The present study aims: a) to strengthen the evidence for the hypocholesterolaemic effect of soy protein in children and adolescents affected with FH b) to monitor the compliance of soy consumption as a possible causal factor linked to the variable lipaemic response observed in the previous study c) to assess certain safety markers of soy food consumption (hormone status, thyroid function, bone metabolism) 4) to monitor the adherence to the soy intervention additionally comprise collections of blood and urine samples.