Cardiovascular Journal of Africa: Vol 22 No 6 (November/December 2011) - page 35

CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 6, November/December 2011 AFRICA 325
Recommendations regarding the daily intake of n-3 fatty
acids vary between 400 and 1 000 mg EPA + DHA in the form
of food or supplements.7-13 Nevertheless, it is still not known
what the optimal daily intake of EPA and/or DHA should be and
how these fatty acids affect the metabolism of 18-carbon fatty
acids and longer n-6 and n-3 fatty acids, and whether this might
result in any adverse health outcomes. Based on the available
evidence, n-3 fatty acid supplements provided in the appropriate
dose would be expected to confer health benefits, especially in
individuals who do not eat fish.1
To obtain these suggested daily intakes might be challeng-
ing for the consumer if only fatty fish is eaten, since ample
amounts of about 220 to 240 g fatty fish (e.g. salmon) must
be consumed weekly to reach a daily intake of 500 mg EPA +
DHA.14 Therefore, fish oil preparations may be helpful to reach
the daily recommended n-3 fatty acid intake. However, the actual
long-chain n-3 fatty acid content of fish may fluctuate greatly,
even within a single species, and is dependent on geographic
origin, season and preparation.15,16
In a recent study17 in Belgium, 15 food supplements formu-
lated as soft capsules containing n-3 fatty acids were evaluated
by desegregation, determination of peroxide values and assay of
the n-3 fatty acid content. All the products contained purified
fish oil rich in n-3 fatty acids, mainly EPA and DHA, and were
available as triglycerides, ethyl esters or free fatty acids. Seven
of the 15 food supplements deviated from one or more of the
criteria with regard to the recommended peroxide value and the
content of one or more of the fatty acids.
In an analysis of n-3 fatty acids in fish oil supplements
conducted in Austria, nine supplements were analysed using
capillary gas chromatography to determine the n-3 fatty acid
content. In comparison with the manufacturer’s information, four
supplements did not differ significantly from the concentrations
given, whereas four supplements contained substantially more
EPA and DHA than stated on the label. One of the manufactur-
ers did not declare the amount of n-3 fatty acids in the product.
Regarding manufacturer’s recommendations for daily intake,
one of the supplements exceeded the amount recommended by
healthcare organisations. Five of the nine supplements lacked
more than 30% EPA and DHA to meet the American Heart
Association’s recommendations. Additionally, two supplements
failed to achieve the range of 0.5 to 1.8 g n-3 fish oil found to be
effective in most studies.18
Currently, no similar existing data are available for n-3 fatty
acid supplements offered on the South African market. Although
n-3 fatty acids in the form of supplements appear to be the safer
and more controllable way of consuming n-3 fatty acids, all
preparations rely on fish oil as a source of EPA and DHA, which
may show the same variability as the natural product these prepa-
rations are derived from. Additionally, South African consum-
ers have grown accustomed to the high quality inherent in the
manufacture of conventional medicinal products and usually
accept without question the consistency, purity and potency of
prescription and non-prescription medications. Consequently,
consumers have little reason to doubt the package label claims
on conventional medications.
However, a similar claim cannot be made for dietary supple-
ments in South Africa since no regulatory structure for dietary
supplements currently exists. As a result, consumers of nutri-
tional supplements must depend on self-regulation within the
nutraceutical industry for assurance of product quality, consist-
ency, potency and purity. Reliable and trustworthy nutritional
information is vitally important for the consumer since mislead-
ing nutritional information can lead to errors in daily dosage,
with serious dose-related side effects.
The aim of this study was therefore to analyse the fatty acid
content, composition and the level of rancidity of commercially
available n-3 supplements on the South African market. The
objectives of the analyses were to compare analysed EPA and
DHA content of capsules to manufacturers’ labelling informa-
tion, to compare the number of capsules and price of supple-
ments to meet international recommended dietary intakes, to
supply an indication of the EPA to DHA ratio of commercially
available capsules, and to measure the conjugated diene content
(early indication of lipid peroxidation) in n-3 fatty acid supple-
ments on the South African market. In addition, the mercury
content of all the products was determined.
Methods
The fatty acid content, composition and conjugated diene
content of 45 commercially available n-3 fish oil supple-
ments were analysed. Brands analysed, in no particular order,
included: Amipro®, Biogen®, Equazen®, Vital®, Clicks®, Clicks
Health Basics®, Bettaway®, Thinkwell ®, AddVance®, NutriLida®,
Dischem®, Golden Products®, Health Balance®, Holstix Fish®,
AddAway®, Tslim Plus®, Amway Nutrilite®, Rejuvenesse®, The
Real Thing®, Solal®, Durbell®, Natrodale®, Optimega®, Revite®,
Vitaforce®, Mum Omega®, Preg Omega®, OmegaCare®, Brain
Child®, Bioter Health® and Unique Formulations ®.
The conjugated diene (CD) content of oils represents an early
stage of oxidation (rancidity). The content of conjugated dienes
in the 45 n-3 capsules were determined spectrophotometrically
as described by Recknagel and Glende.19 Since no CD reference
values were available for oils, the CD content of fresh, unopened
sunflower, olive palm and canola oil were used against which
to compare the supplements’ CD contents. The CD contents of
sunflower, olive and canola oil were 4.28, 6.68 and 8.28 μM,
respectively. The CD contents of sunflower, olive and canola oil
of which half of the contents had already been used were 16.8,
18.2 and 18.7 μM, respectively.
The content of mercury in the 45 n-3 capsules was determined
by atomic absorption spectroscopy according to the method of
Aduna de Paz et al. 20 Samples were digested with nitric acid
(HNO3 ) and hydrogen peroxide (H2O2) in a microwave oven
(Milestone MLS-1200 MEGA, Milestone GmbH) equipped with
a high-pressure rotor for six teflon vessels. Total mercury (Hg)
was determined by cold vapour generation on a Thermo atomic
absorption spectrophotometer (SOLAAR M Series) coupled to
a vapour generator (Thermo model VP100, Thermo Scientific),
using SnCl2 as the reductant. Standard quality-control procedures
were adopted throughout. Spiked samples gave an average recov-
ery of 94.1%.
A Varian model 3300 chromatograph was used and fitted
with a BPX-70 fused silica capillary column (30 m × 0.32 mm
i.d., 0.25-mm film thickness). The injector and flame ionisation
detector was at 240 and 280°C, respectively. The column temper-
ature was programmed from 160 to 220°C at a rate of 3°C per
minute. A hydrogen column flow rate of 30 cm.sec-1 was used.
The method of fatty acid extraction and methylation as