The research team, led by Guochun Lv and colleagues at Chengdu University of Traditional Chinese Medicine, searched eight databases from their inception through June 2026 for randomized controlled trials of oral calcium and/or vitamin D supplementation in healthy pediatric populations. After screening 2,465 records and assessing 103 full-text reports against strict eligibility criteria, the investigators pooled data from 16 randomized controlled trials involving approximately 2,100 children and adolescents aged 3 to 17 years. The trials were conducted in China, the United States, Finland, Australia, Switzerland, the United Kingdom, Denmark, and The Gambia, with calcium doses ranging from 300 to 1,200 milligrams per day, vitamin D doses from 60 to 800 international units per day, and intervention durations spanning 6 to 48 months.

To compare trials of different lengths on equal footing, the researchers standardized growth outcomes to monthly rates. The pooled random-effects analysis found no statistically significant effect on monthly height growth, with a mean difference of 0.0441 centimeters per month and a 95 percent confidence interval spanning from -0.0114 to 0.0996, a range that includes zero. Monthly weight gain showed a similarly null result, with a mean difference of 0.0075 kilograms per month and a confidence interval of -0.0064 to 0.0214. Notably, between-study heterogeneity for weight was essentially nonexistent, with an I-squared of 0.0 percent, suggesting the trials were remarkably consistent in showing no effect on body mass.

Bone mineral density told a more nuanced story. The analysis identified small positive differences in areal BMD at three skeletal sites: the lumbar spine showed a mean difference of 0.0145 grams per square centimeter, the femoral neck 0.0101 grams per square centimeter, and total body BMD 0.0110 grams per square centimeter, all with confidence intervals excluding zero. However, heterogeneity was substantial for the lumbar spine and total body outcomes, with I-squared values of 94.1 percent and 86.8 percent respectively, indicating that the trials varied widely in their reported effects. The femoral neck, by contrast, showed modest heterogeneity at 34.3 percent, lending somewhat more confidence to that site-specific finding.

The researchers then deployed a Bayesian network meta-analysis, a technique that simultaneously compares all supplementation strategies, including indirect comparisons between regimens that were never tested head-to-head in the same trial. Using Markov chain Monte Carlo sampling with four chains and 50,000 iterations per chain, the analysis found no consistent superiority of any active regimen across outcomes. For height, vitamin D ranked highest by SUCRA, a probabilistic ranking metric, at 88.76 percent, but its credible interval versus placebo included zero. For lumbar spine BMD, calcium plus vitamin D ranked highest at 93.16 percent, yet only calcium alone produced a credible interval narrowly excluding zero against placebo. For total body BMD, calcium ranked first at 81.57 percent and was the only regimen with a credible interval excluding zero. The divergence between rankings and effect estimates underscores a critical statistical point: SUCRA values summarize posterior rank probabilities and do not represent the magnitude or certainty of individual treatment effects.

Exploratory subgroup analyses by age revealed statistically significant differences for height growth, lumbar spine BMD, and femoral neck BMD, with the youngest children appearing to benefit most. However, the authors caution that several age strata were informed by only one or two studies, and chronological age is an imperfect proxy for biological maturation. Pubertal stage, sex distribution, body size, hormonal status, and baseline nutritional status all vary simultaneously across age groups and cannot be reliably separated using aggregate study-level data. No significant subgroup differences were found by intervention duration for any outcome.

The biological explanation for these findings lies in the distinction between linear growth and bone mineral accrual. Longitudinal growth occurs at the growth plate, where chondrocyte proliferation, hypertrophy, and endochondral ossification are regulated by the growth hormone-IGF-1 axis, thyroid hormones, sex hormones, and mechanical loading. Calcium and vitamin D act primarily through calcium-phosphorus homeostasis and intestinal calcium absorption, supporting mineralization of the bone matrix. In a child with marked nutritional inadequacy, supplementation can remove a constraint on mineral deposition. Once supply is adequate, however, extra calcium or vitamin D cannot substitute for the endocrine and genetic regulation of the growth plate, which is why the near-zero effect on height and the extremely low heterogeneity for weight are biologically plausible.

The clinical implications are direct. For children without inadequate intake, biochemical deficiency, skeletal disease, or another clinical indication, the evidence does not support routine high-dose calcium or vitamin D supplementation solely to accelerate growth. The authors emphasize that meeting nutritional requirements should not be conflated with making a normally developing child grow taller. A targeted approach, guided by dietary calcium intake, vitamin D deficiency risk, sunlight exposure, pubertal stage, and relevant comorbidities, remains the appropriate standard. The observed BMD changes, ranging from approximately 0.010 to 0.015 grams per square centimeter across sites, are small in absolute terms and their clinical significance remains uncertain, particularly given variation in DXA scanner precision and the absence of established clinically meaningful thresholds.

Safety data were sparse but reassuring where available. Only one trial systematically reported adverse events, all consisting of mild gastrointestinal discomfort, with no serious adverse events reported across the included studies. However, most trials did not adequately document safety outcomes or include long-term follow-up, precluding definitive conclusions about long-term tolerability.

The review has notable strengths, including its focus on otherwise healthy children, its separate evaluation of pairwise and network evidence, and its rigorous re-auditing of BMD outcomes against original reports to ensure anatomical comparability. Yet important limitations temper the conclusions. Age- and sex-standardized growth measures and height-adjusted BMD were not consistently available for synthesis, and differences in DXA scanner systems, calibration procedures, and body-size adjustments could not be fully harmonized, likely contributing to the substantial heterogeneity observed. Most studies also failed to report baseline dietary calcium intake and serum 25-hydroxyvitamin D concentrations, meaning that pooling nutritionally deficient and sufficient participants may have diluted true treatment effects. Future trials stratified by baseline nutritional status and pubertal stage, with standardized DXA acquisition and long-term follow-up, are needed to determine whether the modest childhood BMD gains translate into improved peak bone mass, bone strength, or reduced fracture risk later in life.

Subject of Research: Calcium and vitamin D supplementation shows no meaningful effect on growth in healthy children, with only small site-specific BMD increases of uncertain clinical significance.

Article Title: Comparative effects of calcium, vitamin D, and combined supplementation on growth and bone mineral density in healthy children and adolescents: a systematic review and network meta-analysis

Article References: Lv, G., Liu, P., He, J., Qu, F., Zhou, Y., Wang, S., Xiang, H., & Gou, H. (2026). Comparative effects of calcium, vitamin D, and combined supplementation on growth and bone mineral density in healthy children and adolescents: a systematic review and network meta-analysis. Frontiers in Nutrition, 13, Article 1979566. https://doi.org/10.3389/fnut.2026.1979566

Image Credits: AI Generated

DOI: 10.3389/fnut.2026.1979566

Keywords: calcium, vitamin D, children's health, bone mineral density, network meta-analysis, pediatric nutrition, growth, systematic review, Comparative, effects, vitamin, combined