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Vitamin D and the impact on the health of the UK: our role as health professionals

Lisa Cooke
MA BSc RD, Head of Paediatric Dietetics, Bristol Royal Hospital for Children

In this article we will look at the history of vitamin D in the UK, the status of the population today, the function of vitamin D, and the role we as healthcare professionals play

Rickets, a bone disease of the Victorian era, is making a resurgence in the millennium.1 Since the turn of the 20th century the necessity of cholecalciferol (vitamin D) for the human body has been recognised, primarily due to its involvement in skeletal development and bone mineralisation. In children, the disease commonly presents as bow legs and short stature, while prolonged vitamin D deficiency can result in osteomalacia in adults. Other evidence is emerging to suggest that lack of vitamin D may play a part in a number of serious conditions such as cancer, heart disease, high blood pressure, diabetes, age related cognitive decline, multiple sclerosis, arthritis and more.1

A brief history of vitamin D in the UK diet
During and after the Second World War, Britain experienced food rationing. In recognition of the importance of vitamin D, the diet was supplemented with cod liver oil (a good source of vitamin D). 1947 saw the start of the NHS, followed by the introduction of the welfare scheme offering 'welfare vitamin drops', including vitamin D, for all children under five years old (now Healthy Start vitamins). Following a culmination of a change in the NHS and the company ceasing to produce the original vitamin drops, we have seen reduced accessibility of the new vitamin supplements for these children.

Rickets and incidence
The number of children who have been diagnosed with rickets in the past decade is unclear due to the lack of a central reporting database. However, clinicians acknowledge it is on the rise. In the UK and North America alike, there have been increased reports of the disease via case study presentation or case series obtained from hospital.2 In this modern age and with a good knowledge base on the topic it is concerning that a resurgence of rickets in the UK is being seen.

Vitamin D and how it is measured
Vitamin D is the term used to describe many forms of a similar fat-soluble steroid. Usually, a vitamin is a nutrient that is essentially provided by the diet. For vitamin D, however, sunlight is the primary source, with diet becoming more important when there is limited access to sunlight.3
Skin exposure to ultraviolet B radiation (UVB) causes a reaction with 7-dehydrocholesterol in the skin, which then produces previtamin D3. This is passed into the extracellular space attached to the vitamin D binding protein (DBP).1 This attachment prolongs the half-life of sunlight-induced vitamin D. In contrast, ingested vitamin D3 is cleared through the body more rapidly with only about 40% being carried by DBP.1 Either way, the body then makes D3 into a biologically active compound through a complex process, involving hydroxylation in the liver to produce 25-hydroxycholecalciferol (25(OH)D) and then a final conversion in the kidneys to form 1-25-dihydroxycholecalciferol.

The biologically active form of vitamin D, 1-25-dehyroxycholecalciferol, is required to promote the absorption of calcium and phosphorus from the diet through the gut. Receptors for 1-25-dihydroxycholecalciferol have been identified in other tissues related to immune function and low levels of vitamin D have been linked with infectious and autoimmune diseases, such as diabetes and multiple sclerosis.4

Vitamin D requirements
When comparing published literature, authors refer to vitamin D in many forms. However, it is important to ascertain which form of vitamin D the paper refers to when comparing results.5 Generally, blood 25(OH)D is used to assess vitamin D status. While there is no collective agreement on optimal levels, concentrations below 25 mmol/l are generally considered 'low' or 'deficient' (ie, below the required amount considered to prevent rickets and osteomalacia).

Unfortunately, standard assays vary between countries, making it difficult to compare randomised, controlled trials and study results, define accurate vitamin D requirements for health and, subsequently, the correct supplementation for treatment.

