Protein and all-cause mortality
2 papers in the library, strongest Preliminary.
Graded Preliminary · Controlled diet and gene experiments in fruit flies; results from animals cannot be applied directly to people.
Papers 2
- Less Protein as Larvae Extends Fruit Fly LifespanPreliminary2026NatureWhat a fruit fly eats as a larva still matters when it is an adult. Larvae given little protein grew into flies that lived longer. This held for females and males, even though all of them ate a normal diet as adults. A storage protein called Lsp2 appears to carry this early diet forward. The researchers moved larvae to a low-yeast diet about three days after the eggs were laid. Yeast is the flies' main protein source. Using labelled protein building blocks, the team traced where larval nutrients ended up. They lasted into early adulthood, mostly inside the cell's protein factories. Lsp2 appears to be involved in this. After the low-protein diet, flies had less Lsp2, and their cells made less protein for about a week. When the team turned down the Lsp2 gene, females lived about as much longer. The low-protein diet had a cost. Females weighed up to 28 percent less and laid fewer eggs early on. Turning down Lsp2 did not clearly harm fertility. The authors cannot directly prove that making less protein is what extends life. Whether anything similar happens in people was not studied.
- Less Protein in the Diet: Mice and Flies Live LongerPreliminary2026Cell press blueOlder adults are now told to eat more protein to ward off muscle loss and frailty, and several studies back that advice. A new review lays out the other side from the lab: flies and mice fed less protein lived longer and healthier lives. A few specific protein building blocks seem to matter most, especially the amino acids methionine, isoleucine and valine. One example from the review: male mice whose food held two thirds less isoleucine lived 33 percent longer and were less frail. Cutting the amino acids the body can make itself did not extend life. Human evidence so far comes from short trials. In one four-week trial, blood sugar and insulin control improved when three related amino acids, including isoleucine and valine, were cut by about 60 percent. The review also notes the opposite pull. Adults eating 1.2 grams of protein per kilo of body weight a day lost 40 percent less muscle over three years than those eating 0.8 grams. The authors say the ideal protein intake for people is still unknown. Eating less protein could harm pregnant women, growing children and people recovering from injuries.
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