evidence & practice / hydration
CAFFEINATED BEVERAGES
Tea: hydration and other
health benefits
Ruxton C (2016) Tea: hydration and other health benefits. Primary Health Care. 26, 8, 34-46.
Date of submission: 3 May 2016; date of acceptance: 31 May 2016. doi: 10.7748.phc.2016.e1162
Carrie Ruxton
Freelance dietitian who
heads consultancy Nutrition
Communications based in
Cupar, Scotland
Correspondence:
[email protected]
Peer review
This article has been subject
to double blind review and
has been checked using
antiplagarism software
Conflict of interest
This article was funded by the
Tea Advisory Panel, which is
supported by an educational
grant from the industry
funded UK Tea & Infusions
Association.
For further information, see
www.teaadvisorypanel.
com. The content reflects the
opinions of the author
Abstract
There is concern in some health profession literature and the wider media that caffeinated beverages
may not support normal hydration. To examine this, a systematic review was carried out to identify
intervention trials that tested the impact of tea consumption on validated markers of hydration. The six
trials, which mostly involved males, confirmed that tea performed in a similar way to plain water up to
intakes of six servings daily. Guidelines for safe consumption of caffeine indicate that a caffeine intake
of up to 400mg daily (200mg for a single serving) is safe for adults. Average tea consumption in the UK,
at two to three servings daily, fits within this. Given the potential benefits of tea for heart health, dental
health and cognitive function, tea consumption could rise to eight servings daily and still remain within
safe caffeine limits.
Keywords
caffeine, cardiovascular, diuretic, flavonoid, fluoride, hydration, tea
Aims and intended learning outcomes certain intakes. The issues of tea, caffeine
The aim of this article is to critically evaluate
evidence on tea, hydration and potential health
benefits to provide better patient advice on the
role of tea in the diet.
After reading this article and completing the
time out activities you should be able to:
»» Correctly identify the caffeine content
of various beverages and put them into
context with age-appropriate caffeine
recommendations.
»» Summarise the contribution of caffeinated
beverages such as tea to normal hydration.
»» Critique misinformation associated with
caffeinated beverages reported in the media.
»» Outline the wider health benefits of tea,
noting where evidence is well-established
and where further research is required.
»» Consider the role of caffeinated drinks within
hydration guidelines as part of the new Eatwell
Guide (Public Health England (PHE) 2016).
Introduction
The view that caffeinated drinks contribute
to dehydration by stimulating excess urine
production is less common nowadays but still
influences public health advice (NHS Choices
2015, Queen Elizabeth Hospital Birmingham
2015) and information given in some media
articles (for example, Allard 2015). Yet there
is growing evidence that tea, a caffeinated
drink, does not have a net diuretic effect in
34 / October 2016 / volume 26 number 8
phc.2016.e1162.indd 34
and hydration, as well as the potential health
impact of tea flavonoids (bioactive plant
compounds) and fluoride, will be discussed in
this article.
Tea constituents
Regular black tea is the second most consumed
beverage in the world after water. Black, green
and white teas are all made from the leaves of
Camellia sinensis, with differences in colour
and chemical composition due to the longer
aeration of black tea. Tea naturally contains
caffeine, flavonoids and fluoride (Ruxton
2014a), with levels varying depending on
provenance and brewing time.
Caffeine is a methylxanthine compound
also found in coffee, chocolate, cola and mate,
a tea made from yerba mate leaves (Ruxton
2008). Black tea contains more caffeine
(41.5 to 67.4mg/g dry weight) than green tea
(around 32.5mg/g dry weight) (Cabrera et al
2003). An analysis of a standardised blacktea infusion, brewed for 40 seconds with one
teabag in 240ml of boiling water, reported
a caffeine content of 16.7 to 21.1mg/100ml,
with an average of 18.9mg/100ml, equating
to 42mg for a mug of tea (Ruxton and Hart
2011). Caffeine levels are lower in green
teas (approximately 40mg/serving), and
all teas are lower in caffeine than coffee
(80 to 100mg/serving).
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Revalidation
Find out more at:
rcni.com/revalidation
In the UK, 77% of adults consume tea
regularly, with an average intake of 540ml
daily (2.3 servings) (Bates et al 2014).
