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Ital. J. Food Sci., vol. 27 - 2015 1

- Keywords: trans fatty acids, consumer awareness, Polish students, Dutch students, eating habits -

COMPARISON OF KNOWLEDGE IN THE FIELD 
OF NUTRITIONAL FATS AMONG STUDENTS

S. ONACIK-GüR a, A. ŻbIKOWSKA a and M. KOWALSKA b*
a. Faculty of Food Science, Warsaw University of Life Sciences (SGGW), Poland

b Faculty of Materials Science, Technology and Design, 
Kazimierz Pulaski University of Technology and Humanities in Radom, Poland,

*Corresponding author: Tel./Fax: 48 48 3617547,
email: mkowalska7@vp.pl

AbstrAct

the aim of this work was to analyze the knowledge in the field of trans fatty acids (tFAs) and 
nutritional recommendations related to fats among students at the University of Life sciences in 
Warsaw (sGGW) and Wageningen (WUr). the research was done using a questionnaire composed 
of 16 questions among 194 students from sGGW and WUr in 2012.

In Poland 96% and in Holland 89% of students had heard the name “trans fat”. More than half 
of the questionnaire respondents knew industrial sources of tFAs. After comparing the results of 
the research, in which students succeeded, it was concluded that differences in the level of knowl-
edge were statistically not significant (p<0.05). Eating habits for fatty pastry products represent-
ing a potential source of tFAs were similar. WUr students’ purchase of pastry products was de-
pendent on price, whereas that of Polish students depended on information and ingredients list-
ed on the package.



2 Ital. J. Food Sci., vol. 27 - 2015

INtrODUctION

Fats are one of the fundamental food ingre-
dients, which play a significant role in the hu-
man body. their nutritional value depends on 
the composition of fatty acids (FAs) and content 
of diluted vitamins. the most important for the 
organism are FAs, from the group of EFAs (es-
sential fatty acids) (GUrr, 2000; bAYIr et al., 
2011), and they are easily oxidized.

Fats used for technological purposes should 
be resistant to high temperatures and storage 
conditions. For pastry products and frying fats, 
mainly fats rich in saturated fatty acids (sFAs) 
and sometimes trans fatty acids (tFAs) are used. 
In the manufacture of many food products it is 
necessary to use fats with solid consistency. 
It could be a natural solid fat or a modified fat 
(McDONALD and MOssObA, 1996; MAttHÄUs, 
2007). It is possible to alter the characteristics 
of fats by using hydrogenation, transesterifica-
tion, mixing and fractionation. Hydrogenation is 
one of the oldest methods, where double bonds 
in triacylglycerols (tAG) are saturated. As a re-
sult of this treatment unsaturated fatty acids 
(UFAs) become sFAs. Moreover, trans isomeri-
zation of FAs occurs within the process of hy-
drogenation, which results in tFAs. the modi-
fied fat has a higher melting point and increased 
resistance to oxidation (FLAcZYK and KOrcZAK, 
2002; MAttHÄUs, 2007; DOWNEs et al., 2013).

tFAs may occur in natural products originat-
ing from ruminants. As a result of enzyme ac-
tivity in ruminants’ bodies there occurs trans 
isomerization from cis bonds to trans (GOODMAN 
et al., 2001; EFsA, 2004; GEbAUEr et al., 2007). 
the content of tFAs originating from natural 
sources (from meat and milk) may range from 2 
to 8 g/100 g fat depending on kind, breed, way 
of feeding and season. In Europeans’ diet on av-
erage 30% of consumed tFA comes from milk 
and 10% from meat. Fats developed with indus-
trial hydrogenation way may include even 70% 
of tFA in the whole FAs (MAttHÄUs, 2007; JAstI 
and KOVAcs, 2010; KrAsNOWsKA and sALEJDA, 
2011). Cis-trans isomerization may also happen 
during high temperature treatment, for exam-
ple during deodorization of oils or frying (KrAs-
NOWsKA and sALEJDA, 2011).

