One in four children in Dublin are vitamin D deficient, study shows

Deficiency most prevalent in children in socioeconomically disadvantaged areas and girls, research finds

Helena Scully, Mercers Glanbia bone research fellow and lead researcher, described the findings as 'concerning'. Photograph: iStock
Helena Scully, Mercers Glanbia bone research fellow and lead researcher, described the findings as 'concerning'. Photograph: iStock

One in four children in Dublin are vitamin D deficient, with deficiency most prevalent in girls and children in socioeconomically disadvantaged areas, according to a new study published on Wednesday.

Scientists at Trinity College Dublin found that the number of children in Dublin who are deficient in vitamin D increases to one in three in socioeconomically disadvantaged areas, as well as among girls and children over the age of 12.

Vitamin D levels are also lower among children during the winter months.

This is the largest study of vitamin D status in Irish children (aged one to 17 years), and the first to investigate the association with socioeconomic status. The vitamin D levels of children who attended their GP and whose blood results were submitted to St James’s Hospital for analysis between 2014-2020 were studied.

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Helena Scully, Mercers Glanbia bone research fellow and lead researcher, described the findings as “concerning”.

Speaking to The Irish Times, Ms Scully said girls may be more likely to be deficient in vitamin D than boys due to a number of factors, including that girls are more likely to practice vegan and vegetarian diets than boys.

“Boys spend a lot of time outside playing sports, particularly in the summer months, and they are less likely to wear sun cream than girls. Girls also go through puberty younger and vitamin D is stored in fat cells, so for girls who are putting on more tissue during puberty the vitamin D is potentially getting trapped during that time,” she said.

Children in socioeconomically disadvantaged areas “may not have a good quality diet and generally don’t take supplements at the same rate as those from more advantaged backgrounds”, Ms Scully said.

“They also may not have the same access to outdoor amenities or summer holidays abroad in warm climates.”

The study highlighted the need for “greater awareness” of deficiencies and the importance of improving vitamin D intake among children, particularly in the winter months when parents should consider paying more attention to their children’s diets, or including supplements, she said.

Vitamin D is vital for the rapid bone growth which occurs in childhood and adolescence, when about 90 per cent of peak bone mass is attained, yet studies on the vitamin D status in children in Ireland 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 socioeconomic status in a sample size of 1,226 children.

The study suggested that targeted and tailored guidelines on vitamin D intake may be required for Irish children.

The Food Safety Authority recommends that everyone aged between five to 65 years get 10 micrograms (400 units) of vitamin D — through diet and supplements — per day.

The research team believe the recommended daily allowance may need to include specific targets for children of between 10-15 micrograms.

Jade Wilson

Jade Wilson

Jade Wilson is a reporter for The Irish Times