Slow decline: In young mice (top), the part of a motor neuron that releases chemical signals (green) and the receptors on the muscle that receive those signals (red) align to create a structure known as the neuromuscular junction. The overlap between these two components is shown as yellow. As the animals age (bottom), the structure begins to deteriorate.
Copyright National Academy of Sciences
Caloric restriction and exercise slow muscle decline in mice.
The connections between your nerves and muscle deteriorate with age--a phenomenon that may help explain the serious loss of muscle that often strikes old people. New evidence suggests that caloric restriction--a nutritionally complete but low-calorie diet--could help prevent these changes. According to a study published this week in the Proceedings of the National Academy of Sciences, a very-low-calorie diet, and to a lesser extent exercise, can prevent or slow some aspects of muscle decline in aging mice.
The researchers hope that the findings will point toward new ways to stem loss of muscle mass, one of the most common problems of aging and a major cause of injury. They also say it could help them understand how similar factors affect neural connections in the brain. "Much of the research on aging in the nervous system has been done in the context of neurodegenerative diseases, such as Alzheimer's," says Joshua Sanes, a neuroscientist at Harvard Medical School and one of the senior authors of the study. "Remarkably little is known about the basic phenomenon of aging in the nervous system."
The researchers studied the structure of the neuromuscular junction--the connection between the motor neurons and muscle--in mice that had been genetically engineered to make these neurons glow. Because these junctions are relatively large and tend to have a regular structure, it is easy to see when things go wrong. When the mice were about two years old, roughly the equivalent of a 70- to 80-year-old person, the junctions had clearly deteriorated. "The majority of muscle fibers had abnormal junctions," says Jeff Lichtman, a neuroscientist at Harvard University and a senior author of the study. The connections were generally smaller, and the nerves and corresponding receptors on the muscle, which are normally aligned, were askew. "They looked old and decrepit, kind of like a person looks old," says Lichtman.
The findings, hinted at in previous research, could shed light on a major health issue in aging: sarcopenia, or loss of muscle mass. "That is one of the most robust age-related impairments observed across many species, but it's not really clear what causes it," says Charles Mobbs, a neuroscientist at Mt. Sinai School of Medicine, in New York, who was not involved in the research. "This study provides evidence that an important mechanism involves neuromuscular junctions and the role of motor neurons."
To look for factors to stem this decline, the researchers examined animals that had been on a restricted diet most of their lives. This type of diet has previously been shown to extend lifespan in a number of species and to reduce some signs of aging, such as diabetes and heart disease, in some animals. "With caloric restriction, we saw a striking absence of abnormalities," says Lichtman. "These animals' synapses looked quite young."
To price insurance policies and calculate retirement benefits more accurately, a new breed of life-span modelers is turning to personal data about who you are and how you live your life.
The diet delays or prevents diabetes, cancer, heart disease, and brain atrophy.
in extrapolating mice studies to people.
One is that MICE ARE NOT PEOPLE!
The longevity in particular doesn't work for people. If it did, every poor village where the people by nature work hard and eat less would have people living much longer. Rodale's Hunza paradise which he accepted wide-eyed with no proof doesn't really exist.
Certainly the people avoid many western diseases related to lack of exercise like diabetes and heart conditions but they don't live longer. They are just healthier as they get older.
And claims of extra long life have been disproven by researchers who studied specific claims of long life. Often the young take the names of older relatives in the village. Pages get torn out of church registries or this kind of documentation doesn't exist at all. Once documentation becomes on the part with countries like Sweden, the age maximums start to all be about the same.
That said, there are alot of health benefits to not overeating. I didn't say calorie restriction, which I don't think applies to people. But avoiding excess calories (not the same as reducing drastically your calories) most certainly helps keep you from getting degenerative diseases like diabetes and getting fat which has LOTS of negative health consequences.
If you ARE diabetic, similarly, the one best thing you can do is tightly control your blood sugar to slow and help prevent organ damage and blindness. This is done by not overeating also, or by eating foods with complex carbs that are digested more slowly.
If you as a human tried the caloric restrictions severely enough, your body would start to burn your muscle mass like it does in starving people. This would defeat the purpose of calorie restriction in making you healthier. If you restrict calories simply enough and you have to curtail regular exercise then you have lost the health benefit for your muscles, including your heart muscles. This will lead to earlier death.
If we were mice this study would be directly relevant to human aging. However the basic research into these issues is very important.
The reason poor villagers don't seem to have the benefits of caloric restriction is that it must be accompanied by complete nutrition, which those villagers are unfortunately also missing.
The same must be said regarding the other situations you mention.
Yes but enuf 'health food nuts' people in developed countries have gone to 'nutrient dense' diets to disprove that it would increase the normal human life span.
The human life span is effectively limited to 110 or 120. Any individual claims of longer life are probably suspect. A Russian fellow in a small village in one of the southern republics had his 128th birthday covered by a local newspaper. This prompted someone who knew his father to tell the newspaper the son had acquired the dad's passport and was using it for ID. He was still elderly but much younger. Same thing happens in villages in Peru and other places for cultural reasons.
Ok, they then are not dying at 70 and live to 80 or 90 possibly if they avoid other normal problems of aging such as increased vulnerability to infections, broken bones and their complications, etc. Not sure this shows the result is correct as within normal lifespan.
Guess it depends on how you define the normal lifespan whether it works or not. Maybe the longer life of the rats or mice is normal and they were living shorter thru 'junk food' rat pellets. I've seen lard, hydrogenated oils and many other cheap ingredients used. I've had pet rodents that got fat and mean tempered after eating this stuff. Poor living conditions (lack of exercise, mental stimulation, etc) could also be part of it. Being locked in a tiny cage probably not much fun.
I do see people living longer around us. We had a 103 yo lady at our nursing home and overheard someone who looked elderly but not the least unhealthy in a local supermarket tell her friend she was 97. I don't know if they followed such a regimen.
maintaining an active lifestyle, balancing metabolism with nutritional intake, physical activity burning up as many calories as are being consumed in a fairly constant temperature range, controlled environment where the body's organ systems are functioning in sync within predictable fluctuation to stress and strain, are more than likely today's accepted norm as the way to go to live long and productive lives ...ask any Joshua tree....
barring any near term breakthroughs shedding light on genetic variables underpinning growth factor depletion as the aging process marches on, it is unlikely any magic formula correlating ingestion of nutrients and longetivity have far reaching application beyond laboratory settings
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rjstone
3 Comments
Journal?
The journal where this study was published is missing from the article, but hinted at in the image caption. It would be nice if the full name of the journal were included in the article.
For anyone wondering, the study was published in the journal Proceedings of the National Academy of Sciences. Here's the abstract.
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Brittany Sauser
46 Comments
Re: Journal?
rjstone,
The journal publication has been added to the story. Thanks for pointing that out and for including a link to the abstract.
Brittany
Senior Web Producer
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