High-protein diets may not be a healthy choice for everyone at every stage of life.
Researchers say middle-aged Americans who ate more animal proteins were four times more likely to die of cancer or diabetes.
Rates were lower for those who ate more plant-based protein.
However a high-protein diet had the opposite effect on Americans 66 and older.
They were 60-percent less likely to die of cancer no matter what kind of protein they ate.