How Much Vitamin D do People in Ireland Really Need: a Guide for Pharmacy Staff

This article outlines everything pharmacy staff need to know about the recommendations on vitamin D supplements for people living in Ireland.

Why do people need vitamin D?

Vitamin D plays important physiological roles in the musculoskeletal system, the immune system, and the process of cell division. Vitamin D is key for bone integrity and strength as it is crucial for absorption of dietary calcium and phosphorus.

Vitamin D deficiency impairs bone health at any stage in life, giving rise to osteomalacia in adults. However, deficiency of vitamin D is particularly harmful during bone growth and development, leading to rickets in young children and lower build-up of bone mineral density during adolescence.

Although it has not been proven, several studies suggest vitamin D deficiency may also be linked to non-skeletal health conditions, such as cardiovascular diseases; diabetes; inflammatory disorders; some infectious diseases (including COVID-19) and immune disorders; certain cancers; and higher mortality rates.

In summary, vitamin D is important for bone health but also contributes to the normal function of the immune system and a healthy inflammatory response, as well as the maintenance of normal muscle function. It is generally agreed that the prevention of vitamin D deficiency is a public health nutrition priority.

Where do people in Ireland get vitamin D?

Vitamin D is only naturally available in a few foods eaten in Ireland. Oily fish (salmon, mackerel, trout, herring) represent foods that are richest in vitamin D. While oily fish also provides other valuable nutrients, such as omega 3 fatty acids, recommended amounts of oily fish (once a week) will not provide enough vitamin D. Other important food sources include the increasing number of vitamin D fortified foods (milks, yogurts, breakfast cereals etc. with vitamin D added). Fortified foods tend to be more expensive and are not eaten by everyone so many people in Ireland do not get enough vitamin D in their diet. Therefore, almost everyone in Ireland needs to take a vitamin D food supplement to prevent vitamin D deficiency.

Sunlight is the most important source of vitamin D in the world, but people must protect their skin from strong sunlight to prevent skin cancer. Although sunscreen products (with adequate SPF) also block the sun rays tha make vitamin D in the skin (UVB radiation), studies show that inadvertent sun exposure makes an important contribution to vitamin D status. This inadvertent sun exposure occurs by just being out and about in sunshine while taking all precautions to avoid sun burn – that is wearing a hat, clothing to cover skin, using sun screen and avoiding hottest times of the day etc. It only takes minimal exposure to sunshine to make a big difference to a person’s vitamin D status. This also shows how people who never go outside are much more at risk of vitamin D deficiency.

In Ireland, the UVB radiation needed to make vitamin D from sunlight is only available during the months of April through October. This is due to our geographic location 52o – 55o North and means that Ireland experiences a ‘vitamin D winter’ that stretches from the end of October to late March. In fact, studies in Ireland show that vitamin D status plummets over this wintertime period. So, if people have a blood test to assess their vitamin D status in March it will generally show a lower vitamin D status compared with having the same blood test in September.

People of dark-skinned ethnicity need longer sun exposure to obtain the same amount of vitamin D. This is because the skin pigmentation, melanin, absorbs the UVB rays that stimulate vitamin D synthesis. For these reasons people of dark-skinned ethnicity in Ireland are advised to take a vitamin D supplement all year round. Briefly, inadvertent sun exposure in summertime will not be as effective in making vitamin D from UVB rays in people of darkskinned ethnicity as it would be in people of fair-skinned ethnicity, who have lower amounts of melanin in their skin.

Everyone in Ireland is at risk of vitamin D deficiency, but who is most vulnerable?

Vitamin D deficiency is a problem across Europe as well as in Ireland. Studies in Ireland have shown vitamin D deficiency is common among children, teenagers and adults –particularly pregnant women. This deficiency is more pronounced in the winter months. A recent study showed that the prevalence of vitamin D deficiency among adults of darkskinned Irish ethnicity (e.g., Irish Asian) to be much higher (affecting 70%) compared with those who are fair-skinned (affecting 12%).

Department of Health Recommendations1

There are Department of Health recommendations on the need for vitamin D supplements for people living in Ireland. Detailed information on the amount of vitamin D people need to take according to age, life stage and skin pigmentation is provided in Table 1. A brief overview of these recommendations is described in the box below.

