What is vitamin D?

Vitamin D is a fat-soluble vitamin. That means it can be stored in your body.

Vitamin D comes in 2 forms:

1. vitamin D2 (ergocalciferol)
2. vitamin D3 (cholecalciferol)

Vitamin D2 comes from plant sources. It's also found in:

• fortified food — like some fortified milks and margarines
• some supplements

Vitamin D3 is made in your skin when you are exposed to sunlight. It's also found in some animal foods and supplements.

Vitamin D needs to be activated and turned into a hormone to work effectively. This is done in your liver and kidneys.

Why is vitamin D important for my health?

Vitamin D is very important for our health.

Vitamin D helps your body absorb calcium from the food you eat. This is vital for bone development and strength. It also helps control the amount of calcium in your blood.

Vitamin D is also important for the health of your:

• immune system
• skin
• muscles
• brain

A lack of vitamin D can increase your risk of certain conditions, such as:

• osteoporosis
• cancer
• type 2 diabetes
• high blood pressure
• infectious diseases, including severe infection with COVID-19

What are the natural sources of vitamin D?

Most people are not able to get enough vitamin D from food alone. But in Australia, most people can get enough vitamin D with careful sun exposure.

Exposure to sunlight

The main source of vitamin D comes from your skin being exposed to ultraviolet (UV) radiation from the sun. Australians tend to meet their vitamin D needs from exposure to the sun, mostly in the form of UVB rays.

How much time you should spend in the sun will depend on:

• your skin tone — naturally dark-skinned people need more UV exposure to make enough vitamin D
• the amount of skin you expose
• where you are in Australia
• the season — time of year
• the time of day

You need to balance the need for some sun exposure to make vitamin D with the risk of skin damage from the sun. If UV radiation is high (if the UV index is 3 or above), it's important to wear protection to reduce your risk of skin cancer.

In general, during the summer months in Australia, you only need to spend a very small amount of time outdoors on most days to get enough vitamin D. For many people this will be achieved through incidental sun exposure.

In most southern states in Australia during winter, it's possible to keep up your vitamin D levels by spending time outdoors with sufficient skin exposed during the middle of the day

See the sunshine map to see how much sun exposure you need where you are in Australia.

Foods high in vitamin D

While vitamin D is found in some food, it's in small amounts. Most Australians get only about 10 per cent of their vitamin D from the food they eat. This is because few foods are rich in vitamin D.

Foods that contain vitamin D include:

• oily fish, including salmon, mackerel, sardines and herring
• egg yolks
• mushrooms exposed to UV light

Some foods are fortified with vitamin D (they have added vitamin D). These include:

• margarines
• some fortified milk and soy drinks
• some fortified yoghurts

Check the food label to see if there is added vitamin D.

How much vitamin D do I need from food?

The Australian government publishes recommended dietary intakes (RDIs) for all vitamins. The recommended amount of vitamin D from food depends on your age.

• Babies, children, teenagers and adults aged 19–50 years should have 5μg (micrograms) of vitamin D a day.
• Adults aged 51–70 years should have 10μg of vitamin D a day.
• Adults aged over 70 years should have 15μg of vitamin D a day.

Can I have too little vitamin D?

Some people may not get enough sun exposure to keep up their vitamin D levels. This may happen if you:

• spend lots of time indoors
• have naturally dark skin
• wear clothes that cover most of your body
• live in the southern regions of Australia

There are also conditions and some medicines that can increase your risk of having low vitamin D.

If you think you may be vitamin D deficient, ask your doctor whether a blood test to check your vitamin D level is needed.

What happens if I have too much vitamin D?

There is no negative effect of excess vitamin D from the sun. But extended exposure to harmful UV radiation does dramatically increase your risk of skin cancer and melanoma.

Should I take vitamin D supplements?

If your doctor says you are low in vitamin D, you might need a vitamin D supplement.

Can taking vitamin D supplements cause side effects?

Taking too much of any medicine or supplement has risks.

People with certain conditions should not take vitamin D supplements.

Vitamin D supplements rarely cause vitamin D toxicity. This can lead to hypercalcaemia (where there is too much calcium in your blood).

Before taking any vitamin supplement, speak with your doctor, pharmacist or an accredited dietitian. While vitamins can supplement your diet, they should not be used as a replacement for a healthy lifestyle.

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

Resources and support

See the Australian Guide to Healthy Eating.

The Cancer Council's SunSmart app can help you check your daily local sun protection times.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.