Derbyshire J, Nutrional Insight, Epsom, Surrey, United Kingdom, E-mail: emma@nutrional-insight.co.uk
Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades. Nutr Food
Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166
Copyright: © 2020 Bond TJ, et al. This is an open-access arcle distributed under the terms of the Creave Commons Aribuon License,
which permits unrestricted use, distribuon, and reproducon in any medium, provided the original author and source are credited.
Abstract
An expanse of research has invesgated the eects of black and green teas in relaon to aspects of health. Rooibos tea, also known as Red bush is
derived from the South African Cape fynbos plant, Aspalathus linearis, and is caeine free, naturally sweet and abundant in polyphenols. Evidence
related to the health aspects of drinking Rooibos tea is advancing, but does not appear to have been collated. Therefore, we aimed to examine the
health eects of Rooibos tea through a systemac review of the literature. A PUBMED search was undertaken (2000 up to June 2020) for human and
laboratory studies invesgang the ecacy of Rooibos in relaon to health. Seven human studies and 49 laboratory studies were idened. Overall
Rooibos tea consumpon seems to benet the lipid and redox proles of those at risk of cardiovascular disease. It also appears to possess other
promising ‘general’ eects on glycaemic control, bone, liver, cognive and respiratory health. Ongoing research using standardised intervenons is
now needed to help formulate congruent conclusions that are relevant to public health.
Keywords: Rooibos tea; Poly phenols; Health; Evidence-base
Introduction
e pattern of health and disease is changing-continued shis in
longevity mean that multimorbidity and ‘disease clusters’ are now
on the rise [1]. It is well appreciated that lifestyle e.g. alterations in
diet, physical activity and avoiding smoking can improve outcomes
for medical conditions such as cardiovascular disease [2]. ere is
already an extensive body of evidence showing that drinking two
to three cups of tea daily could be benecial for health, including
reduced risk of cardiac death, coronary artery disease, stroke, type 2
diabetes mellitus and total mortality [3]. Benecial inter-relationships
have also been observed for several cancers, cognitive, skeletal and
maternal health [3]. Most of this research has focused on green, black
and oolong tea [4].
“Rooibos” is Afrikaans for “red bush” [5]. It is prepared from
unfermented and fermented plant material from the Cape fynbos
plant, Aspalathus linearis [6,7]. In South Africa, the proportion of
black tea drinkers has declined between 2011 and 2015, from 58.6%
to 51.5% whilst the percentage of Rooibos consumers has risen from
29.4% in 2011 to 30.9% in 2015.8 e demand for Rooibos tea is also
extending further aeld with South Africa exporting Rooibos tea to
more than 30 countries [8].
Such shis in consumption habits are being attributed to rising
awareness and interest in the health properties of Rooibos tea [8].

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 2
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provided six cups of fermented, traditional Rooibos daily (one tea bag
in 200ml with an infusion time of 5 minutes) for 6 weeks [21].
ree studies reported positive ndings in relation to aspects of
health [21,22,25]. One study used ex vivo samples from atopic adults
showing that extracts prepared from both fermented and unfermented
Rooibos inhibited basophil activation, an eect that was stronger using
the extract of fermented Rooibos [22]. ese ndings are aligned with
that from earlier laboratory models [26] and indicate that Rooibos
appears to possess anti-allergic eects by inhibiting antigen- and
calcium ionophore-stimulated degranulation. One of the largest trials
conducted on 40 participants observed signicant increases in plasma
total polyphenol levels, reductions in markers of lipid peroxidation,
improvements in lipid proles (low-density lipoprotein declined and
high-density lipoprotein increased) and redox status [21]. Eects were
observed aer drinking six cups of fermented (traditional) Rooibos
tea daily for 6 weeks [21]. Another trial looking into underpinning
mechanisms showed that freshly prepared Rooibos tea (made with 10g
tea in 400ml boiled water for 10min using a tea filter) signicantly
inhibited angiotensin-converting enzyme (ACE) activity, 30 and 60
minutes aer ingestion, indicating possible cardiovascular eects via
the inhibition of ACE activity [25].
Two human studies focused on aspects of metabolite absorption
and bioavailability [14,20]. In a human crossover study where 500 ml
unfermented Rooibos tea was ingested aspalathin (a dihydrochalcone
C-glucoside) was found to be particularly bioavailable [20]. An earlier
bioavailability trial comprised of 10 adults drinking a similar quantity
of Rooibos tea also showed that most metabolites were absorbed either
via the small or large intestine [14]. In two trials involving Rooibos
tea ingestion, one did not show any signicant eects on renal stone
formation [23] and the other showed that rooibos tea and plain water
similarly rehydrated 23 athletes [24].
