One in four children in Dublin is deficient in vitamin D, a new Trinity College study has found.
The research also showed the proportion of children with vitamin D deficiency increased to one in three children in disadvantaged areas.
Higher levels of deficiency were found in girls over the age of 12 and during winter months.
The study, published on Wednesday in the Journal of Nutritional Science, is the largest of its kind in Ireland to date.
It is the only study to explore vitamin D deficiency by an accurate measure of socio-economic status.
Researchers said the findings highlight the need to promote awareness of deficiency and to create strategies to improve vitamin D intake in Irish children, especially in those found to be most at risk.
They suggest targeted and tailored guidelines on vitamin D intake may be required for children.
Lead researcher Helena Scully said the findings indicate that low vitamin D levels are common.
“This is concerning as it may have long term implications for bone health. In particular girls, teens (over 12 years) and those living in low socio-economic areas were most vulnerable,” she said.
“Choosing foods such as milk and cereal products with added vitamin D, and taking a supplement (10 micrograms or 400 units per day), particularly in the winter can help prevent low vitamin D levels.”
St James’s Hospital consultant physician Dr Kevin McCarroll said: “The study shows that vitamin D deficiency is just as prevalent in children as in adults, particularly during the teenage years when new bone mass is acquired.
“Reduced sun exposure such as more sedentary behaviour or screen time and lower dietary vitamin D intakes are likely to be important factors.”
Vitamin D is vital for the rapid bone growth which occurs in childhood and adolescence, when about 90% of our peak bone mass is attained – yet studies on the vitamin D status in children in Ireland are limited.
The body creates vitamin D from direct sunlight on the skin, outdoors. From October to March, we do not make enough vitamin D from sunlight in Ireland.
Additionally, food sources of naturally occurring vitamin D are limited.
Vitamin D is also important for the adequate absorption of dietary calcium which is equally important for bone health.
Failure to maintain adequate vitamin D and calcium intake in childhood puts children at risk of brittle bones (osteoporosis) in later life.
Severe deficiency of vitamin D can also cause softening of the bones (osteomalacia) and lead to rickets in young children.
The children in this study had been referred to their GP for vitamin D tests in the Dublin area, and variation was identified by sex, season and socio-economic status in a sample size of 1,226 children.
The research team believe the recommended daily allowance may need to include specific targets for children of between 10-15micrograms (400-600iu).
