People living in some parts of Dublin are much more likely to be deficient in vitamin D, which can have a major impact on their overall health, unique new research has shown.
According to the findings, some areas have deficiency rates that are five times higher than other areas.
Researchers at Trinity College Dublin (TCD) and St James's Hospital have developed a visual map of the vitamin D status of Dublin's inhabitants, using a combination of geo mapping and traditional based research involving over 5,200 people.
"This is the first time that a geographical map of the greater Dublin region or any urban region in Ireland has been developed. Our findings provide useful data to help inform public health policy regarding endemic vitamin D insufficiency to help target the population groups and resident location areas most at risk," explained the research's author, Dr Eamon Laird, of TCD.
The research revealed that one in eight people (12.5%) living in the greater Dublin area is vitamin D deficient. While this falls to 10.8% during the summer months, it rises to 15.2% in the winter.
However, some areas appear to be much more affected than others. The researchers noted that in the most economically deprived and ethnically diverse urban locations - Dublin 8 and Lucan postal districts - rates of vitamin D deficiency are much higher, with one in four people (25%) affected.
This is double the rate for the Dublin region as a whole and up to five times higher than some other areas. For example, in Dublin 16, the deficiency rate is just 5% during the summer. In Kildare, it is just 7.6% during the winter.
Overall, females were found to have much higher rates of vitamin D deficiency than males - 25% higher on average. Furthermore, younger people were also more likely to have lower vitamin D levels than older people.
Those aged between 18 and 50 had 27% lower levels in winter than those over the age of 50. During the summer, their levels were 20% lower. The researchers noted that this finding is contrary to the popular perception that vitamin D deficiency is a bigger problem for older adults.
While vitamin D has long been associated with bone and musculoskeletal health, in recent years, doctors have suggested that deficiency in the vitamin is a risk factor for a range of serious health conditions, such as cancer, heart disease and type 2 diabetes.
The main source of vitamin D is ultraviolet B (UVB) radiation from the sun, however this can be affected by factors such as sunscreen use, cloud cover and season.
The vitamin is also found in certain foods such as oily fish like mackerel and salmon, cheese, egg yolks and foods fortified with vitamin D such as milk and cereals.
Dr Laird noted that there could be a number of reasons for the disparities found in the Dublin region.
"Other studies have shown an association between social deprivation and lower vitamin D, possibly due to diet as vitamin D-rich foods, such as oily fish or fortified foods, tend to be more expensive.
"Also, these locations in Dublin are more ethnically diverse compared to other areas, with higher numbers of non-Caucasians. Increased skin pigmentation plus ethnic lifestyle choices such as traditional clothing and/or dietary habits can also increase the risk of deficiency," he said.
Details of these findings are published in the Irish Journal of Medical Science.