Cutting out fructose for just 9 days — even swapping it for starchy foods — may cut a harmful byproduct in the blood by half in kids with obesity and metabolic syndrome, pointing to fructose as a unique culprit.

What we've found so far suggests that cutting fructose from the diet for 9 days may reduce levels of a harmful byproduct in the blood—specifically d-lactate—in children with obesity and metabolic syndrome, even when the fructose is replaced with starch [1]. The evidence we’ve reviewed leans toward this effect being linked specifically to fructose removal, rather than overall calorie reduction or carbohydrate substitution. Our analysis of the available research shows that in short-term dietary interventions, replacing fructose with starch led to about a 50% drop in d-lactate levels over just nine days [1]. D-lactate is a metabolic byproduct that, when elevated, can contribute to acid buildup in the blood and may be linked to metabolic dysfunction. The fact that this change occurred quickly—and without reducing total calories or carbohydrates—suggests that fructose may play a unique role in driving this metabolic pathway in certain children. We only analyzed one key assertion so far, drawn from 53.0 supporting data points, with no studies or claims that refute it [1]. While the number of supporting data points is high, we are still looking at a limited pool of assertions. That means our current analysis is based on a narrow but consistent set of findings. We don’t yet know if these changes last beyond nine days, or whether reducing d-lactate in this way leads to long-term health improvements. Also, we haven’t reviewed evidence on how this might affect other aspects of metabolism, energy levels, or liver function in these children. Practical takeaway: For children with obesity and metabolic syndrome, cutting out sources of fructose—like sugary drinks and processed foods—might lead to fast, measurable changes in certain metabolic markers, even if those calories are replaced with starchy foods like bread or pasta. This doesn’t mean starch is healthier overall, but it may be less impactful than fructose on this specific marker in the short term.