[email protected]

7/26/2019 [email protected]

1/8

Effect of fluid intake on skin physiology: distinct

differences between drinking mineral water and tap

water

S. Williams, N. Krueger, M. Davids, D. Kraus and M. Kerscher

Division of Cosmetic Sciences (FB 13), University of Hamburg, Martin-Luther-King Platz 6, D-20146 Hamburg,

Germany

Received 3 July 2006, Accepted 20 December 2006

Keywords: bioengineering, drinking, fluid, skin, water

1Part of this study was presented as a poster on the 64th Annual Meeting of the American Academy of

Dermatology, 37 March 2006 in San Francisco, CA, USA.

Synopsis

It is generally stated that drinking plenty of water

has a positive influence on skin condition. How-

ever, there is no published scientific study that has

investigated this matter. The aim of our explorat-

ory before-after study was to evaluate the in vivo

influence of drinking more than 2 L of mineral

water or ordinary tap water per day on skin physi-

ology. Ninety-three healthy subjects were includedin our prospective study. After an initial run-in

phase of 2 weeks to monitor individual drinking

habits, subjects had to drink 2.25 L day)1 of either

mineral water (n 53) or tap water (n 40) for

4 weeks. Bioengineering in vivo measurements on

the volar forearm included sonographic evaluation

of skin thickness and density, determination of

skin surface pH, assessment of skin surface mor-

phology, and measurement of finger circumfer-

ence. Eighty-six subjects completed the study. In

the mineral water group measurements revealed a

statistically significant decrease in skin density.

Skin thickness increased slightly, albeit not at a

statistically significant level. However, when sepa-

rately analysing those individuals from the mineral

water group, who had routinely drunken compar-

ably little before the start of the study, their skin

thickness increased at a statistically significant

level. Skin surface pH remained almost unchanged

in the physiologically optimal range. In the tap

water group, skin density increased significantly,

while skin thickness decreased significantly. Skin

surface pH decreased at a statistically significant

level. While in the mineral water group finger cir-

cumference decreased significantly, measurementsin the tap water group revealed a statistically sig-

nificant increase. Objective skin surface morphol-

ogy did not change in any group. In summary,

drinking more than 2 L of water per day can have

a significant impact on skin physiology. The exact

effects within the skin seem to differ depending on

the nature of the water ingested. Randomized,

controlled, double-blind follow-up trials are war-

ranted to confirm the findings of our exploratory

pilot study.

Resume

Il est generalement etabli que boire abondamment

de leau influence letat de la peau. Cependant,

aucune etude scientifique publiee ne traite de ce

sujet. Le but de notre etude exploratoire avant/

apres a ete devaluer in vivo linfluence de

labsorption de plus de 2 litres par jour deau

minerale ou du robinet sur la physiologie de le

peau. 93 sujets en bonne sante ont participe a

Correspondence: Professor Martina Kerscher, MD,

Division of Cosmetic Sciences (FB 13), University of

Hamburg, Martin-Luther-King Platz 6, D-20146

Hamburg, Germany. Tel.: +49 40 42838 7235;

Fax: +49 40 42838 2592;

e-mail: [email protected]

International Journal of Cosmetic Science, 2007, 2 9, 131138

2007 Society of Cosmetic Scientists and the Societe Francaise de Cosmetologie 131


2/8

cette etude prospective. Apres une phase initiale

de 2 semaines pour controler les habitudes indivi-

duelles des sujets pour se desalterer, on leur a

demande de boire 2,25 litres par jour deau

minerale (n 53) ou deau du robinet (n 40)

pendant 4 semaines. Les mesures biophysiquesin vivo sur la face interne de lavant bras incluai-

