How Eating Protein May Affect Length of Life

Eating less dietary protein extended life and health of middle aged people

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Eating a balanced diet is among the tools for living a long healthy life. Deciding how much red meat, dairy and other animal-based foods to eat can be key to that effort.

Consuming too many animal-based foods led to increased rates of cancer, diabetes and early death among middle-aged adults but not among older adults, according to new research.

"Ask your doctor how to combine healthy foods."

Valter Longo, PhD, director of the University of Southern California Longevity Institute in Los Angeles, was this study’s lead author.

His investigation analyzed health information on 6,831 men and women aged 50 and older who were enrolled in the third National Health and Nutrition Examination Survey (NHANES III). The US Centers for Disease Control and Prevention (CDC) conducted NHANES III, adding that its participants represent the nation’s racial make-up, age groups, levels of education and other identifying markers.

Those aged 50 to 65 numbered 3,039 among this study’s 6,831 participants. Those 66 years and older made up 3,342 of the study's participants. NHANES III participants were enrolled from 1988 through 1994. These researchers tracked their health for 18 years following their enrollment.

Study participants consumed a daily average of 1,823 calories, with carbohydrates accounting for 51 percent of all calories. Of the remaining calories, on average, 33 percent were from fats and 16 percent were from protein. Of the protein calories, on average, 11 percent came from meat, dairy and other food derived from animals.

When it comes to balancing calories, Dr. Longo told dailyRx News, moderate protein consumption means having a daily diet made up of 10 percent to 20 percent protein. High consumption means that 20 percent or more of the diet is made up of proteins. Low consumption means 10 percent or less is comprised of protein.

Individuals between 50 and 65 years old who ate more than 20 percent of their daily calories in the form of animal protein (high-protein diet) were more than four times as likely to die of cancer or diabetes as persons of the same age who consumed less protein, these researchers found. These high-protein eaters were twice as likely to die from any other cause than those whose diets consisted of less protein.

People who ate a moderate amount of protein were three times more likely to die of cancer than those who consumed less protein.

Those who got most of their protein from plant-based foods reduced or eliminated their cancer risks.

However, the disease risks fell among persons older than 65 who ate high-protein diets. Among those older persons, consuming lots of protein cut their risk of dying from any cause by 28 percent, compared to others their age who ate low-protein diets. Also, high-protein eaters in the older-than-65 group cut their risks of dying from cancer by 60 percent.

“Both high and moderate protein intake in the elderly were associated with reduced [deaths], compared to the low protein group,” the researchers wrote.

The research team wrote that a diet in which 10 percent of the calories are from protein may be the healthiest option for people aged 65 and older. "We also propose that, at older ages, it may be important to avoid low protein intake and gradually adopt a moderate to high protein [diet], preferably mostly plant-based consumption to allow the maintenance of a healthy weight and protection from frailty."

Dr. Longo explained that body weight declines naturally with age, "which may explain why older people not only did not benefit but appeared to do worse if they ate a low-protein diet," he said.

This study was published online March 4 in Cell Metabolism.

The National Institutes of Health's National Institute on Aging and the USC Norris Cancer Center funded this study.

Study authors said they had no financial investments or other involvements that would shape study design, outcomes or analysis.

Review Date: 
March 4, 2014
Last Updated:
March 25, 2015