How to increase your vitamin D levels

Are you deficient in vitamin D? We look at how you can increase your levels if you have low vitamin D.

If you live in the UK, you should be able to make all the vitamin D you need from sunlight between April and September (although there are a few exceptions). However, it’s much harder to make enough vitamin D in the UK during the darker winter months.  

Vitamin D is one of the most common deficiencies in the UK, with around one in five people having low levels [1]. Thankfully, vitamin D deficiency is easy to treat once you know what to do and many associated symptoms (like low mood and energy) can improve once levels in the body recover.  

This article will guide you through the three ways you can increase your vitamin D levels if you’ve just received a low vitamin D blood test result, or you suspect your vitamin D levels are low for another reason.  

Three treatments for low vitamin D

  1. Take a vitamin D supplement 
  2. Spend time in the sun 
  3. Eat foods that are rich in vitamin D 

1. Take a vitamin D supplement

In the UK, everyone is recommended to take a vitamin D supplement during autumn and winter (around October to April).  

Some people are recommended to take vitamin D supplements all year, especially people who usually cover up their skin or are often indoors, pregnant and breastfeeding women, and people over 65 and under six months old. 

     Take a vitamin D supplement

What dose of vitamin D should I take? 

  • If you are deficient in vitamin D, you will need to take a supplement with 80 micrograms (4000 IU) per day for 12 weeks. 
  • If your vitamin D level is insufficient, we advise you to supplement with 20-50 micrograms per day for 12 weeks. 

What’s the best vitamin D supplement? 

Most supermarkets, pharmacies, and health shops sell vitamin D supplements.  

Vitamin D3 is preferred over vitamin D2 as the liver is better able to metabolise vitamin D3. 

Am I eligible for free vitamin D supplements? 

If you are more than ten weeks pregnant or have a child under four, you may be eligible for vitamins and healthy food through the NHS Healthy Start Scheme, which helps people during pregnancy, breastfeeding, and infancy.  

What’s the difference between vitamin D3 and 25-OH D? 

D3 and 25-OH D are different forms of vitamin D. Vitamin D3 is made by the skin when it’s exposed to sunlight (you can also get D3 from some foods but in much smaller amounts). It must then be converted into an active form known as 25 hydroxycholecalciferol (25-OH D) before it can be used by your body.

As vitamin D (25 OH) is the major circulating form of vitamin D in your body, it’s commonly used to assess your vitamin D status.  

Are there risks to taking a vitamin D supplement? 

Taking too many vitamin D supplements over a long time can cause calcium to build up in your body, which can weaken your bones and cause damage to the kidneys and heart.  

If you are pregnant, breastfeeding, or taking any medications, you should check with a doctor before starting any new supplements.  

You should also seek advice from your doctor before starting vitamin D supplements if you have: 

  • Bone disease 
  • Kidney stones 
  • Renal impairment 
  • Any conditions that can affect calcium levels 
  • Lymphoma, sarcoidosis, or hyperparathyroidism 

If you have been taking vitamin D supplements for over 12 weeks and your levels have not improved, or you are still experiencing symptoms, seek advice from your GP. 

2. Spend time in the sun

Between April and September in the UK, you’ll most likely be able to make enough vitamin D from sunlight. Here’s how to stay safe in the sun while getting enough sunlight to make vitamin D. 

How much sunlight do I need to make vitamin D? 

Aim for 10-15 minutes in sunlight a day if you have a lighter skin type. If you have darker skin, you’ll need a little longer in the sun - around 25-40 minutes [2]. Researchers have found this daily exposure should provide enough vitamin D while minimising the risks of sunburn and skin cancer. 

Wearing a short-sleeve top and shorts can help increase absorption. If you don’t have any skin on show, your body can’t make vitamin D. You should also make it a regular habit to go outside (preferably between 11 am and 3 pm). 

