Higher Plant Protein Intake Associated With Lower Mortality

By Lisa Rappaport

July 15, 2020

(Reuters Health) - Replacing animal protein with plant protein is associated with lower all-cause mortality and cardiovascular disease mortality, a U.S. study suggests.

Researchers analyzed data on 237,036 men and 179,068 women who participated in the U.S. National Institutes of Health-AARP Diet and Health Study from 1995 to 2011. Overall median (SD) ages were 62.2 (5.4) years for men and 62.0 (5.4) years for women.

Among men, each additional 10 grams of plant protein per 1,000 calories of food intake was associated with a lower risk of all-cause mortality (HR (0.88) as well as mortality due to cardiovascular disease (HR 0.88), stroke (HR 0.70), and injuries and accidents (HR 0.76) during a median 15.5-year follow-up period.

Among women, each additional 10 grams of plant protein per 1,000 calories was associated with lower all-cause mortality (HR 0.86) as well as mortality from cancer (HR 0.91), cardiovascular disease (HR 0.83), stroke (HR 0.73) and infection (HR 0.73) over the same period.

In addition, replacing 3% of calories from animal protein with plant protein was associated with 10% lower all-cause mortality in both men and women, as well as reduced cardiovascular disease mortality (11% lower in men and 12% lower in women).

"These small reductions in risk of overall and cardiovascular disease mortality resulting from increased plant protein intake provide evidence for public health recommendations regarding how dietary modifications including choice of protein sources may influence longevity" said lead study author Jiaqi Huang of the National Cancer Institute's Division of Cancer Epidemiology and Genetics.

Overall, median dietary protein intake from all sources was 15.3% of daily calories, with 40% of protein from plant sources and 60% from animal sources. During the follow-up period, a total of 49,297 men and 28,317 women died.

Multivariate analysis adjusted for age at study entry, BMI, alcohol consumption, smoking status, physical activity, race or ethnicity, education, marital status, diabetes, health status, and certain dietary features including vitamin supplement use, total daily calories, and consumption of fats, fruits, and vegetables.

Researchers found that the results held across subgroups of smoking status, diabetes, fruit consumption, vitamin supplement use, and self-reported health status.

They also found that the type of animal protein people replaced with plant protein made a difference.

The biggest reduction in all-cause mortality was found with replacing egg protein with plant protein (HR 0.76 and 0.79 for men and women, respectively); followed by red meat (HRs 0.87 and 0.85), and dairy (HR 0.92 for both men and women).

One limitation of the study, however, is that the analysis was based on a single diet assessment at baseline, and it's possible that participants made dietary changes over time, the study team notes in JAMA Internal Medicine.

Another limitation is that the vast majority of participants were non-Hispanic white, reducing the generalizability to other racial and ethnic groups.

"The dietary data are also self-reported, and thus measurement errors are inevitable, although such noises in the data tend to obscure the true relationship," said Dr. Frank Hu, chair of the department of nutrition at the Harvard T.H. Chan School of Public Health in Boston. Plant protein might also be a marker of other healthy diet and lifestyle habits, Dr. Hu, who wasn't involved in the study, said by email.

Even so, the study provides further support for current dietary guidelines that recommend increased intake of plant-based foods such as nuts, legumes, and whole grains and reduced intake of animal products especially red and processed meats, Dr. Hu said.

"Swapping some animal foods especially red meat for healthy plant-based protein foods such as nuts, legumes, and whole grains can help to prevent chronic diseases and improve longevity," Dr. Hu said. "However, not everyone should be a vegetarian, and for individuals who consume a meat-centric diet, even a partial shift from meat to plant protein foods can confer some health benefits."

SOURCE: https://bit.ly/2OovfEv JAMA Internal Medicine, online July 13, 2020.