Vitamin D and Health

Serum/plasma 25(OH)D concentration by region
8.48 The HSE 2010 analysed serum 25(OH)D concentration by region and season. The percentage of
people with serum 25(OH)D concentration < 25 nmol/L was lowest in all regions during the summer
months (around 5-7%). During the winter months, 46% of people in the Midlands and North, 38% in
the South (including London) and 35% in the South (excluding London) had a serum 25(OH)D
concentration < 25 nmol/L.
8.49 Data from NDNS Scotland, NDNS Wales or NDNS Northern Ireland were not split by season due to
small sample sizes.
8.50 In Scotland, the mean plasma 25(OH)D concentration was 47 nmol/L for children aged 4-10y,
37 nmol/L for ages 11-18y, 40 nmol/L for adults aged 19-64y and 42 nmol/L for adults aged ≥ 65y. The
proportion of these age groups with a plasma 25(OH)D concentration < 25 nmol/L was: 9%, 4-10y;
26%, 11-18y, 33%, 19-64y; and 29%, ≥ 65y.
8.51 In Northern Ireland, the mean plasma 25(OH)D concentration was 39 nmol/L for ages 11-18y,
33 nmol/L for ages 19-64y and 45 nmol/L for≥ 65y. The proportions with a plasma 25(OH)D
concentration < 25 nmol/L was: 30%, 11-18y, 34%, 19-64y; and 19%, ≥ 65y.
8.52 In Wales, the mean plasma 25(OH)D concentration was 43 nmol/L for children aged 11-18y, 51 nmol/L
for men and 43 nmol/L for women aged 19-64y and 43 nmol/L for adults aged ≥ 65y. The proportion
with a plasma 25(OH)D concentration < 25 nmol/L was: 23%, 11-18y; 20% of men & 16% of women,
19-64y; and 17%, ≥ 65y.
Serum 25(OH)D concentration during pregnancy
8.53 A study in North West London analysed serum 25(OH)D concentrations of pregnant women (n=346;
mixed ethnicity) by season (McAree et al., 2013). The mean serum concentration was 38 nmol/L in
summer (July-September) and autumn (October-December), 26 nmol/L in winter (January-March) and
32 nmol/L in spring (April-June). The percentage with a serum 25(OH)D concentration < 25 nmol/L
ranged from 29% in the summer to 49% in the winter.
8.54 In the Southampton Women’s Survey, the median serum 25(OH)D concentration of pregnant women
(n=977; predominantly white) measured at 34 weeks gestation was 62 nmol/L; 35% had a serum
25(OH)D concentration < 50 nmol/L (Crozier et al., 2012).
8.55 Blood samples (taken throughout the year) were also available for pregnant women (n=3,960;
predominantly white) taking part in the ALSPAC 90 study 1991/1992 (Lawlor et al., 2013). Median
serum 25(OH)D concentrations were 55.1, 60.1 and 67.4 nmol/L in the first, second and third
trimesters respectively. In the third trimester, 34% of women had a serum 25(OH)D concentration
< 50 nmol/L and 6% had a serum 25(OH)D concentration < 27.5 nmol/L.
8.56 A study in Aberdeen (Haggarty et al., 2013) measured plasma 25(OH)D concentrations of pregnant
women (n=1205; mean age at delivery, 31.5y; predominantly white) at 19 weeks gestation. Mean
concentrations were 53 nmol/L in summer (June-August), 34 nmol/L in autumn (September-
November) and winter (December-January) and 40 nmol/L in spring (March-May). The proportions
with plasma 25(OH)D concentration < 25 nmol/L were 25% in summer, 43% in spring, 60% in autumn
and 76% in winter.
90 Avon longitudinal survey of parents and children.
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