Table 1 shows the current UK recommendations for health. The average daily dietary intake for men is 3.7 µg and 2.8 µg for women and we know that there is insufficiency in vitamin D status across the UK population.3

[[Tab 1. Kell]]

Currently, there is no intake recommendation for people between four and 65 years, with the exception of pregnant and breastfeeding women. However, the rise in children presenting with rickets makes it difficult to support current recommendations, suggesting a need to review the recommendations. In order to improve vitamin D status in the UK, guidance needs to be reviewed at a population level.8

Provision from the sun
Both skin colour and factors affecting the sun's rays impact considerably on D3 production. For example, the angle at which the sun hits the earth has an effect: as the sun becomes more oblique the rays travel further, creating seasonal variation. As a result, populations who live in countries above 37o latitude potentially require vitamin D supplementation during the winter months (the UK is situated between 50-60o). In such countries, even the summer months may not provide sufficient sunlight for the body to absorb UVB rays, as the sun's rays are oblique first and last thing in the day.

Skin colour also dictates how long a person needs to stay in the sunlight to activate the vitamin D precursor in the skin. For example, pale skin accrues vitamin D ten times quicker than darker skin.9 In the UK, pale skin types need to spend around half an hour exposing face, neck and forearms to sunlight, with no sun protection factor cream, to allow their body to produce 2,000 IU of vitamin D.1 Ideally, this exposure would be in the in the middle of the day when the sun is strongest. Doing so two to three times per week in the summer is thought to be enough to support adequate vitamin D status, whereas darker skin types and older people would need substantially more.

The conflict arises when looking at public health advice regarding skin cancer. Very successful campaigns encouraging sunscreen application, staying out of the sun especially at mid-day and covering up, along with the increased use of car travel and more people working and socialising indoors, has seen the UK population less exposed to direct sunlight. Air pollution, cloud cover and latitude also have an impact in reducing UVB radiation absorption.

All of this has contributed to a population with deficient or insufficient levels of vitamin D (see Table 2). The UK population groups at greatest risk are pregnant women, breastfed infants, children under five, older people, dark-skinned people and those who consistently cover their skin (eg, for cultural and religious reasons).

[[Tab 2. Kell]]

Dietary vitamin D
Food sources
Few foods contain high levels of vitamin D, with oily fish and their oils being the best sources.1 Farmed oily fish has less vitamin D. Table 3 highlights good dietary sources. It is important to remember that cooking techniques also have an effect on the vitamin D content of a food; for example, frying fish can reduce the content by 50% whereas baking has no effect.2

[[Tab 3. Kell]]

Supplements may be in the form of vitamin D3 or vitamin D2 and evidence is emerging that D3 may be the more effective form. In the UK, the most commonly used supplement (which should be given to children of five instead of the Healthy Start vitamins due to lack of availability) contains vitamin D2. In the Republic of Ireland, this supplement has been reformulated and it now contains D3; however, this form is not currently available in the UK.9

Supplementation is dependent upon age, skin colour and need. Single (200,000 IU) or daily dose of 800 IU from 27 weeks gestation has been shown to improve vitamin D status in pregnant women if given from 27 weeks; however, only a small number of both women and infants were found to be vitamin sufficient following supplementation.13

Food fortification
It has been suggested that there is enough evidence to support widespread food fortification with vitamin D, although this is not the general consensus.14 Fortification does not affect the taste of food and, in the USA, milk, orange juice and cheese have been fortified with vitamin D with no adverse side-effects.15

In the UK, voluntary food fortification began in 1924, followed by mandatory margarine fortification of vitamins A and D during the Second World War (1940).3 Britain also fortified cereals, flour, bread and milk. The only foods since which have continued to be fortified are margarine, at 7 µg/100 g (not spreads) and some breakfast cereals, at 3-8 µg/100 g. Food sources alone probably only provide about 5% of the optimum amount of vitamin for an adult. Finland managed to reduce the number of people with low levels of vitamin D by mandatory milk and margarine fortification in 2003. The Republic of Ireland has recently fortified semi-skimmed milk without issue.9

Understandably, safe food fortification and guidance around this is essential. The European Commission has published a draft proposal, which includes a regulatory framework to support the voluntary addition of vitamins and minerals to manufactured foods.16 The model proposes the level of each nutrient that can be added to food safely. It takes into account those in the population who already have high levels of each nutrient within their unfortified diet and makes sure that a safe upper limit is advised. For vitamin D, the commission have proposed an upper intake level (defined as the level which poses no risk to health) of 25 µg/day for infants and children under 11 years and 50 µg/d for older children and adults.

