The SA Journal Diabetes & Vascular Disease Volume 16 No 2 (November 2019)

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RESEARCH ARTICLE SA JOURNAL OF DIABETES & VASCULAR DISEASE
70 VOLUME 16 NUMBER 2 • NOVEMBER 2019
dietary intake may be a worthy approach to decrease elongation of
n-6 FAs leading to reduced plasma C20:4n-6 levels and increased
plasma levels of C22:6n-3 and C20:5n-3.58 As C18:3n-3 is an
essential FA, this pattern, identified in our study participants, is
probably related to food intake and therefore indicative of a higher
intake of vegetable oils, legumes, nuts and seeds.61
Strengths and limitations
A rigorous methodological approach of sequential regression
modelling enabled us to investigate the associations between
dietary FA and plasma phospholipid FA patterns, respectively, and
measures of adiposity and the MetS. Another strength of our study
is the use of both dietary FA and plasma phospholipid FA patterns,27
which is a preferred method to investigate the association between
diet and diseases.27
Our work is not free of limitations. Firstly, inaccuracies
associated with collecting dietary intake data may have influenced
the dietary FA results; however, in our population, fieldworkers
collecting dietary data were intensively trained and supervised, and
both under- and over-reporters of dietary intake were excluded.50
In addition, repeatability of the QFFQ was also demonstrated.10
Secondly, the cross-sectional design does not account for possible
reverse causation between measures of adiposity and dietary FA
intake or plasma phospholipid FA concentration, nor can causality
be inferred. Thirdly, a possible limitation of the study is incomplete
information on FA composition in the food composition databases.
This limitation was compensated for by our study design that also
considered plasma phospholipid FAs. Fourthly, we assessed the
associations with indirect measurements of adiposity, including
BMI, WHtR and WC, as secondary markers of total and central
adiposity, whereas imaging methods would better differentiate
between lean and fat mass.
Conclusion
To our knowledge, this is the first study to investigate and
document novel data on dietary FA and plasma phospholipid FA
patterns and their association with measures of adiposity and the
MetS in a selected group of black South African adults. This study
presents evidence that although marginal association was found
with dietary FA patterns, some circulating plasma phospholipid
FA patterns were more strongly and significantly associated with
BMI, WC, WHtR and the MetS. The high-Satfat and n-3 VLC-PUFA
patterns were positively associated with adiposity and the MetS,
whereas the n-9 LC-MUFA and n-3 EFA patterns were inversely
associated with adiposity. These patterns may suggest possible
differences in FA metabolism between lean and overweight/obese
individuals. It should also be considered that, in a study population
with low-fat intakes, such as the PURE participants, plasma FA
levels may reflect endogenous FA generation rather than dietary
intakes, which could result in different findings than those reported
in other studies from affluent communities.
Our results are not sufficiently conclusive to make
recommendations on dietary FA intakes in this population. Further
prospective cohort studies that explain possible differences in
characteristics of FA metabolism among black South African men
and women are needed. More studies that apply the use of dietary
FA and plasma or tissue FA patterns are required to determine
whether the results from the current study can be generalised to
the black population of African descent.
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