OMEGA-3 LC PUFA CONTENTS AND OXIDATIVE STABILITY OF ENCAPSULATED FISH OIL DIETARY SUPPLEMENTS
Wojciech KolanowskiUniversity of Life Sciences in Warsaw, Faculty of Human Nutrition and ConsumerSciences, Warsaw, Poland
The aim of this study was to examine omega-3 LC PUFA content and oxidative stability offish oil dietary supplements available in Poland. Nineteen brands of fish body oil and fishliver oil capsules were purchased over the counter and analyzed. Oil content, fatty acidcomposition and peroxide value were determined. The label claims for EPA and DHA forthe majority of the products were presented with reasonable accuracy. However, it can besupposed that the oxidative stability of some fish oil products available on the market mightnot be sufficient to ensure health quality and safety during longer storage.
Keywords: Fish oil, Omega-3 LC PUFA, Oxidation, Supplements.
INTRODUCTION
Fish and other sea animals are the richest source of omega-3 long chain polyunsatu-rated fatty acids (LC PUFA) in human diet. Positive health effects of omega-3 LC PUFA,especially eicosapentaenoic acid C20:5 n-3 (EPA) and docosahexaenoic acid C22:6 n-3(DHA), are well demonstrated. Omega-3 LC PUFA decrease the risk of cardiovasculardiseases, some types of cancer and autoimmune disorders.[1–3] They are also important forproper development and function of the brain and retina.[1–3] Omega-3 LC PUFA arestructural components of neuronal and other cell membranes and desirably modulate theproduction of regulatory eicosanoids and inflammatory cytokines.[2,4] They are also usedin prevention and treatment of many diseases like rheumatoid arthritis, cardiovascular dis-eases and some types of cancer. Desirable effects of omega-3 LC PUFA on human healthwere discovered in the seventies when Dyerberg and co-workers studied the health statusof Greenland Eskimos in comparison to continental Danes. Very low incidence of cardio-vascular diseases and cancer was found among Eskimos despite a diet extremely rich insaturated fats and cholesterol.[5] This effect was associated with high fish and seal con-sumption, which contain high amounts of health protecting omega-3 LC PUFA in the lipidfraction.[4,6]
Received 25 October 2008; accepted 28 November 2008.Address correspondence to Wojciech Kolanowski, University of Life Sciences in Warsaw, Faculty of
Human Nutrition and Consumer Sciences, Nowoursynowska str. 166, 02-787 Warsaw, Poland. E-mail: [email protected]
OXIDATIVE STABILITY OF ENCAPSULATED FISH OIL 499
Depending on fish species, age, season, and area of living, fish oils may contain 100to 300 g kg−1 of EPA and DHA.[7,8] However, there is a large gap between the actual con-sumption of fish and the recommended intake of omega-3 LC PUFA. Because of the lowacceptance of oily fish in many societies—where the so-called Western-style diet is pre-dominant—the average fish intake is currently far below the recommended two to threefish servings per person, per week.[9] Currently, an average level of omega-3 LC PUFAintake in most developed Western countries is approximately 0.15 g per person per day,which is below recommended minimum. Also the ratio between omega-6 and omega-3PUFA in the average diet is 15:1 instead of the recommended 4:1.[9–12] The InternationalSociety for the Study of Fatty Acids and Lipids (ISSFAL) recommends an minimumintake of omega-3 LC PUFA to be 0.5 g of DHA plus EPA per person per day.[13,14] Theupper limit of omega-3 LC PUFA intake was established for the USA in the year 2000.The US Food and Drug Administration stated that daily intake of EPA and DHA shouldnot exceed 3.0 g per person per day in the form of fish oil from food and dietary supple-ments.[15] An adequate intake of omega 3 LC PUFA is particularly important for womenof childbearing age. Higher maternal intake is required during pregnancy and lactation tosupport the development of the fetal and infant brain and may reduce the risk of allergicdisease in the offspring. Women of childbearing age are recommended to eat two portionsof oily fish per week (average 0.4–0.8 g of omega-3 LC PUFA per day).[9,12,16] Besidesfish consumption, alternative ways to ensure an optimal omega-3 LC PUFA intake is sup-plementation of the diet with fish oil capsules.[2,17,18]