Laboratory Studies
A wealth of research has studied the health eects and potential
mechanisms of Rooibos tea and its associated avonoids. Forty-nine
laboratory/mechanistic studies were identied and published over
the last two decades. Of these, eleven focused on aspects of oxidative
stress and antioxidant activity [10,12,27-35]. Four studies observed
improvements in dimensions of sperm function [36-39]. is included
enhanced sperm velocity, vitality, acrosome structure and membrane
integrity [36 38]. ese eects were attributed to high levels of
antioxidants found in Rooibos, sequestering reactive oxygen species
and lipid peroxidation [38,39].
Other research has focused on aspects of metabolic health. Some
work has found associations between unfermented/green Rooibos
extract and improvements in fasting blood glucose levels using type
2 diabetic mice [40]. Similarly, In vitro work showed that Rooibos
extract high in aspalathin had a sustained glucose lowering eect [41].
Other work indicated that aspalathin or nothofagin avonoids inhibit
glucose-mediated vascular hyperpermeability and inammation [42].
A further seven studies showed that Rooibos could improve insulin
resistance and have antidiabetic potential [43-49].
With regard to potential mechanisms aspalathin found in Rooibos
stimulated glucose uptake in muscle tissues and insulin secretion from
pancreatic beta-cells in a type 2 diabetes mouse model [48]. Work
by Ulicna O, et al. (2006) found that the antioxidant compounds in
Rooibos tea prevented oxidative stress concluding that it could be a
suitable adjunctive therapy for diabetic vascular conditions [49]. One
study using a cell model found that a fermented Rooibos infusion
prepared at ‘cup-of-tea’ strength and the soluble matter of the infusion
Increasingly, rooibos has been studied in human populations,
mainly for its antioxidant and cardio protective properties [14,20,21].
Alongside this, over the years a growing body of laboratory and
mechanistic studies have investigated how rooibos tea could impact
on health. Given the gaining popularity of rooibos tea, the current
publication collates evidence from human and laboratory studies,
published over the last two decades. Such a review does not appear
to have been undertaken previously. e present review focuses
on rooibos tea which has been gaining popularity both in its native
province the Western Cape of South Africa and worldwide in recent
years [8].
Methods
e National Centre for Biotechnology Information (NCBI) search
engine (PubMed) was used to extract relevant publications. Two
search phases were undertaken. In Phase 1 English-language human
studies published between January 2000 (month start) and June 2020
(month start) were screened. Publications were included if they used
Rooibos tea or RTE and studied a named health outcome. Studies were
excluded if they were conducted with children due to potential ethical
issues, focused on chemical proling, used a multi-intervention or did
not specify a distinctive health outcome. External health conditions
such as skin healing were also excluded.
e search terms “Rooibos”, “Red bush” or “Aspalathus linearis”
were used. ED and TB identied the scientic publications. In Phase
1 the database search was restricted to human studies. In Phase 2 the
search was restricted to laboratory studies the same search terms were
applied. Data extracted from each human study included: (1) Study
(author, year, location and reference number), (2) Subjects (age,
gender, number), (3) Study design (type), (4) Tea intervention (type)
(5) Intervention type (dosage) and (6) Main ndings. Data extracted
from each laboratory/mechanistic study included: (1) Study (author,
year and reference number), (2) Study Design, (3) Intervention (type),
(4) Main outcome and (5) Main ndings.
Results
In Phase 1 using the applied search terms 47 human studies were
identied. Of these, three were review papers, three had methods that
were unclear or not fully reported, ve were laboratory studies and 29
irrelevant as they did not investigate health outcomes. Subsequently,
aer these exclusions seven human studies were included in the nal
review. Of the human studies three were conducted in South Africa
[21-23], one in the USA [24], one in Italy [14], one in Sweden [25] and
one in Germany [20].
In Phase 2 91 laboratory studies were rst identied. Two of these
were excluded due to them being multi-interventions, two focused
on external (skin) conditions, four were review papers, seven had
methods that were unclear or not fully reported and 27 were irrelevant
as they did not measure health outcomes. is resulted in 49 laboratory
studies being included in the main paper. e algorithm of qualifying
papers is shown in gure 1.
Human Studies
Seven human studies were identied using Rooibos tea preparations
(Table 1) [14,20-25]. Sample sizes ranged from eight to 40 subjects.
