A Protein-rich Diet Helps Older Adults Preserve Muscle Mass and Strength

BOSTON — New research reveals that a protein-rich diet, which includes both animal and plant sources, preserves lean muscle mass and strength in the legs of older adults. The study published in the Journal of Nutrition suggests that the type of dietary protein has different effects, with plant protein displaying a preservation of muscle strength.

As adults age a decline in muscle mass and strength increases the risk of falls and fractures which may lead to disability and loss of independence. In fact, the Centers for Disease Control and Prevention (CDC) estimates that one in three adults 65 years of age and older fall each year, with up to 30% of those falls resulting in injuries such injuries as lacerations, hip fractures, or head trauma. Previous research reports that after age 50 adults may lose 1% to 2% of muscle mass each year, and experience a decline in muscle strength of 1.5% annually up to age 60 and 3% per year after.

“Muscle mass and strength has been examined in older adults, but little is known about how modifiable risk factors in middle age can contribute to a decline in muscle health,” explains lead author Shivani Sahni, Ph.D. from Harvard Medical School–affiliated Hebrew SeniorLife Institute for Aging Research (IFAR) in Boston, Mass.

Douglas P. Kiel, M.D., M.P.H., Professor of Medicine at Harvard Medical School and Director Musculoskeletal Research Center at IFAR and coauthor of the study adds, “Diet is easy to modify and understanding the impact of protein consumption on leg muscle mass and strength in adults may help us uncover interventions that improve quality of life in older age.”
Researchers used data from the Framingham Offspring Cohort—a study initiated in 1971 to investigate familial risk factors for cardiovascular disease—for the present cross-sectional study. Participants were between 29 and 86 years of age, and included 2,656 men and women in quadriceps strength analyses and 2,636 men and women in analyses of leg lean mass. Protein intake, leg lean mass and quadriceps strength were measured at various times between 1998 and 2001.

Findings indicate that protein intake was 80 grams per day for male and 76 grams per day for women. Leg lean mass was higher in participants at the highest levels of total protein and animal protein consumption. Plant protein intake was not associated with lean mass in men or women.

Further analyses determined that quadriceps strength was higher in subjects who consumed more plant protein compared to those with less intake. However, after adjusting for fruit and vegetable intake the association was no longer significant. The authors believe plant protein may help preserve muscle strength in older adults due to the alkaline properties in the plants, or as a marker of the dietary quality of those eating more plant protein.

“Eating a diet rich in protein may help preserve leg muscle mass and strength as we age, which could mitigate risk of falls,” concludes Dr. Marian T. Hannan, Associate Professor of Medicine at Harvard Medical School, Co-Director, Musculoskeletal Research Center and co-author of the study. “Further investigation of the impact of plant protein on muscle strength is needed.”

This study was funded in part by grants from the National Institutes of Health (NIH R01 AR53205, R01 AR/AG 41398), NHLBI’s Framingham study (#N01-HC-25195), institutional grants from the General Mills Bell Institute of Health and Nutrition, NIH's National Institute of Aging (T32-AG023480), and the Melvin First Young Investigator Award and Friends of Hebrew SeniorLife.

About the Institute for Aging Research
Scientists at the Institute for Aging Research seek to transform the human experience of aging by conducting research that will ensure a life of health, dignity and productivity into advanced age. The Institute carries out rigorous studies that discover the mechanisms of age-related disease and disability; lead to the prevention, treatment and cure of disease; advance the standard of care for older people; and inform public decision-making. The Geriomics Program within IFAR studies the genetic architecture underlying diseases of aging. Visit http://www.instituteforagingresearch.org.

About Hebrew SeniorLife
Hebrew SeniorLife, an affiliate of Harvard Medical School, is a national senior services leader uniquely dedicated to rethinking, researching and redefining the possibilities of aging. Based in Boston, the non-profit, non-sectarian organization has provided communities and health care for seniors, research into aging, and education for geriatric care providers since 1903. For more information about Hebrew SeniorLife, visit https://www.hebrewseniorlife.org, follow us on Twitter @H_SeniorLife, like us on Facebook, or read our blog.