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[OUTLOOK]Searching for a fountain of youth

Published: 15 Jun. 2006, 21:44

Everybody wants to live a long life while staying young and healthy. Human efforts to slow aging and live longer started as early as 3,500 B.C.
Alexander the Great sought a spring that to give eternal youth and Shin Huang-ti, the emperor of the Chin dynasty, wanted to possess the herb of eternal life.
All creatures in the universe have limited longevities. Vertebrates can live six times longer than the time it takes for them to fully mature.
If it takes 25 years for a human to mature, more than 150 years is an ideal longevity.
In the past 60 years, the average lifespan for humans has increased by 30 years. Although improved hygiene and nutrition has helped, the major contribution was cures for diseases thanks to the mass production and distribution of medical supplies.
There are two major theories on the reasons for aging. One is that when each human or animal dies is already decided.
The other is that cells are damaged in the course of life.
The first theory argues that human cells genetically have a clock in them and this clock decides the timing of death.
According to this theory, living creatures are programmed to age after a certain number of cell divisions.
For a tortoise, which symbolizes longevity, it is from 90 to 125 times, for a chicken 15 times and for a human 60 times.
Part of the oxygen we inhale changes into active oxygen and accumulates inside our bodies. This causes aging.
Anti-oxidizing agents, such as vitamin B and E, slow this process. However, their effects are miniscule and if too much is taken, they cause the liver to work too hard.
Lately, hormone replacement therapies using melatonin, growth hormone, testosterone and dehydroepiandrosterone have gained popularity.
Hollywood movie stars, including Goldie Hawn, are said to be taking growth hormones regularly in order to stay young.
Taking hormones can improve physical or physiological conditions over a short time. But the problem is that they involve a risk.
According to the U.S. National Institute of Health, estrogen-progestin replacement therapy, which has been used for women experiencing menopause, can increase the rates of breast cancer, stroke and heart attack by up to 40 percent.
Lately, 51 renowned experts on aging issued an announcement that there is no such a thing as a spring that gives eternal youth, because they were concerned at the low efficiency and negative side effects of anti-aging drugs. So far, there is no way to stay young that is free from side effects.
Experts have shown interest in caloric restriction as an alternative. By aging, the basic units for all living creatures, such as DNA, protein and cells, accumulate damage and become weak to stimulus from outside.
Thus, oxidation inside a body should be restricted in order to slow aging. The major process of oxidation is to gain energy by burning food so if we eat less food we can stay young, the theory goes.
In a study on monkeys that was conducted over 15 years, one group of monkeys was given 30 percent less calories than the other group. The rates of cancer, cardiac disease and death decreased 50 percent in the first group. We need to endure hunger in order to slow aging.
To maximize the effect, the daily calorific intake should be reduced from 2,500 to 1,750 calories. Few people might be able to endure this.
Will there be a way to mimic the effects of caloric restriction, while eating the same amount of food? New research to develop a caloric restriction mimetic has emerged.
An element called 2 deoxy-D-glucose, or 2DG, interferes with glucose metabolism and fools the cells as if a person’s food intake has been reduced, even though it has not.
This agent controls the metabolism in mitochondria to produce the minimum amount of adenosine triphosphate. Therefore, a person on this therapy could carry on daily life without problems.
In animal tests, however, overdoses of 2DG proved to be slightly toxic. Researchers are trying their best to find a safer agent or compound.
I hope that the time will come when a caloric restriction mimetic is developed so that we can enjoy a long and healthy life without giving up the joy of eating.

* The writer is the director of the Bio-organic Science Division at the Korea Research Institute of Chemical Technology.

by Kim Sung-soo