Do saponins stunt bone growth ?

Not known: Never heard. It has lipid lowering property. More research to come.

Not clear.: Saponins are aminoglycosides found in certain plants like Quinoa. They can be phytoestrogens. Some phytoestrogens have been investigated 2 prevent bone loss (i.e., osteoporosis). Saponins are used in livestock feed 2 control urea-splitting bacteria in the GI tract, increasing longevity. Some indigenous people use it 2 catch fish. I found nothing about human toxicity in PubMed, but jury's still out

Possibly!: Saponins are soapy like substances that are now being studied. Studies in Europe are looking at the role in red cell lysis, destruction of red blood cells, for possible treatments in leukemia, lymphoma and other cancers. Others believe that it may cause a leaky gut syndrome which may contribute to heart disease and diabetes. Leaky gut may contribute to decreased bone growth. We need more studies.