Monday, 20 July 2015

Wheatgrass juice, Channel 4, and blood oxygen – the data says no!

I just did a piece for Channel 4 on their superfoods program ( It was looking into the claim that wheatgrass juice improved blood oxygen content; allegedly this works by increasing the amount of haemoglobin as haem and chlorophyll look so similar. My incredulity contrasted with the health food expert who supplied the wheatgrass enema to the presenter. The expert said there was a lot of scientific evidence that supported her view. There was not time in the program to give the full account for the reasons for my incredulity so I thought it worth expanding a bit here in case anyone is interested.
·      Haem is an iron porphyrin and chlorophyll is a magnesium chlorin. Superficially haem and chlorophyll appear similar in chemical structure – one of the ideas that led to Charles Schnabel in the 1930s suggesting wheatgrass could be a superfood. Proponents today suggest it can increase the amount of haemoglobin in the blood. However, in the 1930s the structure of proteins was not known. Not only does chlorophyll contain magnesium rather than iron at its centre, but it has a long organic side chain. Even if you could replace the magnesium with iron, you could not put the iron-chlorin into the haemoglobin structure. It just won’t fit.
·      So maybe the chlorophyll provides building blocks to help us make more haem? In this case wheatgrass juice might increase haemoglobin by an indirect mechanism? There are a number of problems with this idea. First there is no evidence that we absorb chlorophyll, whether taken orally or rectally. Even if we did absorb chlorophyll, we cannot convert a chlorin into a haem. The pathways are linked metabolically; plants make haem and chlorophyll from the same organic starting materials. But we have don’t have the enzymes to make this conversion. 
·      In contrast to chlorophyll, we do absorb haem quite efficiently. But we immediately break it down for its iron content, throwing away the porphyrin cofactor. The result. If you want dietary iron, eat black pudding not wheatgrass juice.
·      Still maybe there is an unknown mechanism for the wheatgrass effect? Is there any science that supports the effect of wheatgrass juice increasing blood oxygen content? If there was good human trial data then we could search for a mechanism. After all gut bacteria are increasingly seen as important to health. Maybe feeding our gut chlorophyll has an effect on the body, even if none of that chlorophyll is absorbed? The problem is that there is no good scientific evidence in human studies of any blood oxygen, health benefit or sports performance effects. I looked hard and could find only a very few papers.  The first [1] is full of flaws and, as far as I can see not peer reviewed. However, let’s assume the study was well conducted. The effects observed (0.26% increase in arterial blood oxygen saturation) would have no significant physiological benefit; indeed there was no performance boost reported in this paper.
·      If wheatgrass juice really did increase the number of red blood cells it would be a godsend for many patients who have anaemia. Who needs epo or blood transfusions if you can just eat crushed grass? Two papers looked at this effect. The first, a small pilot study [2], suggested that consuming about 100 mL of wheat grass juice daily could reduce the need for blood transfusions in patients with thalassemia major. However, a later, larger study contradicted this [3]. Neither study was randomised or blinded.
·      Lest I be accused of being a complete cynic there is one study published that holds some promise. In a small double blinded, placebo controlled trial in ulcerative colitis (inflammatory bowel disease), wwheatgrass seemed to have some beneficial effects [4]. This study was conducted in 2002 and, as far as I can tell, has not been followed up. But at least it has the benefit of not straining credulity – the chlorophyll is suggesting to act where we know it goes – the gut.
In short wheatgrass juice is no superfood. At least not when it comes to increasing the number of red blood cells. There is no reason for WADA to put it on the sporting banned list or develop chlorophyll anti-doping tests.

Epo and doping accusations in the Tour de France – the numbers never lie (or do they?)

I was struck by the vehemance of the current anti-Froome accusations. So I thought I would add my tuppence worth to this story. First let me nail my colours to the mast. I have a lot of sympathy with Sir Dave Brailsford when he says “"It is not possible to prove a negative. I can't," [1]. 
Sir Dave is referring to the well-known fallacy in formal logic known as an argumentum ad ignorantiam or “appeal to ignorance”. This poses that “something is true only because it has not been proved false, or that something is false only because it has not been proved true”.
Now there are some cases where versions of this argument are used by philosophers (inductive logic relies on it in part). Indeed you cannot prove any future event true or false until it has happened. Prehistoric man with no knowledge of physics or astronomy had no definite “proof” that the sun would rise tomorrow or that walking off a cliff would result in a fatal fall. However, enough evidence had accumulated from previous life experiences to make these perfectly reasonable assumptions. Indeed it would be impossible for us to live our lives without making these kind of inductive “leaps of faith” every day.
Something ought to go without saying given the scientific literature, but clearly it needs repeating ad infinitum. Doping allegations based purely on performance (in this case speed or power data) fall well short of the strong evidence required for inductive reasoning. Power/time data alone can never prove someone is doping, or even make it probable. If you doubt this please take time to read carefully the recent article by Hein FM Lodewijkx “The Epo Fable in Professional Cycling: Facts, Fallacies and Fabrications” [2].
Not that the Lodewijkx review does not prove that epo does not improve performance; in fact it is careful not to say this.  Times have continually improved in the Tour and doping could be one of many factors that can affect racing times. The devil is in the scientific detail. But it does make salutary reading for people who assume that numbers alone are a reason for crying foul.
One thing that is needed is a proper randomized trail in elite cyclists testing whether epo doping “works”. Crucially, it should include accounting for the likely strong placebo effect (as everyone “knows” epo works – see my previous blog). The definitive study would include giving cyclists epo when they were told they were getting placebo. This kind of approach has been very successful in studies comparing drug and placebo effects on performance following caffeine administration [3]. However, significant ethical issues would need to be overcome before any epo study could start. Worse still cyclists would need to volunteer for a “ban” so it also need an end of career altruistic act.
If such a study were performed, my suspicion is that it would show that epo microdosing is no more effective than a strong placebo. I suspect blood transfusions or high dose epo would outperform placebo, but I doubt those more severe studies could be done. Still I don’t “know” these answers – as a scientist I just want the studies to be done (ethics permitting) to find out!

