Vitamin D deficiency: how to identify and treat

Vitamin D absorbs calcium, supporting bone and teeth health and cell growth. As we are spending more time in our homes, a daily dose of vitamin D has never been more important to help you and your family stay well.

What is Vitamin D?

Vitamin D, aka the sunshine vitamin, is one of the most important vitamins for our bodies – and even better, we can make it ourselves by getting out and enjoying the sun!

This helpful vitamin allows us to absorb calcium and phosphate from the foods we eat to keep our teeth, bones and muscles healthy.

However, if we do not get enough sunlight or eat enough vitamin D-rich foods, it is all too easy to develop a deficiency in vitamin D.

But how do you know if you are lacking in vitamin D?

We have written this definitive guide to help you spot vitamin D deficiency symptoms and find out if you need a little more of the sunshine vitamin in your life.

You will also discover tips on how and where to get more vitamin D and just how much you need to stay healthy.

Why is Vitamin D important for your health?

You might know about the link between vitamin D deficiency and rickets (which is called osteomalacia in adults).

Rickets is a condition which affects the bones. It causes them to become soft and weak, often leading to deformities and fractures. 

In fact, vitamin D3 was first recognised when scientists were trying to work out why cod liver oil was so effective in dealing with rickets.

But our bones are not the only parts of our bodies that rely on enough vitamin D.

Lack of vitamin D has also been linked to muscle weakness and fatigue. Studies have shown that vitamin D deficiency can contribute to an impaired immune system.

Vitamin D receptors in our brains help brain cells receive and understand chemical signals – a lack of vitamin D is likely to affect the way our brain communicates.

Government advice on vitamin D and COVID-19

As a lot of us are spending more time indoors than usual due to COVID-19 restrictions, it’s now even more important to keep our vitamin D levels topped up.

The NHS recommends that everybody should be taking a 10mcg (400IU) of vitamin D a day in the months between October and early March to keep your muscles and bones healthy.¹ And that’s advice for a ‘normal’ year, where most of us would usually be out and about more.

You may have seen some reports about vitamin D reducing the risk of COVID-19 (coronavirus). However, while there are numerous trials currently taking place to see if there is a link between the two, there is currently not enough evidence that taking vitamin D can prevent or treat COVID-19.^2,3,4

Read more: Discover 12 of the best vitamin D supplements

Why aren’t we getting enough vitamin D?

Around 50 to 60 per cent of the British population is insufficient in vitamin D. Increasing sun safety awareness – more of us are using sun block – long winters and poor summer sunshine all mean we are not producing enough of the vitamin.

From October to March in the UK, sunlight does not reach the earth at the correct angle, so, in turn, not enough UVB rays reach us in order to produce vitamin D.⁵

Some groups are also more vulnerable. The elderly or housebound, dark skinned, pregnant or breast-feeding women, those who cover their skin and those with a poor diet could be deficient in vitamin D.

How much vitamin D per day do I need?

The NHS recommends around 10 micrograms a day.

It is recommended to take supplements containing 10 micrograms of vitamin D during autumn and winter, and throughout the year for those who are not often outdoors.

Taking more than 100 micrograms (4,000 IU) a day could be harmful to your health. This applies to adults, children, the elderly, and those who are pregnant or breastfeeding.⁶

What are 7 of the most common symptoms of vitamin D deficiency?

90% of the vitamin D our bodies need comes from getting out in the sunlight and only 10 per cent is from your diet. Even if you eat fortified foods, you could be at risk of vitamin D deficiency. Symptoms of low vitamin D vary from person to person, but if your routine and lifestyle keeps you away from sunlight, look out for these symptoms:

1. Low mood The so-called happy hormone (serotonin) falls with lack of sun exposure. Our bodies need vitamin D to activate to effectively make serotonin in the brain. If you feel low or irritable, it could be a sign that you are deficient in vitamin D.

2. Weak muscles Vitamin D deficiency is strongly linked to muscle weakness in ageing adults.⁷ Legs can feel heavy and it can feel difficult to stand up and climb stairs, all of which make falls and fractures an increased risk. Vitamin D also helps our bodies absorb calcium to keep bones, muscles and teeth healthy, making it even more important to keep topped up.

3. Getting sick often If you seem to catch every cold going around and get sick a lot, it may be down to low levels of vitamin D. This is because vitamin D is essential for keeping your immune system strong and healthy. It is recommended that everybody starts to supplement vitamin D in the early autumn to make sure they have enough vitamin D in the winter.

4. Weight gain If your appetite has gone through the roof or you are gaining weight, vitamin D may be playing a role. Research has revealed that low levels of vitamin D are associated with being overweight and obese, whereas higher levels of vitamin D are associated with reductions in body fat. This may be because vitamin D helps to control a hormone in the body called leptin, which helps to inhibit hunger and reduce fat storage. If the body is low in vitamin D and struggles to produce healthy levels of leptin, this could contribute to overeating and weight gain.⁸ 
   Please note: People considered overweight or obese need more vitamin D than a person with a healthy weight. This also applies if you have a large muscle mass.

