Background

Vitamin D deficiency is a significant public health problem. There is a resurgence of rickets1 and osteomalacia and the association between vitamin D status and many other diseases remains under close scrutiny.2 Recent surveys have suggested that over 1 billion people worldwide are vitamin D deficient3 and 50% of white adults and >90% of South Asians in the UK have insufficient vitamin D levels.4 Young people and those with darker skin or limited sunlight exposure are particularly at risk and it is unlikely that high-risk groups can meet their vitamin D requirements through diet alone. Testing for vitamin D deficiency has escalated in recent years, with significant cost implications for the NHS.5

In November 2014, the National Institute for Health and Care Excellence (NICE) published a guideline entitled Vitamin D: Increasing supplement use among at-risk groups (PH56).6 The aim of this guideline is to increase vitamin D supplement use to prevent vitamin D deficiency. The guideline focuses on the following at-risk groups:

• infants and children aged under 5 years

• pregnant and breastfeeding women, particularly teenagers and young women

• people over 65 years of age

• people who have low or no exposure to the sun, for example, those who cover their skin for cultural reasons, who are housebound or are confined indoors for long periods

• people with darker skin, for example, people of African, African-Caribbean or South Asian family origin.

The Scientific Advisory Committee on Nutrition (SACN) is currently reviewing guidelines for recommended daily intakes of vitamin D and it is advised that people should follow the NICE guidelines in conjunction with future advice published by SACN.

Previous guidelines

NICE guideline PH56 replaces recommendation 3 in NICE guideline PH11, entitled Maternal and Child Nutrition. Recommendation 1.3.2.4 in NICE guideline CG62, Antenatal care has also been updated.

Underlying evidence base/methodology

The at-risk groups were highlighted in a letter from the UK Chief Medical Officers in 20127 and in an update by the SACN in 2007.8 The guideline was designed by the NICE Public Health Advisory Committee for use by commissioners, managers and other professionals working within the NHS, local authorities and the wider public, private, voluntary and community sectors. It is also aimed at manufacturers and providers of vitamin D supplements. NICE recommendations are based on systematic reviews of best available evidence. In accordance with NICE guidelines, PH56 also contains a costing statement, which concludes that the recommendations are likely to be cost-saving for commissioners.

Unresolved controversies

There is not, as yet, an RNI for vitamin D as it was previously assumed that enough vitamin D could be obtained from sun exposure. The SACN is currently reviewing this advice.

While the guideline advises that the Healthy Start vitamin should be universally available, it does not address the cost effectiveness of this; NICE will follow-up on this issue in a separate report to be available later in 2015.

The report highlights several gaps in current evidence:

• Lack of high-quality interventions aimed to increase vitamin D supplement use among at-risk groups.

• Lack of evidence of effectiveness of health professional training, supplement provision and awareness-raising activities on uptake of supplements.

• Whether having a low cost/free supplement affect uptake among at-risk groups.

• Whether particular demographics affects uptake of supplements and effectiveness of interventions designed to increase supplement use in at-risk groups.

• The strategies that encourage people to take a vitamin D supplement regularly.

• Whether training health professionals leads to more effective interventions.

Critical review

Although the NICE guideline aims to clarify those at highest risk of vitamin D deficiency and provide guidance regarding supplementation, unanswered questions remain. Paediatricians may wonder about the role of sunlight in maintaining an appropriate vitamin D status and whether advising supplementation in autumn and winter only may ever be appropriate.

Supplementation in the older child and adolescent also remains a controversial issue. Bone physiology does not suddenly change at 5 years of age, with continuing need for vitamin D during childhood. Additionally, there is an increase in vitamin D requirements, with an associated rise in the incidence of nutritional rickets and hypocalcaemia seen during puberty.10

It is unclear whether neonates should receive supplementation if the mother has not taken vitamin D during pregnancy, as the Department of Health guidelines refer specifically to infants from 1 month of age and the NICE guidelines refer to infants and children under the age of 5 years. It is logical to treat neonates in the same way as an infant of 1 month of age, as their vitamin D status will reflect that of their mothers and they may be susceptible to problems such as hypocalcaemic seizures in the first weeks of life.

There remains a difficulty in using an arbitrary cut-off for vitamin D deficiency/insufficiency. Once deficiency or insufficiency has been identified the most appropriate treatment strategy remains unclear as definitions and supplementation doses vary by guideline.