Vitamin D is important for good bones.
- Young children that don’t get enough vitamin D can develop rickets, which causes bowed legs and knock knees.
- Adults that don’t get enough vitamin D can develop bone weakness and increased risk of fracture.
For most people, it’s easy to get enough vitamin D in New Zealand – our bodies produce it whenever we get the sun on our skin. However, because of the risks of sunburn and skin cancer, we need to be careful how much sun we get.
Vitamin D in food
Some foods contain small amounts of vitamin D. You can get it naturally from:
- oily fish (eg, salmon, tuna, sardines, eel and warehou)
- milk and milk products
Some foods may also have vitamin D added. These include:
- margarine and fat spreads
- some reduced-fat dairy products (eg, milk, dried milk and yogurt)
- plant-based dairy substitutes (eg, soy drinks)
- liquid meal replacements.
Check the ingredients lists on these foods to see if extra vitamin D has been added.
Vitamin D deficiency
Around 5% of adults in New Zealand are deficient in vitamin D (Adult Nutrition Survey 2008/09). A further 27% are below the recommended blood level of vitamin D.
- Having naturally very dark skin. This includes people from Africa, the Indian subcontinent and Middle East.
- Your skin not being regularly exposed to sunlight, eg:
- avoiding the sun because you have a high risk of skin cancer or are on photosensitising medications (these are medicines that make your skin more sensitive to the sun – your pharmacist or doctor will have advised you)
- regularly wearing clothing that covers a lot of your skin (eg, veils or other clothing covering your legs, arms and face), or
- not going outside.
- If you live in the South Island (especially south of Nelson-Marlborough) and get little time outdoors in the middle of the day between May and August, you may be at risk of vitamin D deficiency in spring. You may wish to consider taking vitamin D tablets from May to August.
- If you have liver or kidney disease, or are on certain medications that affect vitamin D levels, you may be at risk of vitamin D deficiency.
If you think you may be vitamin D deficient, talk to your GP – or, if you’re pregnant, your lead maternity carer. They’ll be able to work out whether you’re at risk.
Getting more vitamin D
Sun beds and solariums
Sun beds and solariums are not recommended as they increase your risk of melanoma and other skin cancers.
You can get more vitamin D by:
- sensible sun exposure.
- choosing foods that contain vitamin D.
Some people with a high risk of vitamin D deficiency may need to take a vitamin D tablet. Talk to your GP, dietitian or lead maternity carer if you’re concerned.
Sensible sun exposure
Exposing your skin to the sun increases your risks of skin cancer. It’s important that you balance the risks. You should never get sunburnt.
If you have a history of skin cancer, or are taking medicines that affect photosensitivity, you should use sun protection (shade, clothing coverage and a sun protective hat, sunscreen, sunglasses) all year round. Your doctor may recommend a vitamin D tablet for you.
Between September and April, sun protection is recommended (shade, clothing coverage and a hat that shades the face and neck, sunscreen and sunglasses), especially between 10am and 4pm. A daily walk or some other form of outdoor physical activity in the early morning or late afternoon is recommended.
Between May and August, some sun exposure is important. A daily walk or another form of outdoor physical activity around the middle of the day is recommended.
Sun protection should also be used throughout the year when at high altitudes or near highly reflective surfaces such as snow or water.
You can’t make vitamin D by sitting inside by a sunny window – UVB waves do not pass through glass.
Different people need different amounts of sun exposure to make enough vitamin D. How much sun you should get depends on:
- your skin colour
- your age, weight and mobility
- risk of skin cancer
- how much vitamin D you get from your food
- if you are taking medications – some medications are photosensitising
- where you are in New Zealand, season, and time of day
- certain medical conditions.
Talk to your GP if you have questions about safe sun exposure or if you think you may not be getting enough vitamin D.
Sun exposure during winter months
The Ultraviolet Index (UVI) measures the level of ultraviolet radiation. Throughout winter, particularly in the South Island, the UVI is usually less than 3 (low).
When the UVI is 3 (some North Island regions), skin damage occurs after about an hour in those people with sensitive or fair skin. However optimal vitamin D can still be produced in a few minutes if at least the face, arms and legs are exposed.
NIWA provides a year round daily guide of the UV throughout New Zealand.