Everyone in Ireland needs to take a vitamin D supplement (the only exception are infants up to 1 year of age who take more than 300 ml infant formula)

1The scientific basis for these recommendations are outlined in the following reports from the Scientific Committee of the Food Safety Authority of Ireland (FSAI) and links to Healthy Ireland guidance:

• Update to 2007 Scientific Committee Report: Recommendations for a National Policy on Vitamin D Supplementation for Infants in Ireland

• Scientific Recommendations for Food-Based Dietary Guidelines for 1 to 5 Year-Olds in Ireland

• Vitamin D: Scientific Recommendations for 5 to 65 Year Olds Living in Ireland

• Vitamin D: Scientific Recommendations for Food-Based Dietary Guidelines for Older Adults in Ireland and New advice on Vitamin D supplement for people aged 65 years and older from the Department of Health.

How much supplemental vitamin D is needed?

The daily amount of vitamin D needed varies according to age (see Table 1)

Some people need a vitamin D supplement in wintertime only (end of October to mid-March)

All of fair-skinned ethnicity in the following groups:

• Children

• Teenagers

• Adults up to age 65 years

Some people need a vitamin D supplement all year round:

• Infants on less than 300 ml infant formula need a daily vitamin D supplement from birth to 1st birthday

• Pregnant women

• People of dark-skinned ethnicity

• People aged over 65 years

What unit of measurement is used for vitamin D?

In the EU vitamin D is measured in µg (micrograms) and public health advice from the Department of Health is always given using µg. A problem that confuses many consumers is that many vitamin D supplements marketed in Ireland are labelled using IU (International Units) which is the North American unit of measurement.

IU are very different from µg so to be sure the vitamin D supplement provides the correct amount, people should always look for the Daily Amount in µg!

Can people get too much vitamin D?

The only way people can get too much vitamin D is by taking a supplement that contains excessive amounts. Food supplements are concentrated sources of active vitamin D that are easily absorbed. Too much vitamin D from supplements causes a buildup of calcium in the blood (hypercalcemia). This can lead to nausea and vomiting, weakness, heart rhythm problems and frequent urination. Vitamin D toxicity might progress to bone pain, kidney stones and kidney damage. Therefore, it is very important that people:

1. do not take supplements that contain excessively high amounts of vitamin D

2. do not take more than is stated on the label.

The Upper Level (UL) is the highest level of intake from all sources deemed safe. The UL will vary according to body size and, therefore, is much lower for infants and children compared with adults. The Scientific Committee of the Food Safety Authority of Ireland (FSAI) established a UL for vitamin D and all other vitamins and minerals permitted in food supplements in the EU. These various ULs for all age groups are outlined in an FSAI report.2 In a subsequent report,3 the FSAI developed guidance for the food supplement industry on the Maximum Safe Levels for all vitamins and minerals in food supplement products that ensures even those in each age group who have the highest intakes from food, will have intakes less that the UL. The Maximum Safe Levels for vitamin D in food supplements marketed in Ireland are outlined in Table 2 for each age group.

The information in this article is provided to assist pharmacy staff in guiding consumers through the over-the-counter supplement products, towards appropriate and safe vitamin D products.

Further reading:

1. Update to 2007 Scientific Committee Report: Recommendations for a National Policy on Vitamin D Supplementation for Infants in Ireland

2. Scientific Recommendations for Food-Based Dietary Guidelines for 1 to 5 Year-Olds in Ireland

3. Vitamin D: Scientific Recommendations for 5 to 65 Year Olds Living in Ireland

4. Vitamin D: Scientific Recommendations for Food-Based Dietary Guidelines for Older Adults in Ireland

5. Guidance for Food Businesses: The Safety of Vitamins and Minerals in Food Supplements

References available on request

Written by: T. Flynn1, Oonagh C. Lyons2, Megan G. Thompson3, Rossella De Luca3 and Martyna Sanecka4

1Chief Specialist, Public Health Nutrition at the Food Safety Authority of Ireland (FSAI) and Visiting Professor at Ulster University (UU).

2Technical Executive, Public Health Nutrition Policy at the FSAI and PhD Candidate at UU.

3Placement Student, Public Health Nutrition Policy at the FSAI.

4Research Assistant, Public Health Nutrition Policy at the FSAI.