News · Nutrition & Diet
Shifting nursery menus plant-forward sped up bone turnover in young children
Childcare centers are being asked to serve more plants for climate reasons, with little data on the children. A ten-month randomized trial found bone markers moving, and the researchers are not sure it is benign.
- Markers of both bone building and bone breakdown rose in the intervention group.
- Nutrient intakes did not change, including calcium and vitamin D.
- Faster turnover in growing children could be good, bad or neither.
- The researchers explicitly flag the possibility of harm.
- A ten-month cluster-randomized trial in early childhood education settings.
Institutional catering is one of the few levers that changes what people eat without asking them to decide anything. A nursery menu reaches every child in the building, every day, for years.
That makes childcare centers an obvious target for climate-motivated food policy, and plant-forward menus are being introduced in them across Europe on exactly that reasoning. The environmental case is strong. The evidence about what it does to two-year-olds is thin.
Writing in the European Journal of Nutrition, researchers ran the trial. Centers were randomized rather than children, menus shifted for ten months, and blood markers measured at the end. Previously these menu changes had been evaluated on their climate footprint rather than on the children eating them.
What moved
Three markers rose in the intervention group, and they point in opposite biological directions.
A bone formation marker went up. A bone resorption marker, which reflects bone being broken down, also went up. A third enzyme associated with bone activity rose as well.
So bone was being both built and dismantled faster. The trial reports accelerated bone turnover and stops there, because that is as far as the data go.
What did not move
Just as important, and easier to overlook.
No effects on other biomarkers or any nutrient intakes were observed. The children were not short of calcium, protein or anything else the menu change might have been expected to reduce.
Vitamin D concentrations were adequate in both groups, at levels above the usual sufficiency threshold. That matters because vitamin D is the nutrient most often invoked when plant-heavy diets and bones are discussed, and it was fine.
Why nobody can say whether this is good
Bone in a small child is not the same tissue as bone in an adult. Bone density is a measure of how much mineral bone contains, and in childhood the whole structure is being laid down, lengthened and remodelled continuously.
High turnover in a growing child is normal. It is what growth looks like at the biochemical level. Faster turnover could mean bone is being built more actively, which would be good, or that the balance has tipped toward breakdown, which would not be.
Both markers rose together, which is precisely the pattern that leaves the question open. A shift toward building alone would be reassuring; a shift toward breakdown alone would be alarming; both together is uninterpretable without measuring the bone itself.
The authors’ own caution
The conclusion is unusually direct about its own uncertainty. The clinical relevance of the results requires further investigations to avoid potential harm.
That sentence deserves quoting rather than paraphrasing away, because the temptation with a result like this runs in both directions. Someone hostile to plant-forward catering will read it as evidence of damage. Someone in favor will point out that nutrient intakes were unaffected and dismiss the markers as noise.
Neither reading is supported. The honest position is that something changed in a system that governs how children build their skeletons, and the trial was not designed to say what.
What a proper answer would need
Bone density or bone mineral content, measured by scan, over years rather than months. Turnover markers are a proxy, and the outcome that matters is how much bone a child has when they finish growing, because peak bone mass is the reservoir they draw on for the rest of their life.
Cluster randomization is the right design here, since you cannot serve one child in a room a different lunch. It also means the effective sample is the number of centers rather than the number of children, which usually leaves less statistical power than the headcount suggests.
Ten months is one growing season in a life that will spend two decades building a skeleton.
Where it leaves the policy
Not against it. The climate case for shifting institutional menus is real, nutrient intakes held up, and no child in this trial was shown to be harmed.
Where it lands is on the monitoring. A dietary change being rolled out across a population of small children on environmental grounds should be accompanied by measurement of what it does to them, and this trial is an argument that the measurement needs to include bone.
People also ask
What did the trial find?
The intervention group had higher bone formation marker S-BAP (0.05 log-U/L; 95% CI 0.004-0.104; p = 0.04), higher bone resorption marker S-TRAP5b (2.12 U/L; 0.35-3.90; p = 0.02) and higher S-ALP (0.034 log-U/L; 0.002-0.066; p = 0.04) than controls. No effects on other biomarkers or any nutrient intakes were observed, and vitamin D concentrations were adequate in both groups.
What are bone turnover markers?
Substances in the blood released as bone is built up and broken down. Bone is constantly remodelled, and these track the rate of that process rather than how much bone there is.
Is faster turnover good or bad?
Neither, on its own. In growing children high turnover is normal because bone is being laid down rapidly. What matters is the balance between building and breakdown, and both markers rose here, which is why the interpretation is unresolved.
Why do the authors mention harm?
Because they are being careful. They write that the clinical relevance requires further investigation to avoid potential harm, which is the appropriate stance when a marker moves in children and nobody knows what it means for the bone itself.
Did the children's nutrition suffer?
Not measurably. No effects on any nutrient intakes were observed, and vitamin D was adequate in both groups, which is the reassuring part of the result.
Why are nurseries changing menus?
Mainly for environmental reasons. Plant-forward eating has a much lower climate footprint, and institutional catering is one of the few places policy can change diets directly.
Should parents worry?
No. This measures blood markers over ten months, not bone strength or fractures, and nutrient intakes held up. It is a signal to study, not a finding to act on. This is general information rather than medical advice.