Vitamin D Alone Doesn't Reduce Fracture Risk in Children

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Vitamin D Alone Doesn’t Reduce Fracture Risk in Children

Vitamin D Alone Doesn’t Reduce Fracture Risk in Children

The largest clinical trials to date has found that supplementing vitamin D alone does not reduce the risk of fractures in children.

In conventional wisdom, vitamin D is closely linked to calcium absorption, and many calcium supplements on the market also include vitamin D. However, a recent clinical study published in The Lancet Diabetes & Endocrinology challenges our basic understanding.

A multicenter, double-blind, placebo-controlled study conducted in Ulaanbaatar, Mongolia, revealed that long-term vitamin D supplementation in children aged 6-13 did not reduce the risk of fractures.

About one-third of children and adolescents experience at least one fracture before the age of 18, with the highest risk during the growth spurt in puberty.

Enhancing children’s bone strength through supplements is a preventive approach, and vitamin D, known for its role in promoting calcium absorption, has naturally garnered attention.

Vitamin D Alone Doesn't Reduce Fracture Risk in Children

However, the results of randomized trials do not always align with expectations. Some meta-analyses suggest that vitamin D supplementation has a positive impact on hip joint bone density in healthy children. Still, after checking the mineral content and bone density of children’s femoral neck, lumbar spine, and forearm bones one year after supplementation, no significant changes were found.

The study took place in Ulaanbaatar, where children are at higher risk of fractures and vitamin D deficiency is widespread. Among the 8,348 children finally analyzed, 95.5% had baseline serum 25(OH)D concentrations below 50 nmol/L, and 31.9% below 25 nmol/L.

Generally, a serum 25(OH)D concentration of 75-125 nmol/L is considered ideal, below 75 nmol/L indicates insufficiency, and below 50 nmol/L is considered a deficiency.

The median age of these children was 9.2 years, with 49.4% being girls. They were randomly assigned to the vitamin D group or the placebo group, with the vitamin D group receiving 14,000 IU of vitamin D per week, and the median follow-up time in the study was 3 years.

However, long-term vitamin D supplementation does not seem to benefit children. In the vitamin D and placebo groups, 6.4% and 6.1% of participants, respectively, had experienced at least one fracture, with no statistical difference between the two groups. Subgroup analysis showed that gender, baseline 25(OH)D concentration, and calcium intake levels did not affect the results.

In other words, regardless of gender, pre-existing vitamin D deficiency, or daily calcium intake, supplementing vitamin D did not reduce the risk of fractures in children.

Measuring the participants’ bone density revealed that the bone density of children in the vitamin D group was not significantly different from that of the control group.

But can we say that it was all in vain?

In fact, at the end of the trial, the average serum 25(OH)D concentration in the vitamin D group had risen to 72.1 nmol/L, while the placebo group had only 26.1 nmol/L, indicating some effectiveness.

The researchers believe that not simultaneously supplementing calcium may have had some impact, as 62.2% of participants had a daily calcium intake below 500mg/day, the lowest recommended dose for children and adolescents. However, even in subgroups with relatively adequate calcium intake, supplementing vitamin D still did not reduce the risk of fractures.

This is the largest randomized controlled trial of vitamin D supplementation in children to date, and the results may prompt the scientific community to reconsider the impact of vitamin D supplements on bone health.

The corresponding author of the study, Associate Professor Ganmaa Davaasambuu of the Harvard T.H. Chan School of Public Health, said in an interview, “Continuous, high-dose vitamin D supplementation has no impact on the fracture risk and bone strength of vitamin D-deficient children. This is surprising. In adults, simultaneous supplementation of calcium and vitamin D is most effective in preventing fractures, so the failure of this study may be due to the lack of simultaneous calcium supplementation.”