TABLE 12.
Characteristics of the prospective observational studies reporting on the relationship between vitamin A intake and BMD.
| Study | Houtkooper et al. (1995) | Promislow et al. (2002) | Kaptoge et al. (2003) | Macdonald et al. (2004) | Rejnmark et al. (2004) | Chan et al. (2011) | de Jonge et al. (2015) |
|---|---|---|---|---|---|---|---|
| Design | PC | PC | PC | PC | NCC | PC | PC |
| Country | USA | USA | UK | UK | Denmark | China | The Netherlands |
| Age (years) a | 28–39 | 55–92 | 67–79 | 45–55 | 45–58 | > 65 | > 55 |
| Sex/N |
– F = 66 |
M = 388 F = 570 |
M = 470 F = 474 |
– F = 891 |
– F = 1694 |
M = 1225 F = 992 |
M/F = 5288 |
| Follow‐up | 12–18 months | 4 years | 2–5 years | 5–7 years | 5 years | 4 years | 14 years |
| Vitamin A (exposure) |
Preformed – |
Preformed – |
Preformed – |
Preformed Total |
Preformed Total |
– Total |
Preformed Total |
| Source | Diet | Diet + supplements | Diet | Diet + supplements | Diet + supplements | Diet | Diet |
| Dietary assessment | 1–3 × 4‐day dietary records | 1 × sFFQ | 1 × 7‐day food diary | 2 × sFFQ | 2 × 4 to 7‐day FR | 1 × sFFQ | 1 × sFFQ |
| Preformed vitamin A (μg RE/day) |
Mean (SD) D: 1220 (472) |
Mean (SD) D/F: 497 (460) D/M: 624 (585) D + S/F: 1247 (1573) D + S/M: 1242 (1442) |
Mean (5th ‐ 95th) M: 358 (109–3836) F: 289 (98–3517) |
Mean (SD) D: 820 (602) D + S: 924 (666) |
Median (IQR) D: 530 (309–750) D + S: 1210 (680–1450) |
– |
Median (IQR) Q1: 194 (135–298) Q3 (ref): 356 (212–523) Q5: 1021 (598–1518) |
|
Total vitamin A (μg RE/day) |
– |
– |
– |
NR |
Median (IQR) 1740 (1290‐2360) |
Median (IQR) M: 940 (667–1315) F: 939 (676–1277) |
Median (IQR) Q1: 684 (568–793) Q3(ref):1141 (1050–1257) Q5: 2000 (1712–2485) |
| BMD site |
Total body 3 hip sites(2) Lumbar spine |
Total hip Femoral neck Lumbar spine |
Total hip – – |
– Femoral neck Lumbar spine |
– Femoral neck Lumbar spine |
Total hip Femoral neck – |
– Femoral neck – |
| BMD endpoint | Change (mg/cm2)/year |
% change/year 4‐year change (g/cm2) |
% change/year | % change/year | % change/5 years | % change/4 years | BMD (mg/cm2) at four visits |
| RoB tier | 1 | 1 | 1 | 1 | 1 | 2 | 2 |
Abbreviations: BMD, bone mineral density; FR, food record; IQR, interquartile range; NCC, nested case–control; NR, not reported; PC, prospective cohort; RE, retinol equivalents; SD, standard deviation; sFFQ, semiquantitative food frequency questionnaire; UK, United Kingdom; USA, United States of America.
Age as recruitment target at baseline; (2) femoral neck, trochanter, Ward's triangle.