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23.12.2008


How a low-carb diet helps against aging

If humans resemble the worm Caenorhabditis elegans, they might live to a ripe old age by avoiding carbohydrates as much as possible, and not taking pills with antioxidants like vitamin E and C and N-acetylcysteine. This information comes from a study by researchers at the University of Jena which was published in Cell Metabolism.

Caenorhabditis elegans
That antioxidants increase life expectancy comes from a theory first written up in 1908 by Max Rubner. The higher an organism's metabolism, according to Rubner and his followers, the earlier the organism will die. In the fifties, scientists linked this theory to the creation of free radicals during combustion processes and the antioxidant theory was born. This theory has now been superseded by the hormesis theory, and the Germans' article in Cell Metabolism fits in this trend shift.

The researchers did experiments on a simple worm that consists of just a few hundred cells and lives on bacteria. The Germans fed the worms on 2-deoxy-D-glucose: a glucose analogue that does not provide energy but which the cell mistakenly recognises as glucose and thus messes up the glucose metabolism in the cells. The worms that got the anti-glucose lived longer.


How a low-carb diet helps against aging


The white squares in the figure above represent the worms that got anti-glucose. When the researchers looked at what had changed in the cells, they saw that the mitochondria, the cells' power stations, had become more active. The longer the period that they were given the anti-glucose, the more oxygen the energy producing organelles burned.


How a low-carb diet helps against aging


In the figure above DOG stands for 2-deoxy-D-glucose. More mitochondria activity and more fat burning means an increase in the numbers of free oxygen radicals in the cell. When the researchers gave the worms not only anti-glucose, but also antioxidants like vitamin C and N-acetylcysteine [NAC], the radicals were neutralised. And to crown it all, the life-lengthening effect of the glucose-metabolism sabotage disappeared.


How a low-carb diet helps against aging


Squares: worms fed anti-glucose; black circles: control worms; triangle: worms fed anti-glucose and NAC; white circles: worms fed anti-glucose and vitamin C. The free radicals stimulate the cells to make more endogenous antioxidant proteins themselves, the researchers think.

The Germans also tried to understand more about the genomic mechanism responsible for the effect. The worm sort of SIRT 1, the Methuselah gene that is activated by fasting and resveratrol, doesn't play a big role, the researchers discovered when they repeated the trials with worms in whom that gene didn't work. What is important is the gene that regulates the worms' version of the human AMPK enzyme.


How a low-carb diet helps against aging


This enzyme, AAK-2, became more active when the worms were given anti-glucose. The cell added phosphorus groups more often, which made the protein more active. In the figure above this is phospho-aak2.

The scientists believe that their research is important for diabetics in particular. Doctors try out all sorts of ways to get diabetics' cells to absorb carbohydrates. And although the medical profession is getting better all the time at controlling diabetes, the life expectancy of diabetics is still shorter than that of healthy humans. Perhaps, the Germans suggest, we need to look in a different direction.

For health freaks and life extenders the study is interesting for another reason. It suggests that the low glyc and especially low carb diets may have more advantages than just helping to control fat reserves.

Sources:
Cell Metabolism, Vol 6, 280-293, 03 October 2007.