What is vitamin D deficiency?

Vitamin D deficiency occurs when your body doesn’t get enough vitamin D for healthy functioning.

More than 1 in every 3 Australian adults has mild, moderate or severe vitamin D deficiency.

The Australian government publishes recommended dietary intakes (RDIs) for all vitamins. Babies, children, teenagers and adults aged 19–50 years should have 5μg (micrograms) of vitamin D per day. Adults aged 51-70 years should have 10μg of vitamin D per day. Adults aged over 70 years should have 15μg of vitamin D per day.

What are the symptoms of vitamin D deficiency?

Vitamin D is a fat-soluble vitamin. This means it can be stored in the body. It also means that if you go for a couple of weeks without getting vitamin D from sunlight or the food you eat, you won’t necessarily be deficient.

Ongoing vitamin D deficiency can result in osteoporosis, bone and joint pain. Older people who don’t have enough vitamin D are more likely to fall and fracture their bones.

Vitamin D deficiency can also affect an unborn child. If you are pregnant or wanting to start a family, ask your doctor to check if you are vitamin D deficient.

Vitamin D deficiency can be detected by a blood test. If you are low in vitamin D, you might not experience any symptoms, but Australian health authorities recommend that people with low vitamin D take supplements — even if they do not have any obvious signs of deficiency.

Am I at risk of vitamin D deficiency?

There are 2 main forms of vitamin D needed for healthy body functioning. Vitamin D2 (ergocalciferol) is from plant sources. Vitamin D2 is found in fortified food and some supplements. Vitamin D3 (cholecalciferol) is produced by sunlight on the skin. It is also found in some animal foods and supplements.

Most people are not able to get enough vitamin D from foods. But most people in Australian can get their vitamin D simply by going about their daily outdoor activities.

How much time you should spend in the sun will depend on many considerations, including your skin type, where you live, your lifestyle, the time of year and the time of day. It is important to wear a hat and sunscreen when the ultraviolet (UV) index is high.

See the sunshine map for the recommended sun exposure for your location in Australia.

If you are in any of the following groups, you are at a higher risk of vitamin D deficiency:

• older people or people living in care (such a hospitals, rehabilitation or aged-care facilities)
• people who stay indoors or cannot walk
• people with gastrointestinal (digestive) disease
• people taking certain medications (for example, epilepsy medicines)
• people who cover their skin for religious or cultural reasons
• dark-skinned people
• pregnant people
• postmenopausal people

There are also seasonal changes that may affect your risk of vitamin D deficiency. For example, most people spend more time outdoors in warmer weather when there are more hours of UV light, and they spend more time indoors in winter.

What are the impacts of vitamin D deficiency?

Vitamin D deficiency is linked with calcium deficiency because vitamin D helps to absorb calcium. Babies who have low calcium levels are at risk of seizures. Some children with very low vitamin D will have a condition called rickets. This involves bone and muscle pain as a result poorly formed soft bones.

If you are an older adult with vitamin D deficiency, you are at more risk of fractured (broken) bones due to low calcium levels and a weakened immune system. In cases of long-term vitamin D deficiency, you may develop osteoporosis or osteomalacia (soft bones in adolescents or adults, similar to rickets).

What happens if I have too much vitamin D?

There is no negative effect of excess vitamin D from the sun. However, prolonged exposure to harmful UV radiation dramatically increases your risk of skin cancer. Using sunscreen will not lead to vitamin D deficiency.

Continually taking high doses of vitamin D supplements can cause vitamin D toxicity. A condition called hypercalcaemia (where there is too much calcium in your blood) is the most common condition that results from taking too much vitamin D. Signs of this condition include nausea, dehydration and constipation.

If you are concerned that you have taken too much of a vitamin D supplement, call the Poisons Information Centre (13 11 26) immediately.