Tea contributes 57% of daily caffeine in
UK adults aged 19 to 64 (around 80mg),
40% to 48% in children aged 5 to 18 (5 to
20mg) and 65% in older people (around
108mg) (European Food Safety Authority
(EFSA) 2015a).
Tea is estimated to provide around 80% of
the flavonoids in the UK diet (Lakenbrink et al
2000). Overall flavonoid content is similar in
green and black tea
but the types vary due to differences in
processing methods. Thus, the content of
catechins (a subclass of flavonoids) in green
teas is greater (80% to 90%), while black
teas contain fewer catechins (20% to 30%)
and more theaflavins and thearubigins (50%
to 60%).
Write for us
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phc‑author‑guidelines
TIME OUT 1
Beverage diary
Compile a 1-day beverage diary for an adult where 6 to 8
glasses of fluid could be consumed while staying within the
EFSA caffeine recommendations limit, providing a variety
of beverages. Better still, compile one of your own and add
notes about your premises of the experience of caffeine
intake selected. What do you think shapes your perceptions?
The caffeine content of beverages varies widely (Table 2),
leading to concerns about high caffeine intakes in some
population groups, particularly young consumers of energy
drinks and shots, which can contain up to 422mg in a
serving (Caffeine Informer 2016).
Now do time out 2
Caffeine and hydration
Short-term studies of caffeine pills have
reported modest diuretic effects at caffeine
intakes of 5.6 to 8.75mg per kg of body
weight – that is, 370mg to 612mg per day for
an average 70kg person (Wemple et al 1997,
Bird et al 2005), although longer trials on
lower doses of 3 to 6mg/kg body weight (210
to 420mg per day for an average 70kg person)
have not found significant effects on markers
of hydration such as body mass or blood
and urine indicators (Armstrong et al 2005).
There are few studies of caffeinated beverages
as opposed to pills. Those relating to tea are
reviewed below.
In 2015, the EFSA delivered a scientific
opinion on the safety of caffeine that included
advice on caffeine intakes for different
population groups for which health concerns
would be unlikely (EFSA 2015a). Based
on the available evidence, it was determined
that single doses of caffeine up to 200mg
(about 3mg/kg body weight for a 70kg adult)
would not give rise to safety concerns. This
included consuming caffeine before intense
physical exercise.
Regarding long-term caffeine consumption,
a chronic daily intake of up to 400mg was
deemed safe. Pregnant and lactating women
were advised to limit caffeine intake to 200mg
per day due to concerns about fetal growth
and transfer of caffeine through breast milk
(EFSA 2015a).
The data on children and adolescents were
insufficient to derive safe caffeine limits, so
adult data were used as a basis to estimate
limits for this age group. Table 1 gives details.
Now do time out 1
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phc.2016.e1162.indd 35
TIME OUT 2
Apply your experience
Write a case study using an example where a patient became
dehydrated. What were the reasons and what advice did
you give? Did you enquire about caffeine intake? If so, what
premises did you start from about effects on hydration levels?
TABLE 1. Recommended maximum caffeine intake
Population group
Single serving
Total daily intake
Healthy adults
200mg (3mg per kg body weight)
400mg (5.7mg per kg body weight)
Pregnant women
Insufficient data
200mg
Lactating women
200mg
200mg
Children and
adolescents
Insufficient data but 3mg per kg
body weight is unlikely to cause
concern
Insufficient data but 3mg per kg body
weight is unlikely to cause concern
(EFSA 2015a)
TABLE 2. Average caffeine content of beverages
Beverage
mg/serving
Serving size (ml)
Filter coffee
90
200
Energy drink
80
250
Energy shot
80
60
Espresso coffee
80
60
Black tea
50
220
Cola
42
335
(EFSA 2015b)
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evidence & practice / hydration
A survey commissioned by the EFSA
investigated caffeine intake in 51,000
participants from 16 different European
Union member states (Zucconi et al 2013),
30% of whom consumed energy drinks (28%
in the UK). Adult energy drink consumers
were exposed to 272mg caffeine daily from
all sources, with high consumers (4 or more
days a week) exposed to 382mg daily. In
adolescents, the respective figures were 185mg
in energy drink consumers and 477mg in high
consumers. These data, alongside national
survey data, were used to inform published
estimates of average caffeine consumption
(Table 3). Despite a wide caffeine intake
range in the UK, with older people being the
highest consumers, few adults and no children
exceeded the 400mg daily limit set by the
EFSA (2015a).
