Sweet tooth in old age means inevitable muscle loss
Those who eat large amounts of sugar and refined carbohydrates in old age will lose muscle mass more quickly. An animal study published by nutritionists at the French Inra research institute in the Journal of Nutrition suggests this. The study also explains how a diet rich in refined carbs leads to muscle decline.
The researchers performed their study in the hope of gaining more understanding of sarcopaenia age-related loss of muscle mass and muscle strength. Sarcopaenia is a growing population as the population ages. More and more people are living into their eighties and nineties or older – but more and more are losing so much muscle mass that they are no longer able to care for themselves.
Scientists suspect that a diet containing large amounts of easily absorbed refined carbohydrates leads to sarcopaenia. They think that three processes are involved: inflammatory processes, the activity of aggressive molecules – free radicals – and reduced insulin sensitivity. The French set up an animal study to test these assumptions.
The researchers did experiments on aging rats that were 16 months old. They put one group of animals on a diet in which starch was the main source of energy. The food consisted of 13 percent sugar and 49 percent starch. Another group of animals got food in which sucrose was the main source of energy. Their diet consisted of 62 percent sugar.
Some of the rats in each group were given antioxidant supplements. The researchers put extra selenium, zinc, rutin and vitamins A, D and E in their food. [R+]
The rats that had been given sugar as the main energy source put on weight. Supplementation prevented this from happening.
The rats in the starch group lost 5.4 percent of their muscle mass. The rats in the sugar group lost 8.1 percent of their muscle mass. Supplementation did not have a significant effect.
The researchers found no evidence that a sugar-rich diet increased the activity of free radicals or inflammatory processes. They did discover that a high-sugar diet reduced insulin sensitivity. Once again, supplementation had no effect.
"In conclusion, sucrose feeding accelerated the age-related loss of lean body mass and muscle mass", the researchers wrote. "The mechanism involved could be alterations in insulin sensitivity leading to a weaker stimulation of muscle protein synthesis by the meal."
"Thus, long-term consumption of added sugars can accelerate sarcopenia and should be avoided."
J Nutr. 2015 May;145(5):923-30.
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