ent levaluation sono graphique de lepaisseur de

la peau et de sa densite, la determination de son

pH de surface, levaluation de sa morphologie de

surface et la mesure de la circonference du

doigt. 86 sujets ont termine cette etude. Dans

le groupe traite par leau minerale, les mesures

revelent des diminutions significatives de la densite

de la peau. Son epaisseur augmente legerement

mais a un niveau non-significatif. Cependant,

quand on analyse separement les individus de ce

groupe, on constate que ceux qui habituellement

buvaient peu deau avant le debut de cette etude

ont lepaisseur de leur peau qui augmente de facon

significative. Le pH de surface de la peau reste a

peu pres inchange dans la fourchette physiologi-

que optimale. Dans le groupe traite a leau du

robinet, la densite de la peau augmente de facon

significative, alors que son epaisseur diminue

significativement. Le pH de surface de la peau

diminue de facon significative. Alors que la cir-

conference du doigt du groupe qui a bu de leau

minerale diminue de facon significative, celle du

groupe traite aleau du robinet augmente de facon

significative. La morphologie de la surface de lapeau ne change pas, quel que soit le groupe. En

resume, labsorption de plus de 2 litres deau par

jour peut avoir un impact significatif sur la physio-

logie de la peau. Les effets au niveau de la peau

semble dependant de la nature de leau inge-

ree. Des tests aleatoires controles en double aveu-

gle seront necessaires pour augmenter les resultats

de cette etude exploratoire.

Mots cles: biophysique, boisson, fluide, peau, eau

Introduction

Depending on age, gender and body mass index,

approximately 4570% of our body weight con-

sists of water with one-third of the total body

water being extracellular and two-thirds within

the intracellular compartment [1]. The movement

of water across cell membranes, which are freely

permeable to water, maintains the osmotic equilib-

rium between the two compartments. Our overall

body fluid balance is dependent on the input of

water on the one hand (e.g. from drinking, food

and metabolism) and the loss of water on the

other hand (e.g. through urine, faeces, skin and

lungs). The daily intake of appropriate amounts offluid is of uttermost importance for optimal func-

tion of the human body, as water is one of the

most vital macronutrients for the maintenance of

life [2,3]. Water plays an important physiological

role in temperature regulation, cardiovascular

function, transportation of oxygen and nutrients

to cells, removing waste, tissue structure mainten-

ance and many others [3]. It has been proposed

that fluid consumption in general and water

intake in particular can have an effect not only on

the risk of nephrolithiasis, but also on hyperten-

sion, hyperglycaemia in diabetic ketoacidosis and

constipation [413]. Regarding the potential effect

of water on cancer, the findings of epidemiological

studies investigating the relationship between fluid

intake and bladder or colon cancer are inconsis-

tent [14]. Two new reports confirm this general

statement [1517].

The recommended daily water intake is usually

stated as 1 mL kcal)1 of energy expended for

adults [18,19]. However, this recommendation is

often increased to 1.5 mL kcal)1 to cover varia-

tions in conditions of energy expenditure and envi-

ronmental exposure. The Food and Nutrition

Board of IOM bases water needs on adequateintake which is based on experimentally derived

intake levels that are expected to meet nutritional

adequacy for essentially all members of a healthy

population. The DRIs for water are 3 L day)1 for

an adult man and 2.2 L day)1 for an adult

woman [20], although there are other voices chal-

lenging the frequently encountered advice of

drinking about 2 L of fluid per day [21]. American

Food Consumption Surveys indicated that a signifi-

cant portion of the population may be chronically

mildly dehydrated and it has been stated that

humans, unlike other mammals, have a delay in

rehydration after fluid loss [2,22]. If a fluid deficit

is not replaced adequately, the human body will

eventually extract water not only from the blood,

but also from tissues including skin and mucous

membranes [23]. To restore the bodys fluid

losses, water is especially suited, as added ingredi-

ents such as carbohydrates, proteins and/or fat

themselves affect the bodys water balance. Con-

sumption of alcohol and caffeine-containing bever-

2007 International Journal of Cosmetic Science, 29, 131138132

Effect of fluid intake on skin physiology S. Williamset al.


