Osteoporosis literally means 'porous bone" and is characterized by an increase in bone
fragility and susceptibility to fracture, which typically involves the wrist, spine and hip
(South African Medical Association (SAMA) Working Group, 2000). In South Africa
osteoporosis and fractures are more common in whites than in blacks. African-American
men experience hip fractures at a rate of only half of that of Caucasian men. The bone
mass in Africans were found to be 6 - 12 % higher than in Caucasians at all ages. A
higher peak bone density at skeletal maturity in African-Americans were found, so that
despite comparable age related bone loss, African Americans reach the fracture
threshold less frequently than whites. Age-related bone loss that begins later, is less
severe, or occurs in different skeletal sites in African-Americans than whites (Luckey et
al., 1996). American whites have a higher bone turnover than American blacks, but in
contrast to this American data. South African blacks may have a higher bone turnover
and lower bone density than whites (Daniels et a/., 1995). If it is compared with
Caucasians a lower rate of hip fracture in South African blacks were found, despite lower
bone density at all ages (Villa, 1994). The lower fracture rate in blacks than in whites is
because of greater bone mass and higher bone turnover leading to more frequent
renewal of damaged bone. Blacks excrete less urinary calcium, and show no skeletal
sensitivity towards the parathyroid hormone. Few studies focus on older black South
African men and osteoporosis.
Objectives
The aim of this study was to investigate the relationship of calcium intake, vitamin D
status, anthropometry and physical activity and bone density in black South African men.
Methods
A case-control study design was used, in which variables associated with bone density
were compared. The case group were men with fractures of the proximal femur, the
proximal humerus or the distal radius and an equal number of age-matched healthy
black men (with not more than a 5-year age difference) with no fracture (the proximal
femur and humerus and distal radius) previously, was recruited as a control group.
Bone density was measured with DEXA. Fat percentage was measured with a Tanita
scale. Biochemical analyses were done. Questionnaires were used to gather
demographic, activity and dietary information. To our knowledge, this is the first case-control
study on osteoporotic fractures in South African black men.
Results
Both the groups' bone mineral densities were lower than recommended. The bone
density of the case group for lumbar and hip regions was 0.86 and 0.88 and the control
group's bone density for lumbar region was 0.95 and hip region 0.91. The control group
was more physically active and had a better nutritional status than the case group. The
control group's calcium intake was higher but the vitamin D status was lower than the
case group. Both calcium and vitamin D status were not statistically significant (pc0.5),
between the two groups. Body mass indices of the groups were the same. The serum
albumin was higher in the control group than in the case group. The case group serum
calcium was higher than the control group. Both serum albumin and serum calcium
were statistical significant between the two groups. There were no statistically
significant differences in any of the other biochemical variables between the two groups.
Serum phosphate and serum vitamin D were statistical significant for bone density of the
hip and lumbar regions.
Conclusion
To conclude it seems logical to suggest a healthy diet with optimal macro- and micro
nutrient intake. Maintain ideal body weight and body fat percentage and recommend
regular but moderate-weight-bearing exercise from a young age throughout adult life, as
part of a strategy to prevent and treat osteoporosis. In the present study black South
African men present with low bone mineral density, but other studies indicated a lower
rate of hip fracture in South African blacks, despite lower bone density at all ages. It can
be recommended that other factors may play a role in black South African men with
osteoporosis. Factors such as serum phosphorus, 25-hydroxy-vitamin D, body mass
index (BMI), physical activity index (PAI), animal protein, total fat intake and dietary
calcium are important determinants of BMD in older South African blacks, as shown in
the present study. Osteoporosis is a multi factorial problem and must be treated that
way. / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2004.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/326 |
| Date | January 2003 |
| Creators | Groenewald, Merensia |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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