5. Fatigue People who are tired all the time, especially older adults, may not suspect a vitamin D deficiency could be draining their energy. Increasing vitamin D levels have been seen to improve signs of fatigue.⁹

6. Achy bones and joints Vitamin D deficiency affects bone health, which could result in a throbbing or achy feeling in your bones. This is often most noticeable in the knees and back. Those who do not have enough of this important vitamin may be at more risk of fractures.

7. Head sweats A common sign of vitamin D deficiency is a sweaty scalp (this is one reason new born babies are monitored for head sweats). A sweaty scalp could be an early sign of vitamin D deficiency.

Summary

7 commons symptoms of Vitamin D deficiency are:

• Low mood
• Weak muscles
• Getting sick often
• Weight gain
• Fatigue
• Achy bones and joints
• Head sweats

Can a lack of vitamin D cause depression?

Ever noticed how much happier you feel when you have been outside in the sunshine?

Vitamin D3 is produced by our bodies when we get enough of the sun’s UVB rays on our skin. But that is not the only link between sunlight, Vitamin D, and mood. Research into Vitamin D and emotional health has shown that people with low levels of Vitamin D are up to 11 times more prone to depression than people with normal levels of the vitamin.

Studies in this complex area are few and far between. But more work is being done and we can expect some interesting research to be published in future.

Why does Vitamin D affect the brain?

Experts still do not understand exactly how Vitamin D works within the human brain. But we do know that our brains are full of Vitamin D receptors. These help carry out a number of functions including communicating actions with the rest of our body. It is thought that Vitamin D levels can affect parts of the brain that govern learning, memory, and mood.

Some research suggests it could even play a role in social behaviour. Some researchers think that Vitamin D could affect our levels of brain chemicals, including serotonin, which has a strong effect on mood. More and more large-scale studies are being carried out in the areas of Vitamin D and mental health.

For now, we can be sure of one thing: exposure to sunlight increases Vitamin D levels, and is a great mood booster. So get outside in the sunshine whenever you can. Even 10 minutes will help.

Are you at risk of Vitamin D deficiency?

Did you know that according to national surveys taken out across the UK, approximately 1 in 5 of the population has low vitamin D levels?

It isn’t surprising really when you think about it. Our bodies can only make vitamin D when exposed to direct sunlight, which may be possible in summer for some people, but becomes difficult for everyone during the darker winter months.

You can also get vitamin D from animal produce like meat, fish dairy and eggs, which are either naturally high in vitamin D (red meat, offal, eggs and some seafood) or have been fortified with vitamin D (most dairy).

Other foods like breakfast cereals, fruit juices, faux meat, plant milks are often fortified (please check). Wild mushrooms and those grown under a UV light are also great sources of vitamin D2.

People who do not get outside much, have dark skin, like to cover up, or do not eat animal products are naturally at more of a risk of vitamin D deficiency.

This is why the government now advise that everybody should think about taking a vitamin D supplement, particularly in the Autumn and Winter months.

Groups of people who are more likely to be deficient in vitamin D:

Vegans

Vegans can have low levels of vitamin D, because most natural sources are animal based. Pay extra attention to your diet, and eat fortified foods (cereals, soya milk, almond milk, and orange juice) and take a high-quality vitamin D supplement.

Those not exposed to sunlight

Limited sunlight exposure can put you at risk. If you are housebound for any reason, if you live in a grey climate, or if you cover your skin for work, lifestyle or religious reasons, your skin might not get enough sunlight to make the vitamin D your body needs.

Remember, your skin needs to be exposed to the sun without sun protection or skin covering it to absorb vitamin D. It is recommended that you look to increase your dietary vitamin D or consider a supplement.

People with darker skin

The pigment in your skin can reduce your ability to make vitamin D, even if you get plenty of sunlight. Older adults with dark skin are particularly at risk. A carefully planned diet rich in vitamin D, a supplement or both is recommended.

Those over the age of 50

If you are over 50, you lose some of your natural ability to produce vitamin D from sun exposure – making you one of the most at risk groups. Your kidneys also become less efficient at converting the vitamin, making it important to stay active and spend plenty of time outside in your 50s, 60s, and beyond. Read more about the importance of vitamin D when you’re older here.

Summary

Those most likely to be deficient in vitamin D:

• Vegans
• People not exposed to sunlight
• People with darker skin
• Those over the age of 50

Vitamin D test: Can a blood test detect a deficiency?

If you are feeling more tired than normal at the moment or your aches and pains seem worse, now you are not getting your full quota of vitamin D from the sun’s rays, your instinct may be to get a vitamin D test.

If we follow the trends identified in studies, one in five people in the UK could have low vitamin D levels.¹⁰ It is a common deficiency, but how important is it to be diagnosed with a vitamin D test?

Can you check vitamin D levels at home?

If you suspect your fatigue and aching muscles could be down to dwindling D levels, the only accurate way to reliably diagnose a deficiency is to take a vitamin D test. Your doctor can arrange a simple blood test for vitamin deficiency to make the diagnosis. Vitamin D home tests are also available. These rely on a finger prick blood sample.

Can you rely on a vitamin D test kit?

