Plant mitochondria from food reach the ageing brain
We eat plants, and the energy-producing structures inside those plants may reach our brain. That sounds unlikely, but a new study shows that mitochondria from turmeric travel to the brains of mice and improve the function of brain immune cells.
Mitochondria are the structures inside cells that produce energy. Every cell has them, including plant cells. Researchers isolated mitochondria from commonly consumed edible plants, including turmeric. They administered these plant-derived mitochondria (T-Mit) orally to aged male mice and tracked where they ended up. A portion of the mitochondria travelled from the gut to the brain.
Once in the brain, the plant mitochondria were taken up by microglia, the brain’s immune cells. The study reports that the plant mitochondria then fused with the microglia’s own mitochondria. That fusion process depended on a specific protein called mitofusin 1. After fusion, the energy metabolism of the microglia changed: less harmful oxygen species were produced and the cells functioned better. In treated mice, markers of age-related cognitive decline appeared to improve.
A small RNA does the heavy lifting
The mechanism worked partly through small RNA molecules (microRNAs) carried by the plant mitochondria. These microRNAs suppressed the activity of specific components of the mitochondrial energy chain (complex I). That sounds counterintuitive, but inhibiting complex I in this way reduced a process in which oxygen flows backwards and harmful radicals form. The net effect was cleaner, more efficient energy production in the brain cells of the mice.
This is a striking finding about a mechanism that had barely been described before. Important caveats apply, however. This is mouse research. Whether plant mitochondria from food also reach the human brain and produce comparable effects has not been demonstrated. The authors themselves note that the magnitude of the dietary effect is likely too small for therapeutic applications.
A new idea for therapy?
More interesting is the suggestion that isolated plant mitochondria could be explored as an oral therapy or via direct administration (mitochondrial transfusion). That remains speculative, but the concept of delivering healthy mitochondria externally is attracting growing scientific attention. The key question is whether the effect size is large enough to provide meaningful benefit.
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