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Eat isotopes to live longer


22 March 2007

Food containing heavy isotopes of hydrogen, carbon and nitrogen could slow down the aging process. That's the claim1 of Oxford-based researcher Mikhail Shchepinov, who suggests that seeding key biological molecules with deuterium or carbon-13 could drastically reduce oxidative damage or even avert it altogether. 

Reactive oxygen species (ROS) are a staple of ageing research, as they are believed to cause cumulative damage to biomolecules such as DNA, proteins, and lipids. Typically, breaking a carbon-hydrogen bond is the rate-limiting step of these reactions. But if the carbon or hydrogen atoms involved were replaced by a heavier version of the same element (13C or D), the reaction will be slowed down due to a well-established phenomenon known as the kinetic isotope effect.  

These isotopes could be smuggled into the cell in essential nutrients that the body cannot synthesise from scratch, such as certain amino acids. Nucleic acids are a more difficult target, however, as their building blocks can be synthesized in the body. However, Shchepinov argues that fasting could boost the uptake of isotope labelled building blocks of DNA. 

Shchepinov, who is an academic visitor at the department of biochemistry at the University of Oxford, has already filed several patents on the idea. He is confident that this is the way towards a longer and healthier human life span: 'The first biological experiments conducted in Russia were very promising,' he told Chemistry World. The experiments, studying the longevity of nematode worms, were carried out at the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry in Moscow.

Totally heavy

Heavy water (D2O) is toxic to higher organisms, but Shchepinov argues that isotopes would only be incorporated in the sites that need to be protected from oxidation. 'Ideally, they will slow down the oxidation reaction so much that they will never be released to take part in other reactions. If some of them do break free, they will only occur in small concentrations,' he said.

David Meredith, who investigates the metabolism of amino acids at the University of Oxford, warns that some of the heavy isotopes could get into general circulation. 'It would be impossible to ingest exactly the right amount and mix of amino acids that the body required for protein synthesis,' he said.

But Knud Nierhaus, who routinely uses organisms grown in heavy water for neutron scattering experiments on ribosomes at the Max Planck-Institute for Molecular Genetics, Berlin, Germany, thinks that small amounts of deuterium would be tolerated in the body. 'D2O is modestly toxic for animals at around 25 per cent concentration, and typically lethal at around 50 per cent,' he told Chemistry World. 'But if only a small proportion of the food hydrogen atoms are replaced by deuterium and only a small proportion of those leaked into the body, the resulting concentrations would be unlikely to cause any damage.'

Promising as that sounds, it's still a long way from being tested in humans. And as Nick Bostrom, director of the Future of Humanity Institute at Oxford University, said, 'I don't expect this method to furnish the elixir of life. Don't stop eating your vegetables just yet.'

Michael Gross

References

M Shchepinov Rejuvenation Research, 2007, DOI: 10.1089/rej.2006.0506

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