Many of us experience higher levels of fatigue during the cold, winter months – it’s not uncommon. The problem is, many people go through it year-upon-year without making a change. We wonder: is it normal to be more tired in winterWhy do I feel so tired in cold weather 

You’ll be glad to hear, it’s perfectly normal. In fact, we see questions all the time with people asking for advice on how to fight winter fatigue



  • How Vitamin D Supplements Help Fight Winter Fatigue
  • Why Vitamin D Is Important During Pregnancy
  • How Vitamin D Is Absorbed, Produced, and Stored In The Body
  • The Effects of Vitamin D Deficiency
  • The Benefits of Vitamin D
  • What Vitamin D Supplement Is Best To Take


Many of us notice our energy levels draining as winter approaches, but we have no idea how to fight it, and slowly it becomes an accepted form of normality. If you are pregnant, you might experience this feeling even more – and don’t worry, we will cover that in this article too. 

The good news: it doesn’t have to be this way!

With changes in the weather comes changes in our health – it’s a no brainer, really. We have reduced sunlight meaning less vitamin D is absorbed into the body, colder temperatures that allow viruses to survive more easily, and gloomier skies which can often affect our mood and mental health. 

So, how can we fight this winter fatigue? One of the easiest and most effective ways is vitamin D supplementation. Yep, simple as that! 


How Can Vitamin D Supplements Help Fight Winter Fatigue?

We all want to find out how to get rid of fatigue and get more energy in the winter. But first of all, let’s define exactly what winter fatigue is:

“Fatigue is the general term used to describe physical and/or mental weariness which extends beyond normal tiredness.” (1) Winter fatigue occurs when we experience a lack of energy or enthusiasm - sometimes referred to as lethargy - during the colder months of the year. 

It’s important to note here that winter fatigue is not the same as SAD (Seasonal Affective Disorder) or Chronic Fatigue Syndrome. If you feel like you might be suffering from either of these, you should speak with your GP. 

So, how can vitamin D supplements help boost our energy in the winter? 

Vitamin D has a huge impact on our mood, energy levels, and immune system (amongst other things). And do you know where vitamin D comes from? The sun!

For this reason, it’s unsurprising that we can feel unhappier, more tired, and be more susceptible to illness during the winter, as there is simply far less sunlight.  

The fact that we are more likely to be deficient in vitamin D during the winter means our immune systems can become weaker. This can lead to cold & flu or winter allergies – these are very common problems we all face. As a result, winter allergies or illnesses can lead to even more fatigue.

This is why it’s so important to supplement with vitamin D during the winter. 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.

Does winter make you tired, too? Let us know in the comments!


What About During Pregnancy – Why Is Vitamin D Important?

If you’re pregnant or breastfeeding, taking a vitamin D supplement is even more important – especially during the winter!

But why is vitamin D so important during pregnancy? Well, it’s absolutely vital to help your baby’s bones, teeth, kidneys, heart, and nervous system to develop. Since we need to get enough vitamin D ourselves to stay healthy, it’s even more important if you’re growing another little person inside you!

Here’s what the WHO (World Health Organisation) has to say about vitamin D in pregnancy:

“Vitamin D deficiency is thought to be common among pregnant women, particularly during the winter months, and has been found to be associated with an increased risk of pre-eclampsia, gestational diabetes mellitus, preterm birth, and other tissue-specific conditions.” (3)

The WHO suggests that pregnant women should take 200 IU (5mcg) of vitamin D per day (3), whilst the NHS recommends we need 10mcg per day (2) – however, some of this may be obtained through natural sunlight or our diet. 

We often get asked which vitamin D supplement is best for pregnancy. Simple answer: it doesn’t really matter! Whether you’re pregnant or not, you should take a high-quality vitamin D3+K2 supplement, preferably in liquid form (as these are absorbed more effectively by the body), from a reliable, reputable retailer. 


How Vitamin D Is Absorbed, Produced, and Stored In The Body

So, we know where vitamin D mainly comes from – the sun or supplements (these both provide vitamin D3). But, we can also find it in some food products:

  • Oily fish, such as salmon, sardines, herring, or mackerel (D2)
  • Read meat (D2)
  • Liver (D2)
  • Egg yolks (D2)
  • Fortified foods, such as some fat spreads and breakfast cereals (D3)
  • Mushrooms that were grown in UV light (D3)

Unfortunately, it is pretty difficult to get enough vitamin D from our diet alone – especially if you’re vegan or vegetarian and therefore cannot eat oily fish or red meat. 

As we mentioned above, vitamin D3 is produced when we are exposed to sunlight, and it can also be found in some supplements or plant-based food sources. Vitamin D2, on the other hand, comes from animal sources. Vitamin D3 is thought to be more effective at improving levels of vitamin D in the bloodstream since it is metabolised differently. 

Now we know where vitamin D is found, let’s move on to how it is synthesised and stored in the body… 

When we are exposed to sunlight (more specifically; UV radiation), the epidermal layer of our skin synthesises vitamin D3. 