Now do time out 3
TIME OUT 3
Communication tools
Locate a fluid intake/diet health leaflet used locally. How do
the messages and communication tools about hydration
compare with the latest advice on fluid and caffeine? What
key messages about caffeine intake are presented? Does
the leaflet include references against which readers could
check guidance claims if they so wished?
Tea and hydration
To minimise bias in study selection, a
systematic review was conducted to locate
intervention studies that examined the impact
TABLE 3. Average daily caffeine intakes
Life stage
EU range
(mg/day)
UK
Mean
(mg/day)
95th centile
intake (mg/day)
% exceeding
400mg/day
Very elderly (>75
years)
22-417
—
—
—
Elderly (65-75 years)
23-362
165
377
4.2
Adults (18-64 years)
37-319
138
318
2.4
Adolescents (11-18
years)
17.6-69.5
37
126
0
Children (3-10 years)
9.9-47.1
9.9
46.9
0
(EFSA 2015a)
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phc.2016.e1162.indd 36
of tea drinking on validated blood and
urine markers of hydration. The PubMed
(MEDLINE) database was systematically
searched to identify English-language
human intervention trials published from
January 1996 to 22 March 2016 (Figure 1),
with the key words ‘tea’ plus ‘hydration’,
‘hyperhydration’, ‘hypohydration’, ‘osmolality’
and ‘body water’.
Reference lists of related review papers and
intervention studies were searched for any
missed publications. Studies were included if
they met the following criteria – healthy adult
participants, consumption of any type of tea
versus a control beverage, and estimate of
hydration based on blood or urine markers.
Of the six trials located (summarised in
Table 4), five were randomised controlled
trials (RCT) or randomised crossover studies
(RCS) (where participants acted as their own
controls). The other study, by Scott et al
(2004), applied a non-controlled experimental
design of two 24-hour conditions. Participants
(n=13) either abstained from drinking tea or
drank a minimum of two mugs (240ml per
mug), a blend of Indian black teas prepared
to subjects’ own tastes. The reported reason
for the lack of control in this study was that it
took place in the challenging environment of
an Everest Base Camp.
Except for the RCT by Maughan et al
(2016), which recruited 72 men, most had
sample sizes of 10 to 23 participants and
focused on young males, with three studies
recruiting active individuals such as runners
(Wong et al 2014), mountain climbers
(Scott et al 2004) and wrestlers (Utter et al
2010). People who participate in sport are
more at risk of dehydration as sweating can
result in a 6% to 10% loss of body mass
(Popkin et al 2010). The largest block of
participants (n=103), from three studies, was
healthy males from the general population,
although one group (n=10) was asked to
undertake exercise during the trial (Chang et al
2010). Importantly, most studies followed
a period of caffeine and alcohol washout to
ensure stable hydration at baseline.
It is worth noting the outcome measures
used by the studies. These included body
mass and urine volume, as well as specific
blood and urine markers of hydration such
as osmolality. Armstrong et al (2012) argued
that, while serum osmolality remains the
gold standard for assessing hydration under
controlled laboratory conditions, other settings
require a combination of markers including
urine volume, urine specific gravity, urine
osmolality and urine colour. All the studies,
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except the non-controlled trial by Scott et al
(2004), reported serum osmolality and several
other urine and blood markers, suggesting they
provide adequate estimates of hydration.
60°C or the same tea served cold at 4° to 6°C,
cumulative urine output was no different when
compared with participants randomised to the
other test beverages, including water.
Impact on hydration status
Figure 1. Flow diagram for database search results (tea and hydration)
All the studies found that tea drinking had no
adverse effects on hydration status, indicated
by blood and urine markers remaining in the
normal ranges. Tea provided similar hydration
benefits to water, as no statistical differences
in blood and urine markers were reported
when these conditions were compared. In
four studies (Chang et al 2010, Utter et al
2010, Wong et al 2014, Maughan et al 2016),
carbohydrate-electrolyte beverages were more
effective than tea and water at hydrating
participants, which would be expected given
that their formulation is designed to maximise
water uptake in the gut.
