It’s October and we’re hurtling towards the season of colds and flu, as well as dealing with the threat of COVID-19. So if you aren’t already doing so, then now is the time to prioritise your health and support your immune system. Getting your Vitamin D levels checked is a good place to start and here’s why.
Vitamin D – the ‘sunshine vitamin’, as it’s called – is a superstar. It’s the only vitamin that your body can make itself and it’s absolutely vital for maintaining optimal health. It’s actually a hormone – well, a 'prohormone' to be precise – produced from cholesterol when your skin is exposed to direct sunlight. It’s fat-soluble and can be stored by your body for future use, so it’s important to keep your levels topped up. Unfortunately, due to our location in relation to the equator, most people in the UK are likely to need to supplement to maintain optimal levels. You can get some vitamin D from certain foods, but in fairly small amounts – not enough to maintain adequate levels.
Why is it so important?
Nearly every cell in your body has a receptor for vitamin D so it plays a vital role in many functions, including:
- Maintaining healthy bones and teeth
- Supporting immune system function
- Supporting brain health and nervous system function
- Regulating cell growth and division – which may help prevent the development of cancer cells
- Regulating insulin levels
- Supporting cardiovascular health
Low levels can have far reaching effects on your health – anything from osteoporosis, rickets in children, asthma, tuberculosis, autoimmune diseases, cancer, heart disease, diabetes and depression. They have also been linked to an increased risk of Alzheimer’s and Parkinson’s disease.
According to national surveys, approximately 1 in 5 people in the UK are deficient.
Why do so many people have insufficient levels?
Lack of sunshine: the UK isn’t known for its endless sunshine – even in the summer months – and when the sun does appear most people have been conditioned to slather on the factor 50 – effectively blocking those UV rays from hitting your skin and making the vitamin.
Age: as you get older, your body becomes less efficient at using the sun's rays to make vitamin D and your kidneys become less efficient at converting it to calcitriol (the active form).
Tummy troubles: any digestive problems could affect the absorption of many essential vitamins and minerals, including vitamin D.
Obesity: the fat cells in your body store up the vitamin, making it unavailable to use.
Lack of sleep: just as you need sunlight to make vitamin D, you need sleep to actually use
Stress: both cortisol (the stress hormone) and vitamin D are made from cholesterol. When you’re stressed, your body prioritises cortisol production.
Skin colour: the higher levels of melanin in darker skin protect against UV light and reduces your body’s ability to make the pre-cursor to the active vitamin D.
Nightshift / long working hours: anyone who doesn’t spend much time in the sunlight or even daylight will produce less vitamin D on an on going basis.
Kidney or liver disease of any kind also means vitamin D is not converted to the active form.
Genetics: there are some gene mutations that can cause lower levels of vitamin D.
10 signs that you might have insufficient levels of vitamin D
- Depression or anxiety (including mood changes or irritability)
- Bone softening (low bone density), fractures
- Feeling tired all the time/ decreased performance
- Muscle cramps and weakness
- Joint pain (especially back and knees)
- Difficulty regulating your blood sugar levels/ post lunch energy crash
- Low immunity
- Slow wound healing
- Low calcium levels in the blood
- Unexplained weight gain
Symptoms like these are commonly overlooked because they’re often dismissed as normal, everyday aches and pains or signs of ageing. You should mention them to your GP and ask to have your levels checked.
How can it help with COVID-19?
Vitamin D is essential for the proper functioning of your immune system. Low levels have been linked with an increased risk of respiratory diseases, including tuberculosis, asthma and chronic obstructive pulmonary disease (COPD), viral and bacterial respiratory infections, as well as decreased lung function, which may affect your body’s ability to fight respiratory infections.
One recent study has found that good vitamin D levels can significantly reduce the risk of catching COVID-19. Others have shown the benefit of vitamin D on the outcome of patients with the virus and that a deficiency may increase the risk of severe COVID-19 complications.
There is growing evidence that vitamin D supplementation may reduce complications related to cytokine storms – an aggressive immune system response that can lead to uncontrolled inflammation and tissue damage.
Sources of vitamin D
The majority of your vitamin D comes from exposing your skin to sunlight, though how much you make depends on the colour of your skin, how much of it you expose and the strength of the sun. During the summer months 10 – 30 minutes per day of midday sun (before skin reddening occurs) should be adequate.
You also get small amounts from egg yolks, oily fish (salmon, fresh tuna, sardines, mackerel), liver and grass-fed cheese and butter – but not enough to maintain optimal levels.
How much is optimal?
It’s a good idea to get your vitamin D levels checked every 6 months. Most GPs will only test if you have any signs of deficiency, otherwise you can get a simple at-home finger prick test for around £30.
The test is the 25-hydroxy vitamin D test (25-OH-vitamin D). It’s the most accurate way to measure how much vitamin D is in your body.
Based on the current UK reference range, if your result is < 25nmol/L, (nanomoles per litre of blood), you are deficient; between 25 – 50nmol/L may be inadequate; over 50nmol/L is sufficient.
However ‘sufficient’ does not necessarily mean ‘optimal’ – this is why I always recommend that my clients request a copy of any blood test results, even if their GP has said everything is ‘normal’. There isn’t a set definition for optimal but many labs use the range 75 - 125nmol/L.
There is such a thing as too much vitamin D (known as vitamin D toxicity) – usually only from long-term mega doses – which can cause excess calcium to build up in the body (hypercalcaemia). This can lead to osteoporosis, kidney damage and heart disease.
The NHS recommends that everyone should take a daily supplement of 400 IU, or 10 micrograms (mcg or μg) of vitamin D between October and March. If your levels are way short of ‘optimal’ then you may need a short-term higher dose to get your levels up, but this should be under the instruction of a healthcare professional.
That’s why it’s important to know your baseline.