Interventions also varied between studies. Most studies used Rooibos
infusions that had been seeped for approximately 10 minutes in hot
water infusions [20,23,25]. One study provided Rooibos tea (two 125
ml cups each made with two tea bags, low mineral content water and
a brewing time of 5 min at 90oC) for 30 days [23]. Other research

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Open HUB for Sc ie n t i f i c R e s e a r c h
Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 3
Nutrion and Food Technology: Open Access
Open Access Journal
PubMed and Reference Search. “Rooibos” or “Red
bush” or “Aspalathus linearis” (2000-2020)
47 Human Studies
91 Laboratory Studies
40 papers excluded due to:
A review-3
Laboratory study-5
Methods not fully reported or unclear-3
Other (irrelevant)-29
42 papers excluded due to:
A review-4
External health conditions-2
Methods not fully reported or unclear-7
Multi-intervention-2
Other (irrelevant)-27
7 studies included
(Table 1)
49 studies included
(Table 2)
Figure 1: Algorithm for database search results.
inhibited adipogenesis, also implying a potential role in obesity
prevention [50]. ese ndings imply a potential role in glycaemic
regulation.
Other research suggests benecial eects on aspects of bone health
[51,52], hepatoprotection [31,43,44,53], allergic response [26] and
immune function [54,55]. Rooibos tea has been found to improve
osteoblast activity [52] while fermented Rooibos was found to inhibit
osteoclasts and associated gene expression [51]. Some work has
discovered that Rooibos tea could help to stabilise the liver from injury
[12]. In another study Rooibos extract eased induced liver injury by
suppressing oxidative stress and the formation of pro-inammatory
cytokines [31]. A laboratory model showed that Rooibos tea acted as a
‘hepatoprotector’ showing histological regression of liver cirrhosis and
steatosis in an experimental model of liver cirrhosis [53].
Alongside these ndings, other evidence from laboratory
models suggests inter-relationships between Rooibos ingestion
and improvements in spatial memory, [56] reduced brain oedema
and neuronal apoptosis, [57] reductions in esophageal papilloma
size, [58] antispasmodic eects, [59,60] bronchodilation, [60] and
chemoprotection [61,62].
Discussion
Overall there appears to be a growing body of evidence relating to
Rooibos tea and various biological health outcomes. e largest body
of evidence is currently derived from laboratory and mechanistic
studies although human research is emerging. Research focusing on
cardiovascular health looks particularly promising. e trial conducted
by Marnewick JL, et al. (2011) [21] was well conducted showing that
drinking six cups of fermented, traditional rooibos daily signicantly
improved the lipid prole and redox status which is relevant to adults
at risk for developing cardiovascular disease. Elsewhere other review
ndings also conclude that Rooibos appears to have preventative and
complementary therapeutic benets in the context of cardiovascular
disease [63].
e antioxidant properties of Rooibos tea and its ability to sequester
oxidative stress are also prominent in the research [27,34,49,64]. e
polyphenols aspalathin (present at >5 mg/l) and nothofagin (present
at <1 mg/L) found in Rooibos tea have been attributed to some of its
health benets [65,66]. Antioxidants such as these suppress oxidative
stress in the body which has been implicated in the pathophysiology of
certain diseases including Alzheimer’s disease [67]. Several laboratory
studies concentrated on aspects of sperm function [36-39]. Fermented
Rooibos, in particular, was found to improve several dimensions
including sperm concentration, viability and motility [38]. ese
ndings imply that Rooibos consumption could have a role to play
in supporting male fertility, namely by sequestering oxidative damage
by improving antioxidant defence mechanisms and subsequently
improving the sperm quality and function [39]. Human randomised
controlled trials are now needed to explore this.
Fermented Rooibos extracts have been found to inhibit human
basophil activation [22] a nding that supports earlier laboratory
research showing that Rooibos has allergen-dependent inhibitory

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 4
Nutrion and Food Technology: Open Access
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Study (Author- Year-
Locaon- Reference
Number)
Subjects (age-
gender- number) Study design Tea Intervenon
(type) Tea Intervenon (dosage)
Main ndings (with any
reported signicant
p-values)
Pedre s- et al. (2020)
[22] South Africa n=9 atopic adults
Used ex vivo
samples from
atopic paents
Fermented and
unfermented
Rooibos extracts
Three opmised decreasing
concentraons of unfermented
(0.1- 0.03 or 0.01mg/ml) or
fermented Rooibos extracts
(0.05- 0.017 or 0.005mg/
ml) were used during the
experiments
Rooibos extracts inhibited
basophil acvaon in a
dose-dependent non-
allergen specic manner.