3/8

ages is not ideal as they promote an increased rate

of diuresis [24,25].

All three components of the skin epidermis,

dermis, and subcutaneous fat tissue participate

in water regulation, but the main water reservoir

within the skin is the dermis. However, it is thestratum corneum water content which plays a

crucial role in maintaining many of the skins bio-

physicalproperties [2629]. A healthy stratum cor-

neum consists of about 2030% water and a

water content of less than 1020% results in clin-

ical xerosis with reduced elasticity and increased

skin surface roughness [30]. Already more than

50 years ago, Irvin H. Blanks pioneer work pub-

lished in the Journal of Investigative Dermatology

highlighted the critical role of the cutaneous water

content and its effect on the plasticity of the skin

[31]. Blank concluded that its (the skins) phys-

ical characteristics are a function more of its water

content than its lipid content.

Despite increasing medical and public interest in

water intake, very little scientific data are available

on the effect of water consumption and systemic

hydration state on skin physiology. Although it is

generally said that drinking about 2 L water per

day is supposed to have a positive influence on

skin condition and skin quality, there is no con-

vincing study available supporting this statement.

The aim of our study was to evaluate the in vivo

influence of drinking 2.25 L mineral water or

ordinary tap water per day on skin physiology.

Subjects and methods

The study took place from January 2005 to July

2005 in the skin physiology laboratory of the Divi-

sion of Cosmetic Sciences, University of Hamburg.

A convenience sample of healthy volunteer men

and women aged 1860 years with no systemic

illness or skin diseases was recruited. Exclusion cri-

teria included chronic and acute systemic diseases

(e.g. diabetes, viral infections, etc.), chronic and

acute skin diseases (e.g. eczema, psoriasis, urtic-

aria, etc.), pregnancy, breast feeding, and adminis-

tration of a systemic medication or application of

topical preparations within the test area. Ninety-

three subjects (67 women, 26 men) were included.

All volunteers continued living in their usual envi-

ronment. After an initial non-intervention run-in

phase of 2 weeks to monitor individual drinking

habits, subjects had to drink 2.25 L day)1 of either

mineral water (n 53; 38 female, 15 male) or

tap water (n 40; 29 female, 11 male) for

4 weeks. The water was at room temperature. The

mineral water used was Staatlich Fachingen med-

ium (Fachingen, Germany), a mineral-rich water

of pH 5.8 (measured inside the bottle) and a total

mineral content of 2711 mg L)1 (see Table I for

details). The tap water used for this study (pH 7.0)

was supplied by Water works (Nordheide, Ger-

many; see Table I for details). Subjects in the

mineral water group were provided with 84 bot-tles of Staatlich Fachingen medium (each bottle

containing 0.75 L), of which they had to drink

three bottles per day. Subjects in the tap water

group measured the required amount of tap water

themselves after thorough instruction by one of

the investigators. As the taste of Staatlich Fachin-

gen mineral water and tap water is very different

and thus a double-blind design would not have

been possible, we decided to conduct this pilot

study on an exploratory basis. Subjects were asked

to drink the water evenly distributed over the

whole day, to avoid excessive sun exposure and

intense physical activity and not to change their

dietary and daily life habits during the study per-

iod. To monitor their diet and fluid intake and

screen for potentially confounding influences, all

subjects led a food and drink diary over the entire

run-in phase and study period.

Bioengineering measurements were performed

on the volar forearm at the beginning (baseline)

and after 4 weeks drinking phase at randomized

Table I Mean values (mg L)1) of consumed mineral and

tap water

Mineral water (Staatlich Fachingen medium)

Sodium (in particular as NaHCO3) 560

Calcium 92.5

Magnesium 56.6

Hydrogen carbonate 1812

CO2 4500

Tap water (Water works, Nordheide, Germany)*

Sodium 8

Calcium 42

Magnesium 2

Hydrogen carbonate 130

Potassium 1

Ion 0.03

Chloride 10

Sulphate 12

Nitrate 0.6

Fluoride 0.09

*Mean values, may vary slightly from year to year.

