Soy Food Intervention Trial (SOYFIT)

Familial hypercholesterolemia (FH MIM#143890), an inherited disorder of lipoprotein metabolism, is a risk for early cardiovascular disease (CVD). This autosomal dominant disease is characterized by markedly elevated plasma concentrations of low density lipoprotein (LDL) and total cholesterol (TC), typically well above the 95th percentile for age and sex (1). A defective gene for the LDL-receptor is inherited from one parent (2). The disorder was first noted by Müller in 1939, including familial clustering of tendon xanthomas, high serum cholesterol and early MIs (3).

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.

Hypothesis 1: Soya protein-substituted diets change total and LDL-cholesterol, Apolipoprotein B and uric acid serum concentrations.

Primary parameters: Blood analysis

Hypothesis 2: Children and adolescents with FH, in which the cholesterol, LDL-lipoprotein and Apolipoprotein B concentration is not influenced by means of soy protein substituted diet - is it because of a) the effect of non-responder? or b) subjects, who have no regularly dietary soya intake.

Secondary parameters: isoflavones daidzein, glycetein, genistein and equol in the urine samples