Maughan et al (2016) studied the effects of
13 different drinks on 72 normally hydrated,
fasted males. After drinking 1 litre of hot tea
made in a standardised way and served at
References identified
through PubMed
Total papers: 32
Tea and hydration: 5
Tea and hyper/hypohydration: 0
Tea and osmolality: 5
Tea and body water: 22
Irrelevant: 24
Equisetum bogotense tea 1
Review paper: 1
Six studies included
(Table 4)
TABLE 4. Summary of tea hydration intervention studies
Study
Sample details
Methods and intervention
Markers of hydration
Key findings
Maughan et al (2016)
72 males (mean age 25):
general public
RCT. 1 litre hot tea, iced tea or
water (control) – other drinks
were also tested
Urine volume, cumulative
urine mass, serum and urine
osmolality, serum electrolytes
Cumulative urine output 4
hours after hot and cold tea
ingestion was no different to
water ingestion
Wong et al (2014)
9 males, 10 females (mean
age 22):
active individuals
RCS. Drank lemon tea,
carbohydrate drink or water
(control) equal to 150% of their
body mass loss during the
previous run
Body mass loss, serum
osmolality and electrolytes
The carbohydrate-electrolyte
drink was more effective at
rehydrating female runners
than lemon tea or distilled
water
Ruxton and Hart (2011)
21 males (mean age 36):
general public
RCT. Regular black tea, black
tea plus 168mg or 252mg
caffeine or boiled water (four
cups/day, each 240ml)
Serum and urine osmolality
and electrolytes. Urine specific
gravity, volume and colour
Black tea had similar hydrating
properties to water under
conditions of rest
Utter et al (2010)
23 males (NR):
active individuals
RCS. Rooibos tea or water
(control)
Serum and urine osmolality.
Urine specific gravity
Rooibos tea was similarly
effective to water at
rehydration when ingested by
dehydrated wrestlers
Chang et al (2010)
10 males (mean age 26):
general public
RCS. Ingested tea,
carbohydrate-electrolyte
drink or water (control) equal
to their body weight loss
following exercise-induced
dehydration
Blood viscosity, serum and
urine osmolality, serum
electrolytes
Recovery from high blood
viscosity was greatest with
carbohydrate-electrolyte
consumption compared with
tea or water, which performed
similarly
Scott et al (2004)
9 males, 4 females (mean
age 34):
active individuals
24-hour x 2 intervention. Hot
brewed tea (3,193ml) or water
(3,108 ml)
Urine volume, specific gravity,
potassium, sodium, urine
colour
All outcome measures were
similar under the tea and
water conditions
Key: NR: not reported. RCS: randomised crossover study. RCT: randomised controlled trial
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evidence & practice / hydration
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In another RCT of 21 healthy males,
drinking four or six cups of standardised
black tea (240ml per cup) had no significant
effect on blood or urine osmolality (Ruxton
and Hart 2011) when compared with a water
control. Finally, Chang et al (2010) reported
that recovery from high blood viscosity
was similar when healthy male students
with exercise‑induced dehydration drank
either tea or water.
Scott et al (2004) found no difference in the
percentage of fluid retained by the body, urine
volume or other hydration markers when tea
or water was freely consumed by 13 mountain
climbers at altitude. Interestingly, self-reported
fatigue was significantly lower when the
climbers drank tea (P=0.005), although a
limitation is that information about the test
was not concealed from the participants.
Wong et al (2014) found that a
carbohydrate-electrolyte beverage was
more effective at restoring body mass water
loss in female runners compared with
lemon herbal tea or distilled water, which
performed similarly. However, lemon tea and
the carbohydrate-electrolyte beverage were
more effective than water at maintaining
cognitive performance. Utter et al (2010)
tested the rehydration properties of various
beverages after a 3% reduction in body mass
in 23 wrestlers. They found that plasma and
urine osmolality were similar when noncaffeinated rooibos (red bush) tea and plain
water were compared.
Overall, these studies consistently reported
that teas (black, rooibos, herbal infusion) were
as effective as plain water in supporting normal
hydration, even under conditions of physical
stress such as altitude or exercise. Four of
the six studies concluded that carbohydrateelectrolyte beverages were most effective at
rehydrating, although this would be expected
as neither tea nor water contain electrolytes.
A strength of the collated studies was that
most of the participants were recruited from
the general public. However, an important
limitation was the focus on males and healthy
individuals, indicating that more research is
needed on how hydration status in females,
children, older people and health-compromised
people responds to tea consumption.
