Vitamin D is known as the ‘sunshine vitamin’, because it is synthesized in the skin when exposed to sunlight. However, as more and more people are spending less time in the sun, even in summer, the vast majority of vitamin D people get is from their diet, either through foods (such as dairy) or supplements. Although this is beneficial, it is not the same as getting vitamin D from the sun.
Vitamin D isn’t just as simple as one molecule, and the idea that vitamin D from foods/ supplements can replace vitamin D from the sun is another example of over-simplified science. It is better to think of vitamin D as a group of compounds.
The reason that supplements/ foods sourced vitamin D cannot replace sunshine is because the compounds are actually different. Vitamin D from food/ supplements is usually in the form of vitamin D2 or D3, where as the vitamin D you make in your skin is vitamin D3 sulphate. The body is unable add the sulphate group to vitamin D3, meaning the two molecules, although similar, are not interchangeable in the body.
Vitamin D has been recognised for a number of benefits, but the 6 key ones are:
- Maintaining strong bones
- Supporting the immune system
- Preventing the development of cancer
- Normalizing hormone production
- Keeping healthy skin
- Protecting the cardiovascular system
Vitamin D3 sulphate is sometimes considered to be inactivated by the sulphate group, because it is unable to be involved in calcium transport, and so its effects on bone health are largely non-existent. However, vitamin D3 sulphate is thought to be more important for supporting the immune system, preventing cancer development, and protecting the cardiovascular system than non-sulphated forms. Meaning to obtain the full benefits of vitamin D you need to obtain vitamin D from sunlight and through the diet. This isn’t to say that non-sulphated vitamin D3 isn’t beneficial for these purposes, but it is thought to be to a lesser extent than vitamin D3 sulpate.
There has actually been very little research on vitamin D3 sulphate, although its existence and importance in our body has been known for at least 25 years. It had long been thought that vitamin D3 sulphate could only be obtained through sun exposure, but it has actually been found in raw milk. Whether it will also be in products made from raw milk such as butter is unknown, as the processing may damage/ remove it. It is possible that there are other food sources, but these have not been found yet. There are also no supplements (even fermented cod liver oil) which contain vitamin D3 sulphate.
Image courtesy of hmoong