Why should we all be now taking Vitamin D?

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    Article by Marie Donnellan, ANutr

    Why should we all be now taking Vitamin D?

    For the first time a report published last year from the Food Safety Authority of Ireland (FSAI), examined vitamin D intake in people in Ireland aged between 5 and 65 years. Based on this review, it was recommended that as well as intake from food sources, everyone take a vitamin D supplement especially teenagers, pregnant women and people of dark-skinned ethnicity who are at highest risk of vitamin D deficiency.

    Irish research shows that a high percentage of teenagers and adults (12% to 26% of the population) have serum 25-hydroxyvitamin D (25(OH)D) concentrations below 30 nanomoles per litre (nmol/L). Which is representative of an increased risk of vitamin D deficiency, as it relates to bone health. This is higher during the winter months (1). So, what do we need to do to increase our intake and what are we at risk of, if our intake is not sufficient?

    What is Vitamin D?

    Vitamin D is a fat-soluble vitamin, which plays a central role in our health. It is obtained during exposure to sunlight by skin biosynthesis and from natural dietary sources. Due to the lack of prolonged sunshine in Ireland, our position in northern Europe and the low dietary vitamin D intake, deficiency is a critical problem in Ireland for all age groups (2).

    The following is the recommended total daily intake to minimise deficiency (1):

    • 10 µg for healthy children (aged 5–11 years)
    • 15 µg for healthy teenagers and adults (aged 12–65 years, including pregnant women) of all ethnicities. 

    It is generally agreed by expert groups that Vitamin D deficiency falls within serum 25(OH)D concentrations of <25 or <30nmol/L (3). 

    What is it used for in our body?

    Vitamin D contributes to vital functions within the body including (4, 5): 

    • bone health by regulating calcium and phosphorus metabolism 
    • supporting immunity through helping to maintain and strengthen the body’s defence against infection
    • supporting healthy muscles in the musculoskeletal system 

    Research has also shown that those with low levels of vitamin D have an increased risk of:

    • type 1 diabetes mellitus
    • cardiovascular disease
    • neurological disease
    • autoimmune disease and some cancers.

    The direct and indirect medical costs of which, have been estimated in Europe to be in the hundreds of billions of euros (6).

    Body Anatomy

    What’s our current intake and how can we improve it?

    Data from the national nutrition surveys from 2008–2020 showed that the mean daily intakes of vitamin D from diet and supplements were 4.2 µg for children (5–12 years), 3.7 µg for teenagers (13–18 years), and 4.3 µg for adults (18–64 years). It also showed that 19%, 8%, and 17% of these groups respectively, consumed a food supplement containing vitamin D (1). 

    However, the mean daily intakes of those who did not consume vitamin D-containing supplements were only around 2–3 µg per day (µg/d), compared with current dietary requirements of 10–15 µg/d (1).

    Based on this information, the geographical position of Ireland and low ultraviolet UVB exposure throughout year, the following are other ways to increase your vitamin D intake.

    Through Diet – though, this can be difficult as the variety of foods that are rich in vitamin D are limited. Those that are a source are:

    • Foods rich in vitamin D like animal products including oily fish, eggs, liver and red meat and mushrooms.
    • Fortified foods like milk, breakfast cereals and some breads. However, be mindful when choosing some breakfast cereals and read the labels for those with a high sugar content.

    Supplementation – is recommended in the winter months due to the challenges of getting enough through food.

    • For healthy children (aged 5–11 years) a daily vitamin D supplement containing 10 µg (400 international units (IU)) to meet requirements
      • fair-skinned ethnicity is taken during the extended winter months (end of October to March).
      • darker-skinned ethnicity is taken throughout the full year.
    • For healthy teenagers and adults (aged 12–65 years) a daily vitamin D supplement containing 15 µg (600IU) to meet requirements
      • fair-skinned ethnicity, taken during the extended winter months (end of October to March).
      • darker-skinned ethnicity and for individuals of all ethnic groups who are pregnant, taken throughout the full year.
    • These are considered safe levels of supplemental vitamin D, even when combined with typical vitamin D intakes from natural and fortified foods

    It’s important not to take more than recommended, without consulting with your GP first. As always if you are also taking other supplements, check if these include vitamin D, as you may end up taking more than recommended.

    References

    1. (2023) Vitamin D – Scientific Recommendations for 5 to 65 Year Olds Living in Ireland. rep. Scientific Committee of the Food Safety Authority of Ireland. 
    2. Hill T, O’Brien M, Cashman K, Flynn A, Kiely M. Vitamin D intakes in 18–64-y-old Irish adults. European Journal of Clinical Nutrition [Internet]. 2004;58(11):1509-1517. Vitamin D and Your Baby – HSE.ie [Internet]. HSE.ie. 2019.
    3. Irish Universities Nutrition Alliance (IUNA). Summary Report on: Food and Nutrient Intakes, Body Weight, Physical Activity and Eating Behaviours in Children Aged 5-12 Years in Ireland [Internet]. IUNA; 2019. 
    4. Hossein-nezhad et al,. Vitamin D for Health: A Global Perspective. Mayo Clinic Proceedings. 2013. 
    5. McCarroll et al., Determinants of 25-hydroxyvitamin D in older Irish adults. Age and Ageing, 2015.
    6. Calvo et al., Vitamin D research and public health nutrition: a current perspective, PHN, 2017.