Eating more plant protein and less red meat may lower a woman's risk of dying from dementia, heart disease and other causes, new research shows.

The study, published Wednesday in the Journal of the American Heart Association, found postmenopausal women who got more of their protein from plants such as tofu, nuts, beans and peas, were less likely to develop heart disease or die prematurely from any cause, compared to women who ate less of these foods. And more specifically, substituting nuts for red meat, eggs or dairy also helped them live longer.

The findings mean future federal guidelines about diet should consider the kinds of proteins that are most healthy, lead study author Dr. Wei Bao, an assistant professor of epidemiology at the University of Iowa in Iowa City, said in a news release. "Current dietary guidelines mainly focus on the total amount of protein, and our findings show that there may be different health influences associated with different types of protein foods."

Researchers analyzed the diets of more than 100,000 women from the national Women's Health Initiative study who were ages 50 to 79. The women were followed for up to 25 years to see how what they ate affected their long-term health.

Compared to women who ate the least amount of plant protein, those who ate the most overall had a 21% lower risk of dying from dementia, a 12% lower risk of dying from heart disease and a 9% lower risk of death from all causes.

While eating more chicken compared to less lowered the risk of dying from dementia by 15%, those who ate the most processed red meat had a 20% higher risk of dying from dementia compared to those who ate the least. Eating unprocessed red meat and dairy also raised the risk of dying from cardiovascular disease: Those who ate the most meat were 12% more likely to die and those who ate the most dairy were 11% more likely.

Eating a lot of eggs netted mixed results in long-term health.

Women who ate the most eggs were 24% more likely to die from cardiovascular disease and 10% more likely to die from cancer. However, they were 14% less likely to die from dementia.

Researchers noted that proteins are not eaten in isolation, so the findings should be taken into consideration with other factors, such as what other foods they are served with and how they are prepared.

"It is unclear in our study why eggs were associated with a higher risk of cardiovascular and cancer death," Bao said. "It might be related to the way people cook and eat eggs. Eggs can be boiled, scrambled, poached, baked, basted, fried, shirred, coddled or pickled or in combinations with other foods.

"In the United States, people usually eat eggs in the form of fried eggs and often with other foods such as bacon," he said. "Although we have carefully accounted for many potential confounding factors in the analysis, it is still difficult to completely tease out whether eggs, other foods usually consumed with eggs, or even non-dietary factors related to egg consumption may lead to the increased risk of cardiovascular and cancer death."

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