The inhibitory eect was
stronger using fermented
versus unfermented extract.
Rodgers A- et al. (2016)
[23] South Africa
n=8 calcium
oxalate (CaOx)
renal stone
formers
30-day trial
Green tea from
Japan or Rooibos
from South Africa
Samples were prepared for
analysis by adding 250 ml of
boiling water to each teabag.
These were removed aer
brewing mes of 5 and 10 min.
Ingeson of Rooibos tea
does not reduce the risk
factors for CaOx stone
formaon in humans-
Breiter T- et al. (2011)
[20] Germany
n=12 healthy
males.
24-hr crossover
trial.
Dierent Rooibos
drinksfrom
unfermented
Rooibos or a
placebo
10g Rooibos extracted with
500ml boiling water seeped from
10 minutes
On average a total of
0.76nmol of avonoids were
detected during their peak
concentraon aer intake of
the Rooibos tea- accounng
for 0.26% compared to the
total amount of avonoids
ingested.
Marnewick JL- et al.
(2011) [21] South
Africa
n=40 volunteers 6-week trial Fermented/
tradional Rooibos
Six 200 ml cups daily (one tea
bag per cup; 5 minute infusion
me).
Consumpon of fermented-
tradional Rooibos
signicantly improved the
lipid prole as well as redox
status- both relevant to
heart disease- in adults
at risk for developing
cardiovascular disease.
Persson IA- et al.
(2010) [25] Sweden
n=17 healthy
volunteers.
Three phase
randomized-
three-phase-
crossover study.
Green tea- black
tea or Rooibos tea
(South Africa)
10g tea in 400ml 10 min infusion
freshly prepared and cooled so
the parcipants could drink it
within approximately 2min.
Oral intake of a single dose
of Rooibos tea signicantly
inhibited ACE acvity aer
30 min (p< 0.01) and aer
60 min (p< 0.05).Rooibos
tea may have cardiovascular
eects through inhibion of
ACE acvity.
Uer AC- et al. (2010)
[24] USA n=23 athletes
Randomized-
cross-over design
with three
dierent study
arms.
Rooibos tea-
carbohydrate
beverage or boled
water (placebo)
NR (restricted access paper)
Rooibos tea was no more
eecve in promong
rehydraon than plain
water.
Stalmach A- et al.
(2009) [14] Italy n=10 volunteers Bioavailability
trial
Fermented or
unfermented
Rooibos tea
500ml
The overall metabolite
levels excreted were 82
and 352 nmol- accounng
for 0.09 and 0.22% of the
avonoids in the fermented
and unfermented drinks-
respecvely. Most of the
aspalathin metabolites
were excreted within 5 h of
tea consumpon- implying
absorpon in the small
intesne.
Table 1: Rooibos Tea & Health: Evidence from Human Trials.
Key: ACE- Angiotensin-Converng Enzyme; NR- Not Reported.

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 5
Nutrion and Food Technology: Open Access
Open Access Journal
Study (Author-
Year- Reference
Number)
Laboratory/
Mechanisc study
Rooibos tea Intervenon
(type) Main outcomes Main ndings
Lawal AO- et al.
(2019) [27]
In vitro anoxidant
capacity
Aqueous extracts of
fermented Rooibos- green
Rooibos and Honey bush.
Oxidave stress
Herbal extracts oered protecon against diesel
exhaust parcles that induced oxidave stress and
inammatory response.
Mazibuko-Mbejeet
SE- al. (2019) [43]
In vitro- using liver
cells Aspalathin treatment Hepac insulin
resistance
Aspalathin improved insulin signalling and
mitochondrial bioenergecs.
Mazibuko-Mbeje
SE- et al. (2019)
[44]
In vitro- using rats Aspalathin-enriched green
Rooibos extract
Hepac insulin
resistance
Green Rooibos extract showed potenal in
ameliorang hepac insulin resistance by improving
insulin sensivity via PI3K/AKT- FOXO1 and AMPK-
mediated pathways.
Morishita Y- et al.
(2019) [26]
Rat basophilic
leukaemia cells
Quercen- luteolin and
chrysoeriol were mixed
in the rao that occurs in
Rooibos tea extract
Allergic response
The mixture inhibited angen- and calcium
ionophore-smulated degranulaon to the same
degree as whole Rooibos tea extract. Flavonoids
underly the degranulaon inhibitory acvity of
rooibos tea.
Orlando P- et al.
(2019) [28]
Diabec and non-
diabec vervet
monkeys
90 mg/kg of aspalathin-rich
green Rooibos extract for 28
days.
