Vitamin D Deficiency


Vitamin D Deficiency

Vitamin D is a fat-soluble vitamin that supports the development of bones and teeth, the immune system function. Most importantly, it regulates the absorption of molecules in the body, such as calcium and phosphate. Vitamin D is sometimes known as ‘the sunshine’ vitamin because it is produced naturally by your skin in response to sunlight. Vitamin D is also found in animal-based foods, such as oily fish, milk and eggs.

What is the CYPSR1 gene?

The CYPSR1 gene encodes an enzyme called 25-hydroxylase which is the important enzyme in vitamin D metabolism.

Whether produced in the skin or absorbed from the diet, vitamin D must be first metabolised into 25 hydroxyvitamin D and then to its active form 1,25 dihydroxyvitamin D before it can be used in the body. A number of enzymes are involved in this process but  the most important one is one that is produced by the CYPSR1 gene.

What is the effect of genetic variation at the CYPSR1 gene?

Individuals with no SNP produce an enzyme that can efficiently metabolise vitamin D. Individuals with an allele produce an enzyme with reduced functioning and therefore their body is likely to be less able to convert vitamin D into its active form and therefore they have a higher risk of being vitamin D deficient.

Vitamin D deficiency is a problem all over the world.  Environmental factors, such as sun exposure and diet, do influence vitamin D levels in individuals but they only contribute to 13% of individual variation in vitamin D levels, meaning genetic factors are the main risk factor of vitamin D deficiency.

How common is vitamin D deficiency?

Vitamin D deficiency is estimated to affect nearly 1 billion individuals worldwide. In the UK, it has been shown that 1 in 5 adults have low vitamin D levels.

The likelihood of being vitamin D deficient varies between different groups. It is more common in young women, infants, the elderly and individuals who have dark skin.

How does sunlight aid vitamin D production?

Vitamin D can be synthesised by the skin when exposed to sunlight.

The skin absorbs UVB photons from the sunlight and these photons join with 7-dehydrocholesterol (which is found naturally in the skin). This process produces vitamin D.

Individuals with darker skin are less able to make vitamin D because they have more melanin. Melanin absorbs UVB photons and so prevent them joining with 7-dehydrocholesterol to form vitamin D.

How does vitamin D help keep bones strong?

Vitamin D assists calcium absorption. Calcium is essential for building and maintaining strong bones.

The active form of vitamin D binds to specific receptors that are located on cells. In particular, the binding of vitamin D to these receptors is essential for the absorption of calcium in the intestine. The binding of vitamin D to these receptors stimulates the expression of transport proteins, which then enable calcium to be actively transported and absorbed in the intestine. Once absorbed, calcium can be used in the body to help keep bones strong.

Does vitamin D supplementation enhance cognition?

No, it has not yet been scientifically proven.

Low levels of vitamin D have been associated with dementia and cognitive decline, resulting in some individuals assuming vitamin D supplementation will enhance cognitive function.

Research has shown that visual memory does seem to benefit from higher doses of vitamin D supplementation, especially in individuals whose levels are are insufficient. However, verbal memory and other cognitive processes show no improvement. In fact, research has shown that intermediate levels of vitamin D are optimal for verbal memory.

Therefore, although research is taking place, there is no strong evidence that vitamin D supplementation enhances cognition.

Backed by Science

Our in-house scientists have sorted through thousands of studies and we only use genes that are backed by a significant body of peer-reviewed research. Check out Nell’s Science Standard for more information.