Recent research in nematodes, mice, and primates has shown that living on a severely reduced diet results in an unexpected benefit: longer lifespan. The constant, low-intensity stress from such diets might actually be helpful, shielding against even worse troubles, such as cancer. The downside is that, to enjoy these boons, an organism must cut its food consumption by a third.
Recent research in nematodes, mice, and primates has shown that living on a severely reduced diet results in an unexpected benefit: longer lifespan. The constant, low-intensity stress from such diets might actually be helpful, shielding against even worse troubles, such as cancer. The downside is that, to enjoy these boons, an organism must cut its food consumption by a third.
But perhaps you can have it all.
Frank Rosenzweig, an associate professor of biology at the University of Montana, feels there is "something missing in the puzzle" of caloric restriction studies. As part of CASW's 2009 New Horizons in Science briefing at the University of Texas at Austin, Rosenzweig talked about the effects of an unlimited diet. He decided to see what happens when yeast — the tiny fungi responsible for making bread and wine possible — are fed a nearly everlasting amount of sugar and nutrients to keep them fat and happy.
Most laboratory yeast cells are grown on culture plates with limited access to food. Rosenzweig wanted to simulate a more natural environment. He infused semi-solid, tapioca-sized beads with wild yeast, continuously feeding them a nutritious liquid.
"These conditions are more like the inside of a grape, oak tree, or grain of barley," he says. All are likely places yeast might be found in nature.
His research showed that, similar to their poorly fed brethren, these yeast displayed adaptations against stress, becoming resistant to heat, ethanol, and organic solvents. And like the starved yeast, they enjoyed extended lifespans. The cells were apparently sticking around to let the good times roll.
Furthermore, instead of pigging out and reproducing as fast as possible, they showed strict self-control. Yeast typically replicate often, producing a small bud on their side that eventually detaches as a new cell. But, like couch potatoes with nothing to do but gorge, the yeast in Rosenzweig's experiment stuffed themselves full of glucose and slowed reproduction down to a crawl. After a few days, the majority were "virgins" and produced no buds at all.
The yeast also no longer showed interest in dividing, remaining in the first phase of cell growth, called G1.
Rosenzweig looked for the genetic basis of such behavior and scanned over 5700 genes of these overfed yeast.
"They exhibited patterns of gene expression never before seen," he says.
The organisms switched on coding for proteins to toughen and protect their cell walls. Other genes were blocking the movement of the cells from G1 to the next steps of cell division. And a gene called RIM15, which activates during lean times and is responsible for longevity, was also highly expressed during fat times.
Overall, Rosenzweig hopes to discover new genes that are responsible for lifespan extension. Someday corresponding genes in humans might be found and our own lifespan could be extended.
In reference to the long-lived yet starved yeast, Rosenzweig quoted William Shakespeare, saying, "Sweet are the uses of adversity." Perhaps this new research could claim, "Sweet are the uses of sweets."
Adam Mann is a graduate student in UC Santa Cruz's Science Communication program. He currently writes for SLAC Today at Stanford and has contributed to UC Berkeley's alumni publication, California magazine.
