Advice and guidance on the health needs of migrant patients for healthcare practitioners.
Characteristic skeletal disorders from vitamin D deficiency and low vitamin D status are increasingly linked to a wide range of health problems.
Exposure to sunlight is the major source of vitamin D synthesis. It is also found in a small number of foods. Those at risk of vitamin D deficiency are those:
- with dark skin
- who spend little time outdoors
- who cover most of their skin when outdoors
- whose diets do not contain an adequate vitamin D supply (vegetarian or vegan)
Low vitamin D status is particularly likely during the winter months (October to early March) for people living in the UK, when there is no sunlight of appropriate wavelength for synthesis of vitamin D via the skin.
Consider vitamin D deficiency in migrants who have the above risk factors, and test and treat them appropriately.
New guidance from the Department of Health suggests that everyone living in the UK should consider taking a daily vitamin D supplement, at least during the winter months.
Supplementation is recommended for pregnant and breast feeding women, for infants from birth to one year of age, and for children aged 1 to 4 years, especially in at-risk groups.
Low income families in the UK, who receive one of a range of income related benefits and tax credits, may qualify for Healthy Start. Pregnant women, women with a child under 1 year of age and children aged 6 months to 4 years old can get free Healthy Start vitamin supplements which contain vitamin D.
Suspicions of suboptimal Vitamin D status are often correct. If a child has Vitamin D deficiency, assume the mother and other siblings are similarly affected.
Be aware of the difference between supplementation and treatment. The latter will be at a higher dose and intended to restore optimal Vitamin D levels safety but quickly.
Severe classical vitamin D deficiency causes rickets in children and osteomalacia in adults. It has also been linked to a range of other disorders including:
- infectious and autoimmune diseases
- cardiovascular disease
- type I diabetes
- some cancers
However, the evidence is inconclusive. It is still not possible to specify a relationship between vitamin D and health outcomes other than for bone health.
The main functions of vitamin D are related to calcium and phosphate metabolism.
Vitamin D is a fat-soluble vitamin that is produced when ultraviolet rays from sunlight strike the skin and trigger its synthesis. It also occurs naturally in some animal products, including oily fish (probably the best dietary source), eggs and meat.
In the UK fat spreads are fortified with vitamin D and it may be added to other foods such as breakfast cereals. The vitamin D content of most vegetables is negligible. Sunlight (ultraviolet B radiation) is the most important source for the majority of people worldwide.
People with pigmented skin require considerably greater sun exposure to get the same level of vitamin D synthesis as fair skinned people.
Those at risk of low vitamin D status are:
- people from a minority group, such as African, African-Caribbean or South Asian
- those who are not often outdoors
- populations with inadequate exposure to sunshine, such as:
- housebound or institutionalised people
- deeply pigmented persons living in low ultraviolet radiation settings (like the UK)
- those who, for religious or cultural reasons cover their entire body surface when they are outdoors
- people with inadequate dietary sources eg non-fish eating, vegetarian and vegan diets
A significant proportion of the UK population have low vitamin D status. The National Diet and Nutrition Survey (2008 to 2012) shows that in the general adult population (aged 19 to 64) the proportion of those with low vitamin D status (a plasma 25-hydroxy vitamin D concentration below 25nmol/L) ranged from around 15% for women to 22% for men which puts them at risk of vitamin D deficiency. The survey also found that 21% of men aged 65 years and older fell into this category of low vitamin D status.
In the winter months in the UK, there is no sunlight of appropriate wavelength for synthesis of vitamin D via the skin and the population relies on body stores (liver and body fat) and dietary intake.
Infants of vitamin D deficient mothers are at risk of deficiency as are those that are exclusively breastfed beyond 6 months of age. Poor childhood diet also increases the risk.
The Healthy Start scheme provides vitamin drops to children in families who qualify for the scheme from the age of 6 months to their 4th birthday. Pregnant women and those with a child under 1 year old on the scheme can also get Healthy Start women’s tablets which contain vitamin D.
The children’s drops are available to breastfed babies on the scheme from 1 month on health professional advice if there is any doubt about the mother’s vitamin D status during pregnancy.
