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A guide to vitamin D


May 7, 2017

The North East isn’t famed for having the best weather, with sunny days often few and far between. There’s been a lot of talk around vitamin D recently, but what exactly is it and why is it being hailed as one of the most important supplements we should be taking?

North East-based company, and retailer of vitamin D supplements, Pharma Nord has shared this essential guide to vitamin D:

Vitamin D: the essentials

Essential for human health, vitamin D is a fat-soluble nutrient that our body uses to boost our immune system, muscle functions and bone health. Though it’s naturally found in fish, butter and eggs, the average dietary intake from foods (in the UK) is around 126iu per day, which for most people is entirely inadequate.

Our main source of vitamin D is the sun hitting the skin. The body produces vitamin D from cholesterol, provided there is an adequate amount of UVB light from sun exposure.  There are a wide range of factors which can limit this synthesis though, including:

  • Age — our ability to convert vitamin D from sun exposure declines as we get older.
  • Season and latitude — those living in darker places, including the UK, experience less sunlight, particularly through autumn and winter.
  • Skin pigmentation — those with darker skin need more sun exposure than those with lighter skin to produce the same amount of vitamin D.
  • Regular use of sunscreen — UV rays can be blocked by sunscreen, reducing vitamin D synthesis.
  • Sun avoidance — some medications can cause photo-sensitivity.
  • Covering up for religious reasons.

Most of us aren’t truly Vitamin D deficient, and are only insufficient. Without optimum vitamin D levels, the full health benefits cannot be attained, so many turn to vitamin D supplements.   

Vitamin D in the body

So once vitamin D enters the body, where does it go and what does it do? Once in the bloodstream, vitamin D is transported to the liver in the form of calcidiol and is stored for future use. This calcidiol is then sent to kidneys where it is turned into calcitriol, then sent to different tissues all over the body.

Calcitriol functions in two main ways. This includes managing calcium in the blood, bones and digestive system, and helping cells grow, communicate and express genes. It has long been linked to having a positive impact on immunity too.

Will vitamin D help me protect myself against colds and flu?

The British Medical Journal published a meta analysis which found that vitamin D, when taken either daily or weekly, can protect against respiratory chest infections — including colds, flu and pneumonia — but not in one-off doses. As well as offering protective effects, vitamin D can shorten the duration of colds and flu should they occur.

How can vitamin D help with falls?

The meta-analysis also found that the risk of falling and fracture in 65+ year olds reduced by 29% when vitamin D doses of at least 700iu -1000iu were present. However, lower doses were proven to be ineffective.

Can vitamin D help depression?

As well as assisting in their maintenance, Vitamin D has been found to have a protective effect on neurones. This has shown to have a positive effect on mental health. In a randomised, double-blind control trial, vitamin D supplementation was shown to reduce depressive symptoms associated with major depressive disorder (MDD).

Is there a relation between vitamin D and cancer prevention?

A meta-analysis in the American Journal of Preventative Medicine found a link between daily doses of vitamin D3, and a reduced risk of colorectal cancer with minimal risk. This was based on an investigation of over 1,400 subjects.

How much vitamin D does my body need?

Recommended dosages of vitamin D remains highly discussed, as many factors can impact an individual’s vitamin D status.  

However, the recommendation from the Scientific Advisory Committee on Nutrition (SACN) states that everyone should take at least 10μg/400iu of vitamin D in autumn and winter months per day. As the government recommendation, this is considered enough to prevent deficiency in most people, but many experts agree that it is an insufficient recommendation for most people.   

Choosing a vitamin D supplement

There are two main varieties of vitamin D supplements; D2 and D3. D3 (cholecalciferol) is the isomer formed in human skin, and is typically extracted from sheep’s wool for supplements. D2 (ergocalciferol) is the plant-derived equivalent, typically extracted from fungi.

The D3 variety is widely considered to be the best way to supplement with vitamin D. Compared to the D2 counterpart, D3 tends to be less toxic. It easily binds with D receptors in human tissue and is more stable and effective at raising serum D levels. It is the most common vitamin D type researched in modern nutritional science.

By Emily