You're toast

So, I wake up on Monday morning, turn on the breakfast news, and hear that if I burn my toast I’m going to die of cancer…

Well, I’m pretty sure that's not what any government agency actually said, but by the time it has been filtered through the UK’s popular press, the message that emerges certainly sounds like that.

So why is this suddenly an issue?  I’ve no idea when the first recorded incident of burned toast was but people have definitely been burning baked starchy products since King Alfred was on the run from the Vikings way back in the 9th century.

Where does Acrylamide come from?

The problem is not simply overcooking.  (This is unfortunate – I don’t suddenly have an excuse to persuade my older relatives that boiling broccoli for 45 minutes might give me cancer.)  This only applies to higher temperature cooking.  The proteins and sugars in foods like bread, cakes and starchy vegetables can react together to form a chemical called ‘acrylamide’ – but this chemical reaction only takes place above 120°C.  So, roasting, baking and frying must be the evil demon cooking methods.

Old news…

So why have we only just discovered this?  Well, we haven’t!  The production of acrylamide during cooking was first discovered by Eritrean scientist Eden Tareke in 2002.  Since then, there has actually been a heap of research into it and a whole lot of food safety worries from the kinds of agencies who should care about such things. It is interesting to note this on the Cancer Research UK website:

"Evidence from animal studies shows that acrylamide has the potential to interact with the DNA in our cells, so could be linked to cancer. However, evidence from human studies has shown that, for most cancer types, there is no link between acrylamide and cancer risk"

In 2005 California attorney general Bill Lockyer even managed to file a lawsuit against a bunch of companies that make crisps and got a $3 million out of court settlement from them and a promise to try harder to reduce levels of acrylamide.  So, the cynical amongst us might think that today’s revelation of death by burned toast might just be a tactic to try and divert attention from other more worrying world news.  But do we really have to worry?  And is the advice of ‘go for gold’ going to be effective in keeping us cancer free?  How do we know what shade of gold is too near bronze?

Well, the truth is that you’re not going to be able to avoid acrylamide completely.  Even that nice golden brown colour will have given rise to some of the stuff.  And don’t think that having a bowl of cereal instead of toast will keep you safe – it’s estimated that Americans get around 12% of their intake of acrylamide from breakfast cereals.

Coffee with your toast?

OK, so I think that I might just have a nice cup of black coffee and wait until lunch… Oh!  Can’t do that one either – coffee beans are roasted at well above 120°C and that nice dark brown colour – yep – very similar set of Maillard reactions which give rise to the production of acrylamide.  But – this one is slightly weird because they have found that the levels of acrylamide don’t keep increasing as you keep roasting coffee beans.  In fact, the levels peak at a kind of medium brown roast and continuing to a darker roast actually reduces the levels.  More good news, even though acrylamide is water soluble, the levels are further reduced in the brewing process.  So, although your morning cup of joe is another way of ingesting carcinogens, if you go for a fresh ground, dark roast version then there are fewer nasties in there than a cup a weedy roast instant.

But hang on – beer comes from brewing a cereal that someone has roasted…  Does that mean that I should avoid beer as well?  OK, the correct answer is that I should almost certainly drink less beer, but for quite a few other reasons including my waistline.  But, is golden good in the case of beer?  Is stout the equivalent of burned toast?  Well, the IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 96 suggests that, like coffee, increased roasting of the cereals used to make beer tends to reduce the levels of acrylamide and the medium brown beers have highest levels – but, in all cases, the levels were very low – around 10 x lower than you’d get chips or crisps.  So, realistically, the myriad other health effects from drinking too much beer are probably going to swamp the effects of this particular bad-guy.

Here's the perspective

But how does this all compare to other things that might give me health problems?  Smoking for example?  Well, cigarettes produce acrylamide too – and in far higher levels than any foodstuff.  The Wikipedia page on acrylamide suggests that smoking gives rise to a three times higher increase in levels of acrylamide in the blood than any dietary source.  That’s without the several dozen other known carcinogens that you get alongside it.  So, if you enjoy a ciggy with your coffee and burned toast or you brave the cold so you can smoke with your beer and packet of cheese and onion crisps – finding another source of nicotine is still going to be the most effective way of reducing your risk of cancer.

But, as a non-smoker, will having a diet full of crisps, chips and roast potatoes give me cancer?  Quite possibly – along with heart disease, type-II diabetes and a whole heap of other afflictions that result from the modern western diet.  It's all a question of perspective, just bear in mind that there are a thousand other reasons why reducing the levels refined carbohydrates and replacing fried starch with fresh vegetables might be a good idea.

Steve Thomas
Senior Consultant

Steve is a senior consultant in the Applied Science Group and works on integrating chemistry and materials science into product development and systems engineering.