According to most researchers, trans fatty 
acid isomers have a negative impact on human 
health. because of the hazards related to exces-
sive consumption of tFAs, international organ-
izations such as EFsA and WHO have stated 
that daily intake for adults and children should 
be reduced as much as possible (EFsA, 2004; 
DOWNEs et al., 2013).

Fats rich in tFAs and sFAs have a negative 
impact on the cardiovascular system. they con-
tribute to the cholesterol rise in the blood and 
the higher risk of cardiovascular diseases. there 
are also reports indicating negative influences 
of tFA on other human body organs. consump-

tion of 5 g of sFAs a day may increase the risk 
of heart diseases by about 2% and of tFAs by 
even 25% (MArtIN, 2007).

Due to the unfavorable effect of tFAs on the 
human body, legal restrictions of their content 
in food products have been implemented (Den-
mark and canada). A different solution to re-
duce the consumption of tFAs is to require la-
beling of food products with information about 
the content of tFAs (canada, UsA) (ŻbIKOWsKA, 
2010; DOWNEs et al., 2013). Denmark is the first 
country in the world to introduce a tax on food 
products containing sFAs. the aim of this tax 
is to reduce the consumption of products rich 
in saturated FAs and increase the consumption 
of fruits and vegetables (sIMOPOULOs, 1996).

Due to the negative impact of tFA on the body 
and any actions concerning with reduction of 
their consumption, it is important to follow the 
level of consumer’s education in this area. It can 
be assumed that people with higher education 
related to food and nutrition sciences, interest-
ed in the subject of nutrition, should avoid con-
sumption of products that may adversely affect 
their health, eg: products with trans fatty acids.

the aim of this study was to verify how the 
education of students at both universities in-
fluenced the knowledge in the field of tFAs, 
purchases of food products and eating habits. 
therefore students’ scores from the test were 
compared among students from studies related 
to food and health sciences with different stud-
ies (economic, marketing, agriculture, etc.). In 
addition, it was hypothesized that students of 
a master’s degree course, especially from ma-
jors related to food and nutrition, are charac-
terized by a high level of knowledge in the field 
of tFAs and fats.

MAtErIALs AND MEtHODs

the analysis was based on the results of a sur-
vey carried out in 2012 among students from the 
University of Life sciences in Warsaw (sGGW) 
(in Poland) and the University of Life sciences in 
Wageningen (WUr) (in the Netherlands). 

before the questionnaire was distributed to re-
spondents, a pilot test had been done. 215 peo-
ple participated in the survey, but 194 of these 
questionnaires were qualified. 90 questionnaires 
were completed by students with different na-
tionalities from Wageningen University (table 1), 
while the rest of the respondents were Polish stu-
dents from sGGW. the survey was addressed 
to students finishing their education at univer-
sities, from fields of studies related to food and 
nutrition, and also from other majors, but de-
claring an interest in the issues of food and nu-
trition. At first the study was conducted in the 
Netherlands. Participants of courses related to 
food sciences, which are in the master’s degree 
program, were invited to take part in the sur-



Ital. J. Food Sci., vol. 27 - 2015 3

vey. students taking the bachelor’s degree were 
allowed to participate in these classes (table 1) 
only if they had finished specialized courses. Par-
ticipants of these elective classes were students 
representing different majors. therefore people 
who took part in the study were divided into two 
groups: respondents studying subjects related 
(fs) and not related to food and nutrition scienc-
es (nfs). students from WUr came from different 
countries, mainly of the European Union (ta-
ble 1). Master’s degree studies at this universi-
ty are open, which means that students are re-
cruited from all over the world and classes are 
taught in English. then, the study was conduct-
ed on respondents from sGGW in Poland. they 
were mainly students taking a master’s degree, 
from majors related and not related to food and 
nutrition science. students not attending any 
food faculties declared that they were interest-
ed in food related topics. In this connection, al-
though there was a small population size it is as-
sumed that the obtained results will answer the 
question whether it is necessary to intensify the 
education of students (including those that the-
oretically should have a high nutritional knowl-

edge) in the subject of food fats especially those 
that contain trans isomers.

the survey was held in the classrooms and 
the questionnaire was distributed in a paper ver-
sion to respondents. the interviewer was present 
with the students. surveys that were distribut-
ed to students in the Netherlands were written 
in English, while in Poland they were in Polish.

