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Vitamin D – PHE recommends supplements for all to protect bone health
Public Health England has published new advice which recommends that everyone should take a daily supplement of vitamin D to protect musculoskeletal health.
The recommendations are based on information from the Scientific Advisory Committee on Nutrition (SACN), which has just published its independent report - a review of the most up-to-date evidence relating to vitamin D and health. The new guidance replaces the previous UK dietary recommendations, which were set in 1991.
The SACN is now recommending:
- A reference nutrient intake (RNI) of 10 micrograms of vitamin D per day throughout the year for the general population aged 4 and over
- An RNI of 10 micrograms of vitamin D per day for pregnant and lactating women and groups who are at an increased risk of deficiency
- A ‘safe intake’ of 10 micrograms for children aged 1 to 4 years
- A ‘safe intake’ of 8.5 micrograms – 10 micrograms for babies under 1 year.
The RNI and safe intakes refer to intake from all dietary sources, including natural food sources, such as eggs, milk, liver and oily fish, fortified foods (including some margarines, cereals and formula milk) and supplements. Experts agree that relying on vitamin D via dietary sources is frequently insufficient as amounts are too small to prevent deficiency.
But doesn’t the skin produce vitamin D when exposed to sunlight?
Vitamin D is produced naturally in the body by the skin via exposure to sunlight during the summer months, typically between March and September, but this is said to be unreliable and dependent on variable weather conditions.
The SACN says it has therefore not taken into account sunlight exposure when making its recommendations due to the variety and complexity of factors that affect skin synthesis. These factors include but are not limited to:
- In the UK throughout much of the year there is no ambient ultraviolet sunlight of the appropriate wavelength for adequate skin synthesis of vitamin D
- It is not possible to produce enough vitamin D by sitting near a window, as vitamin D inducing UVB rays do not pass through glass, but harmful UVA rays do and can cause skin damage
- Some people who have little to no exposure to direct sunlight – such as those living in care homes, the housebound, those who keep their skin covered and people who work long indoor shifts, may be deficient even during the summer months.
Why is vitamin D so important?
Vitamin D is an essential nutrient for the maintenance of healthy bones, required to ensure optimum absorption of calcium and phosphorus from the diet. Deficiency can result in bones becoming soft and weakened, leading to bone deformities and osteomalacia, or bone pain.
The vitamin is especially important for growing bones in children, where deficiency can cause rickets. According to NHS Choices, rickets causes pain, poor growth and deformities of the skeleton, such as bowed legs, curvature of the spine and thickening of the ankles, wrists and knees. Children with rickets are also more susceptible to bone fractures. A healthy intake of vitamin D during the first year of life has also recently been linked with more muscle mass and less body fat in toddlers.
A common ailment in the past, rickets had mostly disappeared in the Western world as a result of improved diet, however the NHS says there has been an increase in recent years - 900 cases were diagnosed in England in 2012.
SACN guidance for breast fed babies
The SACN is now recommending that breast fed babies be given a minimum 8.5 micrograms vitamin D supplement daily, although babies who are fed more than 500ml of formula a day do not need additional vitamin D since formula milk is already fortified. The Department of Health recommends that babies are exclusively breast fed until six months, at which point other foods can begin to be introduced. Alongside a balanced weaning diet, breastfeeding is encouraged up to the age of two and beyond as it offers health benefits to both mother and child.
What are the health risks associated with inadequate vitamin D?
Professor Zulf Mughal, Consultant in Paediatric Bone Disorders and Honorary Clinical Professor of Child Health at the Royal Manchester Children’s Hospital, describes the SACN advice as “sensible”. He says if the advice is implemented by the general public “it will only help to prevent cases of rickets, dilated cardiomyopathy of the heart, severe muscle weakness, propensity to fall and fractures, if the advice is implemented.”
But the new guidance does not go far enough when it comes to vitamin D for babies under 1 year, according to Professor Mughal. He says he is “disappointed” that the full 10 micrograms of vitamin D per day has not been recommended from birth, as it is in other countries including the United States.
He adds: “It is well known that infants who are breast fed and not provided with vitamin D supplements are at increased risk of developing florid rickets. In my opinion this advice, if universally implemented, may help to reduce the number of cases of children with rickets and potentially life-threatening dilated cardiomyopathy. I have seen two infants die of dilated cardiomyopathy due to severe vitamin D deficiency.”
Evidence “dispels any doubt”
Professor Peter Selby, Consultant Physician and Honorary Clinical Professor of Metabolic Bone Disease at the University of Manchester, welcomes the SACN recommendations and PHE guidance. He says: “It puts the evidence regarding the effects of vitamin deficiency into a UK context and demonstrates the benefits for bone health that could be achieved by a relatively simple supplementation programme. In particular it dispels any doubt of the place of vitamin D in the maintenance of bone health and should ensure that all people will now be encouraged to receive vitamin D to reduce their risk of bone disease and fracture.”
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