Vitamin D is absolutely essential. It’s responsible for balancing the amount of calcium in our blood and is therefore vital to keep our bones strong and healthy.

What Is Vitamin D?

Technically, vitamin D is a hormone. Around 90% of it is produced by our kidneys, but the remaining 10% must be absorbed through sunlight, food, or supplements. 

Sadly, it’s very difficult to get enough vitamin D from food alone. We can find small amounts of the vitamin in some foods:

  • Oily fish
  • Read meat 
  • Liver 
  • Egg yolks 
  • Fortified foods, such as some fat spreads and breakfast cereals 
  • Mushrooms that were grown in UV light 

But the vast majority of it comes from sunlight. This is why many people struggle to get enough vitamin D between the months of October and March in the UK. 

In this article, we will be explaining the top 6 signs of vitamin D deficiency, and some of them might just surprise you… 

Signs of Vitamin D Deficiency

1) You Have Bone or Back Pain

The first indication of a vitamin D deficiency is bone or back pain. You may be wondering what ‘bone pain’ feels like since we can’t exactly feel our bones. 

Well, it’s often characterised as a deeper, sharper, more penetrating pain than muscle pain. It’s often an ongoing pain that may feel worse at night or when you’re moving the affected area of the body. 

So, how does vitamin D relate to bone and back pain?

Vitamin D is absolutely vital for controlling the absorption of calcium and phosphorus in the body. It communicates with our kidneys, gut, and skeleton to essentially ‘tell’ our parathyroid glands that we have enough calcium in our blood. 

If our parathyroid glands ‘think’ we don’t have enough calcium*, then they will ‘borrow’ it from our skeleton. This leads to there being less calcium in our bones which will cause a loss of bone density. 

*Our parathyroid glands can ‘think’ we are insufficient in calcium for one of two reasons:

  1. We have a genuine lack of calcium in the blood.
  2. We have a lack of vitamin D allowing the calcium to be absorbed and recognised.

So, we need to ensure we get enough calcium and vitamin D every single day. 

But what happens if we develop lower bone density? 

Well, in children it can cause serious bone abnormalities, such as rickets, which can lead to abnormal growth. Children and adults can also be affected by osteomalacia, which is essentially a name for ‘soft bones’. This condition can lead to fractures, breaks, and bowing in the legs.


2) You’re Always Tired or Fatigued!

Many of us tend to feel more tired and fatigued during the winter, and this may be due to a lack of vitamin D from the sun.

A vitamin D deficiency can cause you to get fewer hours of sleep at night and get a lower quality of sleep (i.e. you’re not sleeping deeply enough). This will undoubtedly lead to more tiredness and daytime fatigue.

Research has suggested that people’s self-perceived levels of fatigue reduce significantly after supplementing with vitamin D. And yes, this study did use placebos, meaning participants didn’t know if they were taking a vitamin D supplement or not. 

It’s thought this may be due to the impact that low vitamin D levels have on the functioning of our skeletal muscles*. Vitamin D seems to help the mitochondria - which is the part of a cell that generates energy - to transport energy around the body, including to the muscles. Therefore, if we don’t have enough vitamin D to support this process, we may feel physically fatigued.

*Skeletal muscles are the ones that are attached to our bones by tendons. They are responsible for all voluntary movements of the body, unlike smooth muscle and cardiac muscle. 


3) You Keep Getting Sick or Getting Infections 

Getting sick is another thing that many of us experience more during the winter. This is because our immune systems tend to be weaker during the colder part of the year. This could be, in part, due to a lack of vitamin D.

Our immune cells have vitamin D receptors, meaning vitamin D can interact with them. It seems that vitamin D modulates both of our immune systems – the innate immune system which is responsible for quick immune responses, and the adaptive immune system which is responsible for slower, more complex responses involving antibodies. 

This could explain why the research shows that people with lower levels of vitamin D get more infections

This is especially apparent with respiratory tract infections, like the common cold, pneumonia, and even coronavirus. And, these illnesses are especially common in winter! Do you see the pattern here?

Studies suggest that getting enough vitamin D can also help people with autoimmune diseases, such as Chron’s, asthma, MS, IBS, and rheumatoid arthritis. 


4) You Get Muscle Weakness, Aches, or Cramps

As we explained previously, low levels of vitamin D can lead to skeletal muscle weakness which leads to fatigue. So, of course, muscle weakness, aches, or cramps can be another sign of vitamin D deficiency.

In addition to causing muscle fatigue, it’s also thought that low vitamin D levels can affect inflammation. In other words, our body has less control over inflammation which can lead to more pain, stiffness, and discomfort in the muscles.

There are also vitamin D receptors in the nerve cells that sense pain, meaning we are more likely to experience muscle pain or even chronic pain if we are deficient in vitamin D. 

If you experience joint pain - especially in the knees, legs, and hips - this could actually be a result of muscle weakness. Therefore, this could, too, indicate a vitamin D deficiency. 


5) You’re Experiencing Mood Changes, Like Depression

Vitamin D is commonly known as the sunshine vitamin. And it’s no surprise that most of us feel happier when the sun is shining and the weather is warm! (Why else would we holiday in hot, sunny countries?)

These changes in mood dependent on the weather could be, in part, to do with the amount of vitamin D you’re getting. Since most of our vitamin D is absorbed from sunlight, we get far less of it during the cold winter months.

Studies have found that vitamin D levels are often associated with depression. In other words, people with depression have been found to more commonly have vitamin D deficiencies, and people with deficiencies have a higher risk of developing depression. 

In some cases, vitamin D supplementation has even reduced people’s symptoms of depression.

It’s thought that this happens because vitamin D is vital for healthy brain functioning. In fact, vitamin D receptors have been found in the same area of the brain that’s associated with depression.

This could also cause other changes in your mood and mental health, such as anxiety. 


6) Your Wounds Heal Slowly 

Last but not least, you may be suffering from a vitamin D deficiency if, when you get a wound, it heals more slowly than it should. 

Vitamin D is known to help with skin cell growth and repair. It’s thought that it increases the production of compounds* that are crucial for forming new skin cells as part of the wound healing process.

*These compounds affect the epidermal and platelet growth factors – so, they spur blood clotting and new skin growth, which are both essential for wound healing. 

It’s also thought that, since vitamin D plays a role in controlling inflammation and fighting infection, a lack of it could negatively impact the wound healing process. Vitamin D promotes the production of an antimicrobial peptide called cathelicidin – the immune system uses this to fight off wound infections.


How To Avoid Vitamin D Deficiency

Vitamin D is, clearly, incredibly important for our health – these signs and symptoms of deficiency demonstrate this well. 

This is why it’s so important to be aware of your vitamin D intake, especially during the winter. 

If you feel like you are suffering from a vitamin D deficiency, or you want to avoid developing one through the winter, you should consider using a vitamin D supplement. In fact, the NHS states:

“During the autumn and winter, you need to get vitamin D from your diet because the sun is not strong enough for the body to make vitamin D.

“But since it's difficult for people to get enough vitamin D from food alone, everyone (including pregnant and breastfeeding women) should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter.” (2)

And to be specific, autumn and winter are between the months of October and March.

Some people who are more at risk for vitamin D deficiency should consider using a vitamin D supplement all year round, not just during the winter. These people include:

  • Infants and children aged less than 5 years
  • Pregnant and breastfeeding women
  • People aged 65 and older
  • People with limited exposure to the sun
  • People with darker skin


Do you need more advice on vitamin D or supplementation? Feel free to contact a member of our customer support team who can provide you with further information.