A 10-month cluster-randomized trial to shift towards plant-forward meals in early childhood education and care centres: effects on bone and mineral metabolism in Finnish children

Purpose A shift towards predominantly plant-based diets is emphasized for health and environmental sustainability, but it may affect nutrient adequacy and bone health. We investigated the effects of plant-forward meals in Finnish early childhood education and care (ECEC) centres on bone metabolism and intakes of bone nutrients in 3–5-year-old children. Methods ECEC centres were cluster-randomized for 10 months into 11 intervention (more plant-based products and less red meat served and moderation in milk consumption encouraged; n = 55 children for individual-level study) and 12 control (maintained regular meals; n = 61 children) ECEC centres. In the intervention arm, 18 children and in the control arm 28 children provided complete (baseline and endpoint) blood samples and dietary data (food frequency questionnaire). Circulating biomarkers (e.g. serum tartrate-resistant acid phosphatase 5b [S-TRAP5b], total and bone-specific alkaline phosphatase [S-ALP; S-BAP], 25-hydroxyvitamin D [S-25(OH)D], and plasma parathyroid hormone) and intakes of calcium, vitamin D, phosphorus, and protein were analysed using mixed models. Results The intervention group had higher bone formation marker S-BAP (0.05 log-U/L, 95% CI 0.004–0.104; p = 0.04), bone resorption marker S-TRAP5b (2.12 U/L, 95% CI 0.35–3.90; p = 0.02), and S-ALP (0.034 log-U/L, 95% CI 0.002–0.066; p = 0.04) concentrations than the control group. No effects on other biomarkers or any nutrient intakes were observed. Mean S-25(OH)D concentrations were adequate (≥ 50 nmol/L). Conclusions The clinical relevance of the results indicating accelerated bone turnover without observing any effects on the intakes of critical nutrients requires further investigations to avoid potential harmful consequences for long-term bone health with the shift to plant-forward diets.