Dennis’s Pet Menace

As it happened, I’d already agreed to appear on Jeremy Sallis’ Lunchtime Live Show on BBC Radio Cambridgeshire – the plan being just to chat about cancery topics that might be of interest to listeners. Which would have been fine – if only The World Health Organization had left us in peace. But of course they chose last Tuesday to publish their lengthy cogitations on the subject of whether meat is bad for us – i.e. causes cancer.

Cue Press extremism: prime example The Times, quite predictably – they really aren’t great on biomedical science – who chucked kerosene on the barbie with the headline ‘Processed meats blamed for thousands of cancer deaths a year’.

But – to precise facts – and strictly it’s The International Agency for Research on Cancer, the cancer agency of the World Health Organization (WHO), that has ‘evaluated the carcinogenicity of the consumption of red meat and processed meat.’

But hang on … haven’t we been here before?

Indeed we have. As long ago as January 2012 in these pages we commented on the evidence that processed meat can cause pancreatic cancer and in May of the same year we reviewed the cogitations of the Harvard School of Public Health’s 28 year study of 120,000 people that concluded eating red meat contributes to cardiovascular disease, cancer and diabetes. To be fair, that history partially reflects why the WHO Working Group of 22 experts from 10 countries have taken so long to go public: they reviewed no fewer than 800 epidemiological studies! However, as the most frequent target for study was colorectal (bowel) cancer, that was the focus of their report released on 26th October 2015.

So what are we talking about?

Red meat, which means any unprocessed mammalian muscle meat, e.g., beef, veal, pork, lamb, mutton, horse or goat meat, that we usually cook before eating.

Processed meat: any meat not eaten fresh that has been salted, cured, smoked or whatever and commonly treated with chemicals to enhance flavour and colour and to prevent the growth of bacteria.

What did they say?

Processed meat is now classified as carcinogenic to humans – that is it goes into the top group (Group 1) of agents that cause cancer.

Red meat is probably carcinogenic to humans (Group 2A). Group 2B is for things that are possibly carcinogenic to humans.

Why?

Because 12 of the 18 studies they reviewed showed a link between consumption of processed meat and bowel cancer and because it’s known that agents commonly added to processed meat (nitrates and nitrites) can, when we eat them, turn into chemicals that can directly damage DNA, i.e. cause mutations and hence promote cancers.

For red meat 7 out of 15 studies showed positive associations of high versus low consumption with bowel cancer and there is strong mechanistic evidence for a carcinogenic effect i.e. when meat is cooked genotoxic (i.e. DNA-damaging) chemicals can be generated. They put red meat in the probably group because several of the studies that the Working Group couldn’t fault – and therefore couldn’t leave out – showed no association.

Stop woffling

My laptop likes to turn ‘woffling’ into ‘wolfing’. Maybe it’s trying to tell me something.

But is The WHO trying to tell us something specific about wolfing? To be fair, they have a go by estimating that every 50 gram portion of processed meat (say a couple of slices of bacon) eaten daily increases the risk of bowel cancer by about 18%. For red meat the data ‘suggest’ that the risk of bowel cancer could increase by 17% for every 100 gram portion eaten daily.

And what might that mean?

In the UK about 6 people in 100 get bowel cancer: if you take The WHO maximum estimate and have everyone eat 50 grams of processed meat every day of their lives such that 18% more of them would get bowel cancer, the upshot would be 7 people in 100 rather than 6. So it’s a small rise in a relatively small risk.

As the report points out, the Global Burden of Disease Project reckons diets high in processed meat cause about 34,000 cancer deaths per year worldwide and, if the reported associations hold up, the figure for red meat would be 50,000. Compare those figures with smoking that increases the risk of lung cancer by 20-fold and The WHO’s estimate of up to 6 million cancer deaths per year globally caused by tobacco use and 600,000 per year by alcohol consumption.

All of which suggests that it isn’t very helpful to lump meat eating, tobacco and asbestos in the same cancer-causing category and that The WHO could do worse than come up with a new classification system.

And the message?

Unchanged. Remember mankind evolved into the most successful species on the planet as a meat eater. As the advert used to say: It looks good, it tastes good and by golly it does you good – not least as a source of protein, vitamins and other nutrients. Do some exercise and eat a balanced diet – just in case you’ve forgotten, that means limit the amount of red meat (The WHO suggests no more than 30 grams a day for men, 25 g for women) so try fish, poultry, etc. Stick with the ‘good carbs’ (vegetables, fruits, whole grains, etc.), cut out the ‘bad’ (sugar – see Biting the Bitter Bullet), eat fishy fats not saturated fats and, to end on a technical note, don’t pig out.