2007 International Journal of Cosmetic Science, 29, 131138 133



4/8

times during the day. All subjects were measured

in an air-conditioned room under standardized

conditions after an acclimatization period of at

least 20 min. Noninvasive in vivo measurements

included evaluation of (i) skin thickness and skin

density, (ii) skin surface morphology, (iii) skin sur-face pH and (iv) finger circumference.

Skin thickness (thickness of dermis and epider-

mis) and skin density in the dermal compartment

were quantified with high-frequency ultrasonogra-

phy. The 20 MHz ultrasound scanner DUB 20

(Taberna pro medicum, Luneburg, Germany) was

used to obtain cross-sectional images of the skin

(B-mode), which were analysed digitally. Objective

evaluation of skin surface morphology was per-

formed using the Visioscan VC 98 (Courage &

Khazaka, Cologne, Germany). This instrument

allows a direct optical analysis of skin surface

topography through means of a high resolution

UVA-light video camera together with special soft-

ware. The following Visioscan parameters for skin

roughness und wrinkleness were evaluated: SEr,

SEsm, volume and C_R2. Skin surface pH was

measured using the pH Meter PH 900 (Courage

& Khazaka), which consists of a flat glass probe

combining measurement and reference electrode

in a single probe. The pH metre was calibrated

using standard buffers. Each time three pH mea-

surements were taken on the skin surface with the

mean of these three measurements being used for

subsequent calculations and statistical analysis.Exact finger circumference was measured manu-

ally at the base of the right ring finger.

Statistical analysis was performed on an

exploratory basis using SPSS. All values are

expressed as mean standard error (SEM). Intra-

individual statistical comparison of values before

and after the 4-week drinking period was per-

formed descriptively through means of two-tailed

statistical tests (nonparametric Wilcoxon test

for paired samples). P 0.05 was considered

statistically significant (marked with * asterisk in

diagrams), P 0.001 was considered statisti-cally highly significant (marked with *** in dia-

grams).

Results

Eighty-six subjects completed the study; 50 sub-

jects in the mineral water group (36 female, 14

male; mean SD: 31.8 8.9 years) and 36 sub-

jects in the tap water group (26 female, 10 male;

mean SD: 31.8 8.7 years). Seven of the recrui-

ted 93 volunteers did not complete the study for

personal reasons or protocol violations. An over-

view of our results with exact P-values can be

viewed in Table II.

Skin density

In the tap water group, skin density increased

highly significantly from 47 2.4 at baseline to

54 1.9 after the 4-week drinking phase (Fig. 1).

In contrast, measurements in the mineral water

group revealed a significant decrease from

45 2.15 before to 39 2.49 at the end of our

study (Fig. 1).

Skin thickness

Skin thickness decreased in the tap water group at

a highly significant level (1122 26.66 at base-

line vs. 1062 22.8 after the drinking period, see

Fig. 2). In the mineral water group overall, skin

Table II Summary of results with

P-values (paired Wilcoxon test,

before vs. after the 4-week drinking

phase)

Parameter Mineral water group Tap water group

Skin density fl (P 0.003) (P

0.001)Skin thickness (entire group: P 0.187)

(subgroup of subjects, who had

previously drunken little: P 0.031)

fl(P 0.001)

Skin surface pH fi (P> 0.05) fl(P< 0.001)

Finger circumference fl (P 0.005) (P 0.038)

Skin surface morphology

(SEr, SEsm, R2, and volume)

fi (P> 0.05) fi (P> 0.05)

: statistically significant increase; : slight increase;fl: statistically significant decrease;

fi : no change.




