Citrulline Helps Old Worms Store Fat and Live Longer
Graded Preliminary — controlled lab experiments in worms using gene changes and food additives; results from worms cannot be applied directly to people.
Animal study. Findings may not carry over to people, which is why the grade is capped at Preliminary.
- Design
- Animal study
- Participants
- N/A
- Duration
- —
- Funding
- National Natural Science Foundation of China
In worms, citrulline drives fat storage in old age, and extra citrulline in their food made them live longer.
Gaining fat with age usually sounds like bad news. In the tiny worm Caenorhabditis elegans, though, a moderate fat store in old age seems to help. The driver is citrulline, a natural product of metabolism. Worms raised on plates with extra citrulline lived longer: half of them had died after 17 days instead of 14.5.
The researchers compared young and old worms. Old worms had bigger fat droplets and more stored fat. When worms lacked citrulline, because a gene needed to make it was dialled down or altered, they built up less fat with age and died sooner. Adding citrulline to their food undid this. Worms missing two fat-building enzymes were different: for them, citrulline restored neither the fat nor the lifespan.
The experiments point to a chain of events. With age, a control protein called MXL-3 ramps up citrulline production, and citrulline then switches on fat building. The authors say exactly how this happens still needs work. All experiments were done in worms, and whether citrulline does anything similar in people was not tested.
Conflict of Interest Disclosure: The authors declare no competing interests.
Disclaimer: Research summaries are provided for informational purposes only and do not constitute medical advice. Always consult a qualified healthcare professional before making changes to your health routine.