Consuming high amounts of proteins from processed and unprocessed red meats links to a higher mortality rate compared to those taking in more of their protein from plant sources, finds one of the largest studies to examine the effects of different sources of dietary protein on mortality. The study was published earlier this month in JAMA Internal Medicine.
For lower cancer risk, AICR recommends a plant-based diet, eating 18 ounces or less of cooked red meat a week and avoiding processed meats. AICR research shows that bacon, hot dogs and other processed meats increase the risk of both colorectal and stomach cancers.
Researchers in this study analyzed data from approximately 131,000 participants of the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), which have collected health data since the 1980s. Participants had filled out questions about their health every two years and information on their dietary intake every four years.
The researchers analyzed more than 30 years of data for NHS participants and 26 years of data for HPFS participants. During those time periods more than 36,000 deaths were documented among participants: approximately 13,000 from cancer, 9,000 from cardiovascular disease and 14,000 from other causes. After adjustment for lifestyle and other dietary risk factors, a high consumption of protein from animal sources -- any types of meat, eggs or dairy -- was weakly associated with an increased rate of death, while high consumption of protein from plant sources -- breads, cereals, pasta, beans, nuts and legumes -- was associated with a lower mortality rate.
On average, participants were getting 14 percent of their daily calories from animal protein and 4 percent from plant protein.
When examining specific sources of protein, the study found that the animal-protein-associated mortality risk applied primarily to processed and unprocessed red meats, which include both beef and pork products, and not to protein from fish or poultry.
The researchers calculated that replacing all types of animal protein for plant protein was associated with lower mortality, with the most significant reduction related to processed meats. Substituting 3 percent of plant protein for an equal amount of processed meats linked to 34 percent lower mortality.
More detailed analysis found that the association of animal protein intake with an increased mortality risk only applied to participants with at least one factor associated with an unhealthy lifestyle -- being either obese or underweight, heavy alcohol consumption, a history of smoking, or physical inactivity. The association disappeared in participants with a healthy lifestyle. 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.
Source: Edward Giovannucci et al. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Internal Medicine, 2016.
This study was funded by grants from the National Institutes of Health
Published on August 24, 2016