5/8

thickness did not change at a statistically signifi-

cant level (slight increase from 969 22.19 at

baseline to 977 24.19 after the drinking period,

Fig. 2). However, when separately analysing those

individuals from the mineral water group, who

had routinely drunken comparably little before

the start of the study ( 0.05; see Fig. 4 for details), pH

significantly decreased in the tap water group

(5.19 0.10 before vs. 4.79 0.08 after the

drinking phase; Fig. 4).

Finger circumference

In the mineral water group the finger circumfer-

ence measured on the base of the ring finger

decreased significantly from 6.34 0.09 to

6.16 0.10 cm, while measurements in the tap

water group revealed a significant increase from

6.74 0.10 to 6.81 0.08 cm (Fig. 5).

Discussion

Adequate fluid intake, in particular from non-alco-

holic, non-caffeinated and non-caloric beverages

such as water has been shown to be beneficial

for various aspects of general health and to be

protective against diverse medical conditions

[27,913]. Despite the acknowledged physiologi-

cal significance of water to life and the general

claim that the consumption of ample amounts of

water is somehow beneficial for skin, very little is

known about the objective in vivo influence of

4745

54

39

30

35

40

45

50

55

60

Mineral water Tap water

Skindensity(arbitraryunits)

Day 0

Day 28

**

***

Figure 1 Sonographic skin density before (baseline) and

after 28 days of drinking 2.25 L of mineral water

(n 50) or tap water (n 36) per day (**P 0.01,

***P 0.001).

0.8 %

5.3 % ***

6%

4%

2%

0%

2%

4%

6%

Changeofskinthickness

(%)

Mineral water

Tap water

Figure 2 Change in sonographic skin thickness after

28 days of drinking 2.25 L of mineral water ( n 50) or

tap water (n 36) per day (***P 0.001, compared to

baseline).

Figure 3 Visioscan example (female

subject, 30 years of age) of skin sur-

face morphology on the volar fore-

arm before (a) and after (b) 4 weeks

of drinking mineral water.




6/8

water intake on different aspects of skin physiol-ogy. With our study, we were able to demonstrate

that the consumption of more than 2 L of water

per day can indeed have a measurable influence

on skin physiology in healthy volunteers. Further-

more, the concrete effects seem to depend on the

exact nature of the ingested water. In detail, our

measurements revealed that mineral water causes

a significantly reduced finger circumference, a sta-

tistically significant decrease in sonographic skin

density and in those individuals, who had previ-

ously drunken comparably little a significantly

increased skin thickness. The observed changes

were higher in probands, who had previously

drunken comparably little. Pure tap water on the

other hand led to a significantly increased finger

circumference, significantly increased skin density

and significantly decreased skin thickness.

Not all of the objectively measured changes can

be explained straightforwardly, as the exact under-

lying mechanisms necessitate further research in

this area. However, the decrease in skin density

with increase in skin thickness in the mineral

water group might be due to an increased dermal

fluid content, for example though means of a sti-

mulation of cutaneous metabolism with improve-

ment of dermal water binding capacity. It is well

known that skin thickness does not only dependon the amount of cells and extracellular fibres

such as collagen, but also on the interstitial fluid

content. High-frequency ultrasound studies have

confirmed that an increasing fluid content leads to

increased skin thickness with inverse changes in

cutaneous echodensity [32,33]. The fact that the

finger circumference did not rise, but actually

decreased at a statistically significant level, sug-

gests that our probands did not develop any clin-

ical oedema by tissue fluid retention. The

decreased finger circumference could also be a sign

of a general loss of body weight, which was not

measured in our study. Mineral water originates

from rain water, which over decades and centuries

trickled through various layers of rock in the

ground and thus acquired a mixture of minerals

from these stone layers. The mineral water we

used for our experiment was obtained from a

depth of 400 m. It has been shown that minerals

from mineral water are highly bioavailable and

well absorbed [3436]. In contrast to mineral

water, ordinary tap water contains a much lower

content of minerals such as hydrogen carbonate

and magnesium (Table I). It has previously been

shown that consumption of mineral-rich watercan exert distinctively different effects on the skin

compared to water with low mineral content. In

patients with atopic eczema for example deep sea

water intake was able to improve clinical skin

symptoms and decrease serum IgE, IL-4, IL-13 and

IL-18, while distilled water intake had no effect

[37].

