This complete guide to vitamin D evaluates some of the more important aspects of this essential vitamin - what it is, what you need it for and where to get it.
What is vitamin D?
Vitamin D is often referred to as “the sunshine vitamin” as it is produced from cholesterol when skin is exposed to the sun. There are in fact two different types of vitamin D, vitamin D2 and vitamin D3.
Vitamin D2 (ergocalciferol) is only derived from plant sources and is also often the type of vitamin D found in fortified products. Vitamin D3 (cholecalciferol) is the form that is found in animal sources, as well as some specific plant-sources such as algae and lichen, while also being the type of vitamin D3 we synthesise in our skin from UVB light.
Vitamin D2 and vitamin D3 also differ structurally, with vitamin D3 far more stable with superior bioavailability .
What does vitamin D do?
It would almost be easier to list the things that vitamin D doesn’t do! Vitamin D acts as both a hormone and a vitamin in the body and has a whole string of actions supporting health including:
- The absorption of dietary calcium
- Bone mineralisation
- Bone health including bone mass, bone density, bone integrity and bone strength
- Bone health in certain times of life, specifically post-menopause
- Healthy teeth
- Muscle health
- Muscle strength
- Immune system health and function
- A healthy pregnancy and healthy foetal development
- Helping to prevent a dietary vitamin D deficiency
Where can I get vitamin D?
Vitamin D and the sun
When the sun’s ultraviolet B (UVB) rays hit a person’s skin, processes inside the tissue start making vitamin D for the body to use. The skin produces more vitamin D from the sun during the middle of the day, the time it is at its highest point in the sky. Remember to practice safe sun exposure which helps to avoid sunburn.
Paler coloured skin makes vitamin D faster than darker skin colours and where a person lives in relation to the equator also has a significant impact on how much vitamin D their bodies can make.
Vitamin D and food
Some foods are higher in vitamin D than others. Eggs, sardines and salmon naturally contain vitamin D. You can also commonly find foods fortified with vitamin D on the supermarket shelves including milk, yoghurt, eggs and breakfast cereals.
Vitamin D and supplements
Vitamin D supplements are readily available and generally contain vitamin D derived from either one of two sources, an animal-based source commonly from lanolin from sheep’s wool, or a plant-based source from lichen, an algae rich in the vitamin.
How much vitamin D do I need?
The Adequate Intake (AI) for adults aged 19-50 years is shown in the table below and is based on the amount of vitamin D required to maintain serum vitamin D levels of at least 27.5 nmol/L when there is minimal exposure to sunlight.
| Age | AI |
| Men | |
| 19-30 yr | 5.0 micrograms /day |
| 31-50 yr | 5.0 micrograms /day |
| 51-70 yr | 10.0 micrograms /day |
| >70 yr | 15.0 micrograms /day |
| Women | |
| 19-30 yr | 5.0 micrograms /day |
| 31-50 yr | 5.0 micrograms /day |
| 51-70 yr | 10.0 micrograms /day |
| >70 yr | 15.0 micrograms /day |
Vitamin D levels can be assessed by a simple blood test through your doctor to determine if they fall within a healthy range.
Some of the challenges with Vitamin D
There are a few reasons why your body can struggle to make enough vitamin D in the sun, even during the middle of the day.
UVB rays, which catalyse the production of vitamin D, are blocked by the atmosphere. So, the more atmosphere UVB rays have to travel through, the more they are prevented from reaching your skin – and you. If the sun is low enough, the rays are completely blocked, making vitamin D production impossible.
Clouds also block UVB rays, so on a cloudy or overcast day your chances of producing vitamin D are also significantly limited. UVB rays also don’t penetrate glass or clothing, so if you’re in your car, or covered from clothing (or a strong UVB protecting sunscreen), this can also block the production of vitamin D.
Vitamin D supplement options
Herbs of Gold have a range of supplemental options for vitamin D if your dietary intake is inadequate. Our Herbs of Gold Vitamin D3 1000 contains a vegan-friendly vitamin D derived from lichen, supporting bone health and bone strength, while also supporting the absorption of dietary calcium.
The Herbs of Gold Women’s Multi + and Herbs of Gold Men’s Multi + contain 1000IU of vegan-friendly vitamin D3 in addition to a range of other carefully selected important vitamins, minerals and herbs supporting the general health and wellbeing of females or males.
Finally, for the younger generation, Herbs of Gold Children’s Multi Care contains 100IU of plant-based vitamin D3 to assist healthy bone development and maintain bone health in children. This delicious strawberry-vanilla flavoured chewable tablet is suitable for use in children 2 years and up.
