Those rats who live long lives again
Remember the caloric restriction rats that live much longer lives than ordinary rats? They think they have figured out why that is the case:
The July 20, 2007 issue of Science published the results of research conducted at Children’s Hospital in Boston which provides one explanation for the benefits of improved eating habits and exercise on life span.
Working with mice, Akiko Tachi, PhD, Lynn Wartschow, and Morris White of Harvard demonstrate that reducing insulin receptor substrate-2 (Irs-2) signaling increases life span as well as brain levels of superoxide dismutase, a protective antioxidant enzyme. Acting on the basis of previous research in roundworms and fruit files which found an increase in life span associated with a reduction in insulin signaling, the trio engineered mice to reduce the amount of Irs-2, a protein that carries the insulin signal inside the cell, by half. Because reducing insulin signaling can cause diabetes, the researchers tested their hypothesis that reducing insulin signaling just in the brain, but not the rest of the body, would result in an increase in life span. They engineered two groups of animals to experience a reduction in Irs-2 in their brains alone, while one group of animals was engineered to have lower Irs-2 in all cells, and another group served as controls.
“To our surprise, all of the engineered mice lived longer,” Dr Taguchi remarked. Despite being overweight and having higher insulin levels, animals with diminished brain insulin signaling experienced an 18 percent increase in lifespan compared to the normal controls. The mice were also more active and retained greater levels of superoxide dismutase in old age.
“The idea that insulin reduces lifespan is difficult to reconcile with decades of clinical practice and scientific investigation to treat diabetes,” Dr White noted. “The engineered mice live longer because the diseases that kill them – cancer, cardiovascular disease and others – are being postponed by reducing insulin-like signaling in the brain regardless of how much insulin there is in the rest of the body. The easiest way to keep insulin levels low in the brain is old-fashioned diet and exercise.”
“Our findings put a mechanism behind what your mother told when you were growing up—eat a good diet and exercise, and it will keep you healthy,” White observed. “Diet, exercise and lower weight keep your peripheral tissues sensitive to insulin. That reduces the amount and duration of insulin secretion needed to keep your glucose under control when you eat. Therefore, the brain is exposed to less insulin. Since insulin turns on Irs2 in the brain, that means lower Irs2 activity, which we’ve linked to longer lifespan in the mouse.”
“We are beginning to appreciate that obesity, insulin resistance, and high blood insulin levels are connected to Alzheimer’s disease, Huntington’s disease, and dementias in general,” he added. “It might be that, in people who are genetically predisposed to these diseases, too much insulin overactivates Irs2 in the brain and accelerates disease progression. Thus, insulin resistance and higher insulin levels might be the environmental influences that promote these diseases.” LEF Magazine
I think my first responses have to be “DUH!”, and “I told you so!”
Imagine what would have happened if those caloric-restriction scientists had fed the rats an Atkins diet. They would have got the same positive results on lifespan. Except those results would have been ignored and buried because they didn’t fit the warped dominant nutritional paradigm. Instead they have been harping on about how longevity is all about caloric restriction, because it fits that paradigm.
The most ironic quote:
“The idea that insulin reduces lifespan is difficult to reconcile with decades of clinical practice and scientific investigation to treat diabetes.”
Doctors Atkins and Bernstein wouldn’t agree with that comment. Atkins and Bernstein have both been saying for at least 35 years that insulin ages you and kills you young from cardiovascular disease and cancer. Dr Bernstein, who eats a very low carbohydrate diet, is the oldest living T1 diabetic on the planet. There are no coincidences. Bernstein was an engineer. He was around two years from death when he took matters into his own hands and decided to learn how to control his own blood sugar, and turned his life around. When he realised no one in the medical profession was listening to him he became a doctor. It took an engineer’s mind, rather than a medical mind, to figure out what he had to do to save his life.
Carbohydrates increase insulin output in proportion to the quantity that you eat. If you ask an expert on insulin like Dr Bernstein on how low GI diets affect insulin output, he will point out to you that they just cause the same amount of insulin to be released more slowly with less spikes.
Salicylates also increase insulin levels, by the way. Another reason fruits and vegetables aren’t so good for you after all. Free glutamates, like the ones you find in meat that is too old, also raise your insulin levels.