Vitamin D and Health

10. Overall summary and conclusions
Background
10.1 The two major forms of vitamin D are vitamin D 3 (cholecalciferol) and vitamin D 2 (ergocalciferol). The
principal sources of vitamin D are sunlight exposure (skin synthesis) and foods or dietary supplements
(containing either vitamin D 2 or D 3 ). Between the months of April and September, skin synthesis is the
main source of vitamin D for most people. Vitamin D 3 is the only form produced cutaneously. Vitamin
D 2 is formed in fungi and yeast by UVB exposure of ergosterol.
10.2 Dietary sources of vitamin D include natural food sources, fortified foods and supplements. There are
few naturally rich food sources of vitamin D. Those that contain significant amounts are mostly of
animal origin and contain vitamin D 3 (e.g., oily fish, red meat, egg yolk). Animal products (e.g., meat,
fat, liver, kidney) also contain the vitamin D metabolite, 25(OH)D. Wild mushrooms are a rich source
of vitamin D 2 . Fortified foods (e.g., breakfast cereals, fat spreads) and dietary supplements contain
either vitamin D 2 or D 3 . Dietary sources are essential when the amount of sunlight containing UVB
light is limited (e.g., in winter) or exposure to sunlight containing UVB light is restricted (e.g., lack of
time spent outdoors or little skin exposure).
10.3 UK DRVs for vitamin D, set by COMA in 1991 (DH, 1991), were based on prevention of rickets in
children and osteomalacia in adults. A dietary intake of vitamin D was not considered necessary for
individuals with adequate exposure to sunlight, therefore, a RNI 105 was not set for individuals aged 4-
64y ‘living a normal lifestyle’. RNIs were set only for certain population subgroups considered to be at
risk of vitamin D deficiency: infants 0-6 months (8.5 µg/340 IU per day); infants and children 7m–3y
(7 µg/280 IU per day); pregnant and breast-feeding women (10 µg/400 IU per day), adults aged 65y
and above (10 µg/400 IU per day), those with limited exposure to sunlight (e.g., confined indoors or
wearing concealing clothing) and people of Asian ethnic origin (10 µg/400 IU per day).
10.4 The DRVs for vitamin D were reviewed and endorsed by COMA in 1998. Since then, however, studies
have suggested a range of non-musculoskeletal health benefits of vitamin D. The data on vitamin D
and health outcomes were previously considered by SACN in 2007. It was concluded that there was
insufficient evidence, at that time, to amend existing advice and that evidence on the relationship
between vitamin D and non-musculoskeletal health was inconclusive.
10.5 In 2010, SACN decided to review the DRVs for vitamin D because a substantial amount of data had
accumulated since 2007, including a comprehensive report by the IOM in the USA 106 (IOM, 2011),
which provided an important resource for consideration of the evidence.
Terms of reference
10.6 The purpose of the current SACN review on vitamin D was to consider whether the DRVs for vitamin D
set by COMA in 1991 are still appropriate in the context of current lifestyles (e.g., advice to stay out of
the sun and to wear sunscreen). The terms of reference of the current SACN review on vitamin D was:
to review the Dietary Reference Values for vitamin D and make recommendations. The key issues
considered were:
105 The RNI represents the amount of a nutrient that is likely to meet the needs of 97.5% of the population.
106 Dietary Reference Intakes for Calcium and Vitamin D.
130