Questions in terms of content were divided into 
those which were a test of the respondents’ knowl-
edge (10 questions) and observations of the stu-
dents’ eating habits. In the questionnaire there 
were also basic questions – legal information (ta-
bles 1 and 2). Most of the respondents were wom-
en (table 2). Most of the respondents were aged 
24. In the case of WUr they constituted 24.4% of 
the whole population, while in sGGW 55.8%. the 
average respondents’ age in Holland was around 
25 and in Poland 23. In the Netherlands the age 
range was much wider than in Poland. the eld-
est respondent of the survey was 58 years old.

In the discussion results of students from 
studies related to food and human nutrition and 
students from studies not related to these fields 
were analyzed separately. With regard to ques-
tions concerning the knowledge test a scoring 
system was used in which each respondent re-
ceived one point per correct answer. the max-
imum score was 13 points. such presentation 
of responses helped to interpret the results and 
assess the level of knowledge of the students.

survey results were analyzed in Excel 2011 
and the statistical program statistica v10.0. 
One-way analysis of variance and χ2 test were 
applied, with the significance level p<0.05. In or-
der to conduct statistical analysis the respons-
es were expressed as a percentage of answers. 

rEsULts AND DIscUssION

Analysis of the answers given 
by respondents concerning knowledge 
of trans fatty acids

Over 90% of the examined populations were 
students from studies related to food or health 
and respondents interested in this topic. 

All students studying in the field related to 
food and nutrition had heard earlier the name 
“trans fat”. However, 65% of WUr and 80% of 
sGGW students from other studies had heard 
this term (Fig. 1). similar studies were conduct-
ed in canada, where since 2005 it has been ob-
ligatory to provide information on the content 
of tFAs. On this basis, it was found that food 
selection based on tFAs increased significant-
ly (sMED, 2012). A study conducted in 2007 
among students of different fields of study (re-
lated to food and not related) in the U.s. (where 
since 2006 it has been obligatory to label food 
products containing tFAs) showed that 92% of 
respondents were aware of the term “trans fat” 

table 1 - Nationality of WUr students.

Country Contribution (%)

Netherlands 38
Spain 18
Czech Republic 10
Finland 4
Germany 4
Hungary 4
USA 4
Canada 4
China 4
France 2
Greece 2
Turkey 2
Denmark 2
Sweden 2

table 2 - characteristics of the studied population.
Legends’:*fs – students from studies related to food science 
or human nutrition; 
**nfs – students from studies not related to food science.

Specification Structure of population (%)

  WUR SGGW

sex women 78 81
 men 22 19

age avarage 24.6 24
 SD 5.60 0.99

field of studies Fs* 38 81
 Nfs** 62 19

degree of studies bechelor’s 16 8
 master’s 84 92



4 Ital. J. Food Sci., vol. 27 - 2015

Fig. 1 - students who had heard the 
term “trans fat”.
sGGW - University of Life sciences in 
Warsaw; WUr - Wageningen Universi-
ty; all – all of the respondents; fs – stu-
dents from studies related to food sci-
ence or human nutrition; nfs – students 
from studies not related to food science.

Fig. 2 - sources of tFAs indicated by 
students of (a) WUr and (b) sGGW.
*all - all of the respondents; * fs, nfs - 
explanation under the table 2.

(stAMPFEr et al., 1991). based on this, it can be 
assumed that the subject of tFAs is more wide-
spread in the U.s. (also among students of sub-
jects not related to food or nutrition). 

Most of the respondents correctly indicate as 
the main source of tFAs 3 groups of products: 
shortening, hard margarines and pastry prod-
ucts (Fig. 2). the other correct answers related to 
natural sources of trans fatty acids (milk fat and 

dairy products) were selected much more often 
(30% more) by the students from WUr (Fig. 2a) 
than from sGGW (Fig. 2b). the aim of the fol-
lowing question was to verify whether respond-
ents knew that food products might be a natu-
ral source of tFA developing naturally in bod-
ies of ruminants. In research done by stampfer 
(1991) 59% of students considered confection-
ery products as a source of tFAs in their diet.