Due to low consumption of fish in many Western societies, supplementation ofthe diet with fish oil capsules seems to be the easiest way to elevate the level of omega-3 LC PUFA intake.[15,16] This may result in better health protection. Such supplementsusually contain well-refined, unhydrogenated fish oil from fish liver or whole fishbody. Omega-3 LC PUFA is naturally present in to a greater extent in fish body oilsthan in fish liver oils. Fish liver oil is also a rich source of vitamins A and D. Someomega-3 LC PUFA supplements may contain algal oil (or other single cell oils), krill orseal oil, which are also a rich source of these fatty acids. However, the predominantsource for omega-3 LC PUFA dietary supplements manufacturing is unhydrogenatedfish oil, which may be used in natural or concentrated form, usually stabilized withantioxidants. Some pharmaceutical companies also produce free omega-3 LC PUFAconcentrates, which are isolated from the triacylglycerol structure and subsequentlyesterified. Omega-3 LC PUFA rich oils are often encapsulated, which stabilizes oilsand enables easy administration and dosage. Such products are sold only in drug storesin Poland.
Encapsulated fish oil products are extensively commercialized in developedcountries. Intake of fish oil capsules was shown to increase cardiovascular health, aswell as body immunological defense.[8,22–24] However, some consumer organizationsindicate that the composition and quality of fish oil supplements available on themarket might not reach quality requirements.[25,26] The most important quality fea-tures of fish oil supplements and other fish oil products are concentration of omega-3LC PUFA and stability against oxidation. Due to 5 and 6 unsaturated bounds in thecarbon chain omega-3 LC PUFA are especially susceptible to oxidation resulting inthe formation of peroxides and their byproducts, which can be harmful forhumans.[18,19] Hence the objective of this study was to examine omega-3 LC PUFAcontent and oxidative stability of encapsulated fish oil dietary supplements availableon the Polish pharmaceutical market.
500 KOLANOWSKI
MATERIALS AND METHODS
Samples
Nineteen brands of fish oil capsules, produced by different companies, were pur-chased over the counter in Warsaw drugstores and analyzed. The products were selectedaccording to the market survey carried out in the years 2004–2006 and were characterizedby significant rate of sale on the market.[27] Eleven products containing fish body oils weremarked as FBO (fish body oil) and numbered from 1 to 11. Eight fish liver oil productswere marked as FLO (fish liver oil) and numbered from 1 to 8. All products were closedin thick gelatin capsule. All were in the middle of their shelf life. Identification of exam-ined fish oil products by trade name, manufacturer, fish oil type, label claim for EPA,DHA content, and figures from our own analyses in mg per one capsule are presented inTables 1 and 2.
Oil Recovery
Fish oil content in the evaluated products was examined gravimetrically. Capsulesof each brand were weighed, opened and oil was pressed out to a clean vial. The emptycapsule cover was washed with hexane, wiped on a paper towel to recover any residualoil, and weighed again. Each measurement was done in triplicate.
