The £400 Test That Tells You How Long You'Ll Live

A blood test that can show how fast someone is ageing – and offers the tantalising possibility of estimating how long they have left to live – is to go on sale to the general public in Britain later this year.

The controversial test measures vital structures on the tips of a person's chromosomes, called telomeres, which scientists believe are one of the most important and accurate indicators of the speed at which a person is ageing.

Scientists behind the €500 (£435) test said it will be possible to tell whether a person's "biological age", as measured by the length of their telomeres, is older or younger than their actual chronological age.

Medical researchers believe that telomere testing will become widespread within the next five or 10 years, but there are already some scientists who question its value and whether there should be stronger ethical controls over its wider use. In addition to concerns about how people will react to a test for how "old" they really are, some scientists are worried that telomere testing may be hijacked by unscrupulous organisations trying to peddle unproven anti-ageing remedies and other fake elixirs of life.

The results of the tests might also be of interest to companies offering life-insurance policies or medical cover that depend on a person's lifetime risk of falling seriously ill or dying prematurely. However, there is a growing body of scientific opinion that says testing the length of a person's telomeres could provide vital insights into the risk of dying prematurely from a range of age-related disorders, from cardiovascular disease to Alzheimer's and cancer. "We know that people who are born with shorter telomeres than normal also have a shorter lifespan. We know that shorter telomeres can cause a shorter lifespan," said Maria Blasco of the Spanish National Cancer Research Centre in Madrid, who is the inventor of the new commercial telomere test. "But we don't know whether longer telomeres are going to give...