photos: Mikhail Rulkov, Shutterstock.com
ally used. The main factors here
are the starting material (e.g. the
part of the plant used), extraction
agent and extraction process.
These parameters have a signifi-
cant impact on the components in
the extract and, by extension, on
its properties.
For example, the composition of
an oil extract cannot be readily
compared with that of an etha-
nolic-aqueous extract. Specific
manufacturing processes (e.g.
spray-drying) can also greatly af-
fect the properties of an extract.
Correspondingly, data from the
literature about raw materials
may only be used if they apply to
the substance in the product.
Application studies
Studies with human volunteers are
used to verify general claims about
the way the skin feels and for sub-
jective impressions after using a
product. In planning such user
tests, framework conditions have to
be defined such as the study design,
study protocol and questionnaire.
As a fundamental principle, the
panel of testers must correspond to
the target group of the cosmetic
product. Furthermore, inclusion
and exclusion criteria have to be
defined for those who participate
in efficacy trials, such as the test
subjects’ age, condition of their
skin, and disposition to allergies.
The more rigorously the test sub-
jects are recruited and informed,
the more valid the results are.
Among other things, this means
having an adequate number of
subjects and research findings that
are statistically robust. Generally,
these outcomes are determined by
analysing questionnaires filled in
by the subjects. To increase the va-
lidity of such tests, it is advisable
to have a medical specialist or aes-
thetician involved who can objec-
tively assess the skin from a pro-
fessional’s perspective.
Instrumental tests
For stronger product claims, ad-
ditional instrumental tests are
necessary. Efficacy studies of this
kind are always necessary when
the objectively-quantifiable prop-
erties of a cosmetic product (e.g.
moisture replenishment) are in-
tended to appear on the label. It is
critical to select the appropriate
procedure for the product being
tested. Experience has shown
that relevant efficacy claims can
best be verified by combining in-
strumental tests and user tests.
This compiles subjective and ob-
jective findings and provides a
broad foundation of data on
which to substantiate the respec-
tive advertising claim.
This is important since consum-
ers are not “only” interested in
scientifically-validated data;
above all, they are interested in
the effect the product has when
used upon the skin.
A modular weight of
evidence approach
The following approaches may be
used to substantiate various effi-
cacy claims: the moderate state-
ment “protects the skin” can gen-
erally be supported by published
data about specific ingredients.
For example, avocado oil is known
for having a protective effect that
envelops and cares for the skin.
Furthermore, this product proper-
ty can be proven and confirmed as
needed by conducting an applica-
tion test with test subjects.
For claims about measurable skin
effects such as “the skin is revital-
ised and nourished with mois-
ture,” it is not sufficient to use on-
ly data from literature and
findings from user tests. In this
case, a
Corneometer
test can be
conducted before and after using
the product to quantify the mois-
ture level of the skin.
The claim “regenerates the skin
barrier” can be handled in a simi-
lar fashion. In this case, the prop-
erties of the skin barrier need to be
additionally analysed by means of
a
Tewameter
to quantify transepi-
dermal water loss (TEWL).
The claim “minimises wrinkles”
requires a higher standard for
substantiation. This statement
JUSTIFIED
Claims on a
substance are
only justified if it
is contained at an
effective concen-
tration
For consumers, it’s
the concrete effects
of a product that
count
Combining
instru-
mental tests
and
user tests
is an
appropriate way to
verify efficacy claims
can be confirmed by means of an
FOITS
examination (Fast Optical
In Vivo Topometry of Human
Skin). This imaging procedure
analyses wrinkles on a three-di-
mensional level to examine the
effects that a particular cosmetic
formulation has on the surface
structure of the skin over a de-
fined period of time.
The procedure helps to determine
whether a cosmetic formulation
helps to smooth the skin. Since it
involves a sophisticated test de-
sign, it is important to work with
trustworthy and respected test in-
stitutes that have experience in
the field and are well-versed in
the relevant methodology. For
product claims of all kinds, a user
test conducted with test subjects
can be a useful supplemental
instrument for the aforemen-
tioned modular weight of evi-
dence approach.
A standardised questionnaire
without suggestive questions
makes it possible to determine
specific information about the cos-
metic acceptance and efficacy of a
product. Subsequently, the objec-
tive results from instrument-based
analyses can be compared with
the subjective experiences of
those who participated in the test.
This allows the projected efficacy
claims to be modified if necessary,
and relevant statements which
have been verified by test results
can be selected for the consumer.
In the long term, advertising
claims are only useful if they can
be confirmed by users as well –
that is, when the consumer can
truly experience the desired effect
of the product
.
Q
Additional information on claims can be found
on the Internet – see download panel
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