Concerns regarding safe levels are justified, although actual cases are rare.15 An adult intake in excess of 10,000 IU (250 µg) for several months would be required to cause toxicity.5 It has been shown that some infants have shown sensitivity to levels as low as 50 µg2. Hypervitaminoisis D is rare and has not occurred with ingested vitamin D, neither has it been seen through overexposure to the sun.5

Currently, the following UK guidance and schemes on vitamin D intake and supplementation are available:

  • The Scientific Advisory Committee on Nutrition (SACN) published a report in 2007 expressing that it felt it could not recommend mandatory food fortification of a wider range of foods without some population assessment.9 It is currently reviewing the evidence with regards to the Recommended Nutrient Intakes.
  • The National Institute for Health and Clinical Excellence (NICE) suggests that being out in the sunshine is beneficial, as long as there is not overexposure, which can lead to skin cancer.17 They do not define how long to stay out and at what time of the day. Depending on skin colour and type this will vary between individuals, therefore making specific policy is difficult to implement and follow.
  • In 2004, NICE recommended that at-risk mothers should be supplemented with vitamin D.18
  • The Institute of Medicine reviewed the USA recommendations at the end of 2010 and proposed an increase in RNIs for vitamin D, assuming minimal sunlight exposure. This resulted in the recommendation for children tripling from 5 µg per day to 15 µg per day.19
  • Healthy Start took over from the welfare scheme in 2004 and launched the 'Healthy Start vitamins', including vitamins for pregnant and breastfeeding mothers and children up to five years of age (they are only available to those qualifying for the benefit scheme). In addition, the scheme provides vouchers for the purchase of milk or formula, and fruit and vegetables from subscribed retailers.9,15 The vitamins have a short shelf life and pharmacists are reticent to stock them because of this; consequently, there has been a poor uptake. The rest of the population has been unable to access them unless localities have offered a universal scheme for free access to all.  Therefore, those in need, particularly pregnant and breastfeeding mothers and children under five, have not been routinely receiving a supplement that includes vitamin D.15
  • Clinical studies are showing that it is not necessarily low-income families who have low vitamin D status; therefore, access for non-benefit receivers should be available.9,15
  • Current advice stresses that it is important to have some sun exposure and not to burn rather than avoiding exposure to the sun altogether. Unfortunately, clarity of this recommendation is not apparent from the Health Protection Agency. Advice from the Department of Health does not recommend enough sun exposure to provide the body with adequate vitamin D to maintain optimum levels throughout the winter.9 Therefore, conclusions are that the current vitamin recommendations are inadequate.1

Health professionals' role in raising the awareness of vitamin D
Recent scientific literature has seen a plethora of publications on vitamin D and the issues related to the lack of this essential vitamin. Unfortunately, UK public health teams do not collect data on the numbers of patients with rickets or clinical/subclinical deficiencies of vitamin D. Suggested ways to collect data are:

  • Encourage GPs to case report on a monthly basis.
  • Request laboratory notes of low vitamin D results, and then assess the case notes for the diagnosis (rickets, hypocalcaemia convulsions, muscle weakness, incidental findings). Remember to separate out any, renal, liver and gastroenterology cases, as well as define geographical areas using postcodes in order to exclude out of area cases.
  • Obviously neither method of data collection is particularly easy, so much of the reported rise in clinical cases is by anecdotal reporting within the healthcare environment.

It is vital that, as healthcare professionals, we take responsibility for this emerging issue and highlight when we are seeing deficiencies, working within our local communities to look at localised ways to address the problem.

To ensure the importance of vitamin D is more widely recognised professionals could set up a group or tap into already established groups that pull community, health, education and local authorities together; then communities could work together to help resolve the issue.

