‘Vitamin D supplements advised for everyone', ran the BBC headline back in July, citing the government backed research now recommending that everyone should be getting at least 10 micrograms of the nutrient every single day.

However, as we have frequently referred to in previous blogs, it may not be achievable to get 10 micrograms of vitamin D from your diet alone, which is why supplementation of ‘the sunshine vitamin’ is now advised for everyone.

In this week’s blog we provide a timely recap on why vitamin D is so important for our health and how best to source it, in light of the new government guidelines.

What is Vitamin D?

Vitamin D is known as ‘The Sunshine Vitamin’. This is because sunlight is necessary for the synthesis of vitamin D in the skin and those lacking in sunlight are at high risk of deficiency.

We can’t stress this point enough as vitamin D is not found in abundance naturally in foods. So simply put, not enough sunshine means not enough vitamin D, and hence issues with widespread deficiency in the UK particularly in areas such as parts of Scotland that get even less sunshine. The amount of sunlight (UV) in our winter months is insufficient and over the winter we need to draw on our bodily reserves.

There are some foods rich in vitamin D, primarily oily fish and eggs however fish consumption is poor in this country and as the Vitamin D Mission note:

“Salmon and other oily fish are big in vitamin D, along with liver, eggs and fortified cereals. But because of the quantities needed it’s hard to get enough from diet alone.”

Why is Vitamin D so important?

As noted on the Vitamin D Council website, “Vitamin D is important for good overall health and strong and healthy bones. It’s also an important factor in making sure your muscles, heart, lungs and brain work well and that your body can fight infection.”

Vitamin D has the following permitted health claims.

Vitamin D contributes to the:

• normal absorption/utilisation of calcium and phosphorus
• normal blood calcium levels
• maintenance of normal bones and teeth
• maintenance of normal muscle function
• normal function of the immune system
• process of cell division and
• vitamin D is needed for normal growth and development of bone in children

The Scientific Advisory Committee on Nutrition (SACN) is a government-led organisation that advises Public Health England and other UK organisations on any nutrition and health related matters.

In July this year, they released the report below reviewing whether or not the UK dietary recommendations for Vitamin D (set back in 1991) were still appropriate. Below is a summary of the report provided by gov.co.uk (https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report):

“In a change to previous advice, SACN is now recommending:

• a reference nutrient intake (RNI) of 10 micrograms of vitamin D per day, throughout the year, for everyone in the general population aged 4 years and older
• an RNI of 10 micrograms of vitamin D per day for pregnant and lactating women and population groups at increased risk of vitamin D deficiency
• a ‘safe intake’ of 8.5 to 10 micrograms per day for all infants from birth to 1 year of age
• a ‘safe intake’ of 10 micrograms per day for children aged 1 to 4 years”

As we move into the winter months where sunshine is scarce in this country, the vast majority of us will be well below the updated recommended daily intake of vitamin D which is why supplementation can be so important.

An Improvement, but is 10mcg enough?

The report released by SACN represents a step in the right direction, however many in the field of nutrition believe that 10mcg is still not an optimal level of vitamin D.  In May of this year, Grassroots Health released a report with the following statement:

“The Grassroots Health Scientists Panel of 48 expert vitamin D researchers and medical practitioners hold the position that the serum level should be between 100 to 150 nmol/litre (or 40-60 ng/ml)”

In other words, 4-6 times higher than that recommended by the SACN. This higher range would not be achievable based on an intake of 10 mcg (unless you work outdoors all summer and there is plenty of sunshine!).

Sources of Vitamin D

Vitamin D dietary sources include butter, eggs, oily fish and fortified foods – these sources provide only low levels of vitamin D – most is produced in the skin following sun exposure. In the UK, vitamin D can be synthesised in the skin between April and September, 10.00 am to 2.00 pm, on sunny days (i.e. without cloud cover). Production also depends on genetics, age, sunscreen, clothing, and skin colour. Although vitamin D cannot be synthesised during the winter at our latitude, it can be stored in the body. Levels are likely to be lowest around March.

Vitamin D metabolism

In order for vitamin D to be used by the body, it is transported to the liver and undergoes 25-hydroxylation, yielding the 25-hydroxyvitamin D metabolite, the concentrations of which can be readily measured in blood. This metabolite then undergoes renal hydroxylation, creating the most biologically active vitamin D metabolite, 1,25-dihydroxyvitamin D, which applies its functions through the gatekeeper to multiple cells in the body, the nuclear vitamin D receptor.

Research on the benefits of vitamin D

Vitamin D is the most highly researched nutrient – with a search on “vitamin D” returning over 69,000 hits on PubMed. Although research is often small and inconclusive, it is widely believed that vitamin D deficiency plays a significant role in the onset of conditions such as cardiovascular disease, type 1 diabetes and inflammatory bowel disease.

Cardiovascular disease

Research suggests that Vitamin D deficiency plays a role in the onset of cardiovascular conditions:

“Cross-sectional studies have reported that vitamin D deficiency is associated with increased risk of CVD, including hypertension, heart failure, and ischemic heart disease. Initial prospective studies have also demonstrated that vitamin D deficiency increases the risk of developing incident hypertension or sudden cardiac death in individuals with pre-existing CVD.”

(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851242/)

Diabetes

Research suggests that there is a link between vitamin D and diabetes, with the Vitamin D Council suggesting that “people with high vitamin D intake during their first year of life are less likely to develop type 1 diabetes later in life.”