How to stay safe in the sun 

Wearing sun cream and avoiding long periods in the sun will help to protect you from sun damage. Spending too much time in the sun can lead to burning and skin damage. 

Wearing sun cream won’t affect your body’s ability to make vitamin D [3]. If you have fairer skin that is more sensitive to burning, start with short periods outside and build up. Cancer Research UK has lots of guidance that can help you to protect your skin from harmful damage.

Can I make vitamin D by going on a sunbed? 

You cannot increase your vitamin D levels by using sunbeds. Sunbeds emit high levels of UVA, which doesn’t increase vitamin D levels but does increase the risk of cancer.    


3. Eat foods that are rich in vitamin D

Around 10% of your vitamin D intake can come from food sources. You can’t rely on food alone to give you all the vitamin D you need, but it can help to top up your levels. 

In the UK, the richest sources of vitamin D can be found in oily fish, mushrooms, egg yolks, and fortified foods. In some countries, cow’s milk can be a good source of vitamin D because it’s fortified, however, this isn’t the case for the UK. Generally, in the UK, fortified foods include fat spreads and breakfast cereals.  

How much vitamin D is in food sources? 

  • A 3oz salmon fillet contains 11-17 micrograms per portion. 
  • Mushrooms, especially those exposed to UV light, can provide around 7.9 micrograms per half a cup of mushrooms. 

     Eggs - a food source of vitamin D

We know that vitamin D is essential for healthy bones and teeth, but you also need to maintain adequate calcium levels for the same reason.  

Good sources of dietary calcium include: 

  • Fortified cereals 
  • Cheese 
  • Almond milk 
  • Tofu 

How does the body convert dietary vitamin D? 

The two primary dietary forms of vitamin D are: 

  • Vitamin D3 (cholecalciferol) – in animal foods such as fatty fish and egg yolks. 
  • Vitamin D2 (ergocalciferol) – in some plants, mushrooms, and yeasts. 

When vitamin D enters the body, it enters in a raw form that undergoes two steps to become the active hormone that the body uses to absorb calcium. 

How vitamin D becomes active: 

  1. In the first step, the liver converts vitamin D into calcidiol 25 (OH) D – the stored form of the vitamin. 
  2. The kidneys then convert vitamin D into calcitriol, or 1,25 (OH) 2D, which is the active form of the vitamin. The active form then binds to the vitamin D receptors in your cells and changes them. 

How often should I test my vitamin D levels? 

If you are prone to a vitamin D deficiency and are experiencing symptoms of low vitamin D, then a Vitamin D (25 OH) Blood Test can tell you whether your levels are within the optimal range. 

If your blood test shows a vitamin D deficiency, we recommend re-testing your vitamin D level once you’ve taken vitamin D supplements for 12 weeks. If your level is healthy, you can reduce your vitamin D to a maintenance dose of 10 micrograms per day. 


vitamin D blood test product banner

Vitamin D blood testing in the UK 

Our Vitamin D (25 OH) Blood Test is a simple finger-prick test that you can take in the comfort of your own home. It checks whether low vitamin D levels could be contributing to symptoms like low energy and muscle aches and pains. 



  1. Crowe FL, Jolly K, MacArthur C, Manaseki-Holland S, Gittoes N, Hewison M, Scragg R, Nirantharakumar K. Trends in the incidence of testing for vitamin D deficiency in primary care in the UK: a retrospective analysis of The Health Improvement Network (THIN), 2005-2015. BMJ Open. 2019 Jun 4;9(6):e028355. doi: 10.1136/bmjopen-2018-028355. PMID: 31167871; PMCID: PMC6561453.

  2. Sunlight and vitamin D (no date) British Skin Foundation. Available at: (Accessed: 03 January 2024).

  3. Sunscreen photoprotection and vitamin D status - wiley online library (no date) British Journal of Dermatology. Available at: (Accessed: 03 January 2024).

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Vitamin D (25 OH) Blood Test

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