The two ways in which the body obtains vitamin D are via dermal synthesis, following exposure to natural sunlight, and by absorbing it from the diet.1 With the latter route not being enough by itself to maintain vitamin D levels and the former being unreliable, especially in the UK, deficiency is prevalent across all groups of the general population.1 

In 2016, recommendations regarding vitamin D supplementation, made in a report by the Scientific Advisory Committee on Nutrition (SACN)2, were adopted by Public Health England, following a review of evidence and of the prevalence of vitamin D deficiency in the UK population. In their recommendations, SACN put forward Reference Nutrient Intakes (RNIs) for adults and children to ensure that people have sufficient vitamin D levels to maintain good musculoskeletal health throughout the year.2 The previous advice set out in 1991 had only recommended dietary intakes for the groups most at-risk of vitamin D deficiency, for example pregnant and breastfeeding mothers, people over 65 years of age, infants and children and people who do not get much exposure to sunlight, because they spend a large amount of time indoors, or cover their skin for cultural reasons when they do go outside.3

Advice for patients

Following the SACN review, Public Health England now advises that adults and children above one year old should consider taking a daily supplement of at least 10 micrograms of vitamin D, particularly between October and April.3 People who are in the previously defined at-risk groups should be advised to take a supplement all year round.3 This includes people with darker skin tones, from African, African-Caribbean and South Asian backgrounds, who may otherwise struggle to get enough vitamin D from sunlight, even during the summer months.

The advice for children aged one to four years is that they should have a daily dose of 10 micrograms vitamin D supplement all year round.3 Babies under the age of one who are being breastfed should take a precautionary dose of 8.5 to 10 micrograms to ensure they get enough vitamin D.4 The exception is babies who consume more than 500ml of formula milk per day, as this has already fortified to ensure they get enough vitamin D.4 However, The Global Consensus Recommendations on Prevention and Management of Nutritional Rickets advises 400 IU/day vitamin D from birth to 12 months of age independent of feeding mode and 600 IU/day beyond the age of 12 months.4 Official advice from the government is that babies should be exclusively breastfed until at least six months of age.3

Lifestyle advice for patients

While the key vitamin D advice for patients is that people should take supplements during the winter months, if not all year round, there are certain lifestyle changes people can make to help themselves with vitamin D deficiency and insufficiency.
Patients should be encouraged to increase the amount of vitamin D and calcium they get from their diet, to help with which you can direct them to resources including the British Dietetic Association’s fact sheet on Vitamin D6, which contains useful information for patients around optimising their diets. Being very overweight or obese is a vitamin D deficiency risk factor, which may be linked to the fact that vitamin D is fat-soluble and as such is sequestered in adipose tissue and so becomes less bioavailable when there is a greater percentage of body fat.7In this case you may wish to advise weight loss, particularly for people who have a body mass index
above 30.

Other lifestyle advice, as set out by the National Institute for Health and Care Excellence (NICE), includes the following:

Safe sun exposure

Advise patients that leaving areas of the skin which usually come into contact with sunlight, for example the forearms and hands, uncovered when out in natural sunlight will stimulate production of vitamin D. Note that those with darker skin tones may require longer exposure to natural sunlight. Prolonged exposure to sunlight does not lead to greater production of vitamin D, due to the regulation mechanism in place to destroy excess levels, but it does contribute to the risk of skin cancer. Therefore, any advice given on exposure to the sun should be supplemented with advice on the adequate protection of the skin against the sun’s rays. Patients should use a sunscreen of at least SPF15, which meets the minimum requirements for UVA protection, and they should apply it liberally and frequently while out in strong sunlight. It should further be advised that sunbeds do not contribute to combating vitamin D deficiency, because the rays they emit (UVA) do not stimulate dermal synthesis but do still increase the risk of skin cancer.5

Dietary intake of vitamin D

Advise that patients should maintain their dietary intake of vitamin D by taking supplements, especially between October and April, as it is not possible to obtain all of the vitamin D the body needs from diet alone. However, good food sources of vitamin D include oily fish such as salmon, mackerel and sardines. Other foods such as eggs, red meat, liver, milk and fortified foods (such as margarine and some brands of cereal and yoghurt) contain smaller amounts of vitamin D.5

Dietary intake of calcium

Advise patients that, alongside vitamin D, it is also important for them to keep the amount of calcium they take in from their diet at the correct levels. Vitamin D and calcium work in combination to promote long-term bone health and prevent adverse effects. Good food sources of calcium include dairy foods including cheese, milk and yoghurts, and sardines that have not had their bones removed.5


Ultimately, patients should be reminded that long-term supplementation of vitamin D (and calcium, as and where necessary) is advised in order to promote bone health and prevent the occurrence or recurrence of vitamin D deficiency. Where there is a need, it might also be reasonable to advise patients that, should lifestyle issues such as diet and weight escalate and become medical issues, they may further require testing for vitamin D deficiency and potentially medication to correct it.5





4. Munns CF, Shaw N, Kiely M, et al. Global Consensus Recommendations on Prevention and Management of Nutritional Rickets. J Clin Endocrinol Metab 2016;101(2):394-415.

5. British National Formulary for Children: BMJ Group, last updated April 2 2019. Available at:



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Date of Preparation: June 2019 Date of Revision: January 2020