Vitamin D and Health

6.352 Millen et al. (2011) investigated the relationship between serum 25(OH)D concentration and
prevalence of early AMD in postmenopausal women (n=1313; age, 50-79y) participating in the
Carotenoids in Age-Related Eye Disease Study in the USA. Serum 25(OH)D concentration was
measured at baseline and AMD status was assessed from fundus photographs after 6 years. In
multivariate models, no significant relationship was observed between serum 25(OH)D concentration
and early or advanced AMD but there was a significant age interaction(p=0.0025). Serum 25(OH)D
concentration (highest vs lowest 79 quintile) was significantly associated with a lower risk of early AMD
in women < 75y but an increased risk in older women; however this association was no longer
significant after further adjustment for BMI and physical activity.
6.353 A systems biology-based analysis investigated the role of vitamin D metabolism in the pathogenesis of
AMD in a cohort of sibling pairs (n=481) discordant for AMD (Morrison et al., 2011). After adjustment
for established risk factors for AMD, including genetic polymorphisms and smoking, UV irradiation was
associated with a lower risk of AMD (p=0.001). Serum 25(OH)D concentration (measured in 50 sibling
pairs) was lower in individuals with AMD than in their unaffected siblings, but this was not statistically
significant. A candidate gene approach was used to examine variation in key genes regulating vitamin
D metabolism (including those encoding VDR, CYP27B1, CYP24A1 and CYP27A) in participants
(n=2525) comprising the sibling pairs and their extended families, individuals from a separate casecontrol
study from Greece and a prospective nested case-control population from the Nurse's Health
Study and Health Professionals Follow-Up Study in the US. Single point variants in the CYP24A1 gene
were shown to influence the risk of AMD after adjusting for age, sex and smoking, in all the
populations separately and in a meta-analysis.
Summary - Age-related macular degeneration
6.354 No intervention studies on vitamin D supplementation and AMD could be identified.
6.355 Evidence on serum 25(OH)D concentration and AMD is mainly from cross-sectional studies which are
inconsistent. One small study reported that variation in the CYP24A1 gene may play a role in the pathogenesis
of AMD.
Conclusions – non-musculoskeletal health outcomes
6.356 Intervention studies do not suggest beneficial effects of vitamin D supplementation during pregnancy
on maternal reproductive outcomes. The observational evidence is mixed.
6.357 The contribution made by vitamin D supplementation during pregnancy to the later serum 25(OH)D
concentration of the unsupplemented, exclusively breastfed baby is unclear. Maternal vitamin D
supplementation during pregnancy has beneficial effects in reducing the risk of neonatal
hypocalcaemia but there is little evidence from intervention or observational studies to indicate any
additional benefits for the baby.
6.358 The small number of available RCTs have not shown an effect of vitamin D supplementation on overall
cancer risk. Observational evidence suggests an inverse association between serum 25(OH)D
concentration and colorectal cancer risk. These studies do not provide compelling evidence of a
protective effect of vitamin D on colorectal cancer risk because they might be confounded by other
79 Median (range): Q1 = 30 (7, 38) nmol/L; Q5 = 85 (>75, 165) nmol/L.
97