It’s hard to avoid health fads. It took Google just ten minutes since I read this study in Cancer Research Prevention to begin bombarding me with adverts. ‘7lbs in 7 days Juice Diets’ and ‘Coreflush colon cleanses’ are just some of the regimes proclaiming salvation from ill health, but nothing gets pushed as much as the detox. According to The Internet, the detox diet might as well have descended from Heaven as it's so effective at solving everything from bad breath to erectile dysfunction.
This latest obsession with internal body cleansing has flourished over the last couple of decades. The diet industry, of which detox plays an important role, is rapidly expanding. It’s already worth tens of billions of dollars, despite coming under severe criticism from leading scientists. Author and blogger Dr. Ben Goldacre – famous for calling out examples of ‘bad science’ – once described detox as “meaningless, symbolic, gimmicky short-lived health gestures with a built-in expiry date”. Yet this doesn’t stop the media touting every new superfood or miracle-diet as a panacea for all our ills. News outlets pounce at the first sign of a study purporting to have identified a medical breakthrough, often misrepresenting the author’s original findings in order to grab flashy headlines. (Take a quick look at the A-Z of things the Daily Mail thinks will cause and cure cancer – broccoli has 14 entries).
The trick is not to get carried away by the hype. Look at this latest study. Researchers in the US and China have found broccoli-sprout juice appears to "remove" airborne pollutants from the body, but this isn't a "detox". Unlike the fleeting 'cleanse-your-body-in-5 days' type programmes (which unsurprisingly peak after the Christmas holidays), this research looked at the effects of longer-term consumption of broccoli-sprout juice on removing three specific carcinogens.
In the randomised-study of 291 participants from a highly polluted township in rural China, the team analysed daily urine samples from two groups: the first group was given a daily drink of broccoli-sprout juice, but the others were given a placebo beverage. The multi-institutional collaboration included researchers from the John Hopkins Bloomberg School of Public Health and the Qidong Liver Cancer Institute. The team were looking at how the levels of three carcinogens – benzene, acrolein, and crotonaldehyde – changed in participants’ urine over the three-month period.
The substances involved have been linked to increased risk of cardiopulmonary disease, arguably the second biggest killer in China. As the township in the study is located in the heavily-polluted Yangtze River Delta region (a tiny area of eastern China responsible for a monstrous 15 per cent of the country’s greenhouse gas emissions) there is a huge need to combat the dangers of air pollution.
Did the concoction work? On the face of it, yes. The authors found that juice-drinkers excreted more pollutants than the control group. In particular, they noted:
Rapid and sustained, statistically significant (p ≤ 0.01) increases in the levels of excretion of the glutathione-derived conjugates of benzene (61 per cent), acrolein (23 per cent), but not crotonaldehyde were found in those receiving broccoli sprout beverage compared with placebo.”
So far so good. Juice-drinkers weed out larger quantities of two of the three substances under consideration - but this still doesn’t mean broccoli-sprout juice “prevents against lung and heart disease”, as it might have you believe.
The big question here – does drinking broccoli-sprout juice decrease your risk of disease by causing you to excrete higher levels of carcinogens? – needs lots more research. Without analysing numerous studies alongside one another (and taking sample size into account) you can’t really draw conclusions. A single study of 300 people is evidently not enough to justify claims of preventing lung cancer.
In an article published in The Journal of the American Medical Association, health-policy expert Dr John Ioannidis famously argued that a large amount of research is highly misleading. By comparing publications of “highly cited original clinical research studies” with subsequent papers where a larger sample size was used, he found a third of effectiveness claims to be either contradicted or highly exaggerated. Taking a single study to be gospel truth is foolish.
Let's go back to the broccoli. Research emerges linking this juice with enhanced excretion of pollutants; other studies have already linked those same pollutants to cancer. Extrapolating those statements to claim detoxing with broccoli-sprout juice will prevent disease is understandable, and perhaps even inevitable, but undeniably wrong. We mustn't connect dots to form patterns that aren't there.
This highlights a real problem with the supposed 'science' behind detoxing and other miracle-cures: subtly inviting us to form our own conclusions from the selective evidence they present, which, without comparative studies, is effectively meaningless. In detox diets this manifests itself by ignoring the body's own capabilities for disposing of toxins. Andrew Wadge, former Chief Scientist at the Food Standards Agency, expressed his scepticism that we need extra help cleansing out our insides:
There's a lot of nonsense talked about 'detoxing' and most people seem to forget that we are born with a built-in detox mechanism. It's called the liver. So my advice would be to ditch the detox diets and supplements and buy yourself something nice with the money you've saved.”
However, this doesn't mean we should automatically write off such supplements as useless. Given how few of us get our 5-a-day, you could argue that any initiatives promoting increased consumption of vegetables could only be a good thing. Co-author of the broccoli-juice paper Dr. Thomas Kensler tentatively suggested their findings could be used on a personal level, alongside state measures to improve quality of air.
This study points to a frugal, simple and safe means that can be taken by individuals to possibly reduce some of the long-term health risks associated with air pollution.
This while government leaders and policy makers define and implement more effective regulatory policies to improve air quality.”
Though Kensler might be over-estimating the benefits here, the price tag alone will probably put you off purchasing it. The juice – which weighs in at £16 a glass if you’re interested – may well end hitting supermarket shelves soon, but don’t hold your breath that it’ll save us from the dangers of air pollution. There are plenty of measure to solve that problem already.