CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 9/10, October/November 2013
372
AFRICA
In SA, 25–37% of adults are sufficiently active,
63
and data
from the 2003 SADHS has shown that half the population
are insufficiently active.
9
Moreover, the SA survey shows a
rural-to-urban gradient, with reduced physical activity levels
with increasing urbanisation. Moreover, increasing education
is associated with reduced occupational physical activity and
increased leisure activity. These findings are corroborated by
objective measurement in smaller regional studies in SSA,
which demonstrate similar physical activity trends, with adult
men being more physically active compared to adult women in
both urban and rural settings, and education level affecting the
domain of activity.
68-70
Traditional methods for collecting physical activity by self-
report may over- or under-estimate actual levels.
71
Moreover,
‘light activity’ is overlooked entirely. This is despite the fact that
urban-dwelling persons in low- or middle-income countries such
as SA are likely to spend a relatively large portion of their day
in at least light activity, as opposed to being entirely sedentary
(Kroff, pers commun, 2012). Importantly, work by Cook
et al
.
43
has demonstrated that even light activity (accumulated steps
per day) is associated with a reduced risk for obesity in a dose-
dependent manner. Adjusting for age, motor vehicle access,
education, tobacco use and co-morbidities, and BMI was 1.4 kg/
m
2
lower per 5 000 steps/day, and compared to being sedentary,
the risk of obesity (BMI
≥
30 kg/m
2
) was 52% lower for 10 000
steps/day.
In countries such as SA, factors such as culture, socio-
economic status and the built environment may act as barriers
to physical activity. For example, in a convenience sample of
largely urban-dwelling South Africans, self-reported leisure-
time moderate to vigorous physical activity was significantly
higher in those persons living in neighbourhoods in which crime
was not perceived to be a problem. These results are supported
by recent work from Nigeria where they showed that perceived
safety, aesthetics and cleanliness were inversely associated with
obesity and positively associated with physical activity.
72
However, in SA communities, walking for transport has still
been shown to be higher in persons from communities in which
there are no pavements (Lambert, Tshabangu and Naidoo, pers
commun, 2012), suggesting that many behaviours are outside
of an individuals own volition. Cultural barriers to physical
activity in black SA women include the acceptability of wearing
tight-fitting clothing when participating in sport, as well as the
perception that participating in leisure-time physical activity
takes time away from household chores.
73
Diet and eating behaviour
Dietary intake and quality have been shown to be associated
with the prevalence and risk of obesity.
74
Obesogenic dietary
behaviours include a high-energy intake, high dietary fat and sugar
intake, low-fibre fruit and vegetable intake, or a combination of
the above. Several of these dietary habits and behaviours are
associated with the adoption of a more Western lifestyle and
represent the nutrition transition in developing countries.
When compared to other SSA countries, SA is considered to
be further along the nutrition transition, characterised by higher
intakes of dietary energy (600 kCal above the mean for 39 other
SSA countries) and fat intake (24.5% vs sample mean of 18.9%),
as well as higher levels of obesity than other countries.
46
In a
study of Kenyan and SA women, Steyn
et al
.
75
showed that the
rural environment differed between countries, with more than
60% of rural Kenyan women having access to land, which was
associated with a higher nutrient mean adequacy ratio, dietary
diversity score and food variety score than rural SA women.
This finding highlights the difference in the effect of the rural–
urban environment of different populations along the nutrition
transition.
In SA, data from the 2003 SADHS showed an increase
in dietary quality with urbanisation, as characterised by an
improvement in micronutrient intake (micronutrient score based
on tertiles of the RDA).
9
In contrast, Oldewage-Theron
et al
.
76
reported that nutrient quality was poor in peri-urban black SA
women, with low food variety and diversity scores attributed
to low household food security and availability. Consistent
within all of these SA studies, including the THUSA study,
39
urbanisation was associated with an increase in dietary fat intake,
which corresponded to the increased prevalence of obesity in
urban compared to rural women.
Most black South Africans who urbanise do so into informal
settlements that may not be situated close to any of the large food
chains that offer a greater variety and quality of food. The most
convenient place to purchase food is from informal vendors who
sell inexpensive and less varied foods of poor quality. Indeed,
data from a study in SA children showed that the lack of grocery-
style shops and many accessible tuck shops and street vendors
is shaping new buying habits of children that include a higher
intake of less nutritious foods.
77
For example, a study of adolescents in the same cohort
reported the frequent purchase of the ‘quarter’, a combination
of white bread, polony, fried chips and cheese, as a meal.
78
The
‘quarter’ is of good economical value based on the cost/kCal,
but is low in fibre and micronutrient quality. Temple
et al
. have
shown that a healthy diet is more expensive than a less healthy
diet, and therefore is not affordable for the majority of South
Africans.
79
Socio-economic status is another important factor that
influences dietary quality and food choices. Increased wealth
and disposable income contribute to food choices and are
associated with the aspiration to consume more meat products,
bigger portion sizes, and a more frequent intake of fast foods.
73
Conversely, low household food security is associated with poor
dietary quality, characterised by low food variety and diversity
scores.
80
Household food security may be described as a continuum,
from food secure, food insufficiency (some concern regarding
having enough funds to buy food for the month, without
changing diet), low food security (typically reducing the quality
of the diet), to food insecure (where there is a reduced food
intake and skipping meals).
81
Notably, mothers who are food
insecure are more likely to be overweight or obese than men and
women without children, and food-insecure fathers.
Martin and Lippert
81
showed that this is not as a result of
biological changes that occur with pregnancy, but rather may
be the adoption of strategies, albeit unhealthy, to protect their
children when faced with food insecurity. Furthermore, single
mothers appear to be at greater risk for food insecurity and
obesity, compared to women with partners. However, once
households are truly food insecure, women are more likely to be
underweight.