Fatty acid analysis. Fatty acid composition was determined by gas chromatogra-phy (GC). To convert fish oil fatty acids to methyl esters (FAME) 25 μg of isolated oilwas saponified by 0.5 N solution NaOH with methanol, covered with nitrogen, mixed andheated in a water-bath at boiling point for 40 min. The saponified sample was transmethy-lated with 14% BF3 in methanol reagent, covered with nitrogen, at boiling point for 3 min.After that, the mixture was cooled and 3 mL hexane added, covered with nitrogen andshaken vigorously for 30 seconds while still warm. Then 40 mL of saturated water solu-tion of NaCl was added and shaken vigorously. After separation, the hexane layer wastransferred by syringe to a thin glass tube and additionally dried over anhydrous Na2SO4and decanted to clean a vial, covered with nitrogen, and capped. One μL of preparedFAME was injected into the chromatograph under appropriate conditions. The contents weredetermined with respect to methyl tricosanate (C23:0) internal standard (IS) (Sigma-Aldrich,Steinheim, Germany). FAME were prepared according to slightly modified AOCSmethod Ce 1b-89.[28]
The analysis of FAME was performed using Agilent 6890N GC (Agilent, Böblingen,Germany) equipped with Rtx 2330 silica capillary column of 100 m length, 0.25 mm ID,df 0.1 μm (Restek Corp, Bellefonte, USA). Hydrogen was used as a carrier gas at flow rate0.9 mL s−1. A split-splitless (50:1) injector at 235oC and flame-ionization detector (FID) at250oC were used. Column temperature was programmed as follows: initial 155oC, time55 min, next rate 1.5oC min−1, final temperature 210oC. Each sample was analyzed intriplicate. Results were collected in the Chem-station and transformed using softwareHP-Chem (Hewlett Packard, Palo Alto, USA). Peaks were identified by comparison withknown standards: menhaden reference oil (Supelco, Bellefonte, USA) and Supelco 37component FAME Mix (Supelco, Bellefonte, USA). Results were reported as peak areapercentages and recalculated with respect to internal standard according to AOCS methodCe 1b-89. The EPA-IS-DHA factors of 0.99-1.00-0.97 were used for these omega-3 LCPUFA.[28,29]
OXIDATIVE STABILITY OF ENCAPSULATED FISH OIL 501
Oxidative Stability
Peroxide value (PV) was measured as a primary oxidation indicator to determine theoxidative stability during storage. To accelerate the oxidation process capsules werestored at 43ºC in a Heareus B6 Function Line automatically controlled incubator (Kendro,Langenselbold, Germany). As controls fish oil capsules stored at 20ºC, limited lightaccess were used. The measurements were done at the beginning, after 11 and after 22days of storage. Each measurement was done in triplicate.
The applied iodometric method was based on ISO 3960 with chloroform and glacialacetic acid as solvents.[30] Samples representing 1.0 g of fish oil, isolated from thecapsules by pressing, were placed in the Erlenmeyer flask, and dissolved in 20 ml of chlo-roform. Then 30 ml of glacial acetic acid was added and the mixture was stirred for a fewseconds to ensure complete mixing. After that, 0.5 ml of the potassium iodide (KI)solution was added. After 1 min, 30 ml of deionized water was added and the titrationstarted. When the dark-yellow color changed to a pale-yellow, 0.5 ml of starch-solutionwas added. Titration was finished when the color disappeared. The mixture was stirredmagnetically during the procedure. Results were calculated as micro equivalents of activeoxygen per kg of oil (mEq O kg−1).
Data Analysis
The obtained results were statistically analyzed using an un-paired t-test to comparethe claimed and measured omega-3 LC PUFA contents and one-way analysis of variance(ANOVA) to assess the oxidation over the three time periods.[31] Results were analyzedusing Statgraphics Plus version 4.1 software package (Statistical Graphic Corp., Herndon,VA, USA) at a significance level P < 0.05.
RESULTS AND DISCUSSION
Fish Oil Content
Fish oil content ranged from 350–1000 g in fish body oil products (FBOs) and from250–570 g in fish liver oils (FLOs). The differences between the label claims and analyzedoil contents were not significant and ranged ± 1.8%, except FBO 4 where the experimentallevel was 2.8% higher than the label claim. (Tables 1 and 2). In all FBOs EPA and DHAcontents were claimed on the labels. The determined EPA and DHA contents were similaror even higher by 2.5–24% than label claims, except FBO 10. In FBO 10 the measuredEPA and DHA contents were respectively 5 and 7% lower than the claimed amounts. Infive FLOs, the EPA and DHA contents were not claimed on the label. However, in threesamples with EPA and DHA claims the determined contents were higher by 2.5 to 20%,depending on the sample.
