Adequate Protein Intake in Midlife Tied to Healthy Aging

Healthy aging was defined as freedom from 11 major chronic diseases, good mental health, and no impairments in cognitive or physical function, as assessed in the 2014 or 2016 NHS participant questionnaires. Diseases/treatments included cancer, type 2 diabetes, myocardial infarction, coronary artery bypass graft or coronary angioplasty, congestive heart failure, stroke, kidney failure, chronic obstructive pulmonary disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis.

Mean total protein consumption as a percentage of energy was 18.3% (standard deviation, 3%), slightly higher than the average 16.0% in the US diet. Of this, 13.3% was derived from animals, 3.6% from dairy products, and 4.9% from plants.

Total protein intake was positively associated with higher education levels, being physically active, higher BMI, and a baseline history of hypertension and hypercholesterolemia. Conversely, total protein intake was inversely associated with intakes of total carbohydrates, nuts, alcohol, and sugar-sweetened beverages.

The associations between protein intake and healthy aging are complex and not fully understood, the authors stated.

Effects of Protein Intake

In studies of older adult populations, lower protein intake has been associated with lean mass loss. Animal protein supplementation studies in older adults have shown lean mass gains potentially related to amino acid composition.

In terms of mechanisms, evidence suggests that protein-related activation of the rapamycin complex 1 pathway may play a role, the authors suggested. The activity of this signaling pathway decreases with age.

Rapamycin, a compound used to prevent organ transplant rejection, has been associated with delayed aging. In the body, dietary protein and exercise activate this pathway, thereby stimulating muscle protein synthesis and possibly improving physical function.

As for the differential associations of plant and animal protein on the chronic disease domain of the healthy aging phenotype, Dr Ardisson Korat and coauthors said plant protein has been associated with favorable levels of important risk factors for cardiometabolic diseases, such as reduced LDL cholesterol, lower blood pressure, and insulin sensitivity, as well as decreased levels of proinflammatory markers.

Conversely, total and animal protein intakes have been positively associated with concentrations of insulin-like growth factor 1, which is implicated in the growth of malignant cells in breast and prostate tissue.

This study is the first step in evaluating the long-term health effect of protein intake in midlife, the relevant development window for most chronic conditions, the NHS study authors said. More research is needed, however, to corroborate the study findings in other populations and identify underlying mechanisms.

This study was supported by the USDA Agricultural Research Service and the National Institutes of Health. The authors reported no conflicts of interest. The commentators disclosed no relevant competing interests.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.