A study suggests that middle age people who are on high-protein diet are at greater risk of dying from cancer than those who favour a less protein-rich diet.
But not all researchers agree with the study's findings.
Morgan Levine at the University of Southern California in Los Angeles and her colleagues analysed a dietary survey of more than 6300 people in the US aged over 50.
Those aged 50-65 at the time of the survey and who had a high-protein diet - one where protein supplied a fifth of calories - were 75 percent more likely to have died over the next 18 years than peers who only got 10 percent of their calories from protein.
The high-protein eaters had a cancer death rate four times that of their low-protein peers. Statistical analyses showed that the findings only held for animal protein diets - in other words, protein from meat and dairy rather than beans and pulses.
But Tim Key, a Cancer Research UK epidemiologist based at the University of Oxford, said that the dietary survey is too small to provide any robust conclusions, New Scientist reported.
Different health organisations recommend consuming different amounts of protein.
Study co-author Valter Longo, also at the University of Southern California said that people in middle age should try to eat at the lower end of these recommendations.
