Dr Eamon Laird Bsc, PgDIP, Phd
Research Scientist, University Limerick, Physical Education and Sports Science, Visiting Nutrition Senior Research Fellow, TCD
Prof. Rose Anne Kenny, MD, FRCP, FRCPI
President IGS, Professor Medical Gerontology Trinity College and St James Hospital, Director MISA, founding PI TILDA Irish longitudinal study on Ageing
Vitamin D is an essential micronutrient that is needed for bone health and has been linked with reduced risk of cardiovascular disease, cancers and cognitive impairment.
More recently, vitamin D has been linked with the immune system’s function, with low levels leading to a higher risk of severe symptoms from respiratory infections, which could also include Covid-19.
Getting the necessary nutrients
Vitamin D is made in the skin by exposing the body to just 10–15 minutes per day of sun. In Ireland, however, vitamin D can only usually be produced between late March and early October. From Halloween to St Patrick’s day, we cannot make vitamin D from sunlight and are reliant on meeting our requirements from our diet.
Only a few foods are rich in vitamin D (oily fish, eggs, mushrooms), and these are not frequently consumed. Only a few foods are fortified with vitamin D (eg. some cereals, milk, etc.), and these tend to be more expensive and not widely available. The lack of a vitamin D food fortification policy in Ireland, coupled with inadequate sunlight, means we experience some of the highest deficiency rates in Western Europe.
In the Irish Longitudinal Study on Ageing, a nationally representative sample of older adults in Ireland, we found that:
- 47% of all adults over 85 are vitamin D-deficient in winter
- 1 in 8 adults over 50 are deficient all year round
- Only 4% of men and 15% of women take a vitamin D supplement
Only a few foods are rich in vitamin D (oily fish, eggs, mushrooms), and these are not frequently consumed.
Those most at risk of deficiency include:
- People who get little sun exposure or eat low amounts of fortified foods, especially housebound people
- People who are obese or physically inactive, have asthma/chronic lung disease or inflammatory conditions
- Those from poorer backgrounds
- Males and those who live alone
- Ethnic minorities/non-Caucasians
Some recommendations
New recommendations from the Department of Health and the Food Safety Authority of Ireland in 2020 advise that ‘all older Irish adults aged 65 and older take a vitamin D supplement of 15 micrograms (μg)/600 International Units (IU) every day to ensure they get the vitamin D needed for bone and muscle health.’
This can be either through a multivitamin, a calcium and vitamin D supplement or a vitamin D-only supplement. Older adults are also encouraged to try and eat vitamin-rich foods such as oily fish which can infer additional health benefits.