Dietary Treatment Strategies and Metabolic Control in Glycogen Storage Disease Type I

Dietary Treatment Strategies and Metabolic Control in Glycogen Storage Disease Type I (GSD-DIET)

The present project will specifically assess metabolic effects of dietary interventions with controlled intake of fructose and fructose/galactose in GSDI, with the aim to provide evidence whether relaxed dietary restrictions of fructose and galactose may be justified in treatment recommendations at least for adults, which would considerably enlarge food choice in everyday life of the patients with an expected positive impact on the quality of life of patients with this rare disorder.

To assess relaxed restriction of fructose and fructose/galactose intake on secondary metabolic alterations in GSDI, (i) by looking at the traditional parameters for assessing metabolic control in clinical chemistry (lactate, triglycerides, uric acid), and (ii) by using a broad analytical approach relying on targeted metabolomics/lipidomics.

It is hypothesized that relaxed restrictions on the intake of fructose and/or galactose as part of the diet in everyday life may lead to an increase in blood lactate levels (=primary outcome), triglycerides, and uric acid to a certain degree compared to baseline. However, this increase is expected to remain within a range that is not clinically relevant for adult patients, especially when fructose/galactose intake is not excessive and stays within the usual daily allowances for healthy individuals, as planned in this study.

Inclusion Criteria:

• Genetically and/or enzymatically confirmed diagnosis of GSDI (GSDIa or GSDIb)
• Male or female ≥ 18y
• Restriction of fructose intake in usual dietary treatment
• Written informed consent

Exclusion Criteria:

• Non-compliance with routine dietary treatment
• Pregnancy or lactation
• Liver transplant
• Recurrent hospitalisations due to metabolic decompensation within the last 12 months
• Severe chronic kidney disease with glomerular filtration rate (GFR) < 30 ml/min
• For GSDIb: Severe, uncontrolled symptomatic inflammatory bowel disease