Black and green Japanese japonica rice contain distinctive lipids and digest more slowly than white rice, indicating possible benefits for blood‑sugar management.
Researchers at Hokkaido University examined 56 japonica rice cultivars from Japan, including brown, red, green and black types, using liquid chromatography and mass spectrometry. The analysis identified 196 lipid molecules spanning five major groups.
Pigmented varieties, particularly black and green rice, scored higher on the team’s health‑promotion index because they contained fatty acid esters of hydroxy medium‑chain fatty acids (FAHMFAs) and N‑acyl‑lysophosphatidylethanolamines (LNAPEs). These lipid classes have been associated in some biological systems with anti‑inflammatory activity and improved metabolic health, and FAHMFAs were detected in rice for the first time.
In laboratory simulations of human digestion, cooked black and green rice showed a slower starch‑breakdown rate than typical white rice, suggesting a more gradual post‑meal rise in blood glucose.
The authors propose that these characteristics could support the development of functional rice products aimed at blood‑sugar and metabolic health, but they acknowledge that the health implications have not been tested in humans and further research is required.