Rice remains a staple for over half the global population, yet its nutritional profile is not fully understood. While starch constitutes more than 85% of rice, it also contains about 10% protein, a small amount of fats, and trace vitamins and minerals. Despite their minimal presence, lipids in rice significantly impact nutrition, flavour, and grain quality but have been largely overlooked.
Researchers at Hokkaido University addressed this by examining 56 japonica rice cultivars from Japan, including brown, red, green, and black varieties. These rice types, known for their soft and sticky texture when cooked, represent approximately 15% of global rice consumption. The study, published in Food Research International in January 2026, leverages advances in analytical technologies like liquid chromatography and mass spectrometry to identify 196 lipid molecules across five major groups.
The study reveals that black and green japonica rice varieties exhibit a higher health-promotion index due to unique lipid compositions. These varieties contain fats such as FAHMFAs (fatty acid esters of hydroxy medium-chain fatty acids) and LNAPEs (N-acyl-lysophosphatidylethanolamines), which have been associated with anti-inflammatory effects and improved metabolic health. This marks the first identification of FAHMFAs in rice.
In laboratory simulations of human digestion, black and green rice demonstrated a slower starch breakdown than white rice, implying a more gradual release of glucose into the bloodstream. This suggests potential applications for these pigmented rice varieties in developing food products that support cardiovascular health, assist in blood sugar management, and mitigate risks of conditions like type 2 diabetes.
The research contributes to a broader initiative to explore bioactive lipids in underutilised Japanese food resources. Associate Professor Siddabasave Gowda notes their ongoing efforts have identified novel lipids in Japanese fish, herbal teas, and seaweeds. He anticipates these findings will inform consumer decisions and foster the development of ‘functional’ rice products aimed at managing diabetes and other lifestyle-related diseases.