For females of child-bearing age, this is likely
to be challenging as body water and mass can
fluctuate by 1kg to 3kg during the course of a
28-day menstrual cycle due to the influences of
progesterone and estradiol on fluid-electrolyte
balance (Armstrong et al 2012).
A final point about the evidence is that it
is possible that caffeine tolerance may have
38 / October 2016 / volume 26 number 8
phc.2016.e1162.indd 38
contributed to some of the findings (for
example in Scott et al 2004).
Now do time out 4
TIME OUT 4
Critique the research
Select one of the studies from this review and write a
short critique of the methodology. Those published in the
American Journal of Clinical Nutrition or British Journal of
Nutrition are free to download. What are your views on the
sample size, duration and markers of hydration used and
the standardisation of the beverages consumed?
Tea and health
There is growing evidence from observational
studies and clinical trials that regular
consumption of tea is associated with
health benefits. Preference has been given
to systematic reviews and meta-analyses as
these provide an overview of the evidence in
a specific health field rather than a snapshot
of individual studies, which may be subject to
bias. Limitations of systematic reviews include
a lack of homogeneity in participants, type of
tea consumed and settings. They also make it
difficult to identify an optimal intake of tea as
each study may have examined a different level
of consumption.
Cardiovascular health
The most compelling research relates to
associations between tea drinking and reduced
risk of cardiovascular disease (CVD), which
is supported by RCTs and proposes likely
mechanisms of action.
In a meta-analysis of 22 prospective studies,
Zhang et al (2014) concluded that increasing
baseline tea consumption by three servings
daily reduced CVD risk factors, leading to
a statistically significant 26% lower risk of
coronary heart disease. Arab et al (2013)
looked at the findings from 14 observational
studies on stroke risk, reporting a 21% lower
relative risk for regular tea intake (highest
versus lowest intakes compared).
Turning to systematic reviews of RCTs,
Hartley et al (2013) examined 11 RCTs of
more than 3 months duration, finding that
black-tea consumption significantly lowered
low density lipoprotein (LDL) cholesterol by
0.43mmol/L, while average systolic blood
pressure reduced by 1.85mmHg. For green
tea, significant reductions were seen for total
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and LDL cholesterol (mean of 0.62mmol/L
and 0.64mmol/L respectively) and for systolic
and diastolic blood pressure (mean reductions
3.18mmHg and 3.42mmHg respectively). A
meta-analysis of RCTs (Liu et al 2014) found
that green tea significantly reduced systolic
blood pressure by 2.1mmHg and diastolic
blood pressure by 1.7mmHg, while the
corresponding reductions for black tea were
1.4mmHg and 1.1mmHg respectively. Similar
results were demonstrated in a recent small
RCT (Grassi et al 2015).
Several feasible mechanisms for these effects
have been proposed relating to the bioactivity
of tea catechins, such as enhanced antioxidant
activity, reversal of endothelial dysfunction,
inhibiting the angiotensin-converting enzyme,
preventing cardiac hypertrophy and protecting
the mitochondria from damage (Liu et al
2014). Tea flavonoids may also influence
markers of inflammation by suppressing
signalling pathways (Suzuki et al 2009)
or reducing platelet activation and plasma
C-reactive protein (Steptoe et al 2007). The
most likely mechanism is the positive action of
tea flavonoids on endothelial function.
Weight management
Caffeine and catechins may stimulate fat
oxidation via the sympathetic nervous system,
promoting energy expenditure and potentially
supporting weight loss by counteracting the
decrease in metabolic rate that can occur
during body weight loss (Hursel et al 2011,
Hursel et al 2013). However, there is a lack of
human trials in Western populations.
A review of 18 studies (Jurgens et al 2012)
reported that green tea induced no meaningful
weight loss in overweight or obese adults.
In contrast, a recent RCT (Bohn et al 2014)
found that consuming three cups of black tea
daily (made from tea extract) for 3 months
corresponded with a small reduction in
body weight (0.64kg) and a smaller waist
circumference (reduced by 1.88cm).
Another RCT (Li et al 2015) in patients with
type 2 diabetes found that tea consumption
reduced waist circumference by 2.70cm. While
these effects are clearly modest compared with
the impact of prescription drugs or low-energy
diets, unsweetened tea could be recommended
instead of sugar-containing beverages as part
of an holistic approach to weight management.
