Life Cycle Sustainability Assessment of Gluten-Free Food Systems: Evidence Gaps & Integration of Nutritional Functional Units

Gluten-free foods are critical for managing coeliac disease; however, the evidence on the sustainability of GF product systems is fragmented and methodologically inconsistent. This protocol-driven systematic literature review (SLR) examines (i) the application of Life Cycle Sustainability Assessment (LCSA) to gluten-free (GF) food systems, (ii) the use of nutritional Life Cycle Assessment (nLCA) or nutrition-linked functional unit approaches, (iii) the reported environmental, nutritional, economic and social trade-offs, and (iv) the methodological challenges that limit synthesis. A structured search of major bibliographic databases for English-language studies published between 2009 and March 2025 yielded 14,723 records, of which 553 were assessed for eligibility. Only six studies met the inclusion criteria, highlighting a significant evidence gap and limited methodological convergence in GF LCSA.

The reviewed studies include gluten-free bakery products and cereal or legume-based products, with most employing cradle-to-gate or cradle-to-grave environmental life cycle assessment (LCA). Although this review is framed by LCSA, the evidence is largely environmental. Economic (Life Cycle Costing, LCC) and social (Social Life Cycle Assessment, S-LCA) aspects are minimally addressed or discussed narratively, limiting systematic analysis across sustainability pillars. Nutritional integration is inconsistent, as most studies rely on mass-based functional units rather than nutrient-linked methodologies.

Scenario and sensitivity analyses indicate that ingredient reformulation, local sourcing, or changes in waste management can improve climate outcomes. However, such interventions may shift environmental burdens to freshwater eutrophication, climate change, or ozone depletion, and multi-dimensional trade-offs are rarely quantified. Cross-study comparability is limited by heterogeneous system boundaries, incomplete specification of the background database, and limited reporting of uncertainty. Current sustainability claims for GF food systems rely on a small and heterogeneous evidence base. Advancing credible LCSA requires harmonised nutrition-relevant functional-unit reporting, transparent inventory and LCIA disclosure, and systematic integration of environmental, economic, and social indicators to support decision-making for healthier and more sustainable GF food systems.