Ital. J. Food Sci., vol. 27 - 2015 5

Analysis of answers given by respondents 
concerning knowledge of the nutritional role 
of TFAs and fat

Most tFAs, mainly coming from industrial 
fats, have a negative influence on the human 
body. they contribute to increase of cardio-
vascular diseases. Only in the case of conju-
gated linoleic acid (cLA), which is present in 
the fat of ruminants, is it believed that the ef-
fect is positive (GEbAUEr et al., 2007). there-
fore, the next question was to check the stu-
dents’ knowledge about the impact of tFAs 
on human health. At both universities more 
than two thirds of the students answered that 
tFAs have an adverse effect on human health 
(Fig. 3). similarly, in another survey (stAMP-
FEr et al., 1991) 73% of American students 

considered tFAs as negative food components 
for health. 

Another question, testing knowledge in the 
field of fats with particular emphasis on tFAs, 
considered nutritionally valuable elements 
which are supplied to the body from fat. As 
nutritionally beneficial elements, respondents 
chose the following answers: essential fatty ac-
ids (EFAs), vitamins and, unfortunately incor-
rectly, saturated fatty acids (sFAs). All of the 
students who study food and nutrition and re-
lated fields at sGGW selected EFAs and half of 
them vitamins (Fig. 4a). Among those students 
who study food science and nutrition at WUr, 
89% of them selected the answer for EFAs and 
32% for vitamins. several people (12%) from the 
Dutch university thought that tFAs are nutri-
tionally important (Fig. 4b).

Fig 4 - Nutritionally valuable elements indicated by students of (a) sGGW and (b) WUr.
Explanation under the Fig. 1.

Fig. 3 - structure of responses to the 
question “Are tFAs good for one’s 
health?”.
a - no, b - yes, c - it depends on their 
origin, d - I do not know;
explanation under the Fig.1.



6 Ital. J. Food Sci., vol. 27 - 2015

Results of the knowledge test

From the test of knowledge in the field of fats, 
students from sGGW in Warsaw scored around 
9 points and students from WUr 8 points, from 
the 13 possible (Fig. 5). Polish students from 
studies related to food and nutrition sciences 
did not show any statistically significant dif-
ferences (p < 0.05) in higher knowledge in the 
field of tFAs and fats than the respondents from 
unrelated studies (Fig. 5). However, differences 
were significant in the case of students from the 
Dutch university. 

Eating habits of respondents

students of both universities were eating 
pastry and confectionary products at a similar 
frequency (table 3). It could be due to similar 
availability of these types of products in shops 
and vending machines at universities. Wom-
en were consuming much more of these types 
of products than men. In the Netherlands 80% 
and in Poland 62% of female students declared 
that they consume sweet snacks at least sever-
al times a week. Men had better eating habits, 
because two thirds of sGGW male students and 

nearly all male students from Wageningen Uni-
versity stated that they eat such products very 
rarely. Men from the Polish university were eat-
ing confectionary and pastry products more of-
ten than men studying in Holland. researchers 
(UrbAŃsKA and cZArNIEcKA-sKUbINA, 2007) 
previously reported that 21% of high-school stu-
dents were eating sweet snacks every day, while 
31% consumed them several times a week. thus, 
it can be concluded that university students eat 
fewer sweets than high-school students. 

tFAs develop during frying. the most sen-
sitive to trans isomerization in heat treatment 
are oils rich in unsaturated FAs. MOrENO et al. 
(1999) reported that the tFA content substan-
tially increases at 150°c and at 200°c reaches 
357% compared to the initial content of trans 
isomers, while at 300°c it reaches the level of 
3026%. that is why, for frying, it is advisable to 
use fats with a high thermal resistance. Almost 
all of the students declared that they use vege-
table oil for this reason (94% of WUr respond-
ents and 90% sGGW). FLAcZYK and KOrcZAK 
(2002) obtained a slightly different structure of 
answers of the question related to the fat used 
for frying. they found that, for frying meat, the 
most popular fat was lard (32% of answers) and 
vegetable oil (25%), for fish vegetable oil (91%), 

