Eat Less, Live Longer: By Diet or Drugs

For years, studies have shown that an almost foolproof way to live longer is to cut back on calories. In mice, cutting calories has not only extended their lifespan, but also their reproductive period. It is hypothesized that a low calorie diet in humans can have a similar effect.

In yeast, it was demonstrated that decreasing caloric intake of these cells decreases SIR2, an inhibitor of an anti-aging enzyme. Lower production of SIR2 meant the longevity system of the cell flourished. We humans have similar genes, and it is likely it is modulated in a similar manner.

We already know that cutting back on calories can lower cholesterol, fasting glucose, and blood pressure. These parameters have also been termed biomarkers of aging, as they can be correlated with age related diseases.

Don’t want to cut back on your gastronomic experiences? Then pop an antidepressant. Unlike Prozac or Zoloft, when worms were given another anti-depressant called mianserin (trade name Tolvon), their appetite center was tricked into thinking they had consumed much less calories than they actually did. Their lifespan was increased significantly, from 3 weeks to more than four.

According to Linda Buck, Nobel Prize winner and leader of this study, the drug works by modulating neurotransmitter serotonin, which controls appetite and hunger sensation in both these worms as well as in humans. It also stimulates octopamine, which is a trigger for starvation. While the worm’s nervous system was tricked into thinking they were starving, the organisms did not consume less food. Furthermore, when the worms were put on a diet on top of the antidepressant treatment, there was no additional increase in lifespan beyond the basal effect of a caloric cutback. This suggests that mianserin uses the exact same mechanism as a strict diet to make the worms live longer.

While these findings have yet to be shown in humans, we see ample evidence that diet does have a similar effect in us. For example, inhabitants of the Ryukyu Islands of Japan have the highest life expectancy. These people consume a low calorie diet which is positively correlated with the number of people living over the age of 110.

References

• Lin, S. Genes & Development, 18, (2004)
• Petrascheck, M. et al. Nature 450, 553-557 (2007)