Type 2 diabetes
In a review of the evidence on tea and type 2
diabetes, Ruxton and Mason (2011) reported
a potentially protective effect of drinking one
to four cups of black tea daily, while a major
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phc.2016.e1162.indd 39
meta-analysis of nine cohort studies, which
followed over 300,000 people for up to 18
years, reported that four or more cups of green
tea daily was associated with a significant
reduction in type 2 diabetes (Jing et al 2009).
More recently, a meta-analysis of ten RCTs
found that green tea, or its extract, significantly
decreased fasting glucose and haemoglobin
A1c concentrations in patients with diabetes
(Liu et al 2013). Animal studies suggest that
tea flavonoids improve postprandial glycaemia
by inhibiting the degradation of disaccharides
into monosaccharides in the gut, thus reducing
their bioavailability (Satoh et al 2015). These
early results need to be confirmed in other
clinical trials, especially in human subjects.
Cognitive function
Tea drinking is associated anecdotally with
relaxation, mental focus and improved mood
but it is unclear whether these effects arise from
interactions with bioactive tea constituents
(for example, caffeine and L-theanine), the
sensory properties of tea such as smell, colour,
temperature and how it feels in the mouth
(Einöther and Martens 2013), or cultural and
social norms. Although caffeine is known
to increase acetylcholine and dopamine
transmission in the brain, which is implicated in
attention and higher cognitive functions, less is
known about L-theanine, a highly bioavailable
amino acid that is virtually unique to tea. Bryan
(2008) suggested that L-theanine may interact
with caffeine to enhance attention switching
and the ability to ignore distraction, while
Vuong et al (2011) reported that L-theanine
improves concentration and learning.
One review reported a consistent finding
that acute tea intake improves attention,
self-reported alertness and mental arousal
(Einöther and Martens 2013). A recent metaanalysis (Carnfield et al 2014) reported small
to moderate effects on cognitive function and
mood that were attributable to L-theanine
and caffeine. The cognitive effects of caffeine
are seen in non and occasional consumers,
as well as habitual consumers of caffeinated
beverages (Ruxton 2008). The potential role of
tea in cognitive function deserves further study,
particularly to tease out which effects relate
to tea constituents rather than hydration or
expectations.
Dental health
There is emerging evidence that fluoride and
flavonoids in tea may protect against caries
and periodontitis, as studies have found fewer
decayed, missing or filled teeth in adult tea
drinkers (Abd Allah et al 2011, Varoni et al
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23/09/2016 12:07
evidence & practice / hydration
2012). Suggested mechanisms include antiviral
and antimicrobial effects, inhibition of plaque
bacteria and changes in the salivary milieu
(Abd Allah et al 2011). Additionally, green
tea polyphenols have been reported to reduce
halitosis through modification of odorant
sulphur components (Narotzki et al 2012).
Tea provides the majority of fluoride in the
UK diet, and as black tea infusions have an
average fluoride content of 4.9mg/L it could
claim to be beneficial for dental health under
EU regulations (Ruxton 2014a). Fluoride
is recognised for its role in promoting oral
health, since incorporation of fluoride into the
enamel matrix of teeth improves resistance to
decay (EFSA 2013). Tea should be consumed
without added sugar to maximise these effects
(Benelam and Wyness 2010).
Practical aspects
This article has considered the hydrating
properties of tea, finding that it is an
appropriate beverage to include within the
recommended guidelines for fluid, currently six
to eight servings daily, according to the Eatwell
Guide (PHE 2016). For the first time, this guide
says specifically that unsweetened tea can be
part of a recommended diet. Further research is
needed into non-healthy populations and older
people to confirm the findings from the mostly
male-dominated studies.
Now do time out 5
TIME OUT 5
Eatwell guide
Read the latest hydration advice in the Eatwell Guide (www.
gov.uk/government/publications/the-eatwell-guide). Is this
suitable for all patients? Think of cases where there are
different hydration needs.
European experts (EFSA 2015a) recommend
that adult caffeine intakes should remain
below 400mg daily, which equates to eight
servings of tea. A previous review considered
that unsweetened tea would be an appropriate
drink for children aged over 5, since one to
two servings of tea daily would be within
safe limits for caffeine and fluoride (Ruxton
2014b). It could be argued that the fluoride
content of tea and its low erosive potential
(Simpson et al 2001) make it a particularly
suitable beverage for childhood and youth,
a time when dental health can be an issue.