Individuals who are high risk would benefit from the development of local guidance from healthcare professionals. Many areas in the UK have already developed targeted advice, which is often available on local websites and outlines various treatment pathways in place, explaining how to support their implementation.
Additionally, healthcare professionals can collaborate with:

  • Local midwifery services to make sure that all pregnant mums are getting appropriate access. If possible, screening during the antenatal period and supplementation as required, not just for at-risk women with skin types IV and V.
  • Retail pharmacies to promote the Healthy Start vitamins for those who do not qualify for the scheme but may wish to purchase over the counter.
  • Childcare workers in early years settings, where they can promote the benefits of diet, supplementation and outdoor play.
  • Ethnic groups, linking in with the local community support groups to create an opportunity to assess the best way to advise and educate.
  • Where possible, groups who support obese clients.
  • Residential and aged-care homes, looking at the menu, food provision, supplementation and access of residents to sunshine during the summer months.

It is concerning that such a historical disease is affecting the health of our nation today, despite well established scientific knowledge, education and healthcare provision. At the centre of the problem is a vitamin deficiency. As healthcare professionals, it is our responsibility to use the tools and information available to us, and perhaps some of the tactics listed in this article, to do our best to reverse the current situation and work towards eliminating vitamin D deficiency.

1.    Pearce SH, Cheetham TD. Diagnosis and management of vitamin D deficiency. BMJ 2010;340;142-7.
2.     Misra M, Pacaud D, Petryk A, Collet-Solburg PF, Kappy M. Vitamin D deficiency and it's management: review of current knowledge and recommendations. Paediatrics 2008;122:398-417.
3.     Mason P. Vitamin D. Complete Nutrition 2007;7(5):21-4.
4.     Hollis B, Wagner C. Assessment of dietary vitamin D requirements during pregnancy and lactation. Am J Clin Nutr 2004;79:717-26.
5.     Department of Health. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom: Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. London: HMSO; 1991.
6.     Lanham-New SA, Buttriss JL, Miles LM et al. Proceedings Of The Rank Forum On Vitamin D. Br J Nutr 2011;105:144-56.
7.     Thompson RL. Is low vitamin D status a problem in Britain? British Nutrition Foundation Bulletin 2007;32:311-13.
8.     Gillie O. Sunlight robbery: a critique of public health policy on vitamin D in the UK. Mol Nutr Food Res 2010;54:1-15.
9.     Michie C, Bangalore S. Managing vitamin D deficiency in children. London Journal of Primary Care 2010.
10.     Yu CK, Sykes L, Sethi M, Teoh TG, Robinson S. Vitamin D deficiency and supplementation during pregnancy. Clin Endocrinol 2009;70:
11.     National electronic Library for Medicines. Consensus Vitamin D position statement. Available from:
12.     Michie C, Bangalore S. Managing vitamin D deficiency in children. London Journal of Primary Care 2010.
13.     Flynn A, Moreiras O, Stehle P, Fletcher RJ, Muller DJG, Rolland V. Vitamins and minerals: a model for safe addition to foods. Eur J Nutr 2003;42(2):118-30.
14.     National Institute for Health and Clinical Excellence (NICE). Available from:
15.     NICE. Improving the Nutrition of Pregnant and Breastfeeding Mothers and Children in Low-Income Households. London: NICE, 2008.
16.     Ross AC, Taylor Cl, Yaktine Al. Dietary Reference Intakes For Calcium And Vitamin D. Washington DC: The National Academy Press; 2011.

CPD questions
1.    Who is at risk of low vitamin D status and what are the ways to increase status?
2.    What are the main issues you have learned from this article?
3.    What are the main issues with using the information in the article and implementing it in practice?
4.    How do you think you can influence policy?
5.    Do you think vitamin D is a nursing issue and why do you think it is or isn't?
6.    What questions has it raised for you as a practitioner?
7.    How will you implement any changes into your practice?