CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 7, August 2012
AFRICA
377
employed in the rural areas. None of these three variables is an
ideal, independent indicator of SES, but it was assumed that each
could be used to distinguish between higher and lower socio-
economic groups. Nevertheless, the data should be interpreted
with care.
Patterns of dietary intakes and risk factors for CVD emerged,
regardless of which indicator of socio-economic status was used,
with agreement between results of being urban, highly educated
and employed. However, as indicated above, there were also
some exceptions, which could be explained.
The analysis of the relationships between socio-economic
position and CVD risk factors in the participants of the THUSA
study
4
showed that nine years earlier, most (but not all) of the
CVD risk factors were significantly higher in the subjects from
the higher socio-economic group. The major difference between
the THUSA study results and the PURE study results reported
here was that total serum cholesterol levels did not differ between
the higher and lower socio-economic groups, and that increased
plasma fibrinogen levels were higher in subjects from the lower
socio-economic groups in the PURE subjects.
Although blood pressures were higher in urban subjects, in
those groups with higher educational levels or employed, blood
pressures did not differ significantly or were even lower than
in those with lower educational levels or unemployed. These
results suggest a drift of CVD risk factors (lipids and fibrinogen)
from participants with high SES to those with lower SES.
The changes in dietary intakes are intriguing. The typical
increases in energy and fat intake associated with urbanisation
were seen in the PURE subjects (Table 1). However, in
women with the highest educational level, there were significant
decreases in total energy and fat intake, suggesting that these
women were now following a more prudent diet. As for urban
participants, men with higher educational levels and employed
men and women still had higher energy and fat intakes, reflected
in higher BMIs and serum triglyceride levels. This raises the
question whether diet was in anyway responsible for the drift of
the CVD risk factors.
It seems that the contribution of low intake of macronutrients
should also be considered. It has been mentioned that
although micronutrient intake of the urban subjects increased,
recommended values were not reached. James and co-workers
26
showed in the THUSA study that low micronutrient status was
associated with increased plasma fibrinogen levels. Also, it is
known that several antioxidant micronutrients protect against
CVD and other NCDs.
17
It is therefore reasonable to suggest
that not only a prudent diet regarding macronutrients, but also
an adequate diet regarding micronutrients is a prerequisite for
dietary protection against CVD.
The intakes of dietary fibre in all groups were low (see
Table 1). High intake of dietary fibre (from whole grains, fruit
and vegetables) is known to protect against CVD.
29
Physical activity is a key determinant of CVD risk and should
always be taken into account. In this study it was not reported,
as the focus of this study was to observe whether a shift had
occurred prior to the results we published on the THUSA study.
4
Different demographics, including racial and religious
heterogeneity of populations, may have an impact on dietary
patterns. Since this epidemiological survey was composed of
2 010 black Africans undergoing transition and predominantly
Christian, we state that religion did confound our results or act
as modifier effectors to these associations.
These are baseline results from a prospective epidemiological
study that is on-going. Therefore findings reported here give us
an insight into the associations between SES and specific CVD
risk factors. These observations have limitations in that they
were carried out at one point in time and give no indication of the
sequence of events – whether exposure occurred before, during
or after the onset of the outcome. This being so, it is impossible
to infer causality.
After subsequent follow ups (prospective), one of the
advantages of such a study is that it can help determine and
observe risk factors in those participants previously free of risk
factors. Because the studies are longitudinal over time, and
the collection of results is at regular intervals, recall error is
minimised.
Conclusions
South Africa is undergoing political changes which have led
to rapid economic development and urbanisation of its African
people. This has led to an increase in rural–urban migration, thus
exposing the ‘once-protected’ black rural population to more
Westernised dietary habits. These ultimately lead to the observed
increase in incidence of NCDs in this population.
30
The results of this study showed that urban, educated and
employed subjects had high levels of several dietary and
biochemical risk factors for CVD. However, the results also
indicated that many people living in the rural areas of the North
West province and those who had lower educational levels and
were unemployed also had an increased risk of CVD despite still
following a prudent but micronutrient-deficient diet.
It was therefore concluded that the burden of CVD is shifting
from the more affluent groups with higher SES to the poor. At
this time, it seems that many of the risk factors of CVD are
prevalent in all SES groups of black South Africans.
It is therefore recommended that intervention programmes
to prevent CVD and other NCDs should be targeted at all SES
groups. Furthermore, efforts to improve dietary and nutrient
intakes should not only focus on steering the nutritional transition
into consumption of a more prudent, low-energy, low-fat diet,
but should also ensure that sufficient micronutrients are taken in
by emphasising the importance of a varied diet with sufficient
amounts of nutrient-dense foods.
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