Vitamin D facts
Vitamin D is a fat-soluble vitamin that plays a role in musculoskeletal health. Like vitamins A and E, it’s soluble in fats, or lipids, rather than water, which means your body’s able to store it.
Unlike other vitamins, vitamin D is also considered a hormone and it’s produced from cholesterol when the skin is exposed to the sun – which is why it’s often referred to as the ‘sunshine vitamin’.
What does vitamin D do?
The main function of vitamin D is to support calcium in the body/blood stream by enhancing the absorption of calcium from food in the small intestine
Vitamin D helps to maintain bone health and supports muscle strength. Vitamin D also supports a healthy immune system.
Vitamin D and the immune system
Research suggests that vitamin D is involved in the innate immune system. Our innate immune system is our “first line of defence” and helps to stop the entry and spread of pathogens in the body.
The activation of immune cells that form part of this defence is dependent on vitamin D in the body.
Where to get vitamin D
Most people do not need to obtain vitamin D from food if they spend enough time in the sun. The questions still remain: how much sun is enough and how much is too much?
Vitamin D and sun exposure
Unlike other vitamins, vitamin D is primarily produced by the body with the help of sunlight. Most people do not need to obtain vitamin D from food if they spend enough time in the sun.
It is important to be mindful of getting enough sun exposure to achieve adequate vitamin D levels, but not too much to cause permanent skin damage.
The recommended guidelines for safe sun exposure to maintain healthy levels of vitamin D are:
- For most people, sun protection is needed when the UV index is moderate or above i.e. UV index is 3 or higher
- Most people should get adequate vitamin D through sun exposure in day-to-day outdoor activities which expose the face, arms and hands to a few minutes of sunlight, however this should be outside peak UV times
- In winter where sunlight may not be intense, 2-3 hours of sunlight exposure over a week is required to maintain vitamin D levels
Food sources of vitamin D
While exposure to sunlight is the main way to get vitamin D, there are a few food sources too. Including:
- Fatty fish such as herring, salmon, tuna and sardines
- Beef
- Livers
- Butter
- Eggs
- Fortified foods such as margarine and milk
How much vitamin D do you need?
An adequate intake of vitamin D for children and adults under 50 years of age is 5 micrograms (200 IU). This increases to 10 micrograms between 51 and 70 years, and then increases to 15 micrograms for adults over 70 years of age.
Vitamin D helps calcium absorption
Vitamin D helps the uptake of calcium into bone, a diet deficient in calcium can lead to osteoporosis in adults later in life.
Who is at risk of low vitamin D?
You may be at risk of low vitamin D if you are:
- Naturally dark-skinned
- Cover your skin for religious or cultural reasons
- Spend a high amount of time indoors
- Use certain medications
- Avoid sun exposure for other health reasons
What’s the difference between vitamin D2 and vitamin D3?
There are two types of vitamin D available in supplements- Vitamin D3 (cholecalciferol) and Vitamin D2 (ergocalciferol) and people are often unsure as to which type they should get.
Vitamin D3 is the form that we make in the skin when we are exposed to sunlight.