Fig. 5 - Averages of achieved points from 
students’ test results.
a, a – statistically not significant; a, a – 
statistically not significant; A, b - statis-
tically significant (p = 0,00291).
*explanation under the Fig. 1.

table 3 - Frequency of pastry product consumption among sGGW and WUr students.

Frequency of consumption Contribution of answers (%)

  WUR   SGGW

 women men all women men all

Once a month / not at all 11 10 11 19 10 17
2-4 times a month 9 90 27 19 60 27
2-4 times a week 43 0 33 31 0 25
almost everyday 37 0 29 31 30 31



Ital. J. Food Sci., vol. 27 - 2015 7

and for eggs table margarine (63%). to fry flour-
based products 40% of the respondents favored 
the use of vegetable oils.

students’ decisions related to purchase of 
pastry and confectionery were influenced by 
different factors (table 4). In the Netherlands 
the most popular factors of purchase taken 
into consideration were price (29% of answers) 
and information on the package (24%). Howev-
er, Polish students indicated first of all the in-
gredients and the information on the packages 
(38%) and then the brands (27%). therefore the 
Polish students appreciated above all quality of 
these products and were guided as well by the 
trust of previously eaten products of the brands. 
regardless of universities, one fifth of students 
claimed that they always chose the same prod-
ucts. In the following question the obtained an-
swers among the students from both universi-
ties were different and statistically significant 
(p = 0.04654). 

In turn, the studies of Krasnowska and salej-
da [2011] showed that 37% of respondents were 
influenced by the price of products and then by 
the expiration date and brand (each 26%). the 
results of this research are very different from 
the answers obtained by the students from the 
Polish university. 

cONcLUsIONs

Differences in the level of students’ knowl-
edge, independently of university, were statis-
tically not significant (p<0.05). taking into ac-
count the fact, the all of the examined popu-
lation’s interest in nutrition aspects, it can be 
concluded that knowledge in the topic of trans 
FAs was not satisfactory. Most of the examined 
populations had heard the term ‘trans fats’ be-
fore and were aware of their negative influence 
on human health. some of the students, inde-
pendently of the university, could not indicate all 
of the products constituting a potential source 
of tFAs (around 30%). Polish students were not 
aware of natural sources of tFAs (less than 10%) 
compared to students from the Dutch universi-
ty (around 40%). Polish students from studies 
not related to food and nutrition sciences had 
less knowledge in the topic of tFA than respond-
ents in the UsA and canada. based on this, it 
can be concluded that Polish society should be 
further educated and food producers should be 
encouraged to label packages about nutritional 
characteristics of fat.

Eating habits related to consumption of pas-
try and confectionery products, which constitute 
a potential source of tFAs, of both populations 
were similar. Worrisome is the fact that wom-
en (independently of population) were consum-
ing these kinds of products definitely too often. 

taking into account the level of knowledge of 
Polish students (sGGW) and from different re-

table 4 - Factors influencing students’ decisions of the pur-
chase of confectionery and pastry products (p = 0.04654).

 Product features  Contribution
 influencing the choice of answers (%)

 WUR SGGW

ingredients and information on the package 24 38
price 29 10
brand 5 27
attractive package 20 4
always the same products 22 21

gions of the EU (studying in the Netherlands 
– WUr) finishing master’s degree studies (fs 
and nfs) it should be considered that there is 
still a need for education about the negative ef-
fect of tFAs on health and to inform consum-
ers which products can be a source of them in 
the diet. based on the obtained results it can be 
assumed that people coming from different EU 
regions who were not educated may have even 
less knowledge in this subject. Moreover, eating 
habits of women should change as they consume 
sweet snacks far more often than men, which 
could be a potential source of undesired fatty 
acids in the diet.

rEFErENcEs

bayir A. sirkecioğlu A.N. Aksakal E. bayir M. Haliloğlu H.I. 
Güneş M. and Aras N.M. 2011. changes in the fatty ac-
ids of neutral and polar lipids of silurus glanis and bar-
bus capito during an annual cycle. IJFs. 2: 173.