Objective assessment of skin surface profile did

not reveal statistically significant changes in any

group. This is interesting, as it is generally claimed

that drinking lots of water might reduce visible

signs of cutaneous ageing such as wrinkles and

lines. We could not confirm any objective improve-

ment of wrinkles or skin surface roughness after

increasing the daily water uptake to more than

2 L over 4 weeks. Whether there might be meas-

urable changes after a longer drinking phase

remains to be investigated in future research. In

this context, it would also be interesting to objecti-

fy the in vivo elasticity of the skin through means

of bioengineering measurements, e.g. cutometry.

6.34

6.746.81

6.16

4.5

5.0

5.5

6.0

6.5

7.0

7.5


Fingercircumference(cm)

**

*Day 0

Day 28

Figure 5 Ring finger circumference before (baseline) and

after 28 days of drinking 2.25 L of mineral water

(n 50) or tap water (n 36) per day (*P 0.05,

**P 0.01).

5.195.38

4.79

5.49

4.0

4.5

5.0

5.5

6.0


SkinsurfacepH ***

Day 0

Day 28

Figure 4 Skin surface pH before (baseline) and after

28 days of drinking 2.25 L of mineral water (n 50) or

tap water (n 36) per day (***P 0.001).




7/8

The skin surface pH is another important

parameter of skin physiology and influences var-

ious other factors such as composition of stratum

corneum lipids, hydration, epidermal barrier func-

tion and growths of physiological and pathological

micro-organisms. Even small alterations in stratumcorneum pH may cause significant modifications

at the molecular level. While after drinking min-

eral water, the skin surface pH remained in the

physiologically optimal range of approximately

5.5, the pH actually decreased at a statistically sig-

nificant level in the tap water group, although the

ingested tap water itself had a neutral pH of 7,

while the mineral water was with 5.8 within the

acidic range. The exact reason of the lower skin

surface pH after drinking ample amounts of tap

water remains unclear. However, these data are in

accordance with a study from Boelsma et al., who

described an inverse relationship between fluid

intake and skin surface pH in men [38]. It remains

to be elucidated why there was no decrease

observed when drinking mineral water, especially

after Boelsma et al. also described a significant

association between increased dietary calcium

intake and decreased skin surface pH in men [38].

However, there might have been confounding

influences of other minerals such as magnesium

with impact on, for example, regulation of prolifer-

ation, differentiation and desquamation of kera-

tinocytes [39], which potentially could have

prevented the pH from decreasing.In conclusion, drinking more than 2 L of water

per day can have a significant impact on skin

physiology, the exact pathogenetic factors of

which remain to be revealed in future research.

Interestingly the effects within the skin seem to

differ depending on the nature of the water inges-

ted. Randomized, controlled, double-blind follow-

up trials are warranted to confirm the findings of

our exploratory pilot study. However, this is an

important new area of research into applied skin

physiology which will in future hopefully bring

out many more insights into the influences of

macro- and micronutrient intake on skin physiol-

ogy, especially as in recent years, commercial

offers of functional foods claiming skin benefits

have increased enormously.

Acknowledgements

We are indebted to all participating subjects for

their cooperation and compliance throughout this

study. We would also like to thank Heike Bunt-

rock, Volker Braun, Sandra Schroder, Alexandra

Butehorn, Annette Schuler and Tatjana Schwill

for their dedication and diligence, which made the

successful execution and completion of this study

possible.Part of this study was sponsored by Staatlich

Fachingen, Fachingen, Germany.

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