A new study suggests that high animal protein intake is associated with a greater risk of mortality in individuals with at least one unhealthy risk factor.
A recently published JAMA Internal Medicine study examined how animal and plant protein sources influence longevity. The study analyzed records of two long-running national cohort studies, the Nurses’ Health Study and the Health Professionals Follow-up Study. More than 131 000 adults provided information on diet, lifestyle and medication for a period up to 32 years. Participants submitted detailed food frequency questionnaires every four years.
The questionnaires tabulated weekly servings of fruits and vegetables, legumes, nuts, beans and whole grains. Animal protein categories included unprocessed and processed red meat, chicken, fish, eggs and dairy.
Smoking, heavy alcohol intake, overweight or obesity and physical inactivity were classified as lifestyle risk factors.
Cox proportional hazards models were used to estimate the hazard ratio for cardiovascular and all-cause mortality associated with plant and animal protein intake.
The results of the study indicate that higher animal protein intake was associated with higher cardiovascular mortality while higher plant protein intake was associated with lower risk of both cardiovascular and all-cause mortality. However, the results were confined to individuals with at least one unhealthy lifestyle factor.
Among animal high-protein eaters, participants with at least one lifestyle risk factor tended to consume more processed and unprocessed red meat. The healthy group, those without lifestyle risk factors, ate more chicken and fish. This suggests that the source of animal protein may affect the mortality risks observed.
The consumption of processed red meat was strongly associated with a higher risk of mortality. The most noticeable improvement came by replacing processed red meat with plant-based protein, suggesting that components in processed red meat such as sodium, nitrates, and nitrites may be harmful.
In conclusion, the associations between higher intake of animal protein and increased cardiovascular mortality, and higher intake of plant protein and lower overall mortality were confined to participants with at least one unhealthy lifestyle factor.
The authors suggest that the source of protein is important and that replacing plant protein for animal protein, especially processed red meat, favors long-term health.
Written By: Lynn Kim