Thu, Sep 10, 26
Vitamin D in Ireland: A Pharmacist’s Guide to Supplements, Dosage Deficiency
By Lauren O’Reilly, Pharmacist
Vitamin D is one of those nutrients I think is particularly worth paying attention to in Ireland. Unlike other vitamins that we can generally get enough of through a balanced diet, our ability to make vitamin D from sunlight depends on the time of year, and during the Irish winter there simply isn't enough UVB sunlight for our skin to make sufficient amounts.
Dietary sources can help, but vitamin D is naturally found in relatively few foods and it can be difficult to get enough from diet alone. Oily fish such as salmon, sardines and mackerel are some of the better natural sources, while smaller amounts are found in foods such as egg yolks and meat. Some foods, including certain milks and breakfast cereals, may also be fortified with vitamin D. This combination of limited dietary sources and reduced sunlight during the winter is why vitamin D supplementation is particularly relevant in Ireland.
But how much do you actually need? Should you take it all year? And is more necessarily better?
Here’s my Pharmacist guide to vitamin D, including who may benefit from supplementation and how to take it safely.
Vitamin D supports more than just your bones
Vitamin D helps the body absorb calcium and is important for maintaining healthy bones and teeth. It also contributes to normal muscle function and the normal function of the immune system.
However, vitamin D has become something of a wellness superstar, with claims ranging from preventing infections to improving mood and energy. It's important to separate established benefits from associations that haven't yet been proven.
Taking more vitamin D than you need doesn't automatically provide additional health benefits. I have included dosage guidelines below in accordance with HSE recommendations. If you suspect you have a vitamin D deficiency – it is always best to check this with your GP rather than assuming you have one and taking a higher dose of Vitamin D.
Why living in Ireland makes vitamin D supplementation more relevant
Your skin can produce vitamin D when exposed to UVB sunlight. The problem is that, in Ireland, sunlight isn't strong enough during the winter months for this process to provide us with sufficient vitamin D.
The HSE therefore recommends vitamin D supplementation for most people aged 13–64 from Halloween until St Patrick’s Day.
Some people are advised to take vitamin D throughout the year, including those with darker skin, people who have limited exposure to sunlight, pregnant women and adults aged 65 and over.
The Irish vitamin D guide
Group |
Recommended supplement |
When |
|
Adults aged 13–64 |
15 µg (600 IU) daily |
Halloween → St Patrick’s Day |
|
People with darker skin |
15 µg (600 IU) daily |
All year |
|
People with limited sun exposure |
15 µg (600 IU) daily |
All year |
|
Pregnancy |
15 µg (600 IU) daily |
All year |
|
Adults aged 65+ |
15 µg (600 IU) daily |
All year |
These are general HSE recommendations. Your needs may be different if you have been diagnosed with vitamin D deficiency or have a medical condition affecting vitamin D absorption or metabolism.
Children & Vitamin D
Vitamin D is important throughout childhood for healthy bones and teeth, and the HSE has specific supplementation advice for different age groups.
-
Babies under 12 months: 5 µg (200 IU) daily if breastfed or taking less than 300 ml of infant formula per day.
-
Children aged 1–4: 5 µg (200 IU) daily from Halloween to St Patrick’s Day.
-
Children aged 5–12: 10 µg (400 IU) daily from Halloween to St Patrick’s Day.
Children aged 5–12 with darker skin or reduced sun exposure are advised to take 10 µg all year round.
For babies and young children, always choose a product specifically suitable for their age and follow the dosing instructions on the product. If you're unsure which supplement or dose is appropriate, ask your pharmacist, GP or public health nurse. All recommendations were accurate at the time of writing. Please see the HSE website for up-to-date information.
Vitamin D deficiency isn't always obvious. Severe deficiency can affect bone health and cause osteomalacia in adults, which may lead to bone pain and muscle weakness.
If you're concerned that you may be deficient, particularly if you have symptoms or fall into a higher-risk group, it's worth speaking to your GP rather than simply taking a high-dose supplement.
D2 or D3? The difference is simpler than it sounds
You'll usually see two forms of vitamin D:
- Vitamin D2 (ergocalciferol)
- Vitamin D3 (cholecalciferol)
Both can increase vitamin D levels, but vitamin D3 is the form most commonly found in supplements.
For most people, I wouldn't get too caught up in D2 versus D3. Getting an appropriate amount consistently is much more important than choosing a supplement based purely on the form.
How to take Vitamin D
There's no special morning or evening window that you need to hit. The best time is one you can stick to consistently.
Vitamin D is fat-soluble, and the HSE recommends taking supplements with a meal to help absorption. I generally suggest taking it alongside your main meal, particularly if that meal contains some dietary fat.
If you're already taking a multivitamin, check the label before adding a separate vitamin D supplement. You may already be getting some vitamin D from your existing products.
More vitamin D isn't necessarily better
Because vitamin D is fat-soluble, excessive amounts can accumulate in the body. Taking too much over time can lead to hypercalcaemia, where calcium levels in the blood become too high, potentially damaging the kidneys and heart.
For adults, the tolerable upper intake level is 100 µg (4,000 IU) per day from all sources.
Importantly, 4,000 IU is not a recommended daily dose. It's an upper safe intake level, not a target.
You generally don't need a high-dose vitamin D supplement unless it has been recommended by a healthcare professional to treat a confirmed deficiency or specific medical need.
My pharmacist approach to choosing a vitamin D supplement
When choosing a vitamin D supplement, I would keep it simple:
Check the dose. For general supplementation in Ireland, 15 µg (600 IU) is the key amount in current HSE guidance for adults.
Look at the form. Vitamin D3 (cholecalciferol) is a straightforward option. From there, it is your choice as to whether you prefer a spray, tablet or other form. A lovely spray option is the Better You 1000IU Spray, whereas for someone who prefers a soft capsule which is also easy to swallow, Solgar 1000IU Softgels come in a bottle of 100, so could keep you going throughout the colder months.
Check what else you're taking. Vitamin D can appear in multivitamins, women's supplements, calcium products and other combinations, so check your total daily intake. For example, Revive Active Tropical Flavour contains 1000IU Vitamin D, so no extra Vitamin D would be required for an adult taking this supplement who has no reason to believe they are deficient and in need of a higher dose.
Don't automatically choose the highest strength. More isn't better when you don't need it.
At Millie's, you'll find vitamin D in a range of standalone supplements and combination products, so the right choice depends on whether you're looking for straightforward vitamin D supplementation or already taking other nutritional products.
The bottom line
For most people living in Ireland, vitamin D is worth thinking about routinely rather than only when you feel tired or run down.
For adults aged 13–64, current HSE guidance recommends 15 µg (600 IU) daily from Halloween to St Patrick’s Day, with year-round supplementation recommended for certain higher-risk groups and adults aged 65+.
Take it with food, check what you're already getting from other supplements, and don't assume that a higher dose is a better dose.
Vitamin D is important - but when it comes to supplementation, getting the right amount is the goal, not the biggest amount.