Oxidave stress- LDL
cholesterol
Green Rooibos extract could counteract hyperglycemia-
oxidave stress and dyslipidemia- lowering
cardiovascular risk factors linked to diabetes.
Pyrzanowska J- et
al. (2019) [56]
Sprague-Dawley
male rats
Infusions- prepared using
1- 2 and 4 g of ‘fermented’
Rooibos leaves for 100 ml of
hot water.
Spaal memory
All treated rats showed improvement of long-
term spaal memory. Striatal dopamine and
3-methoxytyramine levels were increased in treated
rats.
Uličná O- et al.
(2019) [12]
Rats with carbon
tetrachloride-
induced liver
damage
Rooibos tea administraon Anoxidant acvity-
liver damage
Improved histological features support the view of
anoxidant and membrane-stabilizing acvity of
Rooibos tea. This may play a role in the protecon of
the liver from injury caused by known toxins.
Dludla PV- et al.
(2018) [45] Diabec mice Aspalathin intervenon Glycaemic control
Meormin and a high dose (130 mg/kg) of
aspalathin ameliorated diabec symptoms i.e.
abnormally raised fasng plasma glucose levels.
Moosa S- et al.
(2018) [51] Murine study Rooibos tea extract Bone health
Fermented Rooibos had a more potent inhibitory
eect on osteoclasts and associated gene expression
than unfermented Rooibos extract.
Yang S- et al. (2018)
[71] Murine study Aspalathin and nothofagin
from green Rooibos Sepsis Aspalathin and nothofagin appear to protect mice
against sepsis-triggered renal injury.
Akinrinmade 0- et
al. (2017) [57]
Adult male Wistar
rats
Fermented Rooibos herbal
tea
Brain oedema-
neuronal apoptosis
Long-term consumpon of fermented Rooibos tea
signicantly reduced brain oedema and neuronal
apoptosis.
Dludla PV- et al.
(2017) [46] Diabec mice Aspalathin intervenon Glycaemic control
Aspalathin maintained cellular homeostasis and
protected the myocardium against hyperglycemia-
induced oxidave stress by acvang Nrf2 and its
downstream target genes.
Johnson R- et al.
(2017) [72] In vitro Aspalathin intervenon Cardioprotecon Aspalathin co-treatment could protect the
myocardium from Dox-induced cardiotoxicity.
Johnson R- et al.
(2017) [73]
Cardiomyocyte
model Aspalathin intervenon Cardioprotecon
Aspalathin acvated Adipoq and modulated the
expression of Pparγ and Srebf1/2- decreasing
inammaon via Il6/Jak2 pathway- which increased
expression of Bcl2 prevenng myocardium apoptosis.
Table 2: Rooibos Tea and Health: Evidence from Laboratory Studies.

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
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Open Access Journal
Ros-Santaella JL- et
al. (2017) [36] Boar semen
Four concentraons both of
fermented and unfermented
Rooibos extracts
Sperm funcon
Rooibos extract enhanced sperm velocity- protected
acrosome structure- and preserved membrane
integrity during semen storage.
Johnson R- et al.
(2017) [74] In vitro Aspalathin intervenon Cardioprotecon
Aspalathin increased glucose oxidaon and
modulated fay acid ulizaon and induced a
favourable substrate shi in H9c2 cardiomyocytes
exposed to high glucose.
Nash LA- et al
(2016) [52] Saos2 cells
Rooibos- green and black tea
-normalized to 1 or 10 μg /
mL gallic acid equivalents.
Bone health Green- black and Rooibos tea improved osteoblast
acvity at a low level.
Kamakura R- et al.
(2015) [40]
Obese diabec
mice Green Rooibos extract Blood glucose-
andiabec potenal
Green Rooibos extract suppressed the increase in
fasng blood glucose levels in type 2 diabec model
mice.
Ku SK- et al. (2015)
[42]
Human umbilical
vein endothelial
cells and mice
Aspalathin and nothofagin
from green Rooibos
High glucose-induced
inammaon
Treatment of aspalathin or nothofagin inhibited
high glucose-mediated vascular hyperpermeability-
adhesion of monocytes toward human umbilical vein
endothelial cells- and expression of cell adhesion
molecules.
Lee W- et al. (2015)
[65]
Human umbilical
vein endothelial
cells and mice
Aspalathin and nothofagin
from green Rooibos
An-inammatory
funcons
Aspalathin and nothofagin possess an-inammatory
funcons are could be a useful therapy for vascular
inammatory diseases.
