Overview
Vitamin D helps the body control the calcium and phosphate that keep bones, teeth and muscles healthy. The skin makes it when sunlight falls on it, and a smaller amount comes from food and supplements. Deficiency means the body does not have enough.
Long-term deficiency can weaken the bones. In children it can cause rickets, in which the bones become soft and bend. In adults it can cause osteomalacia, with bone pain and muscle weakness. Low vitamin D is common in India, even though sunshine is plentiful.
Symptoms
Many people with low vitamin D have no clear symptoms. When it is more severe, signs can include:
- Pain in the bones, or in the back, ribs, pelvis or legs
- Weak muscles, and trouble climbing stairs or getting up from a chair
- Tingling, cramping or muscle twitching
- Getting tired more easily
- Bones that break easily or after a minor accident
In children with rickets the main sign is bowed legs. A child may also have swollen, painful wrists, or be small for their age.
When to see a doctor
See a doctor if you or your child has symptoms like those above, or if you are in a higher-risk group. Do not start high-dose supplements on your own.
Causes
Low vitamin D has four main causes: too little sunlight on the skin, too little in the diet, poor absorption from the gut, and a body that cannot turn vitamin D into its active form, as in some liver or kidney problems. Some medicines can also lower vitamin D levels.
Risk factors
- Babies who are only breastfed, because breast milk has little vitamin D
- Older adults, and pregnant or breastfeeding women
- People who are rarely outdoors, or who cover most of their skin
- People with dark skin
- People with obesity, or who have had gastric bypass surgery
- People with bowel, kidney or liver disease that affects absorption or activation
Complications
If it is not treated, long-term deficiency can lead to:
- Rickets in children, with soft, bowed bones and slow growth
- Osteomalacia in adults, with bone pain, weak muscles and difficulty walking
- Loss of bone density, which can add to osteoporosis and fractures
Prevention
- Spend short, regular periods outdoors with some skin uncovered, but avoid long hours in strong sun
- Eat foods that contain vitamin D, such as oily fish, egg yolks, mushrooms and foods with vitamin D added
- Eat enough calcium, for example from dairy products and green leafy vegetables
- Ask a doctor about supplements if you are at higher risk
- Do not take large doses on your own
Diagnosis
A blood test measures the vitamin D level. A doctor usually advises it when symptoms or risk factors suggest deficiency, and may check calcium too. X-rays may be used if rickets or osteomalacia is suspected.
The doctor also looks for the cause, such as poor absorption or a liver or kidney problem.
Treatment
Treatment is vitamin D supplements. The doctor decides how much to take, how often and for how long. Calcium supplements may be added, and a balanced diet that includes calcium is advised.
Sensible time outdoors and foods that contain vitamin D help too. Any underlying cause, such as poor absorption, is treated. Bone problems such as bowed legs may need further treatment, and some people need surgery.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“I live in a sunny country, so I cannot be short of vitamin D.”What is true?
Fact
Low vitamin D is common in India even though sunshine is plentiful. How much the skin makes depends on how much of it is uncovered and in the sun, and on skin colour. Dark skin, clothes that cover most of the skin, avoiding the sun, indoor and city living, and diets low in vitamin D all contribute.
Myth“Milk and a normal diet give all the vitamin D we need.”What is true?
Fact
Few foods contain much vitamin D. The main ones are oily fish, egg yolks, liver, mushrooms and foods with vitamin D added. Milk and other staples are not always fortified with it in India, so food alone may not be enough for some people.
Myth“More vitamin D is always better, so high-dose sachets or injections are safe to take on my own.”What is true?
Fact
Too much vitamin D, usually from overusing supplements, can raise the calcium in the blood to harmful levels and damage the kidneys and heart. A doctor decides how much to take and for how long.
Myth“Sitting in the sun for hours is the best way to fix it.”What is true?
Fact
Short, regular time outdoors with some skin uncovered helps, and the sun cannot cause an overdose. But long hours in strong sun raise the risk of skin damage and skin cancer, and sun alone may not be enough for people with dark skin or who cover most of their skin. Food and supplements are the other sources.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
How is vitamin D deficiency diagnosed?
With a blood test that measures the vitamin D level. A doctor usually advises it if you have symptoms or are in a higher-risk group, and may add tests for calcium. Your doctor will look at the result together with your symptoms and risk factors.
How long will I need to take supplements?
The dose and the length of treatment depend on the cause and on your blood level, so a doctor decides them. Do not stop or change a prescribed supplement without asking.
How much sun do I need?
Short, regular periods outdoors with some skin uncovered help the skin make vitamin D. People with dark skin may need more time in the sun to make the same amount. Long hours in strong sun raise the risk of skin damage, so ask a doctor what is sensible for you.
Can children have vitamin D deficiency?
Yes. Severe deficiency in children causes rickets, with soft, bowed bones. Babies who are only breastfed are at higher risk because breast milk contains little vitamin D. Ask a doctor whether your child needs a supplement.
