Vitamin D and Health

concentration < 25 nmol/L due to spending less time outdoors, either because of frailty or being
institutionalised.
9.55 An additional increment is not considered necessary for population groups who spend less time
outdoors or wear concealing clothing because the recommendation for the proposed RNI to be
applicable throughout the year is intended to take account of those with minimal sunshine exposure
who would be at risk of having a serum 25(OH)D concentration < 25 nmol/L in summer.
9.56 Lower serum 25(OH)D concentrations have been observed in ethnic groups with dark skin. However,
dark skin is only one of many factors, including cultural (e.g., wearing concealing clothing) and
biological (e.g., genetic background), that might affect serum 25(OH)D concentration. Findings from
dose-response RCTs of African Americans in the USA have produced conflicting estimates of the RDA
for vitamin D even within a life-stage subgroup and also conflicting data as to whether the RDA
estimates differ among African American and white adults (Gallagher et al., 2013; Gallagher et al.,
2014; Ng et al., 2014) (see paragraphs 5.17-5.19). It is also not known if the lower serum 25(OH)D
concentrations observed in people with dark skin are associated with any adverse health outcomes
since the evidence on vitamin D and health outcomes has been obtained from studies that include
predominantly white skinned people. It is uncertain, therefore, whether the vitamin D requirement
for people from ethnic groups with dark skin is higher than the RNI of 10 µg/d (400 IU) proposed for
the general population. On the basis that there are currently insufficient data to set a higher RNI for
people from different ethnic groups, the proposed RNI of 10 µg/d (400 IU) is considered appropriate
to cover the needs of ethnic groups within the UK population.
9.57 Evidence suggests that obese people are also at risk of low serum 25(OH)D concentrations. However,
there are currently insufficient data to make a different recommendation from that proposed for the
general population.
9.58 If the proposed RNI is achieved by almost all of the UK population, the current distributions of vitamin
D intakes and serum 25(OH)D concentrations would shift to the right with an increase in
mean/median intakes and serum 25(OH)D concentrations. It is unlikely, however, that this would lead
to those with intakes at the top end of the distribution reaching vitamin D intakes/serum 25(OH)D
concentrations that might pose a risk of adverse effects. Findings from a study (Allen et al., 2015)
which used NDNS (2008-2010) data (n=2127) to model the effect of vitamin D intakes resulting from
different fortification scenarios on population groups at risk of vitamin D deficiency 102 , estimated that
a vitamin D intake of 10 µg/d (400 IU) would reduce the proportion of at-risk groups estimated to have
intakes below the current RNI from 93% to 50% with no individual exceeding the UL 103 (EFSA, 2012).
102 For the purposes of this study, at risk groups were defined as young children (aged 18m-3y), women of child-bearing age (aged 15-49y
representing pregnant & breastfeeding women) and adults aged ≥ 65 y.
103 The ULs used in the analysis by Allen et al (2015) were based on the levels set by EFSA in 2002: 0-10y, 25 µg/d (1000 IU/d); 11-17y & adults,
50 µg/d (2000 IU/d). The ULs were revised by EFSA in 2012: < 1y, 25 µg/d (1000 IU/d); 1-10y, 50µg/d (2000 IU/d); 11-17y & adults, 100 µg/d
(4000 IU/d). The revised ULs were considered appropriate by the COT and accepted as the ULs for the UK (COT, 2014).
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