Daily Consumption of a Specially Formulated Essential Amino Acid-Based Dietary Supplement Improves Physical Performance in Older Adults With Low Physical Functioning

Abstract

We have investigated the hypothesis that nutritional supplementation of the diet in low-physical-functioning (LPF) older individuals with a specially formulated composition based on essential amino acids (EAAs) would improve physical function as compared to supplementation with the same amount of whey protein. A third group of comparable volunteers were given nutrition education but no supplementation of the diet.After 6 weeks of whey protein supplementation (n=32) there was no effect on the distance walked in 6 minutes, but the distance walked improved significantly from the pre-value after 12 weeks of whey supplementation. EAA consumption (n=28) significantly improved walking distance at both 6 and 12 weeks. The distance walked at 12 weeks (419.0 +/- 25.0 m) was 35.4 m greater than the pre-value of 384.0 +/- 23.0 m (p< 0.001). The increase in distance walked by the EAA group was also significantly greater than in the whey group at both 6 and 12 weeks (p< 0.01). In contrast, a decrease in distance walked was observed in the control group (n=32) (not statistically significant, NS). EAA supplementation also improved grip strength and leg strength, and decreased body weight and fat mass. Plasma LDL concentration was significantly reduced in the EAA group, as well as the concentration of macrophage migration inhibitory factor. There were no adverse responses in any groups, and compliance was greater than 95% in all individuals consuming supplements.We conclude that dietary supplementation with an EAA-based composition may be a beneficial therapy in elderly individuals with low physical functional capacity.

Prevention of Loss of Muscle Mass and Function in Older Adults during COVID-19 Lockdown: Potential Role of Dietary Essential Amino Acids

“…Therefore, the optimal formulation of an EAA composition to stimulate MPS will have disproportionately greater amounts of leucine and lysine as compared to their respective contributions to the composition of muscle protein. In line with this notion, it was shown that a specially formulated composition of all the EAAs containing approximately 35% leucine and 15% lysine (which exceeds their contributions to the composition of muscle protein) effectively overcame anabolic resistance and stimulated MPS [9,20] and improved functional performance in older adults [5].…”

“…It was therefore thought that mimicking the EAA profile in muscle protein would be the most effective composition to stimulate muscle protein synthesis. However, clinical research discovered that the optimal composition of EAAs is different from the EAA profile of muscle protein for several reasons [5,31,36,37]. First, leucine is oxidized in muscle in addition to being incorporated into muscle protein by MPS.…”

“…Dietary EAA intake, particularly when combined with resistance exercise training, increases muscle mass, strength, and function as well as muscle quality (defined as muscle strength or function per unit of muscle mass) [5,6,27]. Older adults typically experience a faster loss of muscle strength than muscle mass (i.e., loss of muscle quality).…”

“…However, it seems that EAA intake can counteract the loss of muscle quality in older adults. For example, recent clinical studies reported that consumption of free EAA as a dietary supplement (from 8 g to 22 g/day) for 8-24 weeks enhanced hand grip strength, leg strength, or walking speed without gains in lean body mass in older adults, indicating improved muscle quality [5,7,26]. The improvement of muscle quality may stem in part from increased muscle protein turnover, leading to replacements of old, non-functional with new, functional contractile [6,[51][52][53] and mitochondrial [52,54] proteins.…”

“…An appropriate composition of dietary EAAs induces a greater anabolic response (i.e., an increase in net protein synthesis) than isocaloric protein intake [4]. The superior efficacy of EAAs in inducing an anabolic response translates to improved physical performance in older adults [5][6][7].…”