Vitamin D and Health

2.75 Another RCT 21 (Cashman et al., 2014a) investigated the effect of habitual calcium intake on serum
25(OH)D concentration. Healthy adults (n=125; age, ≥ 50y; mean calcium intake=814 mg/d) were
stratified according to habitual calcium intake (< 700 compared with > 1000 mg/d; mean intakes, 496
& 1437 mg/d for low and high calcium intake groups respectively) and received either vitamin D 3
(20 µg/800 IU per day) or placebo for 15 weeks throughout winter. Mean serum 25(OH)D
concentration increased significantly (p≤ 0.005) in the vitamin D 3 group and decreased significantly in
the placebo group (p≤ 0.002) and were of the same magnitude irrespective of calcium intake. These
findings suggest that calcium intake does not modify the requirement for vitamin D within the range
of calcium intakes studied. However, since this study was conducted in adults without metabolic bone
disease, the findings may not be applicable to children (who have higher calcium requirements
because of increased metabolism) or to those with metabolic bone disease.
Physiological requirements by life-stage
Infants
2.76 Vitamin D, together with calcium and phosphorus, is required during infancy and early childhood
(< 3y) to meet the demands of rapid growth for healthy skeletal development. Prolonged deficiency
of vitamin D during periods of bone growth in children leads to a failure or delay of endochondral
calcification at the growth plates of the long bones which results in rickets and an accumulation of
excess unmineralised osteoid (bone matrix) in all bones; the low mineral to bone matrix ratio in bone
results in osteomalacia (Pettifor, 2012). The main signs of rickets are skeletal deformity with bone pain
or tenderness; and muscle weakness. Deficiencies of calcium and phosphorus can also cause rickets.
Children and Adolescents
2.77 Adolescence is a critical developmental period for bone health when there is rapid growth. Vitamin D
is important for bone accretion during this time of skeletal development. Although rickets is most
commonly observed during infancy and in young children, it can also occur during the pubertal growth
spurt and adolescence. Children presenting with rickets have histological features of both rickets and
osteomalacia. Once the growth plates of the long bones have fused during adolescence, only features
of osteomalacia are found (Pettifor, 2012). Insufficient vitamin D during this time could also affect
bone mineral density and lead to children and adolescents not achieving their full potential at peak
bone mass.
Adults
2.78 In adults, vitamin D is required to maintain healthy bone. Deficiency can lead to osteomalacia,
presenting as muscle weakness and bone tenderness or pain in the spine, shoulder, ribs or pelvis (DH,
1991; DH, 1998).
2.79 In addition to evidence suggesting a link between vitamin D status and rickets/osteomalacia,
numerous epidemiological studies have reported associations between vitamin D status and other
musculoskeletal and non-musculoskeletal health outcomes. Relationships between vitamin D status
and health outcomes are considered in chapter 6.
21 This study was specifically commissioned by the Department of Health to inform SACN’s review of the DRVs for vitamin D.
16