The findings in the Journal of the American Medical Association (JAMA) Internal Medicine confirm what many health experts have said for decades, but also contained some surprises.
For instance, diets high in red meat and fatty proteins like eggs and cheese were not linked to a higher risk of dying among people who were otherwise healthy.
However, people with one other risk factor -- such as drinking lots of alcohol, being overweight, inactive or smoking -- were more likely to see their death risk rise if they ate more red meat.
"Our findings suggest that people should consider eating more plant proteins than animal proteins, and when they do choose among sources of animal protein, fish and chicken are probably better choices," said co-author Mingyang Song, a research fellow at Massachusetts General Hospital.
"While previous studies have primarily focused on the overall amount of protein intake -- which is important -- from a broad dietary perspective, the particular foods that people consume to get protein are equally important."
The lowest mortality rate was seen among people who got their protein mainly from breads, cereals, pasta, beans, nuts and legumes.
Song said researchers were surprised to see there was no apparently higher risk of dying among otherwise healthy red meat eaters.
"While we expected we might find the associations to be weaker in the healthy lifestyle group, we did not expect them to completely disappear," he said.
"But when we looked deeper into the data, we found that -- at similar levels of animal protein intake -- those in the unhealthy lifestyle group consumed more red meats, eggs and high-fat dairy, while the healthy lifestyle group consumed more fish and poultry.