Mazibuko SE- et al.
(2015) [47]
In vitro- using
cultured
adipocytes
Treated with green Rooibos
extract or aspalathin
Glucose and lipid
metabolism
At a protein level green rooibos extract and
aspalathin suppressed markers of insulin resistance
i.e. insulin receptor substrate one.
van der Merwe JD-
et al. (2015) [29] Male Fischer rats Aspalathin-enriched green
Rooibos extract Anoxidant acvity
Glutathione reductase acvity signicantly (p<0.05)
increased aer 28 days- while glutathione content
was decreased aer 90 days- suggesng an altered
glutathione redox cycle.
Waisundara & Hoon
(2015) [30]
In vitro models
of diabetes and
cancer
Rooibos tea Oxidave stress-
diabetes- cancer
The Rooibos tea extract was observed to have
increased the CAT and SOD acvies in two in vitro
disease models.
Ajuwon OR- et al.
(2014) [31] Male Wistar rats Fermented Rooibos extract Hepatoprotecon-
Oxidave stress
Aqueous Rooibos extract aenuated LPS-induced
liver injury possibly by modulang oxidave stress
and suppressing pro-inammatory cytokines
formaon.
Ayeleso AO- et al.
(2014) [37] Diabec rats Aqueous Rooibos tea extract
(2%) for 7 weeks. Sperm funcon
Signicant (p<0.05) elevated levels of wobble and
sperm linearity were observed following Rooibos tea
extract treatment
Canda BD- et al.
(2014) [32]
Forty male Wistar
rats
Fermented Rooibos-
unfermented rooibos- a
rooibos-derived commercial
supplement- or water.
Oxidave stress-
Anoxidant acvity
Fermented Rooibos caused a decrease (p< 0.05) in
superoxide dismutase acvity.
Dludla PV- et al.
(2014) [33] Diabec rats Aqueous extract of
fermented Rooibos Oxidave stress
Aqueous extract of fermented Rooibos protected
cardiomyocytes- derived from diabec rats- against
experimentally induced oxidave stress and
ischemia.
Hong IS- et al.
(2014) [34] Laboratory model Rooibos tea Oxidave stress
Rooibos tea appears to (i) reverse the increase
in stress-related metabolites (ii) prevent lipid
peroxidaon- (iii) restore stress-induced protein
degradaon- (iv) regulate glutathione metabolism
and (v) modulate changes in the acvies of
anoxidant enzymes.

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 7
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Opuwari CS- et al.
(2014) [38] Male rats Fermented Rooibos Sperm funcon
Fermented Rooibos signicantly improved sperm
vitality (p<0.01)- but caused a signicant increase in
spontaneous acrosome reacon (p< 0.05)- whereas
unfermented did not.
Sanderson M- et al.
(2014) [50] In vitro Fermented Rooibos Obesity prevenon
Hot water soluble solids from fermented Rooibos
inhibited adipogenesis- suggesng its potenal in
prevenng obesity.
Schloms L- et al.
(2014) [75] Rats Rooibos Inammaon
In vivo studies demonstrate that Rooibos signicantly
decreased glucocorcoid levels in rats and steroid
metabolite raos linked to metabolic disorders.
Mazibuko SE- et al.
(2013) [76]
In vitro using
skeletal muscle
cells
Treated with aspalathin-
enriched green
(unfermented) Rooibos
extract
Insulin resistance Rooibos aenuated palmitate-induced insulin
resistance in C₂C₁₂ skeletal muscle cells.
Awoniyi DO- et al.
(2012) [39] Male Wistar rats
Fermented Rooibos- 'green'
Rooibos- Chinese green tea-
Rooibos supplement- green
tea supplement or water.
Sperm funcon
Both Rooibos extracts oered a measure of
protecon against induced oxidave damage by
increasing the anoxidant defence mechanisms
improving the sperm quality and funcon.
Muller CJ- et al.
(2012) [41] In vitro Rooibos extract high in
aspalathin content
Hypoglycaemic
potenal
In vivo the extract sustained a glucose lowering
eect comparable to meormin over a 6h period
aer administraon (25mg/kg body weight (BW)) to
STZ-induced diabec rats.
Pantsi WG- et al.
(2011) [77] Male Wistar rats Aqueous Rooibos and green
tea Cardioprotecon
Results demonstrate the cardio-protecve properes
of aqueous Rooibos extracts via the inhibion
of apoptosis which can possibly be related to its
avonol content.
Sissing O- et al.