_65259128_6136791400_49fc5aaece_b

‘The Divine Swine’ Castelnuovo Rangone, Italy

Meanwhile back on the Beeb

When the meat story broke I was a bit concerned that we might end up spending the whole of Lunchtime Live on how many bangers are lethal – especially as we were taking calls from listeners. Just in case things became a bit myopic I had Rasher up my sleeve. Rasher, you may recall, was Dennis the Menace‘s pet pig (in the The Beano‘s comic strip) who had a brother (Hamlet), a sister (Virginia Ham) and various other porky rellos. To bring it up to date we’d have introduced Sam Salami and Frank Furter and, of course, Rasher’s grandfather who was the model for the bronze statue named ‘The Divine Swine’ to be found in the little town of Castelnuovo Rangone in Pig Valley, Italy, the home of Parma ham.

But I shouldn’t have worried. All was well in the hands of Jeremy Sallis who, being a brilliant host, ensured that we mainly chatted about meatier matters than what to have for breakfast.

References

Press release: IARC Monographs evaluate consumption of red meat and processed meat.

Q&A on the carcinogenicity of the consumption of red meat and processed meat.

Carcinogenicity of consumption of red and processed meat. www.thelancet.com/oncology Published online October 26, 2015

Advertisements

A Very Odd Coincidence

UntitledOne of the great pleasures of swanning round giving talks on biology and stuff to anyone who’ll listen is meeting an amazing range of wonderful folk with a seemingly limitless number of interesting and clever questions, asked either at the end of a lecture or, quite often, when they queue up afterwards to raise personal points or chat about their own experiences. Wide-ranging though the topics are, there’s one word I can’t recall coming up even once. No surprise really. It’s a very rare disease, even though it’s a kind of sub-group of the lung cancers that kill more people every year than any other type – over one and a half million world-wide in 2012 when there were 23 new cases in every 100,000 people. In the USA the incidence is 38 per 100,000, in Australia it’s 27. The very rare form is called mesothelioma – that’s the one where there’s almost always a history of exposure to asbestos. Rarely mentioned though it is, mesothelioma came up after a lecture I gave last week in the sumptuous premises of the Union, Universities & Schools Club, just up the road from Circular Quay in Sydney, when a gentleman from the audience revealed that his wife had contracted the disease and described how he was seeking the next round of treatment options for her. He was kind enough to say that he was a follower of my blog but he hadn’t trawled sufficiently far back to track down a piece I wrote about a lady called Heather Von St. James. To my considerable embarrassment, I couldn’t on the spur of the moment recall what I’d called it (What’s it all about?  Serves me right for trying to be clever with titles: the idea of this one was convey Heather’s determination to have a life with her children and husband in spite of being dealt the really rough hand of mesothelioma). What is it all about? In contrast to the overall incidence figures for lung cancer, mesothelioma afflicts just under one white American in every 100,000, so it is indeed pretty unusual. The UK has the highest rate (top of something then!) but Australia comes second with 2.9 new cases of mesothelioma per 100 000. Since the early 1980s over 10,000 Australians have died from the disease and the rate is still rising. It’s predicted to start falling after 2020 but, even so, a further 25,000 Australians are expected to die from it over the next four decades, the majority being men. Now Sydney, as you may recall, is the largest city in Australia and it’s in New South Wales, so you might predict that, if you were going to run into mesothelioma anywhere outside the UK, Sydney would be the spot. But why? Well, NSW was the first state in Australia to mine asbestos and it produced the bulk of the chrysotile (white) and amphibole forms. Asbestos of whatever type is now classed as carcinogenic but it was not until the end of 2003 that the use of all forms of asbestos was banned in Australia. The hazard remains, however, because of the widespread use that had been made of asbestos for construction, both residential and commercial. The risk can be seen from the near doubling of mesothelioma incidence in NSW between 1987 and 2006, with an even bigger increase being seen in women – attributed largely to second-hand exposure. And the freaky happening? The very next day after my conversation at the Universities Club, and completely out of the blue, I received an email from Heather about what she describes as her ‘life’s mission to educate people about this deadly disease’. Having told the story, perhaps the most helpful thing I can do by way of supporting this remarkable lady is to spread the word of her initiative by advertising the web site.