In adults, vitamin D deficiency may present with pain and muscle weakness, or as osteopaenia or low bone density indicating possible osteomalacia.
In children, failure to thrive may occur, particularly in terms of height, and bone and muscular weakness may lead to bony deformity and impaired respiratory function, with increased susceptibility to infections and respiratory symptoms.
Severe deficiency can lead to hypocalcaemic seizures or cardiomyopathy and heart failure and also hypophosphataemia. Low vitamin D levels or vitamin D insufficiency can also be subclinical. It is often associated with decreased bone density such as osteopenia or osteoporosis. It can result in lower calcium levels and lower phosphate levels leading to elevated parathyroid hormone. This reduction in bone density through bone reabsorption can also present as an increased risk of falls and fractures.
Maintenance of Vitamin D levels may also improve the health of other body systems, such as the immune, muscular, and cardiovascular systems, although more research is needed in these areas.
Practitioners should be alert to the possibility of vitamin D deficiency in at risk patients with consistent symptoms.
Testing for vitamin D deficiency or insufficiency is recommended for anyone considered at risk according to their lack of sunlight exposure or poor dietary intake. It is also recommended for those:
- who are home-bound
- with chronic medical illness
- who show signs and symptoms compatible with osteoporosis (such as low impact fractures)
- with low blood calcium (hypocalcaemia) or phosphate (hypophosphataemia)
Vitamin D deficiency is diagnosed most reliably by measuring serum 25-hydroxyvitamin D 25(OH)D. Less than 25nmol/l (10µg/l) is defined as a deficiency and is associated with rickets and osteomalacia. Values of between 25 to 30 ng/mL (50 to 75nmol/L) are considered to represent vitamin D insufficiency
The National Osteoporosis Society have produced Vitamin D and Bone Health: A practical Clinical Guideline for Patient Management. Many areas of the UK also have local guidelines.
For a recent British Medical Journal clinical review, see ‘Diagnosis and management of vitamin D deficiency’.
Treatment options depend upon the level of Vitamin D deficiency.
Prevention and control
The Department of Health (DH) recommends daily supplementary vitamin drops for all infants from 6 months to 5 years.
The Healthy Start Children’s vitamin drops contain a combination of vitamins A, C and D, and are available free of charge to children aged 6 months to 4 years in families who qualify for the Healthy Start scheme.
- breastfed babies should be given 8.5 to 10mcg/day
- babies fed infant formula should not be given a vitamin D supplement until they are receiving less than 500ml of infant formula/day, because the formula is fortified with vitamin D
- children aged 1 to 4 should be given 10mcg/day
For adults, the elderly, pregnant and breastfeeding women and children aged 11 to 17, more than 100mcg/day could be harmful:
- children aged 1 to 10 should not exceed 50mcg/day
- infants <12 months should not exceed 25mcg/day
See NICE guidelines for antenatal care and in Royal College of Obstetrician and Gynaecologists guidance for pregnancy recommendations.
Advise all pregnant women and breastfeeding mothers to take supplements containing 10 micrograms of vitamin D each day (such as the Healthy Start women’s vitamin tablets which also contain vitamin C and folic acid and are available to women who qualify for the Healthy Start scheme during pregnancy and until their baby is 1 year old.
All pregnant under 18s qualify for Healthy Start regardless of their income or benefits.
NHS organisations may have local arrangements where they provide Healthy start vitamins free to those not on the scheme or at a small cost.
People of Asian origin, older people, and people who rarely go outdoors or who always cover all their skin when they are outdoors should also consider taking vitamin D.
See NICE guidelines on increasing Vitamin D supplement use among at-risk groups.
Find out about vitamin D on NHS Choices.
Healthy Start has information on vouchers for healthy food for children and pregnant women.
The ‘Vitamin D: an essential nutrient for all..but who is at risk of vitamin D deficiency?’ leaflet has important information for healthcare professionals.
The ‘Update on vitamin D: position statement by the Scientific Advisory Committee on Nutrition (2007)’ highlights the prevalence of low vitamin D status throughout the UK population, and the re-emergence of rickets in subgroups of the population.