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Tis the Season for….Vitamin D Supplements!

02 Dec Tis the Season for….Vitamin D Supplements!

  • 30-40% of UK adults have low levels of vitamin D in their body between January and March.1
  • It is difficult to get sufficient amounts of vitamin D from food alone.
  • In the UK, our skin does not produce enough vitamin D from the sun between October and late March.
  • Most people in the UK will need to take a supplement to meet their requirements for Vitamin D, particularly between October and late March. Adults need 10 μg/d (400 IU) of vitamin D per day.


Vitamin D is an important nutrient that our skin produces when exposed to sunlight.  It is the UVB radiation in the sun which is needed to produce vitamin D.  It’s worth noting that sitting indoors (or in your car) and enjoying the sunshine through the window will not produce vitamin D because the glass blocks the UVB rays.2 When outdoors, the amount of UVB radiation that reaches our skin is very much affected by the time of day, season, latitude, altitude, cloud cover, air pollution, clothing and sunscreen use.  Due to the latitude of the UK, our bodies cannot produce Vitamin D from the sun between October and late March.   As a result, many people in the UK tend to have low levels of vitamin D, particularly in the winter months.  Between January to March, low vitamin D levels have been found in 40% of people aged 19-64 years and 30% of people aged 65 years and over.1

Why is vitamin D important?

Vitamin D helps keep our muscles working properly, reduces the risk of falls (in adults over 50 years) and helps to develop and maintain strong bones.  Vitamin D also helps to regulate the levels of calcium and phosphorus in the body.

How much do I need?

The intakes recommend by the Scientific Advisory Committee on Nutrition (2016)3 are as follows:

  • Infants aged under 1 year – 8.5-10 μg (340-400 IU) per day
  • Children aged 1-18 years – 10 μg (400 IU) per day
  • Adults – 10 μg/d (400 IU) per day (including pregnant and lactating women)


These are the amounts required from a combination of natural food sources, fortified food sources (such as infant formula milk) and supplements.  You do not generally need a blood test prior to starting a vitamin D supplement.Speak to your GP if you are concerned. 

Food sources of vitamin D:3

It is difficult to get enough vitamin D from food alone.

Food – Amount – Vitamin D Content

Whole eggOne egg1.7 μg (68 IU) each

Oily fish (salmon/mackerel/herring) – 100 g cooked weight8-16 μg (320-640 IU)

Sardines100 g canned in brine, drained3.3 μg (132 IU)

Liver (calf/lamb) – 100 g cooked weight0.3-0.9 μg (12-36 IU)

Beef (rump steak) – 100 g cooked weight0.7 μg (28 IU)

Infant formula milk100 calories – 1.0-2.5 μg (40-100 IU)

Margarine, breakfast cereal and evaporated milk may have vitamin D addedCheck the product label


Since it is difficult to get enough vitamin D from food alone, many people will want to take a supplement to ensure they get adequate amounts, especially between October and late-March.  If you spend much of your time indoors, you will want to take these supplements year-round.

There are two types of vitamin D supplements that you can buy:

Vitamin D3 (cholecalciferol) – is produced from sheep’s wool.  It’s been found to do a better job of raising Vitamin D levels in the blood (compared to Vitamin D2) but is not suitable for vegans.1,3

Vitamin D2 (ergocalciferol) – is produced from fungi and is suitable for vegans.  It may not be as effective at increasing the vitamin D levels in your blood as Vitamin D3.1,3

Note that vitamin D is often added to multi-vitamin and mineral supplements.  It is also added to many oral nutrition supplements (eg. EnsureTM).  One word of caution about cod liver oil.  While cod liver oil is a good source of vitamin D, it also contains vitamin A which can be toxic in high amounts.  Adults should limit their intake of vitamin A from supplements to no more than 1500 μg RE/day and women who are pregnant or could become pregnant, should not take supplements containing vitamin A unless advised to do so by their GP.4

How much is too much?

You can get too much vitamin D.  Too much vitamin D can lead to too much calcium in your blood and this can cause irreversible damage to kidneys and blood vessels.  The European Food Safety Authority recommends keeping vitamin D intakes to less than 25μg/d (1000 IU) for infants,  50μg/d (2000 IU/d) for children aged 1-10 y, 100μg (4000 IU/d) for children aged 11- 17 y and 100μg/d (4000 IU/d) for adults.3

If you are looking for reliable nutrition advice, Dietitian & Nutritionist Sheri Taylor offers a clinic at Halo Physio each month.  She can review your intake of food and supplements and advise you on whether your are getting too little or too much of any one nutrient.  Please contact her at 07787 603863 or for a free, no obligation discussion of your needs and how she can help.

Blog compiled by Sheri Taylor, Dietitian & Nutritionist at Halo. Find out more about Sheri here


  1. National Institute of Clinical Excellence (UK). Vitamin D deficiency in adults – treatment and prevention.  2016, Nov.  Available from:


  1. NHS Choices. How to get vitamin D from sunlight.  2015 Nov.  Available from:


  1. Scientific Advisory Committee on Nutrition (UK). Vitamin D and Health.  2016, Jul.  Available from:


  1. Scientific Advisory Committee on Nutrition (UK). Review of dietary advice on vitamin A.    Available from:
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