Welcome back to my series on the nutrients behind the diet, where I help you to reach that “aha” moment that will allow you to piece together your healthy eating habits! I started this post series a little while ago, and you can find the links for the various posts in the series here: nutrients overview, carbohydrates, fats , proteins andVitamin C .

Today we will be delving into the science of Vitamin D, helping us to discover HOW we can get enough, WHAT actually IS enough, and WHERE we can get it from (without damaging our skin)

First of all, what is a vitamin?

A Vitamin is a micronutrient, meaning it is a substance that we need in small amounts to help our bodies to function correctly. Most of our vitamins cannot be made within our bodies, and so we need to get them from our diet.

However, this is where vitamin D is a little different – we can actually make it inside our bodies, in our skin to be accurate.

So what is Vitamin D?

As we can get our vitamin D from either or both our skin and our diet, in some ways it can be considered both a vitamin and a hormone!

What is Vitamin D good for?

Vitamin D is vital for our bone health as it helps us to absorb calcium from our gut, and maintain healthy calcium and phosphate levels in our blood. Because of these important roles, it helps us to build strong bones.

Getting enough vitamin D in childhood helps to prevent a condition called rickets which can cause bone pain, poor growth and bone deformities. In adults, vitamin D deficiency can lead to osteomalacia, where bones become softer and are a higher risk of breaking. Calcium is also very important for our teeth, and so vitamin D also helps to keep your teeth healthy.

More and more studies however are now also finding links between vitamin D and muscle health, falls in adults, certain neurological conditions such as multiple scelorosis, certain cancers, diabetes and high blood pressure. However, many of these links come from studies done in labs, animal studies or studies looking at global trends. We are still waiting on high quality studies such as large randomised controlled trials that show a more concrete link between vitamin D and these conditions. 

If you are interested in learning more about ways in which nutrition and health are studied, and which types of studies will give us more definite answers, you can find my post on research methods HERE.

How much Vitamin D can I get from the sun?

Unfortunately this question is difficult to answer as it will depend on a lot of variables.

Strength of the sunlight

For example, how much vitamin D you make will depend on how strong the light of the sun is, and so you will often make more during the middle of the day than early in the morning or evening, and you will also make more when you are in direct sunlight rather than in the shade or on a cloudy day.

Skin exposure to sunlight

It is the ultraviolet rays of the sun that allow us to make vitamin D when they reach our skin. So your skin will need to be exposed to the ultraviolet rays to produce the vitamin. However, strong sun can also burn your skin, so you will need to balance your vitamin D making with protecting your skin! Take care to cover your skin and use sunscreen before you turn red or burn.

Nowadays, many people do not produce as much vitamin D as before. Many of us spend most of our summer working indoors, and some groups of people may find themselves less able to expose their skin to the sun, or go outside altogether.

Time of the year

To top it all off, depending on where you are on our planet, during some months of the year, the sun may not be strong enough allow your skin to make vitamin D – no matter how much skin you expose… For example, in the UK and Ireland, the sun is only strong enough to make vitamin D during the months of April to September.

How common is vitamin D deficiency?

As Ireland is relatively far from the equator, and we have our fair share of cloudy days, it not surprising that vitamin D deficiency in Ireland is quite common. On average, one in 8 adults over the age of 50 is vitamin D deficient, and this number rises to over one in 3 for those over 80 years old!

How do you know if your vitamin D is low?

Deficiency can be diagnosed by your doctor using a simple blood test. If the doctor diagnosis a vitamin D deficiency, you will often be recommended to take a vitamin D supplement to allow your body to build up vitamin D stores again. You will rarely feel unwell from having a low vitamin D level, so most people will require a blood test.

Who is at risk of vitamin D deficiency?

Several groups of people are more at risk of low vitamin D levels. These groups include:

• Babies and young children, as well as children and teenagers who are spending little time playing outside.
• Women who are pregnant and mothers who are breastfeeding.
• People over 65 are more at risk as their skin is not as good at making vitamin D as before.
• People with darker skin tones who live in Ireland, the UK or further north.
• Those of us who cover most of our skin when we are outside.
• Anyone who spends little time outside during the summer, such as those we are night shift workers, work in offices or are housebound.

How do you get vitamin D?

As we discussed, during summer, we can get some vitamin D by producing it in our skin. Anyone living in northern climates during autumn and winter will be getting their vitamin D from the stores they have built up during times of sun exposure in summer, and from their food sources. Some people also get a substantial amount of their vitamin D from vitamin D supplements.

What foods are high in Vitamin D?

The amount of vitamin D that we can get from our diet varies based on what we choose to eat, and can even be influenced by the season during which the food was produced.

Foods that naturally high in Vitamin D are oily fish such as salmon, sardines, kippers and trout. Cod liver oil is also a good source of vitamin D, but we don’t recommend this if you are pregnant. Egg yolks, meat, offal and milk may contain a small amount of vitamin D, but this will vary season to season. Some foods are also fortified with vitamin D, such as margarine, some breakfast cereals and some dairy foods. However, for most people, the amount of vitamin D that we can get from our food is not enough to meet our daily needs.

Should I take a vitamin D supplement?

As it is difficult to get enough vitamin D from our diet, some people may be recommended to take a vitamin D supplement. For example, it is recommended in Ireland that all babies under 1 year old who are breastfed or take less than 300mls of formula milk are to take a 5 microgram vitamin D supplement daily (1). And while we do not feel that everyone should take a vitamin D supplement, your doctor or dietitian is best to advise you on whether you specifically should take a supplement. Definitely consider asking your doctor to check your vitamin D levels if you feel you may be in the at-risk group.

So, to help you keep your bones and teeth healthy, and reduce your risk of vitamin D deficiency, we recommend that you make the most of the nice weather during summer to get active outside. Of course protect your skin from getting burnt by covering up and using sunscreen if you will be outside for a longer period of time, but several minutes now and again of sun exposure during summer will help you to build up your stores of vitamin D for winter. And throughout the year, include plenty of oily fish and fortified foods to keep those stores replenished.

Have you had your vitamin D levels checked recently? And what time of the year were they checked? Were you surprised by your results? Let us know in the comment section below!

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