(2011) [58] Male rats Rooibos- Honeybush and
Camellia sinensis teas
Esophageal
papillomas
The mean total papilloma size was reduced by
unfermented Rooibos (87%).
Hendricks R- et al.
(2010) [54]
Whole blood
culture assays
Rooibos tea and Camellia
sinensis Immune funcon
Rooibos and black tea modulate immune funcon in
vitro. Rooibos tea smulated whole blood cultures
induced higher Interleukin-6- lower Interleukin-10-
and had no eect on Interferon gamma secreon
Baba H- et al.
(2009) [10]
Seven-week-old
Wister rats Rooibos tea and water. Oxidave stress-
Anoxidant acvity
Serum SOD levels were signicantly higher in the
Rooibos group compared to the controls (p< 0.05).
Kawano A- et al.
(2009) [48]
Type 2 diabetes
model mice in vivo
Aspalathin- a green Rooibos
tea component
Andiabec
potenal
Aspalathin appears to have benecial eects
on glucose homeostasis in type 2 diabetes by
smulang glucose uptake in muscle ssues and
insulin secreon from pancreac beta-cells.
Marnewick JL- et al.
(2009) [61] Rat liver Unfermented and fermented
Rooibos Chemo protecon
Unfermented rooibos signicantly (p<0.05) to
marginally (p<0.1) reduced the total number of foci
(>10microm). Fermentaon seems to reduce the
protecve eect of the herbal teas.
Gilani AH- et al.
(2006) [59]
Isolated ssue
preparaons
Aqueous extract of Rooibos
tea
Anspasmodic
eects
Rooibos tea possessed a combinaon of dominant K
(ATP) channel acvaon and weak Ca(++) antagonist
mechanisms jusfying its use in hyperacve
gastrointesnal disorders.
Khan AU- et al.
(2006) [60]
Isolated ssue
preparaons
Aqueous extract of Rooibos
tea
Bronchodilator-
anspasmodic
The bronchodilator- anspasmodic and blood
pressure lowering eects of Rooibos tea appear to
be mediated predominantly through K (ATP) channel
acvaon with the selecve bronchodilatory eect.

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 8
Nutrion and Food Technology: Open Access
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eects [26]. is research suggests promise for conditions such
as allergic rhinitis [22] but further investigations are needed.
Additionally, its eects on bone health [51,52], cognitive health
[56,57] and potential hepatoprotective eects [12,31,53] warrant
further exploration in the form of human trials. Recently, a review of
experimental evidence [68] concluded that blood glucose levels were
signicantly lower in diabetic rodent models treated with rooibos
extracts providing phenolic compounds. Other work suggests that
Rooibos extracts and its constituent C-glucosyl avonoids, and Z-2-
(β-D-glucopyranosyloxy)-3-phenylpropenoic acid may elicit positive
eects on cellular oxidative stress, inammation and transcription
factors that control genes regulating glucose and lipid metabolism
helping to attenuate features of metabolic disease [69].
In the present review human subjects tended to drink Rooibos
beverages aer they had been infused for approximately 10 minutes
[20,23,25]. Recently, from a consumer stance the ideal ‘optimal cup’
of Rooibos tea has been dened as one that had been seeped for 10
minutes or longer [70]. Unfortunately, recent research shows that
only 15.9% of respondents consumed an ‘optimal cup’ of Rooibos in
an amount that enables its potential cardioprotective health benets
to be provided (dened as a minimum of 4 to 6 cups per day) [70].
Interestingly, compared with cold and regular-brewed Rooibos
infusions of unfermented/green and red Rooibos prepared by boiling
have the highest antioxidant capacities and total polyphenol proles
[9]. Such ndings suggest that more information needs to be imparted
to consumers’ regarding preparation methods and the potential health
benets that drinking Rooibos tea could bring.
With regard to limitations and future research directions greater
uniformity is needed in forthcoming studies. For example, some
studies used fermented and others unfermented Rooibos extracts or
infusions the fermented form appeared to have stronger impact on
some health eects [38,51]. Others used Rooibos tea and Rooibos
‘extracts’ or unfermented/green Rooibos. Production seasons and
grade quality could also alter the phenolic proles and antioxidant
capacity of Rooibos samples and should be considered [66]. Future
trials should also better encompass how ndings could be translated
into public health messages. For example, Marnewick JL, et al. (2011)
[21] asked volunteers to drinks six cups Rooibos tea daily for 6-weeks
to study its cardiovascular eects. Similar studies are now needed for
other health outcomes such as bone health, liver or brain (cognitive)
function.