Fatty Acid Analysis
In the analyzed products, over 40 different fatty acids were found. However, significantlevels were shown for 15–22 fatty acids, depending on the product (Fig. 1, Tables 3 and 4).The predominant fatty acid in most fish body oil products (except for FBOs 3, 6, and 7)was EPA C20:5 n-3 (19.1 to 24.5% of total fatty acids). Other major fatty acids were:
502
Tab
le 1
Cla
imed
and
exp
erim
enta
l con
tent
s of
fis
h oi
l, E
PA a
nd D
HA
in r
etai
l fis
h bo
dy o
il pr
oduc
ts e
valu
ated
in th
e st
udy,
with
pro
duct
type
.
Sam
ple
num
ber
Fish
oil
pro
duct
s tr
ade
nam
e an
d co
mpa
nyPr
oduc
t typ
eL
abel
ed o
il co
nten
t in
1 c
apsu
le, m
g
Exp
erim
enta
l oi
l con
tent
in
1 ca
psul
e, m
g
Om
ega-
3 L
C P
UFA
le
vels
in 1
cap
sule
- la
bel
clai
ms,
mg
Om
ega-
3 L
C P
UFA
leve
ls in
1
caps
ule
- de
term
ined
by
GC
, mg
EPA
DH
AE
PAD
HA
FBO
1O
meg
a-3
Lys
i (L
ysi H
F, R
eyki
avik
, Is
land
)U
nspe
cifi
ed f
ish
oil
1000
986
± 11
.418
012
018
8.3
± 3.
313
1.7
± 2.
9
FBO
2O
meg
a-3
fort
e (H
asco
-Lek
, Wro
claw
, Po
land
)U
nspe
cifi
ed f
ish
oil
1000
1000
± 2
.118
012
019
1.0
± 8.
113
5.0
± 9.
1
FBO
3B
ioC
ardi
ne 9
00 (
Mar
inex
Int
., L
odz,
Po
land
)S
ardi
ne a
nd a
ncho
vies
oil
900
915
± 19
.430
020
037
4.2
± 25
.221
3.2
± 21
.0
FBO
4D
oppe
l her
z ac
tiv O
meg
a-3
(Que
isse
r Ph
arm
a G
mbH
, Fla
nsbu
rg, G
erm
any)
Sal
mon
oil
800
814
± 10
.114
496
161.
9 ±
17.1
102.
5 ±
9.6
FB
O 5
Tri
enyl
(L
ek, L
ubli
ana,
Slo
veni
a)Fi
sh o
il s
ourc
ed f
rom
no
rth
seas
500
504
± 6.
290
6097
.7 ±
4.1
57.9
± 3
.8
FBO
6O
leka
rdin
(C
apsu
gel,
Ploë
rmel
, Fra
nce)
Fish
and
oliv
e oi
l, 25
0 m
g ea
ch50
050
4 ±
5.1
4530
45.3
± 3
.128
.7 ±
2.2
FBO
7B
io O
meg
a 3
Plus
(Ph
arm
a N
ord,
V
ojen
s, D
enm
ark)
Uns
peci
fied
fis
h oi
l50
050
7 ±
7.1
185
118
206.
3 ±
11.1
118.
6 ±
2.1
FBO
8O
meg
a-3
Nat
urel
l (N
atur
ell A
B,
Sagv
agen
, Sw
eden
)S
alm
on o
il50
048
6 ±
12.1
9060
98.2
± 7
.161
.7 ±
2.9
FBO
9G
alom
ega
(Gal
, Poz
nan,
Pol
and)
Uns
peci
fied
fis
h oi
l35
035
0 ±
8.1
6342
67.9
± 2
.945
.1 ±
2.2
FBO
10
Mol
ler’
s O
meg
a-3
vita
lity
(Mol
lers
, Osl
o, N
orw
ay)
Uns
peci
fied
fis
h oi
ln.
c.a
584
± 11
.115
015
014
2.5
± 9.
