Frontiers in Nutrition · Nov 9, 2026
Underutilized Grains and Pseudocereals in Human Nutrition and Health: Grain-Specific Evaluation of Processing, Food Matrix, Biological Mechanisms, and Human Evidence
By Tiantian Jing, Zhong Tang, Honglei Zhang et al.
Underutilized grains and pseudocereals may contribute to dietary diversity, food and nutrition security, and metabolic health, although the evidence varies by species, processing method, and study design. This narrative critical review evaluates millets and sorghum as core underutilized cereal grains, oats and barley as whole-grain comparators, and buckwheat, quinoa, and amaranth as representative pseudocereals. It applies a framework linking grain identity and processing to food matrix properties, bioaccessibility, absorption and metabolism, biological mechanisms, and human outcomes. The strength and directness of human evidence are assessed qualitatively. Milling, dehulling, thermal processing, germination, and fermentation alter cell-wall integrity, starch structure, fiber functionality, and phytochemical release. These changes alone do not demonstrate improved bioavailability or clinical benefit. Proposed mechanisms involve digesta viscosity, bile acid turnover, microbial metabolites, and signaling pathways involving Nrf2 and NF-κB. Many of these proposed mechanisms remain supported primarily by preclinical evidence. Randomized evidence is most consistent for LDL-cholesterol lowering with oat and barley β-glucan. Acute glycemic effects do not demonstrate sustained glycemic improvement, and associations with total whole-grain intake cannot be attributed to individual underutilized grains. Millet interventions suggest glycemic benefits, but heterogeneity in study design and food form limits causal inference. Sorghum and quinoa trials remain small, while a systematic review of buckwheat studies does not demonstrate consistent cardiometabolic benefits. Food safety and sustainability require assessment for each grain and context. Health effects depend on cultivar, processing, food matrix properties, dose, and host characteristics. Future research should compare defined grain species and processing forms in adequately powered human trials, connect processing-induced matrix changes to nutrient absorption and microbial metabolism, and identify reproducible, population-specific responses.