It ain't heavy, it's my water...

Well actually, it is heavy, it in this case being water in which some of the hydrogen atoms are replaced with the 'heavier' isotope deuterium. Why the interest in heavy water? Well, it's being touted by the People's Medical Journal (aka The Daily Mail) as a way to reduce the effects of ageing and extend lifespan. Before we all rush down to the local health food shop and stock up on deuterium-rich water, let's take a closer look at 'the science behind the headlines:' (discalimer: this is not way an attempt to subvert the cause of NHS Choices, who do a pretty good job of investigating science in the news...)

The theory goes as follows. Free radicals (anything with an unpaired electron), and in particular reactive oxygen species (ROS), are highly unstable by-products of many metabolic processes within living cells. ROS strip electrons from other molecules, thereby altering their chemical structure and leaving them prone to further damage and degradation; entities such as DNA, lipids and proteins are particularly susceptible to such oxidative damage, which can result in cellular disruption ranging from DNA mutations and structural damage to cell death. So far, so A-level biology textbook. There is a great deal of published, empirical evidence supporting this so-called 'oxidative damage theory of ageing,' and there's just as much interest in preventing ageing by slowing/preventing oxidative damage (hence the multi-billion pound market for anti-oxidant supplements). Here's where the fun starts.

In the Mail article, we are told that

the key to prolonged life could be as simple as a glass of water. Scientists believe 'heavy water' enriched with a rare form of hydrogen could add as much as ten years to life.

"Tell me more," I hear almost none of you cry.

The idea is the brainchild of Mikhail Shchepinov, a former Oxford University scientist.

Great. A name I can put into PubMed - always handy (see below)! But what does this former Oxford Universtiy scientist propose exactly?

He found that water enriched with deuterium, which is twice as heavy as normal hydrogen, extends the lifespan of worms by 10 per cent. And fruitflies fed the 'water of life' lived up to 30 per cent longer.

He now believes people could also benefit from the sweet-tasting water, or from deuterium-enriched 'heavy foods'.

Shchepinov has indeed published peer-reviewed papers (available here and here for those with academic journal access, or by sending me an e-mail!) on deuterium and its potential effect on longevity, but they contain no experimental data. In fact they're both a mix of literature review and speculative musings based on data that others' have published. Which is fair enough - Shchepinov appears to be proposing an hypothesis, an eminently falsifiable one, where ingesting 'heavy' isotopes less vulnerable to oxidation would lead to them being incorporated into proteins, lipids and DNA, thus making these cellular components more robust and less vulnerable to free radical damage.

But let's be clear, that's all he's doing. He's proposing an hypothesis. His big idea is to feed livestock with deuterium-enriched feed, eat a load of meat produced in this way, and end up living longer. But all this is just an idea - he hasn't actually fed pigs deuterium, and there's no data available to back up the theory that eating deuterium-laden pork will enhance lifespan - indeed, I can't find the data the Mail article refers to involving worms and fruitflies (I'm happy to be corrected though...). Just because 'heavy' isotopes appear to be resilient to oxidative damage in a laboratory setting, does that mean we'll live longer if we drink heavy water? The point is we don't know, and Shchepinov doesn't either - he just had an idea, but the Mail reported it as though havey water really could be the best way to prevent ageing. Again, just to emphasise, this is not a story based on research into how heavy isotopes extend life - it's based on thinking that heavy isotopes could extend life.

But that's not the end of it. Turns out that Shchepinov is "a former Oxford University scientist" because he's a current founding member of Retrotope, a company founded with the explicit mission of developing 'heavy' amino acids and lipids essentially as dietary supplements. As of yet the products he describes appear to be theoretical (or 'in development as industry insiders say...) And it turns out that the press have covered his theoretical products' theoretical anti-ageing properties before. Last year the Mail themselves wrote a remarkably similar piece to yesterday's story, and spookily the Telegraph did the same thing - here's their piece from last year, and here's today's apparent repeat. [Thanks for flammableflower for pointing out the press' previous coverage here!].

There's nothing wrong with having an idea and talking about it - it's how science progresses. In fact academics have ideas about how to treat/cure all sorts of things all the time. Perhaps ten years from now Shchepinov will collect a Nobel for revolutionising research on ageing. Perhaps eating deuterium-laden pork will help us all live longer. Or perhaps, journalists have been taken in by a well-articulated, plausible theory, postulated by someone with a rather large interest in the theory being correct. Perhaps the journalists were not put off by the fact that nothing has been done to investigate whether the theory plays out in real life, and perhaps they couldn't tell the difference between a reference to a speculative theoretical article and one with actual hard data in it. Perhaps this is an instance where Dr*T's First Theory is played out to perfection.

But then again, these are just theories, ideas. Hang on, maybe I should call the Daily Mail and tell them about these theories, I could be famous...!