Why we need to take notice of vitamin D before winter

It’s the hottest day of the year and I’m sitting here contemplating getting my vitamin D levels (aka ‘the sunshine vitamin’) tested ahead of winter.  My vitamin D status tends to run low and I have a hard time getting it to optimal levels.  I have also spent too much time behind a Zoom screen this summer rather than enjoying the outdoors.

Vitamin D is a steroid hormone which is produced from cholesterol when your skin is exposed to the sun.  It can also be obtained from some foods but dietary intake alone is unlikely to be in sufficient quantities to be beneficial, often making it necessary to supplement, especially during winter.  It is very common for people to be vitamin D deficient.   

Vitamin D may reduce the risk of viral respiratory infections as it influences several immune pathways, with the effect of boosting mucosal barrier defences as well as reducing inflammation.

Maintaining optimal vitamin D status is important given the potential of a second Covid-19 wave later in the year.  Sadly there is very little consistent advice from health authorities on vitamin D as a preventative measure despite numerous studies indicating that a deficient vitamin D status (<50nmol/L) may increase the probability of becoming very ill with Covid-19.

Whilst there are currently no controlled studies demonstrating vitamin D’s effectiveness in COVID-19, (but as of early June there were over 20 studies in progress), I did spot a recent systematic review of seven previous studies which pooled the data of 1368 Covid-19 patients, suggesting that insufficiency may be a culprit in poor COVID-19 outcomes. Those with poor prognosis had a difference of -5.12nmol/L, indicating that just a small correction may have a big difference on outcomes. Equally there are many studies that show vitamin D does not work across a number of immune or inflammatory settings. However this may be either due to the fact that they do not individualise the dose based on the person’s current level of vitamin D, or they are not addressing the root cause of their condition; which is what we do in functional medicine.

Two Public Health England reports released recently have been highly criticised by the research, science and nutrition communities for being too ‘narrow minded’ when reviewing the evidence for vitamin D.  The year round supplement dose still being suggested is likely too low and there are calls to strengthen recommendations on supplementation, especially given poor sunlight exposure, age, hypertension, diabetes, obesity and ethnicity are all factors implicated in low vitamin D levels and are also associated with an increased risk of Covid-19.  Supplementation to certain levels is safe and is inexpensive.  

One reason for the decline in Covid-19 cases over the summer may be due to a level of immunity from increased vitamin D status from being in the sunshine.  However if you have been on a shielding notice/stay at home order and have not spent sufficient time outdoors during the summer due to lockdown restrictions, unless you have been supplementing at the right levels, your vitamin D status is likely to be very low.   

Other reasons for vitamin D

It is recognised that vitamin D may play numerous roles in the generation and management of human health, and for over a decade papers in their thousands have been published exploring its usefulness.  Key functions include:

  • Facilitating immune system function and improved resistance against some diseases.  It helps to create enzymes used by the immune system to fight off pathogens and viruses.

  • Growth and development of bones and teeth.  Vitamin D regulates the absorption of calcium and phosphorus and insufficient vitamin D leads to the risk of developing osteopenia, osteoporosis or osteomalacia.

  • An anti-inflammatory action, inhibiting several processes involved in inflammation.  People with inflammatory diseases frequently have low vitamin D status.

  • It may also play a key role in regulating mood and depression/anxiety.

How to get vitamin D

Summer is the best time to top up on vitamin D levels.  To get vitamin D from the sun, your shadow needs to be shorter than you are, as that is when UVB levels are strong enough to provide a dose.  This is normally between the end of April and early October in the Northern Hemisphere.  If you have not spent enough time in the sunshine this summer, now is the time!

How long you stay in the sun depends on:

  • Age – the older you are the harder it is to synthesise vitamin D. Low vitamin D status in older adults is also associated with an increased incidence of cognitive decline.

  • The shade of your skin; darker skin has a harder time absorbing vitamin D.

  • Your levels of body fat; fat soluble vitamins are stored in body fat and have a hard time getting released to be properly metabolised by the body if you are overweight.  

  • You may also have a genetic variant which may make it harder for you to properly metabolise vitamin D (likely true in my case). 

  • How much of your skin is exposed (without sunscreen), is also key to good absorption and whether you are sitting or lying in full sun, as well as how much pollution there is in the environment.

It is better and safer to have a short dose of vitamin D every day during the summer rather than going out at the weekend and risk getting sunburn. 9 minutes a day may be sufficient for white caucasians with your arms and legs exposed. People with a darker skin or who tan easily and never burn may need 25 minutes.  

Vitamin D from food

Very few foods contain vitamin D naturally. Because of this you may see foods that are fortified – meaning vitamin D has been added.  Foods that contain vitamin D naturally include cod liver oil, salmon, sardines, egg yolks and prawns/shrimp. It is said that we get 80% of our vitamin D from the sun and just 20% from food.

How much do I need?

That depends on how much vitamin D you currently have in your blood serum levels.  There is controversy about what is the optimum level; it can be too low and it can also be too high.  Once your vitamin D status is known, then it is possible to dose accordingly to get to optimum levels.  The Journal of Preventative Medicine and Public Health suggest that blood serum levels of ≥100 nmol/L (40ng/ml) should be aimed for.

Unfortunately the year round supplement dose of 400 IU currently recommended in the UK is unlikely to achieve these levels for many people. 

Vitamin D levels rise slowly, which is why it is important now to get your levels checked before winter. Vitamin D testing is relatively cheap and easy to obtain via a qualified professional.  If you are concerned about your vitamin D levels and would like to be tested and receive advice on the right level of supplementation for you, please get in touch.

 

Previous
Previous

Choosing the right hand sanitiser

Next
Next

Nourishing a migraine brain