113
9.5
± 6.
1
FBO
11
Mol
ler’
s O
meg
a-3
hear
t pr
otec
tion
(Mol
lers
, Osl
o, N
orw
ay)
Sard
ine
and
anch
ovie
s oi
ln.
c.87
7 ±
18.4
200
200
214.
8 ±
11.1
207.
8 ±
8.1
a n.c.
: Not
cla
imed
on
the
labe
l.
503
Tab
le 2
Cla
imed
and
exp
erim
enta
l con
tent
s of
fis
h oi
l, E
PA a
nd D
HA
in r
etai
l fis
h liv
er o
il pr
oduc
ts e
valu
ated
in th
e st
udy,
with
pro
duct
type
.
Sam
ple
num
ber
Fish
oil
prod
ucts
trad
e na
me
and
com
pany
Prod
uct t
ype
Lab
eled
oil
co
nten
t in
1 ca
psul
e, m
g
Exp
erim
enta
l oil
cont
ent i
n 1
caps
ule,
mg
Om
ega-
3 L
C P
UFA
le
vels
in 1
cap
sule
- la
bel
clai
ms,
mg
Om
ega-
3 L
C P
UFA
leve
ls in
1
caps
ule
- de
term
ined
by
GC
, mg
EPA
DH
AE
PAD
HA
FL
O 1
Vit
amex
(V
itam
ex A
B, N
orrk
opin
d,
Swed
en)
Cod
live
r oi
l57
056
5 ±
9.2
5070
58.2
± 2
.185
.3 ±
3.3
FL
O 2
Bio
Mar
ine
570
(Mar
inex
Int
., L
odz,
Po
land
)Sh
ark
liver
oil
sour
ced
from
Tas
man
ia57
056
1 ±
7.1
n.c.
an.
c.19
8.9
± 2.
913
.8 ±
0.6
FLO
3N
atur
Kap
s T
ran
(Has
co-L
ek, W
rocl
aw,
Pola
nd)
Cod
live
r oi
l50
049
5 ±
4.4
4455
45.0
± 2
.762
.8 ±
3.0
FLO
4G
al T
ran
(Gal
, Poz
nan,
Pol
and)
cod
live
r oi
l35
034
5 ±
5.1
3239
34.8
± 3
.243
.1 ±
3.6
FL
O 5
Sela
mer
(T
ymof
arm
, Wro
claw
, Pol
and)
Sha
rk li
ver
oil s
ourc
ed
from
Gre
enla
nd30
029
6 ±
4.7
n.c.
n.c.
11.5
± 2
.015
.1 ±
2.1
FL
O 6
Lys
i Tra
n (L
ysi H
F, R
eyki
avik
, Isl
and)
Cod
live
r oi
l27
527
7 ±
3.1
n.c.
n.c.
27.1
±1.
935
.7 ±
2.0
FL
O 7
Eco
mer
(E
xpos
an A
B, A
neby
, Sw
eden
)Sh
ark
liver
oil
sour
ced
from
Gre
enla
nd25
024
8 ±
2.8
n.c.
n.c.
9.2
± 0.
711
.6 ±
0.5
FL
O 8
Iski
al (
Nat
urel
l AB
, Sag
vage
n, S
wed
en)
Shar
k li
ver
oil
250
247
± 3.
2n.
c.n.
c.5.
9 ±
0.5
5.7
± 0.
3
a n.
c: N
ot c
laim
ed o
n th
e la
bel.
