A new study from the University of Southern California shows that a diet rich in plants and fish, low in protein, and with a small amount of the amino acid methionine can help mice stay healthier as they get older. The mice on this diet had less body fat, lived longer in good health, and were less frail.
What the researchers did
Scientists gave four groups of 20‑month‑old mice different foods:
- Regular lab chow
- A Western‑style diet high in fats and sugars
- A low‑carb ketogenic diet
- A low‑protein, methionine‑supplemented “longevity” diet (called LDMM)
The mice that ate the LDMM performed the best. They stayed healthier longer, kept less fat, and showed fewer signs of weakness.
Why the diet works
Even though these mice ate more food overall, they did not gain extra fat. Their bodies showed higher levels of hormones like GLP‑1 that help control metabolism and aging. The key appears to be keeping methionine low enough to avoid frailty but high enough to support muscle.
Do humans see the same pattern?
Researchers looked at health data from over 200,000 people in the United States, Canada and other countries. People who ate a lot of animal protein – and therefore more methionine – were more likely to be obese and twice as likely to have Type 2 diabetes compared with those who ate little or no animal protein. This was true even though the high‑protein group often ate fewer calories.
What comes next?
The team plans to test the LDMM diet in a controlled human trial to see if the same benefits appear in people.
Study background
The research was a joint effort by scientists from USC, the University of Toronto, Harvard University, and other institutions. Funding came from the National Institute on Aging, the National Institutes of Health, and the USC Edna Jones Chair Fund.