Downes s.M. thow A.M.  and Leeder s.r. 2013. the effec-
tiveness of policies for reducing dietary trans fat: a sys-
tematic review of the evidence. bull. World Health Or-
gan.91: 262. 

EFsA. 2004. Opinion of the scientific Panel on Dietetic Prod-
ucts, Nutrition and Allergies on a request from the com-
mission related to the presence of trans fatty acids in 
foods and the effect on human health of the consump-
tion of trans fatty acids (request N° EFsA-Q-2003-022). 
the EFsA Journal. 81: 1. 

Flaczyk E. and Korczak J. 2002. Influence of selected fac-
tors on consumer behavior on edible fats market. Acta 
sci. Pol., technol. Aliment. 1: 113.

Gebauer s.K. Posta t.L. and Kris-Etherton P.M. 2007. the 
diversity of health effects of individual trans fatty acids 
isomers. Lipids. 9: 787.

Goodman s. Hammond D.  Pillo-blocka F. Glanville t. and 
Jenkins r. 2001. Use of nutritional information in canada: 
national trends between 2004 and 2008. JNEb. 43: 356.

Gurr M. 2000. the role of Lipids in Human Nutrition. ch. 
13. In „Handbook of olive oil”. ed. J. Harwood and r. Apa-
ricio. p. 521-563. Publisher springer Us.

Jasti s. and Kovacs s. 2010. Use of trans fat information of 
food labels and its determinants in a multiethnic college 
student population. JNEb. 42: 307.

Krasnowska G. and salejda A. 2011. consumer knowledge 
about food product labeling. Żywność. technologia. Nau-
ka. Jakość. 74: 173. 

Martin c. Milinsk M. Visentainer J. Matsushita, M. and 
De-souza N. 2007. Trans fatty acid-forming processes in 
foods- a review. Anais da Academia brasileira de ciên-
cias. 79: 343. 



8 Ital. J. Food Sci., vol. 27 - 2015

Matthäus b. 2007. Use of palm oil for frying in comparison 
with other high-stability oils. Eur. J. Lipid sci. technol. 
109: 400.

McDonald r. and Mossoba M. 1996. Trans fatty acids: la-
belind, nutrition, and analysis, Food Lipids and Health. 
chicago, Min D. Marcel Dekker. 

Moreno M. Olivares D. Lopez F. Adelantado J. and reig F. 
1999. Determination of unsaturation grade and trans 
isomers generated during thermal oxidation of edible oils 
and fats by FtIr. J. Molec. struct. 482: 551.

richter E.K. Albash shawish K. sheeder M.r.L. and co-
lombani P.c. 2009. Trans fatty acids content of selected 
swiss foods: the Trans swiss Pilot study. J. Food comp. 
Anal.  22: 479. 

simopoulos A. 1996. trans fatty acids, Handbook of lipids 
in Human nutrition. ed. spiller G. borca raton, UsA: 
crc Press Inc., 91. 

smed s.2012. Financial penalties on foods: the fat tax in 
Denmark. Nutrition bulletin.  37: 142.

stampfer  M.L. sacks F.M. savini s. Willett W.c.  and Hen-
nekens c.H. 1991. A prospective study of cholesterol, 
apolipoproteins, and the risk of myocardial infarction. 
N. Engl. J. Med. 325: 373.

Urbańska I. and czarniecka-skubina E. 2007. Food prod-
ucts consumption frequency of youth offered by school 
shops. Żywność. technologia. Nauka. Jakość. 52: 193. 

Żbikowska A. 2010. Formation and properties of trans fatty 
Acids – a review. Pol. J. Food Nutr. sci .60: 107.

Paper Received October 22, 2013  Accepted April 13, 2014