CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 8, September 2013
298
AFRICA
cell values varied between 3 and 5%.
5
According to Harris’s
proposed n-3 index,
6
these levels position participants in a
high- to intermediate- risk zone for the development of CVD.
As Cape Town is located on the west coast of South Africa with
its cold sea currents, one could expect that cold-water fatty
fish consumption will be higher among people residing here
compared to residents living in the provinces without a coastline.
Consumers further away from the coast may therefore experience
even lower n-3 fatty acid levels in their blood.
However, canned fatty fish such as pilchards, sardines,
salmon and mackerel are rich in n-3 fatty acids. These products
are readily available to the majority of consumers and should
theoretically help them to obtain their daily n-3 fatty acid intakes.
Unfortunately the affordability of the products as well as some
consumers’ preferences for red meat as a protein source may
prevent them from purchasing these products. It therefore seems
that progressively more consumers turn to fish oil supplements
to augment their n-3 fatty acid intakes, as it is perceived to be an
easy, effective and safe method to rectify poor dietary intakes.
Yet controversy exists whether n-3 fatty acids consumed via
supplementation is the best way to combat disease. Some reviews
investigating the risk of major cardiovascular events reported
no association between n-3 fatty acid supplementation and a
reduced risk of all-cause mortality, cardiac death, sudden death,
myocardial infarction or stroke,
7
or for the secondary prevention
of cardiovascular disease.
8
On the other hand, other reviews
9,10
did
indicate associations between risk reduction of cardiovascular
disease and n-3 fatty acid dietary supplements. According to
Jump
et al.
,
9
conflicting results may be attributed to people at
risk for cardiovascular disease who take medications such as
statins and fibrates as well as drugs
with anti-inflammatory,
anti-arrhythmic and anti-thrombotic effects, minimising the
detectable effect of supplemental n-3 fatty acids.
Dietary recommendations and advice for the intake of n-3
fatty acids have progressed notably during the past five years. No
formal dietary reference intakes (DRIs) currently exist for EPA
and DHA but intakes that vary from 250 to 600 mg EPA + DHA
are recommended; however there are still many gaps in research
7
.
Achieving these amounts through fish intake alone might be
problematic without supplementation. To reach a 500-mg/day
EPA + DHA as recommended by the International Society for
Fatty Acids and Lipids (ISSFAL
12
) with purified fish oil, about
2 000 mg of oil with a 180-mg EPA to 120-mg DHA content
ratio would be required. To consume these amounts of EPA +
DHA through diet/non-supplementation, approximately 79 g/day
of tuna or 60 g/day of pilchards or 52 g/day of salmon should be
consumed. In addition, fish is not the dietary protein of choice
for many South Africans.
For an n-3 fatty acid supplementation to be effective, good-
quality fish oil is essential. The quality of fish oil supplements
is highly affected by the storage conditions of the refined oil
before encapsulation, the nature of the preservative added to
prevent oxidation, the time period of storage and light exposure.
The EPA and DHA content of fish oil is also subjective to the
fluctuation of long chain n-3 fatty acids even within single fish
species and is further dependent on geographic origin, season
and preparation of the oil.
In a survey
13
conducted in 2009 by our research group, where
we studied the quality of 45 fish oil supplements available on the
South African market, it appeared that supplements varied to a
large extent in terms of the measured versus the claimed content
of EPA and/or DHA, the level of lipid peroxidation, the EPA-to-
DHA ratios as well as the number of capsules and price to meet
international dietary recommendations. These findings are of
concern since no regulatory structure to monitor the quality of
dietary supplements currently exists in South Africa. Consumers
therefore depend on self-regulation within the neutraceutical
industry for assurance of product quality, consistency, potency
and purity of fish oil supplements.
Since the survey was conducted in 2009, no new labelling
and quality-assurance regulations have been published. It
was therefore decided to repeat the survey, this time on 63
supplements, to assess if there were any improvements in
the quality of fish oil supplements available to the South
African consumer. Specific objectives for the survey included
analysis and comparison of the EPA and DHA contents of the
supplements with the contents claimed on the product label;
number of capsules and price to achieve international n-3 fatty
acid intake recommendations; to determine the conjugated
diene (CD) and peroxide content of the supplement oils; and to
determine whether the long-chain n-3 fatty acids present in the
capsules were in the form of triglycerides (TG) or ethyl esters
(EE) or a combination of TG and EE.
Methods
Sixty-three n-3 fatty acid supplements were analysed for fatty
acid composition and content, CD and peroxide values as
well as EE content. Two independent researchers de-identified
the supplements and stored them in numbered containers
until commencement of analyses, hence a blind sample of
supplements was received by the researchers conducting the
analyses. Products from various brands were analysed, and in
no particular order included: Pharmamark, ReVite, ADD Vance,
Bettaway, Vitaforce, Biogen, Amipro Metagenics, Keynote
Health, Dis-Chem, Holistix, Naturelle, Natrodale, SOLAL
Technologies, Medi+Rite Pharmacy, Nativa, Pharmafrica, Clicks
Group Limited, Georen Preg, Bioharmony, Rejuvenesse, Solgar,
Amway, Pinnacle, Scientific Sports Nutrition, Equazen, Patrick
Holford, The Real Thing, Durbell, Vital, Holgoun Healthcare,
Absolute Organix, Vitabiotics, Kenzahealth, Annique, Bioter,
Ocean Gold Fish Liver Oil, and TNP Healthcare.
To determine the CD content of the fish oil supplements, a
spectrophotometric method was used as described by Recknagel
and Glende.
14
CD values were compared against reference
values as described by Opperman
et al.
13
Peroxide levels were
determined spectrophotometrically as described by Khodaparast
et al.
15
Fatty acid composition and content of fish oil
capsules
The oil content of each capsule was determined by the difference
in weight between the whole capsule and the weight of the
capsule gelatin. An aliquot of oil, about 600 mg, was weighed
in a 25-ml volumetric flask and made up to volume with
chloroform–methanol (2:1) containing butylated hydroxyl
toluene as anti-oxidant. To 50
μ
l of this stock solution was added
100
μ
l of heptadecanoic acid as internal standard (100
μ
l in
chloroform-methanol 2:1).
