7.12 g leucine daily stops muscle loss in elderly
As we age we lose muscle mass. How and why the process of aging causes muscles to break down scientists still don't know, but perhaps they do now know how to stop the process. All you have to do is make sure you get enough leucine by eating protein-rich foods every day. According to the Australian nutritionist Cameron Keith McDonald, a daily dose of 7.12 g leucine is enough to halt age-related muscle loss.
McDonald, who works at the University of Queensland, analysed data on 368 Danes aged between 35 and 65. The Danes had taken part in a study on cardiovascular disease, and had been monitored for six years at some point. Before the study started and at the end the researchers had measured the participants' body composition. In addition, they knew whether the participants exercised, and how much protein and leucine they consumed.
Among the participants who were younger than 65, McDonald found no correlations, but among the over 65s there were some. The over 65s lost more lean body mass [i.e. muscle mass] the less leucine there was in their diet. In the group of over 65s with the highest leucine intake the muscle mass loss was nil.
In the figure below the researchers have filtered out as many other factors as possible, such as baseline lean body mass, sex, age, energy intake and physical activity.
To make sure you consume 7.12 g leucine every day you need to eat about 1.25 g protein per kg bodyweight, McDonald calculated. If you consume this amount, and spread your protein intake over three meals a day, then you'll consume about 2.5 g leucine per meal.
And that's exactly the minimum amount of leucine that is capable of stimulating muscle growth.
Br J Nutr. 2016 May;115(9):1556-62.
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