Bridging the gluten-free gap: A critical review of grain amaranth as a functional ingredient in global and east African food systems

This critical review explores the possibilities of incorporating grain amaranth (Amaranthus spp.) as a functional ingredient to bridge gaps in the nutritional status of global gluten-free diets, thus enhancing food and nutritional security in East Africa. A comprehensive literature search was conducted across Web of Science, Scopus, PubMed, ScienceDirect and Google Scholar on peer reviewed papers, government policies and reports covering years 2015-2025, including some seminal earlier publications. The grains have ~16.6% protein content in the dry matter, contain high amounts of lysine (5.3-6.3 g/100g protein), ~7.2% lipids that consist of significant amounts of squalene (2-8% of total oil) and a high concentration of dietary fibre (7.1-16.4%), as well as extremely high amounts of iron (7.6 mg/100g), magnesium (248 mg/100g) and manganese (3.4 mg/100g). Processing methods like germination, extrusion, fermentation and Instant Controlled Pressure Drop decrease phytate levels by ~30%, oxalate levels up to 83% and tannin levels by ~32%, and increase protein digestibility in vitro to greater than 83% compared to 76%. Global market analysis shows that the industry is worth USD 9.3-12.58 billion (2024) and expected to grow to USD 19.26-30.07 billion by 2030-2032 (CAGR 9.4-18.1%). Unique nutritional benefits, climate resistance, processibility and other properties make the grain ideal for use, but its widespread adoption remains hindered by poor value chains in East Africa and competitive positioning of quinoa in Europe. Strategic investments in breeding, decentralized processing, informed communications, and formal inclusion in food policies are necessary for promoting amaranth as a functional ingredient.