25 Sept 2022

EXPLAINER: Everything you need to know about vitamin D


EXPLAINER: Everything you need to know about vitamin D

You might have heard lately about Vitamin D and why it’s important for some of us to take it, but did you know why?

As many of us find ourselves confined to our houses due to social distancing measures, concerns tend to arise about the lack of sunlight – and possible vitamin D deficiency. For many, a go-to fix is to take supplements.

Both vitamin D2 and D3 supplements are available over the counter without a prescription and have been linked to improving immunity, tiredness and muscle weakness, bone pain, and depression. They’ve also been said to help stave off cancer and the consequences of ageing.

Joana Da Silva, Chief Specialist in Nutrition with safefood has all the answers.

What is Vitamin D?

Did you know that Vitamin D (also known as the ‘sunshine vitamin’) is one of the few vitamins our bodies can produce itself? From the months of April to October, our bodies make vitamin D through direct sunlight on our skin. However, many factors will impact our body’s ability to create vitamin D, such as the use of sunscreen (which reduces the risk of skin cancer), our clothing choices and the amount of time we spend indoors.

As Irish winters are not very sunny, our skin cannot produce enough vitamin D and so we must get the sunshine vitamin from elsewhere. Some foods are rich in Vitamin D, including:

  • Oily fish such as mackerel, salmon, and herring
  • Red meat
  • Organ meats such as liver
  • Egg yolks
  • Fortified foods such as some fat spreads, milk, and breakfast cereals

Certain groups in society are at higher risk of not getting enough Vitamin D. A recent report from the Food Safety Authority of Ireland found that Irish adults aged 65 years and older do not get sufficient vitamin D from direct sunlight on their skin or from their diet and for this reason, need to take a vitamin D supplement. Similarly, people with darker skin have a lower ability to make vitamin D and are at a higher risk of deficiency.

What does vitamin D do?

Vitamin D helps us to regulate the amount of calcium and phosphate in our bodies, which are needed for strong healthy bones and to maintain healthy muscle mass. Not only that, evidence shows that vitamin D also supports the normal functioning of our immune system.

A lack of vitamin D can increase the risk of osteoporosis over time, causing our bones to weaken and become brittle and increasing the risk of fractures and breakages.

Vitamin D deficiency has also been linked to various health conditions such as cardiovascular disease, diabetes, some inflammatory disorders, certain cancers, and higher mortality.

What is the recommended daily intake of vitamin D?

For adults aged 65 and older, the recommended daily intake of vitamin D is 15 micrograms (15µg).

This can be taken as:

  • A multi-vitamin supplement that contains 15 microgram (15μg) of vitamin D
  • A calcium and vitamin D supplement that contains 15 microgram (15μg) of vitamin D
  • A vitamin D only supplement that contains 15 microgram (15μg) of vitamin D

If you have been prescribed a vitamin D supplement at a dose higher than 15 micrograms from a healthcare professional, you should continue to take the supplement at the prescribed dose. Talk to your healthcare professional if you are unsure.

Is there such thing as too much vitamin D?

It is possible to have too much of the sunshine vitamin. Excessive intakes are usually due to consuming large doses of vitamin D supplements. Taking too much over a long period of time can weaken the bones, kidney, and heart due to a build-up of calcium in the body. Unless advised by your healthcare professional, you should not exceed the recommended daily intake of vitamin D.

Where can I buy a vitamin D supplement?

Vitamin D supplements can be bought in your local pharmacy or supermarket and do not require a prescription. As doses of 15 micrograms are not yet widely available, you may need to take one and a half tablets of the 10-microgram dose, which are widely available. If you need advice about vitamin D supplements, -speak to your healthcare professional or local pharmacist.

I read that Vitamin D protects against Covid-19 – is this true?

At present there is insufficient high-quality evidence to support claims that vitamin D supplementation is beneficial in preventing or treating Covid-19.

For more information and practical advice on healthy eating, being active and easy recipes, visit

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