504 KOLANOWSKI
palmitic acid C 16:0 (9.4–19.3%), DHA C22:6 n-3 (11.5–23.9%), oleic acid C 18:1 n-9(7.4–10.1%), and palmitooleic acid C16:1 n-9 (3.9–9.9%). In FBO 6 the predominant fattyacid was oleic acid C18:1 n-9 (48.8%) and the EPA and DHA levels were much lowerthan in other fish body oil products (9 and 5.7%, respectively). However, FBO 6 wasclaimed to be a half/ half mixture of fish oil and olive oil. In contrast, FBO 3 and 7 con-tained much higher EPA and DHA level than other FBOs (40.7–40.9 and 23.3–23.4%,respectively) which suggested that these products contained fish oil concentrate. How-ever, this was not claimed on the label.
In the majority of fish liver oil products, except FLO 2, the predominant fatty acidwas oleic acid C18:1 n-9 (14.6–31.7% of total fatty acids). Other main fatty acids in FLOswere: C16:0 (8.2–17.7%), C22:1 n-9 (6–14.3%) and C20:1 n-9 (7–11.7%). EPA was thepredominant fatty acid in FLO 2 (35.9%) which suggests that this product contained liveroil with an elevated EPA level. In typical fatty acid profile of liver oil, the EPA level islow, like it was shown in FLO 5, 7, and 8. In other FLOs, the EPA and DHA levels ranged2.4–10.3% and 2.3–15.1% of total fatty acids, respectively.
Generally, the EPA and DHA contents were significantly higher in FBOs than inFLOs, except for FBO 6 and FLO 2. However, the EPA and DHA levels in FBOs, as wellas in FLOs, were significantly differentiated. FBO capsules contained from 67.9 to 374mg of EPA and from 45.1 to 213 mg of DHA, except FBO 6, which contained much lessamount of these fatty acids—45.3 and 28.7 mg, respectively. FLO capsules containedfrom 5.9 to 58.3 mg of EPA and from 5.7 to 85.3 mg of DHA, except FLO 2, which con-tained much higher level of EPA (198.9 mg). The results showed that the label claims forEPA and DHA for the majority of the examined products were presented with reasonableaccuracy.
The amounts of total saturated fatty acids (SFA) in FBOs ranged from 3.3 to 32.1% oftotal fatty acids, monounsaturated (MUFA)—from 15.2 to 55.9% and polyunsaturated—from5.7 to 23.7% of total fatty acids (Table 3). In FLOs SFA ranged from 10.8 to 23.9%,
MUFA—from 43.9 to 71.2%, PUFA—from 5.0 to 38.9% of total fatty acids concentration(Table 4). In the majority of FBOs the total SFA and PUFA contents were significantlyhigher than in FLOs, though MUFA content was significantly lower. This general propor-tion of main fatty acids groups in FBOs was typical for fish body and in FLOs—for fishliver oils. Exceptions from these results were FBO 6 (mixture of fish oil and olive oil) aswell as FBO 3, 7, and FLO 2 containing concentrates.
Oxidative Stability
The PV of FBOs and FLOs at the beginning of the storage test at 43ºC were signifi-cantly differed ranging from 1.0–5.5 or even 9.8 (FBO 5) mEq O kg−1, depending on thesample. During the accelerated storage test at elevated temperature PV significantlyincreased in all products reaching at the end of the test from 2.2–12.5 mEq O kg−1, depend-ing on the sample (Tables 5 and 6). However, PV of control samples stored at 20ºC were sta-ble during all the storage time and differed from the initial values only by 10–20%.Nevertheless, in all products, except for FBO 5, the PV did not reach the upper tolerablelimit for fish oil, which is estimated as 10 mEq O kg−1.[32,33] Formation of the primary
Table 4 Fatty acids composition of fish liver oil products evaluated in the study, % of total fatty acids.
oxidation products was the highest in FBO 8 and FBO 10, among all evaluated products.In these samples the PV increased by 230 and 241%, respectively compared to the initialvalues (Figure 2). In FBO 1 and 9 PV increased by 53 and 75%, respectively. The rest ofFBO samples showed smaller increases—from 27 to 39%. In FLO 1 and FLO 7 the PVincreased by 181 and 122%, respectively (Fig. 3). In FLOs 2, 3 and 5 the PV increase wasby 45–47%. In the rest of the FLOs (4, 6, and 8) the increase was much lower—from 36 to50% of the initial value. However, the PV increase in control samples stored at 20ºC wasnot significant reaching up to 20% of the initial value.