Considering such evidence Rooibos tea, like teas from Camellia
sinensis (e.g. black, green and oolong tea) could be regarded as a
‘general health’ tea, potentially providing an array of benets to human
health and wellbeing [56] Rooibos tea is naturally slightly sweet [16]
thus does not require the addition of extra sugar or articial sweeteners.
It is also caeine free with a favourable phenolic composition [9,10].
(Table 2)
Ulicná O- et al.
(2006) [49]
Streptozotocin-
induced diabec
rats
Aqueous and alkaline
extracts of Rooibos tea
Andiabec
potenal
Anoxidant compounds in rooibos tea parally
prevent oxidave stress and they are eecve in
both hydrophobic and hydrophilic biological systems.
van der Merwe JD-
et al. (2006) [78]
Comparave- in
vitro
Rooibos and honey bush tea
compared with black- oolong
and green teas
Anmutagenic
Anmutagenic acvity of the South African herbal
teas was mutagen-specic- aected by fermentaon.
Unfermented Rooibos was less eecve than
fermented Rooibos
Lee EJ- et al. (2004)
[79]
DNA strand
scission Rooibos tea Anoxidant acvity
Result suggests that total soluble phenolics- specially
avonoid- of Rooibos tea are responsible for several
kinds of anoxidant acvies and prevenve acvity
on peroxyl radical induced DNA strand scission.
Kucharská J- et al.
(2004) [35]
Rat model
of carbon
tetrachloride-
induced liver
damage
Rooibos tea Oxidave stress
Rooibos tea restored liver concentraons of CoQ9H2
and alpha-tocopherol and inhibited the formaon of
MDA.
Marnewick JL- et al.
(2004) [62] Male Fischer rats
Unprocessed (not oxidized)-
processed (oxidized) rooibos-
honey bush- green and black
teas
Mutagenic response
The mutagenic response of aatoxin B1 against
Salmonella strain TA 100 was signicantly (p<0.05)
inhibited by cytosolic fracons from rats treated with
processed and unprocessed herbal teas.
Ulicná O- et al.
(2003) [53]
Rat model of liver
injury Rooibos tea Hepatoprotecon
Rooibos tea showed histological regression of
steatosis and cirrhosis in the liver ssue with a
signicant inhibion of the increase of liver ssue
concentraons of malondialdehyde- triacylglycerols
and cholesterol.
Kunishiro K- at al.
(2001) [55] In vitro and in vivo. Rooibos tea extract Immune funcon
Rooibos tea extract may facilitate the angen-
specic anbody producon through selecve
augmentaon of IL-2 generaon both in vitro and in
vivo.
Key: ATP-Adenosine Triphosphate; CAT-Chloramphenicol Acetyltransferase; DNA-Deoxyribonucleic Acid; IL-Interleukin; LDL-Low-Density Lipoprotein;
LPS-Lipopolysaccharide; MDA- Malondialdehyde; ROS- Reacve Oxygen Species- SOD-Superoxide Dismutase; STZ- Streptozotocin.

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Citaon: Bond TJ, Derbyshire EJ (2020) Rooibos Tea and Health: A Systemac Review of the Evidence from the Last Two Decades.
Nutr Food Technol Open Access 6(1): dx.doi.org/10.16966/2470-6086.166 9
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Conclusions
In conclusion previous health research has tended to focus on
black or green tea. Rooibos is widely consumed in South Africa but
is gaining popularity globally. is has been attributed to the fact that
it is caeine free, naturally sweet and abundant in polyphenols with
potent antioxidant properties. Now, a growing body of evidence from
7 human studies and 49 laboratory studies suggests that Rooibos could
be regarded as a ‘general’ health tea. Evidence for cardioprotective
eects (especially lipid prole) looks promising, particularly as a
potential adjunctive therapy. It is suggested that future research now
builds on the other potential aspects of health including glycaemic,
bone, liver and cognitive wellness enhancing eects that also appear
to be emerging.
Disclosure
e views expressed are those of the authors alone and personnel
from the UK TEA & INFUSIONS ASSOCIATION (UKTIA) had no
role in writing this review.
Conicts of Interest
e authors declare no conicts of interest.
Acknowledgements
e authors received funding provided by the Tea Advisory
Panel which is supported by an unrestricted educational grant from
the UK TEA & INFUSIONS ASSOCIATION (UKTIA), the trade
association for the UK tea industry. UKTIA plays no role in producing
the outputs of the panel. Independent panel members include
nutritionists, biochemists, dietitians, dentist and doctors. See www.
teaadvisorypanel.com
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