
Want to live a longer, healthier life? The paradoxical answer may be to eat less, a lot less.
For a while now, it's been known that lifespans can be increased by drastically reducing calorie intake, at least for certain animals. It's called calorie restriction, and many people are already trying it in an effort to extend their lifespans. You can find a couple of good articles on calorie restriction here and here.
What's particularly interesting is that scientists are starting to find their way around the actual biological processes involved. A new study reveals that mitochondria, the cell's natural energy battery, plays a key role:
Researchers report in the journal Cell that the phenom is likely linked to two enzymes—SIRT3 and SIRT4—in mitochondria (the cell's powerhouse that, among other tasks, converts nutrients to energy). They found that a cascade of reactions triggered by lower caloric intake raises the levels of these enzymes, leading to an increase in the strength and efficiency of the cellular batteries. By invigorating the mitochondria, SIRT3 and SIRT4 extend the life of cells, by preventing flagging mitochondria from developing tiny holes (or pores) in their membranes that allow proteins that trigger apoptosis, or cell death, to seep out into the rest of the cell.
Here are some quotes from another
report on the same study:
Sinclair and his colleagues found that, when either rat or human cells were deprived of nutrients (as in a caloric-restriction diet), the overall cellular concentration of a compound known as NAD dropped precipitously -- but not within mitochondria. Indeed, following any kind of cellular stress, mitochondrial NAD concentration actually increased.
Sinclair's team found that mitochondria can synthesize their own NAD to withstand stress, thereby helping the cells stay alive long enough to repair themselves.
Two members of a family of genes called sirtuins were required for this effect to occur, the authors found. Those proteins, SIRT3 and SIRT4, both reside within the mitochondria, and they need NAD to do their jobs.
"We were able to mimic calorie restriction in a dish," said Sinclair, "and that's important, because for decades, people knew calorie restriction made the cells less prone to death, but not how it worked, and we tracked it down to the mitochondria and to SIRT3 and SIRT4."
... This suggests that if SIRT3 and SIRT4 could be chemically activated, it might be possible to achieve the benefits of caloric restriction without the diet. That could slow the progress of diseases based on cell death, such as Alzheimer's, cancer and diabetes, he said, and possibly extend life span as a result.
A tablet for extending your life is some way off, but it's encouraging that progress is being made in this important field. In the meanwhile, you could join the society of calorie restictors, reducing your daily intake to a mere 1,500 calories a day (for men). Personally, I favour eating, and will probably continue to keep eating like a horse . . . and when those tablets eventually come along, well, I'll eat them as well.