Vitamin D prescriptions for children have ballooned 25-fold in eight years, with academics warning that the rise poses a “huge, potentially avoidable, expense” to the NHS.
GPs are not consistently following national recommendations on vitamin D supplementation, according to a study by London universities and hospitals.
They found that children are being prescribed a large variety of doses while some are being given higher levels without their concentrations of the hormone being tested first.
Annual spending on vitamin D prescriptions has swollen from £0.5 million in 2007 to £40 million in 2016, NHS Digital figures show, a rise which has been partly attributed to the increase in prescriptions for children.
This is despite the supplement being widely available over the counter.
The researchers say the risk of toxicity from excess amounts of vitamin D is low but “requires further exploration given its widespread, and sometimes unregulated use”.
The study looked at records of vitamin D prescriptions for 2,051,403 eligible children from 723 general practices between January 1 2008 and December 31 2016.
Of those, 12,277 were prescribed vitamin D for the first time, according to the records submitted by GPs to the Health Improvement Network.
The annual incidence of vitamin D prescribing increased by more than 25-fold between 2008 and 2016, rising from 10.8 to 276.8 per 100,000 person-years.
Official guidance recommends prescribing therapeutic doses of the supplement only to those actually diagnosed with vitamin D deficiency.
But for between 29% and 56% of prescriptions each year, there were no linked blood test results for vitamin D levels recorded in the three months prior to issuing.
And less than a third (29.5%) of the children prescribed the supplement had symptoms indicating vitamin D deficiency, including aches and pains, tiredness or fatigue.
The researchers say the “marked and sustained increase” may be a result of the success of the Department of Health and Social Care (DHSC) in raising awareness about deficiency.
But while low concentrations of vitamin D have been linked to a variety of conditions in children, such as asthma, eczema and diabetes, evidence has not conclusively shown better outcomes with supplements.
The researchers also identified “wide variations in supplementation regimens prescribed, deviating in part from UK recommendations”.
They identified 109 different pharmaceutical preparations of at least 32 dosage strengths prescribed over the period.
They wrote: “Furthermore, with no clear evidence to support the use of vitamin D supplementation on health outcomes, other than for the prevention or treatment of rickets and osteomalacia, this aberrant prescribing practice incurs a huge, potentially avoidable, expense to our healthcare system.”
The paper is published in the journal BMJ Open.