Amino Acids May Improve Nutrition, Muscle Function, and Depression Symptoms in Elderly

June 8, 2011

Results published in the journal Clinical Nutrition.

According to new research published in the journal Clinical Nutrition, supplementing the diets of the elderly with amino acids may improve nutrition and a variety of quality-of-life factors.

Italian researchers assigned 41 nursing home patients to two four-gram mixtures of essential amino acids or placebo daily for eight weeks. Supplementation was provided as snacks at 10 a.m. and 5 p.m. each day.

Before randomization and after 8 weeks of supplementation, the researchers measured nutritional status (Mini Nutritional Assessment and serum albumin and prealbumin levels), muscle strength (hand grip strength), depression symptoms (Geriatric Depression Scale), amino acid profiles, and other quality of life measurements. All measures were similar before randomization.

On average, patients supplementing with essential amino acids experienced improvements in nutritional status after the eight weeks. Patients in the intervention group saw greater increases in serum prealbumin levels and increases in albumin levels (compared to decreased albumin levels in the placebo group).

Muscle strength records improved in both groups, but to a greater extent in the intervention group.

Average Intervention group depression scores improved over the course of the trial, but average placebo group scores worsened.

Improvement of depression is of great clinical significance as depressive symptoms is associated with a number of adverse conditions, including increased cardiovascular risk, silent cerebral infarctions, white-matter hyper intensities, amplified immune response, falls, unintentional weight loss, decreased muscle strength and frailty, poor psychosocial adjustment after a somatic event,” wrote the lead researcher.

The author of the study went on to explain greater implications of adding essential fatty acids (EAA) to the elderly diet:

First, EAA-induced protein synthesis leads to increased muscle mass/function and physical functioning, a factor that positively affects HRQoL. Second, several EAAs are precursors of brain neurotransmitter synthesis, including serotonin, dopamine, norepinephrine, relevant for mood and behavior. Moreover, in clinical practice, increasing protein intake in order to improve body protein synthesis may be challenging for elderly patients since even healthy subjects (from 15% to 41%), may eat less protein than their minimal requirement (0.8 g/kg/day) and even if they take adequate protein supplementation, they might be ingesting proteins less efficiently. Finally, recent studies demonstrated that supplementation of the diet with EAAs improves lean body mass, strength and physical function in elderly subjects and it is potentially an efficient method of increasing protein intake without affecting satiety. So, using EAAs may be an obliged method to boost protein synthesis in elderly patients.

It should be noted that common disease incidence (i.e., stable coronary heart disease, femoral fracture, and hypertension) was similar in each group. Patients with diseases that might affect protein synthesis were excluded from the study.

Professional Dietetics (Milan) produced the essential amino acid mixture for this study. The mixture’s composition is as follows:

Kilocalories 35.3

Kilojoule 149.9

L-Leucine 1250 g

L-Lysine 650 mg

L-Isoleucine 625 mg

L-Valine 625 mg

L-Threonine 350 mg

L-Cysteine 150 mg

L-Histidine 150 mg

L-Phenylalanine 100 mg

L-Methionine 50 mg

L-Tyrosine 30 mg

L-Tryptophan 20 mg