At-home tests are convenient when it is difficult to attend a surgery appointment, but the following should be considered:¹¹

• User error. This is a possibility with at-home tests and can affect results. Make sure you follow guidance closely.
• Understanding results. A test can show you are deficient, but without the support of a nutritionist or doctor it can be difficult to interpret what your results mean for you. For example, in the context of your age, gender and other personal factors. You will also need to seek further advice on the best course of action to take.

What is vitamin D listed as on a blood test?

Measuring the concentration of 25-hydroxyvitamin D in your blood is the best way to identify a vitamin D deficiency.¹² This is measured in in nanomoles/litre (nmol/L) or nanograms/millilitre (ng/mL). A level of 20 ng/mL to 50 ng/mL is a healthy range. If less than 12 ng/mL is detected, it implies a vitamin D deficiency.¹³

Does a CBC test show vitamin D deficiency?

A complete blood count (CBC) is a common blood test that gives a snapshot of your overall health. It can be helpful in identifying a number of health conditions, including vitamin deficiencies.¹⁴

What can you do if you are vitamin D deficient?

The first thing you need to do when you find out that you are deficient in any nutrient is to consult with your GP. Normally, the best way for your body to make vitamin D is through exposure to the sun however, sunlight is often not enough to reverse an already existing deficiency.

Sunlight is, unfortunately, an unreliable commodity during the long, dark days of the UK autumn and winter. So, during these times of the year, you need to get more vitamin D from your diet.

However, it is difficult to get enough vitamin D from food alone. The NHS suggests taking a daily supplement containing 10 micrograms of vitamin D year-round.

How to increase your Vitamin D levels

If you think you or someone you care for is at risk of low vitamin D, there is plenty you can do.

Consider what you eat

Enrich your diet with natural sources of vitamin D, here are some of the best foods you can eat if you are low on vitamin D:

• Salmon
• Mackerel
• Herring
• Sardines
• Red meat
• Eggs
• Offal, e.g. animal stomach, tripe, brains, heart, liver, tongue and kidneys
• Wild mushrooms or mushrooms grown under UV light

You can also choose foods fortified with vitamin D, such as:

• Dairy
• Plant milks
• Breakfast cereals
• Fruit juices
• Meat alternatives
• Fat spreads

Try a Vitamin D supplement

Another option is taking a daily multivitamin or vitamin D supplement.

There’s a supplement out there for everybody, from the elderly and newborn babies to people following a vegan diet, discover the best vitamin D supplements here.

Get out in the sunshine more

Most people can make enough vitamin D by simply being out in the sun every day for short periods of time with their hands, forearms or lower legs uncovered and without sun protection – you don’t have to go and sun it up in a bikini (unless you want to!).

However, there is no definitive answer to how long you have to stay out in the sun for because everyone is different.

Skin colour and skin exposure play a big part in how much vitamin D your skin will absorb, e.g. people with dark skin such as those from an African, Caribbean or South Asian origin will need to spend longer exposed in the sun to produce the same amount of vitamin D as somebody with lighter skin.

You also need to make sure you don’t burn in the sun, so make sure you always have sun protection and sunglasses handy for when it gets super sunny and you can feel your skin getting red or burnt.

Please seek shade if you plan to be out in the sun for a long time – the longer you stay in the sun unprotected, the greater your risk of skin cancer is.

Myth busting:

Your body cannot make vitamin D with sunlight that shines through a window – the glass will block the ultraviolet B (UVB) rays from getting to your skin.¹⁵

If you think you are at risk, seek advice from a medical professional or ask your Doctor for a blood test to assess your Vitamin D levels. With your Doctor’s support, start taking a quality vitamin D3 supplement to meet UK Government guidelines.

Summary

The best way to increase your Vitamin D levels:

• Consider what you eat
• Try a vitamin D supplement
• Get out in the sunshine more often

Can you take too much vitamin D?

Yes, you can and that is why there is a recommended allowance that you should not exceed.

Too many supplements over a prolonged period can lead to hypercalcemia, which is the build up of too much calcium in the body. Hypercalcemia can weaken bones and cause damage to the kidneys and heart.

It is impossible to overdose on vitamin D by being in the sun too much, however, it is always recommended to take precautions when exposing your skin to UV light.¹⁶

Side effects from too much vitamin D

The following side effects could be a sign that you have had too much vitamin D:¹⁷

1. Elevated blood levels
2. Elevated blood calcium levels
3. Feeling nauseous and vomiting
4. Loss in appetite
5. Pain in the stomach
6. Constipation or diarrhea
7. Bone loss (due to reduced vitamin K2 activity)
8. Kidney injury

Summary of vitamin D

You should hopefully be clearer about how much vitamin D you should aim to get daily and the associated health benefits.

Before taking vitamin D supplements, and especially if you have a pre-existing health condition or currently take medication, it is always a good idea to have a chat with your GP.

We have a range of vitamin D supplements that come in various forms including tablets, capsules, liquids, gummies, sprays and more.

We also have a range of vegetarian and vegan options too.

We hope this guide has helped you. As always, this information cannot replace medical care, so please check with your doctor before trying any remedies.

Last updated: 25 February 2021