Effects of Allium fistulosum L. (Green Onion) Root and Avena sativa L. (Oat) Mixtures (WCO31) on the Height of Children: A Multi-Center, Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Background/Objectives: Following prior in vitro and in vivo investigations on the bone health benefits of green onions and oats, we aimed to assess the effects of WCO31, Allium fistulosum L. (green onion) root and Avena sativa L. (oat) mixtures, on height growth and safety. Methods: This multi-center, randomized, double-blind, placebo-controlled study included 150 children aged 6–8 years (75 males and 75 females) who fell between the 3rd and 50th percentiles of the Korean National Growth Charts but had not yet developed secondary sexual characteristics. They were randomly assigned to receive daily oral administration of WCO31 (1.2 g/day) or a placebo for 24 weeks. For efficacy analysis, height, growth rate, growth rate standard deviation score (SDS), height SDS, and growth-related parameters were measured. To evaluate the safety of the intervention, several safety parameters (including the incidence of adverse events, laboratory tests, and vital signs) were monitored. Results: The WCO31 group demonstrated significantly superior outcomes, including height, growth rate, growth rate SDS, height SDS, and height-for-age Z-score, than the placebo group (all p < 0.001). Moreover, no safety-related concerns were identified. Conclusions: WCO31 positively influences height growth and demonstrates a favorable safety profile, with no observable adverse effects. This study provides the first clinical evidence supporting growth enhancement using natural extracts, suggesting that WCO31 could serve as a cost-effective, safe, and accessible complementary strategy for promoting child growth.