Children may need several exposures to ensure
acceptance of unsweetened tea if they have
been used to drinking sweet beverages.
With older people, tea makes a larger
contribution to both fluid and caffeine intakes.
As EFSA data shows, relatively few individuals
exceed the recommended daily caffeine limit
of 400mg (EFSA 2015a).
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consumption on attention and mood. American
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Allard S (2015) The Benefits of Water. Do You
Know How Much Water to Drink Every Day? www.
goodtoknow.co.uk/wellbeing/180475/Why-water-isso-good-for-you (Last accessed: 5 August 2016).
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primaryhealthcare.com
23/09/2016 12:07
The potential impact of tea polyphenols on
heart health is an important consideration in
this age group, as is the emerging evidence
highlighting a role for tea in supporting
glucose control, cognitive function
and weight management.
Older people may prefer drinking tea to
water or soft drinks, yet in some patient
literature (NHS Choices 2015, Queen
Elizabeth Hospital Birmingham 2015)
warnings that are not based on evidence are
given about the dehydrating properties of
caffeinated beverages. This, and the results
of a small online survey of 95 dietitians and
nutritionists (Ruxton 2013), may suggest that
health professionals’ views on caffeinated
beverages are out of date.
The survey found that the caffeine content
of tea and coffee was often underestimated,
while caffeine in cola and energy drinks
was overestimated. It found that 30% of
participants believed tea was unsuitable for
primary school-age children due to the caffeine
content (the figure was 60% for coffee) but this
fell to about 10% when the caffeine content
was known.
Health professionals need to improve
their knowledge of the caffeine content
of different foods and drinks, the new
EFSA caffeine recommendations, and how
much tea and coffee can be consumed
within daily fluid intakes.
The best studies to date (Ruxton and Hart
2011, Maughan et al 2016) suggest that up
to six servings of tea daily provide similar
hydrating benefits to plain water. This would
tend to contain 260 to 300mg of caffeine,
which is within safe limits. Other constituents
in tea, such as flavonoids and fluoride, appear
to be associated with benefits to heart health,
cognitive function and dental health. The
role of tea in type 2 diabetes and weight
management may be positive, but this requires
further research to confirm early findings from
human studies.
TIME OUT 6
Nutrition policy
Check to see if there is a local hydration policy. Discuss
with colleagues if this does not take into account the
Eatwell Guide hydration advice and evidence on the
hydrating properties of caffeinated drinks.
Add to your portfolio
TIME OUT 7
Reflective account
After reading this article you may like to write a reflective
account (typically 750 to 1,000 words) about how latest
hydration advice could be embedded into practice.
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cognitive function, performance and hydration:
a review of benefits and risks. Nutrition Bulletin.
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randomized trial to assess the potential of different
beverages to affect hydration status: development
of a beverage hydration index. American Journal of
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drinks for children: a systematic review of
randomised controlled trials, observational studies
and expert panel guidelines. Journal of Human
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(Last accessed: 5 August 2016.)
Queen Elizabeth Hospital Birmingham (2015)
Hydration. www.uhb.nhs.uk/Downloads/pdf/
PiHydration.pdf (Last accessed: 5 August 2016.)
primaryhealthcare.com
phc.2016.e1162.indd 41
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Liu K, Zhou R, Wang B et al (2013) Effect of green tea
on glucose control and insulin sensitivity: a metaanalysis of 17 randomized controlled trials. American
Journal of Clinical Nutrition. 98, 2, 340-348.
NHS Choices (2015) Water, Drinks and Your Health.
www.nhs.uk/Livewell/Goodfood/Pages/waterdrinks.aspx (Last accessed: 5 August 2016).
Online archive
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bags and estimates of daily fluoride consumption
based on typical tea drinking habits in UK adults
and children. Nutrition Bulletin. 40, 4, 268-278.
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different from water in the maintenance of normal
hydration in human subjects: results from a
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106, 4, 588-595.
Ruxton C, Mason P (2011) Associations
between black tea consumption and the risk
of cardiovascular disease and type 2 diabetes.
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volume 26 number 8 / October 2016 / 41
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