Research into this area has been relatively small and inconclusive however studies have suggested that supplementing with vitamin D may improve insulin sensitivity and help to control blood glucose levels in subjects who suffer from type 1 and type 2 diabetes. Secretion of insulin, by pancreatic beta cells, may be impaired if there is a lack of vitamin D.

Inflammatory Bowel Disease

Vitamin D helps to reduce levels of inflammatory proteins that are overproduced in the immune system. One of these proteins is called tumour-necrosis factor (TNF). Much research has suggested that vitamin D may be the natural alternative to medication when it comes to reducing inflammation in the digestive tract. This is because medications that are frequently used to manage IBD are involved in blocking the production of this particular protein.

Research into osteomalacia and rickets provided early evidence of the important role of vitamin D. These diseases represent vitamin D deficiency and present symptoms of hypocalcaemia (low serum calcium levels) and skeletal deformity due to poor mineralisation of the bones. Patients with these diseases usually have serum vitamin D levels below 20 nmol/L.

Rickets, a condition that affects bone development in children, has seen a dramatic rise in cases in recent years. Indeed, the number of children suffering from this condition has reportedly doubled in the last decade. According to an article in the Daily Telegraph from last year, this is partly down to an increase in children staying indoors and playing video games as opposed to going outside and being exposed to sunlight (therefore not getting enough vitamin D!).

The NHS Website states that “any child whose diet doesn't contain enough vitamin D or calcium can develop rickets, but the condition is more common in children with dark skin, as this means they need more sunlight to get enough vitamin D, as well as children born prematurely or taking medication that interferes with vitamin D.”

Are you deficient in Vitamin D?

Vitamin D deficiency is very common in the United Kingdom. Indeed, Public Health England stated that 1 in 5 people in the United Kingdom are low in vitamin D and are not even aware of it. According to the Vitamin D Council, the following criteria leaves you more susceptible to deficiency of this particular vitamin:

• People who spend a lot of time indoors during the day. For example, if you’re housebound, work nights or are in hospital for a long time.
• People who cover their skin all of the time. For example, if you wear sunscreen or if your skin is covered with clothes.
• Older people have thinner skin than younger people and this may mean that they can’t produce as much vitamin D.
• Infants that are breastfed and aren’t given a vitamin D supplement. If you’re feeding your baby on breast milk alone, and you don’t give your baby a vitamin D supplement or take a supplement yourself, your baby is more likely to be deficient in vitamin D.
• Pregnant women.
• People who are very overweight (obese).

According to Healthline, these are some of the main bodily symptoms associated with vitamin D deficiency:

• difficulty thinking clearly
• bone pain
• frequent bone fractures
• muscle weakness
• soft bones that may result in deformities
• unexplained fatigue

A vitamin D blood test is the only way to categorically determine if you are deficient in vitamin D. You can either get a blood test at your doctors or you can purchase a home fingerprick test.

Choosing the right supplement – vitamin D3 vs vitamin D2

Choosing the correct form of vitamin D to supplement with is just as important as supplementation itself, and although the new government guidelines now advise that everyone takes a vitamin D supplement, actual advice in this area has been scarce.

Vitamin D3 vs Vitamin D2

Vitamin D3 is the most bioavailable form of this nutrient and far preferable to Vitamin D2 to supplement with.

Vitamin D2 is also known as ergocalciferol and is commonly produced by plants in response to UV radiation. Some fortified foods contain vitamin D2 as an inexpensive way to boost nutrient, however it is not well absorbed or utilised by the body.

Vitamin D3 (also known as cholecalciferol) is the most bio effective and biologically active form of this nutrient and is found in humans and animals. When sunlight hits the skin it then converts cholesterol into the bioactive form of vitamin D3 hence why sunlight is so important – without it, vitamin D3 cannot be utilised by the body.

So when choosing a vitamin D supplement, you are looking for vitamin D3 and not vitamin D2. Where you wish to take a multivitamin and mineral that includes Vitamin D3 it is always important to select such a multi-formula with a nutrient content tailored for your age, gender, pre-existing medical conditions, or specifically for children where appropriate. If you are considering taking a vitamin D3 supplement and a multivitamin make sure that you assess the total combined dosage of the vitamin that you will be taking.

Relevant Cytoplan products

Wholefood High Potency Vegan Vitamin D3 - From Vitamin D3-rich lichen extract. High potency at 1250% RDA per tablet.

Wholefood Vitamin D3 15μg -  this Wholefood vitamin D3 comprises a natural plant base of lichen and is suitable for children and perfect to be taken alongside a suitable multivitamin.

NEW Vitamin D3 & K2 - This product is ideally designed for short term use to elevate levels of K2/D3 and is ideally used in conjunction with any of our multiformulae.

Related Cytoplan blogs

Vitamin D - A timely reminder on its importance

Vitamin D "reduces the risk of falling" - The mechanisms unfolded

New approved claims for Zinc, vitamin D, calcium and selenium

Vitamin D infographic

If you have any questions regarding the topics that have been raised, or any other health matters please do contact me (Amanda) by phone or email at any time.

amanda@cytoplan.co.uk, 01684 310099

Amanda Williams and the Cytoplan Editorial Team: Clare Daley, Joseph Forsyth and Joanna Doverman.