What is vitamin D deficiency?
Vitamin D deficiency means that there is not enough vitamin D in the
body. Vitamins are a group of chemicals that are needed by the body for
good health. Vitamin D is important for strong bones and muscles.
Possibly, it may also help to prevent other diseases such as cancer,
diabetes, tuberculosis and heart disease.
Who gets vitamin D deficiency?
It is easiest to understand this if you know where vitamin D comes
from. Vitamin D is made in the skin with the help of sunlight – this is
the main source of vitamin D. It needs bare skin and direct sunlight
(not through a window). People with darker skins will need more sun to
get the same amount of vitamin D. Vitamin D is also found in certain
foods: liver, some types of fish, and egg yolk. Some cereals or
margarines contain added vitamin D.
Growing children, pregnant
women, and breastfeeding women need extra vitamin D because it is
required for growth. So, vitamin D deficiency is more likely to develop
in the following groups of people:
- Pregnant or breastfeeding women.
- Breastfed babies whose mothers are lacking in vitamin D, or with
prolonged breastfeeding. (These babies do not need to stop
breastfeeding, they can have breast milk plus vitamin drops – “breast
is still best”).
- People who get very little sunlight on their skin such as those who
are stay indoors a lot, or cover up when outside, for example, if
wearing a veil.
- People with conditions that affect the way the body handles vitamin
D such as those with coeliac disease, Crohn’s disease, and some types
of liver and kidney disease.
- People taking certain medicines: carbamezepine, phenytoin, primidone or barbiturates.
- People with dark skins or of South Asian origin, elderly people, and those with a family history of vitamin D deficiency.
How common is vitamin D deficiency?
It is very common. Research suggests that in the UK around 2 in 10
adults, and 9 in 10 adults of South Asian origin, may be vitamin D
deficient. Most people don’t have symptoms and are unaware of the
problem.
What are the symptoms of vitamin D deficiency?
Many people have no symptoms, or only vague ones such as tiredness or aches. Other symptoms may be:
- Muscle
pains or muscle weakness. In more severe deficiency, this may cause
difficulty standing up or climbing stairs, or can lead to the person
walking with a ‘waddling’ pattern.
- Bone pains, often in the back, hips or legs.
- Children with severe deficiency may have soft skull or leg bones.
This can make the legs look curved or bow-legged. Other symptoms in
children are poor growth and delayed/weak teeth.
- Muscle spasms (cramps), seizures and breathing difficulties can occur in babies and children with very severe deficiency.
How is vitamin D deficiency diagnosed?
It may be suspected from your medical history, symptoms, or lifestyle.
A simple blood test for vitamin D levels can make the diagnosis. Also,
blood tests for calcium and liver function may show changes linked to a
low level of vitamin D.
Sometimes, a wrist x-ray is done for a
child. This can assess how severe the problem is by looking for changes
in the wrist bones.
Extra tests may be needed if the cause of
the deficiency is in doubt, or if there are other vitamin or mineral
deficiencies. For example, if anaemia is found as well, you should have
a blood test to look for coeliac disease.
What is the treatment for vitamin D deficiency?
Note: if you are pregnant or breastfeeding, see the next section after this.
The
treatment is to take vitamin D supplements. This is a form of vitamin D
called ergocalciferol or calciferol. (The dose of ergocalciferol is
written in units known as international units or IU. Some people use
microgrammes or μg instead, which are not the same as units.) There are
various different ways of taking vitamin D, which are:
Injection
A single small injection of
vitamin D will last for about six months. This is a very effective and
convenient treatment. It is useful for people who do not like taking
medicines by mouth, or who are likely to forget to take their tablets.
High dose tablets or liquids
There are
different strengths available and a dose may be taken either daily,
weekly or monthly. This will depend on your situation and on which
particular treatment guideline your doctor is using. Always check with
your doctor that you understand the instructions - with high doses of
vitamin D it is important to take the medicine correctly. The advantage
of the higher dose treatment is that the deficiency improves quickly -
important in growing children.
Standard dose tablets, powders or liquids
These
need to be taken every day for about 12 months in order that the body
can "catch up" on the missing vitamin D. This is a rather slow method
of replacing vitamin D, but is suitable if the deficiency is mild, or
for prevention. A disadvantage is that all these preparations contain
either calcium or other vitamins, giving them a strong taste which some
people dislike. Cod liver oil is an alternative.
Note: care is needed with vitamin D supplements in certain situations:
- If
you are taking certain other medicines: digoxin or thiazide diuretics
such as bendroflumethazide. In this situation, avoid high doses of
vitamin D, and digoxin will need monitoring.
- If you have other medical conditions: kidney stones, some types of
kidney disease, liver disease or hormone disease. Specialist advice may
be needed.
- Vitamin D should not be taken by people who have high calcium levels or certain types of cancer.
- You may need more than the usual dose if taking certain medicines
which interfere with vitamin D. These are: carbamezepine, phenytoin,
primidone and barbiturates.
If you are pregnant or breastfeeding
Vitamin D is especially important for pregnant or breastfeeding women, and their babies, because it is needed for growth.
Prevention
Vitamin D supplements are recommended for all pregnant women, breastfeeding women and breastfed babies.
-
Pregnant women and breastfeeding mothers:
400 units (10 micrograms) daily of vitamin D is recommended. This can
be either as a calcium/vitamin D tablet, or as a multivitamin tablet
labelled as suitable for use in pregnancy. Some experts think that
women who get no sunshine need a higher preventative dose such as 800
units (20 micrograms) daily. Pregnant women can get free prescriptions
and vitamins.
-
Babies: all breastfed babies should be given vitamin drops
(Abidec or Dalivit in the dose advised on the label). Free vitamins are
available with the Surestart scheme via your health visitor.
