Table 2.
Studies assessing vitamin D status, as 25-hydroxyvitamin D [25(OH)D] levels, in various populations of children, adults and the elderly in South Africa (listed chronologically by year in each section).
| Study Population, Sampling Frame | Age (Years) | Location (Latitude), Season of Sampling when Specified | Assay | Serum or Plasma 25(OH)D Concentration Means (Unless Specified), nmol/L | Reference (Year) |
|---|---|---|---|---|---|
| Children | |||||
| 285 Coloured (mixed race) children; community based | 1–17 | Western Township, Johannesburg (26° S), winter | Competitive protein binding | 78.0 in age 1–12 y, 58.5 in age 13–14 y, 56.8 in age 15–16 y; none <25; no difference between boys and girls | [23] (1978) |
| 60 Black African children; school sample | 7–12 | Rural, small urban and large urban communities near Johannesburg (26° S) | Competitive protein binding | 72.3 in rural, 77.3 in small urban, 82.8 in large urban; none <25 | [24] (1979) |
| 114 hospitalised Black African infants; random hospital admissions | 0–2 | Witwatersrand (26° S), throughout year | Competitive protein binding | 37.3 aged 1–24 months, no correlation with age or season; <12.5 in 7%. 19.8 aged 0–1 month, probably reflecting vitamin D status of mother | [25] (1985) |
| 20 Black African pre-school children; cluster sample of villages | 3–5 | Villages in Northern Transvaal, now Limpopo (24° S), end of summer | Competitive protein binding | 85.5, no difference between underweight and normal weight children | [26] (1986) |
| 82 Black Africans with OCA, 58 Black Africans; school sample | 6–18 | Pietersburg, Northern Province (24° S) | Radioimmunoassay | 125 in OCA Blacks, 103 in Blacks, 6–9 y; 116 in OCA Blacks, 86.3 in Blacks, 10–13 y; 90.3 in OCA Blacks, 90.8 in Blacks,14–18 y | [27] (2000) |
| 295 Black African children, 90 White children; bone health subcohort of Birth-to-Twenty longitudinal cohort | 10 | Johannesburg (26° S), all seasons | Chemiluminescence (DiaSorin Liaison) | 100 in Black boys, 129 in White boys, 86 in Black girls, 112 in White girls; <50 in 8% Blacks and 1% Whites; higher values in White children in summer/autumn than in winter/spring, no seasonal variation in Blacks | [28] (2011) |
| Adults | |||||
| 43 healthy Black African women and cord blood of their babies, shortly after delivery; hospital based | 16–40 | Transkei (31° S) | Competitive protein binding | 81.8 in mothers; 171 in cord blood | [29] (1987) |
| 105 healthy White and 74 Black African premenopausal nurses; 50 healthy White and 65 Black African postmenopausal nurses; hospital based | 20–64 | Witwatersrand (26° S) | Competitive protein binding | Medians–65.8 in premenopausal White, 48.3 Black; 64.5 in postmenopausal White, 67.5 Black | [30] (1997) |
| 216 requests for vitamin D testing (39% with suspected osteoporosis); hospital based | All ages, peaks at 2 and 64 | Western Cape (32° S), all seasons | Competitive protein binding | Medians–48.3 (range 5.5–106); <45 in 41%; no seasonal effect on level | [31] (2009) |
| 658 rural healthy Black African women, 603 urban healthy Black African women; random selection from Prospective Urban and Rural Epidemiology Study or community based | >35 | North West Province (27° S), rural and urban seasonally matched | Roche Eledsys 2010 COBAS system | Levels decreased with age in both rural and urban women from about 78 at <50 y to about 65 at >70 y; levels lower in urban than in rural women, aged 50–70 y | [32] (2011) |
| 373 Black Africans, 344 Asian/Indians; cohort from Birth-to-Twenty longitudinal study | Mean 42 | Johannesburg-Soweto (26° S), all seasons | HPLC | 70.9 Blacks, 41.8 Asian/Indian; <30 3% Blacks and 13% Asian/Indians; females lower than males in both groups; highest level in autumn | [33] (2013) |
| 291 healthy urban Black African women; random selection from Prospective Urban and Rural Epidemiology Study or community based | >47 (mean 57.6) | North West Province (27° S) | Roche Elecsys 2010 COBAS system | 65; those with levels <75 two-times more likely to have higher systolic blood pressure than those with >75 (151 vs. 146 mmHg) | [34] (2013) |
| 368 healthy Black Africans and 347 healthy Asian/Indians; random selection from Birth-to-Twenty longitudinal study | 18–65 | Johannesburg (26° S) | HPLC | 58.3 in Black females, 72.7 in Black males, 35.7 in Asian/Indian females, 45.4 in Asian/Indian males | [35] (2014) |
| 371 healthy Black Africans and 343 healthy Asian/Indians; random selection from Birth-to-Twenty longitudinal study | 18–65 | Johannesburg (26° S) | HPLC | 56.8 in Black females, 72.4 in Black males, 32.4 in Asian/Indian females, 43.9 in Asian/Indian males; <30 in 5% Blacks and 28.6% Asian/Indians; levels 40%–60% higher in autumn than in winter/spring; little 25(OH)D2 | [36] (2014) |
| 502 Black Africans; population sample from Modelling of the Epidemiologic Transition Study | 25–45 (mean 33.4) | Cape Town (34° S), winter and summer months | LC-MS/MS | 59.3; <30 in 6.6%, >50 in 65.9%; negative correlation of 25(OH)D level with distance from the equator (by comparing levels in Blacks living at latitudes 41° N, 17° N, 6° N, 4° S and Cape Town) | [37] (2014) |
| 50 healthy Black Africans, 50 healthy Coloured (Cape mixed); community based longitudinal study | 18–24 | Cape Town (34° S), winter and summer months | Chemiluminescence (DiaSorin, Liaison) | Medians: 72.6 Black, 65.5 Coloured in summer; 45.5 Black, 43.8 Coloured in winter | [38] (2015) |
| Elderly | |||||
| 232 patients with femoral neck fractures, ethnicity not specified; hospital admissions | Mean 72.7 | Johannesburg (26° S), throughout year | Competitive protein binding | 44.3 throughout year; 51 in summer/autumn, 38.1 in winter and spring; <25 in 17% subjects in winter/spring | [39] (1978) |
| 60 females living in old-age homes, ethnicity not specified | Mean 80 | Pretoria (26° S), winter | Not specified | 32 | [40] (1991) |
| 173 non-institutionalised Coloured (mixed race), 52% women; population sample | 65–92 (mean 73.7) | Cape Town (34° S), late winter | Not specified | 37; <25 in 17% | [41] (1996) |
HPLC, high-performance liquid chromatography; LC-MS/MS, liquid chromatography-tandem mass spectroscopy; OCA, oculocutaneous albinism; y, years.