Sunday, 7 June 2015

Catch me if you can – the science

I haven’t been able to blog for a while, in part due to work constraints, but also due to working on my next book (Blood: A Very Short Introduction). Still the book will be finished by the end of this month and I should have more time to write soon.

Still I couldn’t resist commenting on the latest BBC documentary about doping - Mark Daly’s Catch Me If You Can. I was actually invited to talk about it last week on BBC2s Newsnight; I couldn’t make it as I was busy talking about my artificial blood research at a blood transfusion conference in Scotland (for the latest info see

What I would like to do here is explore some of the science behind the allegations. First up, the least interesting part of the piece – the reporter taking EPO himself to see if he could fool the anti doping biological passport. I am growing to hate this aspect of science TV documentaries [1].  They all do it now (I blame Michael Mosley!) and, although I understand it is used to engage the viewer, it rarely adds anything to the science. In this case we know that microdosing is an issue with the biological passport. We also know that EPO can theoretically improve VO2 max and performance. Actually what we don’t know is whether in this particular case the EPO enhanced the performance. The reporter clearly expected the drug to work He also admitted feeling very different as soon as he took the EPO. One would expect a large placebo effect under these conditions and, as a non-elite athlete, there was a large room for improvement. Did the drug really work or was the effect all in the mind? What the documentary should really have done of course was a double blind crossover study with a placebo. In fact as a watching scientist I wanted the Swiss expert Carsten Lundby’s view, not on the passport data, but on whether he thought the EPO-induced haematocrit change was enough to trigger the measured VO2 max increase. Lundby is a world authority on the performance link between blood oxygen content and performance and it would have been really interesting to hear his opinion about this.

That said the journalistic scoops were really interesting. For me personally the most concerning were the allegations about Alan Wells, one of my childhood heroes. High dose anabolic steroids can clearly increase muscle mass and I would be genuinely saddened if his victories were in part due to steroid use.

But, of course, the most concerns have been raised about the Galen Rupp and Alberto Salazar allegations (hotly denied). Leaving aside the truth or otherwise of the stories what about the science? Well, unlike sprinting, anabolic steroids such as testosterone are not game changers in long distance running (especially in men). They have turned up occasionally, the “steroid in my toothpaste” excuse from Dieter Baumann being perhaps the most famous occasion. The most likely benefit is in training where they might aid recovery and allow for longer, more intense, sessions (although even that is not based on mostly anecdotal data). Likewise asthma therapies like oral corticosteroids. They can stimulate activity, but in some cases could actually be detrimental to performance. Similarly pre race IV drips should not be required for a healthy athlete.

My conclusion, albeit on a one off viewing of a one-hour TV program, is that what was exposed, even if true, was not what led to Galen Rupp’s strong performances. If he got his medals by cheating there was most likely something else going on. What the documentary did expose was a culture that might not have been averse to using a scientific approach to doping methods (and detection prevention) that really could make a significant difference in long distance running events. These include EPO and blood transfusions. That’s what Mo Farah needs to find out when he returns to America to meet with Salazar.

[1] Hypocrite alert – I have just taken part in a Channel 4 documentary where this is done. However, at least this means I can talk with authority about its limitations!

Monday, 9 March 2015

Changes to blog

Dear readers,

I have chosen to make some changes to this blog:

1           I have instigated a rolling program of deleting older blogs. The blog is not meant as a formal reference site and this is to ensure that the information in the blog remains up to date

2       I have unfortunately had to prevent user comments by external users. Whilst some were really interesting they are outnumbered over 20:1 by comments solely sent with the purpose of redirecting readers to the commenter’s web pages. The vast majority of these are commercial pages selling products (such as peptides). These were taking too much of my time to filter out.