Treatment - if you are diagnosed with vitamin D deficiency
Doses
of up to 1000 units (25 micrograms) daily of vitamin D can be used. (In
some situations, higher doses have been used to treat pregnant women.)
Important note:
if you are pregnant or breastfeeding you should not use high doses of
vitamin D (the injections and high dose tablets/liquids described
above). This is because of uncertainty about whether these doses are
too high for the baby. Doctors tend to be cautious about the dose of
vitamin D given to pregnant or breastfeeding women, and will often
limit the dose to 1,000 units daily. This is a safe dose. It is likely
that higher doses are safe for pregnant women, but we are waiting for
more guidance on this subject.
Important note: if you are
pregnant, do not take supplements containing large amounts of vitamin
A. Supplements labelled as suitable for pregnancy are safe to use.
Also, do not eat liver which contains large amounts of vitamin A, as
too much can harm the baby. Vitamin A is safe if you are breastfeeding.
Are there any side-effects from vitamin D supplements?
It is very unusual to get side effects from vitamin D if taken in the
prescribed dose. However, very high doses can raise calcium levels in
the blood. This would cause symptoms such as thirst, passing a lot of
urine, nausea or vomiting, dizziness and headaches. If you have these
symptoms, see a doctor immediately so that your calcium level can be
checked with a blood test.
Some guidelines advise that people
taking high vitamin D doses should have their calcium levels checked
during the first few weeks. In practice, this is not usually done
unless you have symptoms of high calcium as described above.
What is the outcome with vitamin D deficiency?
The outcome is generally very good. Both the vitamin levels and the
symptoms usually respond well to treatment. However, it can take time
(months) for bones to recover. So, if you have symptoms such as bone
pain, this will also take time to improve.
There are some possible complications of severe deficiency (see below). Most of these will improve or recover with treatment.
Very
severe, prolonged deficiency may cause bone problems (rickets or
osteomalacia) which could lead to a deformity if treated very late.
Are there any complications from vitamin D deficiency?
Mild or short-lived vitamin D deficiency usually causes no symptoms.
With prolonged deficiency, the risk of getting osteoporosis (bone
thinning and fractures in old age) is probably increased. The risk of
getting other diseases might also be increased. This is uncertain, but
it is possible that vitamin D helps to prevent some conditions such as
diabetes, heart disease and cancer.
Prolonged, severe deficiency can cause medical problems, which are:
- Softening of the bones. This leads to rickets in children and osteomalacia in adults. See separate leaflets on 'Rickets' and 'Osteomalacia'.
- With severe deficiency, there may be low levels of calcium in the
blood. If calcium levels get very low, this can cause muscle spasms
(cramps) or seizures. Babies may get breathing difficulties. These
symptoms need urgent treatment.
- Very rarely, severe deficiency has been reported to cause heart muscle weakness, which was cured by vitamin D treatment.
Follow up
Most people who are treated for vitamin D deficiency will need to be
reviewed a few weeks or months after starting treatment - depending how
severe their symptoms are. A further review after one year is advised.
Prevention
Once you have been treated for vitamin D deficiency,
prevention is needed to stop the deficiency from recurring again in the
future. Diet change and sunshine can help (see below). Many people find
it hard to change their diets or to get more sunshine, and so will need
to take long-term vitamin D supplements. Supplements to prevent
deficiency are:
-
Babies under one year: should have
200 units (5 micrograms) daily of vitamin D. Breastfed babies should be
given vitamin drops (see breastfeeding section above). Babies fed by
formula milk do not need vitamin drops, as this milk already contains
vitamin D.
-
Children aged over one year: should have 280-400 units (7-10
micrograms) daily of vitamin D. This is usually given as vitamin drops
or tablets. Babies fed by formula milk do not need vitamin drops, as
this milk already contains vitamin D. But when weaned on to ordinary
milk they should have supplements, as ordinary milk in the UK contains
little vitamin D. (Note: some countries outside of the UK do add
vitamins to ordinary milk.)
-
Adults: supplements of 400 units (10 micrograms) daily.
However, people who get no sunshine, and the elderly, probably need
more - approximately 800 units (20 micrograms) daily.
-
Higher preventative doses may be needed in certain situations.
For example, for people on certain medicines (carbamezepine, phenytoin,
primidone and barbiturates) and with other conditions such as liver or
kidney disease.
Cod liver oil can be taken instead of the usual vitamin D
supplements (to give the same dose of vitamin D). However, be careful
about using cod liver oil if you are pregnant, as it also contains
vitamin A, which may be harmful in large amounts (see pregnancy
section). Another option, instead of daily supplements, is to use the
higher dose tablets, liquids or injections, taken at longer intervals.
For example, this could be a weekly or monthly high dose tablet, or an
injection every six to twelve months. You can discuss these options
with your doctor.
Diet and sunshine for vitamin D
Foods
containing good amounts of vitamin D are: liver, some fish (mainly oily
fish such as herring, sardines, pilchards, trout, salmon, tuna and
mackerel), egg yolk, and 'fortified' foods (which have vitamin D added)
such as some margarines and breakfast cereals.
Sunshine: 15
minutes three times weekly from April to September, with hands, arms
and face uncovered, is said to be enough for fair-skinned people.
Darker-skinned people will need more sunshine (we don't know how much
more). However, in winter in cold climates, there is not enough
sunshine to maintain vitamin D levels.
A useful source of information
Healthy Start Scheme
Web: www.healthystart.nhs.uk
A government run scheme. With Healthy Start, you can get free vouchers
every week which you swap for milk, fresh fruit, fresh vegetables and
infant formula milk. You can also get free vitamins. You could qualify
if you're on benefits or you're pregnant and under 18.
References
© EMIS and PiP 2008 Updated: 25 Feb 2008
