Use of ancient grains for the management of diabetes mellitus: A systematic review and meta-analysis

Aims: A systematic review and meta-analysis of published randomized controlled trials was conducted to collate evidence from studies implementing ancient grains and investigate the impact of ancient grain consumption on health outcomes of patients with Diabetes Mellitus (DM). Data synthesis: Twenty-nine randomized controlled trials were included, and 13 were meta-analyzed. Interventions ranged from 1 day to 24 weeks; most samples were affected by DM type 2 (n = 28 studies) and the ancient grains used were oats (n = 10 studies), brown rice (n = 6 studies), buckwheat (n = 4 studies), chia (n = 3 studies), Job's Tears (n = 2 studies), and barley, Khorasan and millet (n = 1 study). Thirteen studies that used oats, brown rice, and chia provided data for a quantitative synthesis. Four studies using oats showed a small to moderate beneficial effect on health outcomes including LDL-c (n = 717, MD: 0.30 mmol/l, 95% CI: 0.42 to -0.17, Z = 4.61, p < 0.05, I2 = 0%), and TC (n = 717, MD: 0.44 mmol/l, 95% CI: 0.63 to -0.24, Z = 4.40, p < 0.05, I2 = 0%). Pooled analyses of studies using chia and millet did not show significant effects on selected outcomes. Conclusions: For adults affected by DM type 2, the use of oats may improve lipidic profile. Further experimental designs are needed in interventional research to better understand the effects of ancient grains on diabetes health outcomes. Prospero registration: CRD42023422386.