High-Protein Diets in Middle Age Might Shorten Life Span
But same study found the reverse was true when people reached old age
The effects of protein consumption on a person's risk of an early death may be partly due to the activation of natural growth hormone and a cellular growth factor called IGF-1, the researchers explained.
"Notably, the activity of these factors, but also body weight, declines naturally with aging, which may explain why older people not only did not benefit but appeared to do worse if they ate a low-protein diet," Longo said.
The researchers believe the studies will boost understanding about links between diet and health.
"We have shown explicitly why it is that calories aren't all the same -- we need to look at where the calories come from and how they interact," Steve Simpson, senior author of the mouse study, said in the journal news release.
"This research has enormous implications for how much food we eat, our body fat, our heart and metabolic health, and ultimately the duration of our lives," said Simpson, a researcher at the University of Sydney in Australia.