Vitamin D, the Sunshine Vitamin

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Posted: 29/04/2014 Print

Vitamin D, the Sunshine Vitamin

Vitamin D – the Sunshine Vitamin

Don’t you just love waking up to clear blue skies and the sun shining? It makes you feel happy, healthier and eager to get up and go. But there’s another reason why it’s good to be outside in the sun and that’s because exposure to sunlight is the primary source of Vitamin D for the majority of people.

What Does Vitamin D Do?

Vitamin D, so called because it was the fourth vitamin to be named, is needed to help build strong bones and teeth and to deactivate the immune system once an infection has passed. It, also helps regulate the amount of calcium and phosphate in the body and works pretty much in harmony with calcium in the way the body uses it.

A deficiency can lead to deformities such as rickets in children, and bone pain and tenderness in adults from osteomalacia, which is when the bones soften. A recent article suggested that a mother’s low vitamin D level was linked to an increased risk of cavities in their children1.

How Can We Get Sufficient Vitamin D?

Though called a vitamin, it isn’t actually an essential dietary vitamin as it can be synthesised (made) from the sun, unlike an essential vitamin which can only be made in sufficient quantities from the diet. There are only small amounts of vitamin D in only a few foods, which is why it’s almost impossible to get what you need from food alone.


It can be found naturally in foods such as alfalfa, egg yolks, salmon, mackerel and sardines whilst some foods are fortified with it such as milk, cereals and orange juice. Interestingly, if you fry an egg in oil, you’ll lose more of the vitamin D than if the egg is poached – not sure why, it just is!


As you can see there are very few foods that naturally contain vitamin D so it’s important to ‘stock up’ on it from sunlight. A recent study2 in Sweden even suggests that mortality rates are higher in women who don't sunbathe in summer, compared to those that do, citing a deficiency in Vitamin D which led to aggressive skin cancer.

There are several considerations to take into account that will affect production of Vitamin D from the sunlight:

Blue Sky

  • Time of day - the closer to midday, the more vitamin D is produced.
  • Time of year - as a tip, if your shadow is longer than you are tall, you’re not making as much vitamin D as you would when your shadow is shorter. You’ll notice that in winter, your shadow is longer than you for much of the day, whereas in summer it’s much shorter in the middle of the day. Hence, more vitamin D is produced from summer sunlight.
  • The amount of skin that’s exposed. As you’ve probably guessed, the more skin you expose, the more vitamin D you can produce. I remember reading once that we should expose our forehead to sunlight for 15 minutes every day in the summer to ‘stockpile’ the vitamin D.
  • Using sunscreen – although suntan lotion has been shown to reduce the production of vitamin D, it should not cause insufficient levels of vitamin D. It is always important to make sure you are careful and that you do not burn your skin, as with long exposures without protection can increase your risk of skin cancer3. Another factor to consider is altitude – the higher up you are and closer to the sun, the more vitamin D can be produced, hence when you see skiers return with beautifully bronzed faces despite the cold temperatures!
  • Whether it’s a cloudy day or clear day will affect the UVB that reaches your skin.
  • Air pollution soaks up UVB or reflects it back into space which means your skin will make less vitamin D.
  • Are you inside or outside? Probably sounds obvious enough but if you’re behind glass, this will block all UVB so even though it might be the sunniest day of the year, if you’re inside, you won’t be producing any vitamin D – as if you needed another reason to skip the office on a sunny day!
  • Skin colour has a huge impact on the ability to produce vitamin D. Melanin protects against UVB, hence darker skin allows less UVB to enter which is why people with this type of skin take longer to burn and so need to be exposed to sunlight for longer than those with fair skin, to produce the same amount of vitamin D. 

Recommended Supplement Amounts:

The NHS recommendations, which are based on research and evidence by SACN (Scientific Advisory Committee of Nutrition) in 2016 are as follows (this committee advises the government and other organisations):

  • 0-1 years require 8.5-10mcg/d, and 10mcg/d for those aged 1 – 4 years. Babies who have more than 500ml of infant formula do not need supplements as the formula is fortified.
  • For those aged 4 years and above the recommended nutrient intake (RNI), 10mcg/d (400IU/d), this the average amount needed for 97.5% of the population to maintain a vitamin D (25(OH)D) serum concentration more than or equal to 25nmol/L. This recommendation includes pregnant and lactating women, and those who are at risk of low vitamin D serum levels. This is a change from previous advice.
  • The European Food Safety Authority (EFSA) recommends that adults and those between 11-17 years have no more than 100mcg/d (4000 IU/d), those between 1-10 years have no more than 50mcg/d (2000IU/d), and infants no more than 25mcg/d (1000IU/d)

Generally speaking, we should get sufficient vitamin D from a balanced diet and sunlight during the summer months, however, there has been some discussion within the UK about individuals supplementing with 10mcg/d of vitamin D3 during the winter months due to our skin being less efficient in synthesising vitamin D during the winter sunlight. This is especially important in those who are housebound or cover up completely when outdoors.

A word of caution with this though as it is possible to take too much, known as vitamin D toxicity and means the liver produces a chemical which causes high levels of calcium to develop in the blood. This can damage the kidneys. Further, too much vitamin D can encourage calcium to be removed from bones, which can soften and weaken them.

Really, it’s all about balance, as it is with everything.

Enjoy the sun!

Not that you need it, I’m sure, but now you have yet another reason to have a smile on your face when you see the sun shining and the sky that brilliant blue. Enjoy soaking up those rays from the brightest star in the sky – another of Nature’s perfect ingredients!





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Lucy Bee is concerned with Fair Trade, ethical and sustainable living, recycling and eating close to nature with additive free products for health.

Members of the Lucy Bee team are not medically trained and can only offer their best advice. Any information provided by us is not intended to diagnose, treat, cure or prevent disease.

Please note you should always refer your health queries to a qualified medical practioner.

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