“We each have vitamin D receptor cells [in the skin] that, through a chain of reactions starting with the conversion of cholesterol in the skin, produce vitamin D3 when they’re exposed to ultraviolet B (UVB) from the sun.” (4)

Alternatively, when we get vitamin D from supplements or food, it is absorbed in the small intestines into the bloodstream. Since vitamin D is fat-soluble, it’s better absorbed when paired with high-fat foods. This is why you should take vitamin D supplements alongside a meal to enhance absorption. 

You should also use a liquid supplement with a mixture of vitamins D3 and K2, but we’ll get into that properly later on. 

So, where is vitamin D stored after absorption? It gets stored in the body’s fat cells where it remains inactive until it’s needed. The liver and kidneys are responsible for turning this stored vitamin D into the active form the body needs (calcitriol) through a process called hydroxylation (4)


What Does Vitamin D Deficiency Cause?

You may have guessed by now that vitamin D deficiency can lead to tiredness and fatigue, hence the entire premise of this article! But what else can vitamin D deficiency cause 

  • Bone pain 
  • Muscle weakness, aches, or cramps
  • Mood changes like depression

Are you worried about how vitamin D deficiency affects the body and whether it could be affecting you? We often see questions from people asking whether vitamin D deficiency can cause hair loss, acne, weight gain, constipation, dizziness, or joint pain, so let’s address all of these points here: 

Hair loss – Hair loss can be caused by many different things, including stress, hormones, and genetics. However, vitamin deficiencies, including vitamin D, could have a part to play. 

Acne – There is no link between vitamin D deficiency and acne. 

Weight gain – Whilst vitamin D deficiency will not directly affect your weight, it could indirectly cause weight gain through an increased likelihood of depression, fatigue, and hormonal imbalances. 

Constipation – Again, vitamin D deficiency will not directly cause constipation. However, vitamin D deficiency could affect your mood and cause depression or anxiety – constipation sometimes comes as a symptom of these. 

Dizziness – Research suggests that vitamin D deficiency can lead to diagnosable BPPV (benign paroxysmal positional vertigo), however, there does not appear to be a link between vitamin D deficiency and regular dizziness.  

Joint pain – As we mentioned above, vitamin D deficiency can cause muscle weakness, aches, or cramps which can cause joint pain, commonly in the knees, legs, and hips.  

These symptoms of deficiency show why vitamin D is so important – we must avoid deficiency in order to stay healthy all year round and fight winter fatigue along with many other things. 

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


What Vitamin D Is Good For – How It Helps The Body

Whilst we see many questions about how vitamin D deficiency could negatively impact your health, we also see a lot of questions surrounding the benefits of vitamin D. 

People often ask whether vitamin D can give you energy, help with skin problems like psoriasis, help with arthritis, keep you awake, help with weight loss, and so much more. 

So, again, let’s cover each of these questions below: 

Will vitamin D… 

… help me lose weight?  Getting a sufficient amount of vitamin D everyday can help to keep your hormone levels balanced which could enhance weight loss and fat burning. Vitamin D can also decrease the risk of depression and lethargy – both of which can make it more difficult to lose weight. 

… give me energy?  Yes, if you are deficient in vitamin D, then taking a vitamin D supplement will likely boost your energy levels. This is why vitamin D is great for fighting winter fatigue.  

… help my skin? – Vitamin D plays a very important role in skin protection and rejuvenation. It contributes to skin cell growth and repair, and can also help prevent premature ageing. This is why the sun is so good for our skin (in the right doses), and why we need to supplement vitamin D during the winter when we don’t get as much sunlight.

… help me tan? – Despite being named the sunshine vitamin, vitamin D will not make you tan. That being said, it’s thought that vitamin D3 can help to protect the skin against UV damage. This means that, if you are outside trying to get a suntan, D3 could help to prevent burning and health-damage. 

… help psoriasis? – Research indicates that, since vitamin D can help to strengthen the immune system, it could help to treat autoimmune conditions like psoriasis internally. 

… help my arthritis? – Vitamin D’s main role is helping the body to absorb calcium which is what keeps our bones and joints strong. Therefore, it could help to relieve symptoms of rheumatoid arthritis. 

We mentioned there that vitamin D’s main job is helping the body to absorb calcium, which leads us onto our next point: what is vitamin D for? What exactly does this vitamin do and what is its purpose in the body?

Vitamin D helps the body to absorb calcium and phosphorus. These are both vital for:

  • Keeping the bones and teeth strong
  • Keeping the muscles healthy
  • Keeping the immune system healthy

A serious lack of vitamin D in children can lead to bone deformities such as rickets. In adults, it can cause a condition called osteomalacia – this is characterised by a softening of the bones that can lead to bowing and fractures. (2)


What Vitamin D Supplement Is Best

If you’re wondering which vitamin D supplement to take to combat tiredness and fatigue during the winter, or for any other reason, we would recommend you choose a D3+K2 liquid. 

Firstly, vitamin K2 works as a natural partner to D3, helping it to be effectively distributed to the bones and body. Secondly, liquid vitamins are taken sublingually (under the tongue) which maximises absorption into your bloodstream. 

If you’re wondering: the type of vitamin D we produce when exposed to the sun is D3, and this is thought to be more effective than the alternative (D2) due to the way it’s absorbed by the body. 


So, keep an eye out for a liquid vitamin D3+K2 supplement, rather than a simple D3 tablet or capsule.