The significant PV increase in some evaluated samples during the accelerated stor-age test suggest that despite thick gelatin capsule cover, the oxidative stability of somefish oil products might be limited. This could be a result of the type, level and combinationof antioxidants substances added, as well as the initial purity and stability of fish oil andconditions during manufacturing or concentration. Presence of conditions promoting oxi-dation of PUFA, like oxygen permeability, elevated temperature, light access, iron andcopper ions presence during processing may impair the stability of encapsulated fish oilproducts.[19,24,36] Fish oil tends to be unstable during processing due to the high suscepti-bility to oxidation of the omega-3 LC PUFA. During oxidation of fish oil the fishy offflavor significantly increases, which is the natural and strong indicator of fish oilrancidity.[8, 35,36] However, it cannot be detected in fish oil capsules covered by thick
Table 6 Peroxide values of fish liver oil products evaluated during storage, mEq O kg−1.
Figure 2 Percentage of peroxide value increase in fish body oil products of the lowest oxidative stability duringstorage test.
OXIDATIVE STABILITY OF ENCAPSULATED FISH OIL 509
gelatin coat prior to being swallowed. Our results showed that the oxidative stability ofsome of the evaluated fish oil products was significantly impaired by the accelerated stor-age test. However, only one of the evaluated products reached the upper PV tolerablelimit.
In recent years, encapsulated fish oil supplements have been strongly commercial-ized in many developed countries. However, some consumer organizations have indicatedthat the content of omega-3 LC PUFA, as well as oxidative stability of fish oil products insome cases did not meet quality guidelines. Nevertheless, as a result of the improvementin technology, the purity and stability of fish oil products is increasing. Unfortunately,published data about the composition and quality of fish oil products is still lacking. In thestudy of Fantoni and co-workers,[37] the oxidative stability of fish oil products was shownto be much lower than in the present study.[37] In 1989, Ackman and co-workers showedthat in the tested fish oil products the EPA and DHA label claims for the majority of testedfish oil products were reasonably accurate.[29] Some recent evaluations conducted byConsumerLab in USA or Consumer in New Zealand indicated that some of the fish oilproducts available on the market did not contain claimed amounts of EPA and DHA orwere oxidized, which could be harmful for consumers health.[25,26] This problem was alsoreported in 1989, by Shukla and Perkins, as well as in 1992 by Sagredos.[38,39] Sufficientoxidative stability is the most important concern related to safety of all fish oil products.Nevertheless, because of the low level of omega-3 LC PUFA in the Western-style diet,supplementation with good quality fish oil capsules seems to be advisable for health pro-tection.[40] Moreover, due to good processing technology, the food and pharmaceuticalgrade fish oil used for dietary supplements production is free from toxic contaminationsuch as mercury or PCB, which in the recent years have often been detected in many fishspecies and seafood.[41]
Figure 3 Percentage of peroxide value increase in fish liver oil products of the lowest oxidative stability duringstorage test.
510 KOLANOWSKI
CONCLUSION
The results obtained in this study showed that the label claims for EPA and DHA forthe majority of the evaluated fish oil supplements were presented with reasonable accu-racy. However, oxidative stability of some fish oil products available on the market mightbe not sufficient to ensure health quality and safety during longer storage. Increasingomega-3 LC PUFA intake is a challenge not only for the pharmaceutical, but also for foodindustry. The possibility of food fortification with omega-3 LC PUFA by fish oil additionshould be also explored. For individuals with low fish consumption regular intake of goodquality fish oil supplements or fish oil fortified foods can help to ensure adequate dietarylevel of omega-3 LC PUFA, thus decreasing the risk of many diseases.
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