Vitamin D Deficiency

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.