ScienceHealthyLongLife by Crabsallover: Bacon battered? Today’s headlines explained

Sunday, 10 March 2013

Bacon battered? Today’s headlines explained

crabsallover highlights, key points, comments / links.

Posted on March 7, 2013 by Henry Scowcroft

Another study has linked processed meat to ill health

As if the horsemeat scandal wasn’t bad enough, this morning’s headlines brought further news of the dangers of eating too much processed meat: an increased risk of an early grave.

The news come from a huge Europe-wide study –called EPIC – that Cancer Research UK helps fund, and this is no flash in the pan – the findings are robust and important.

But many people are well aware of the downsides of a high-meat diet, and one could be forgiven for a certain amount of headline fatigue on this topic – after all it seems to come up at least once a year.

So what exactly does this study add to what we already know – and, importantly, should we care?

What’s the difference between ‘processed’ meat and ‘red’ meat?

The distinction is slightly artificial, as it’s basically a tool to allow researchers to classify elements of people’s diets into things like red meat, processed meat, poultry, fish, etc, and then carry out statistical analysis comparing these different groups (see below).

But there is a difference – as explained in this excellent interview from the BBC Today programme this morning. In essence, ‘processed’ meat is meat that has been either cured (like ham, salami etc), or salted or otherwise preserved (e.g. frozen supermarket mince – including burgers – sausages, and bacon).

But it doesn’t include fresh meat or mince – so if you make your own burgers from steak (lucky you), that’s counted as ‘red’, not processed meat.

What did we already know?

We’ve blogged before about meat and cancer, and this lengthy post from a few years back, on a similar large US study, is worth reading.

The long and short of it is a) that certain cancers – particularly bowel cancer – are more common among people who eat the most red or processed meat, b) that these people are also at higher risk of dying from these cancers and c) this is probably because of certain chemicals found in red meat (naturally occurring haem) and processed meat (‘nitroso’ preservatives).

Where do the new findings come from?

EPIC is an enormous study, and has been tracking the diets, lifestyles, medical records and death certificates of around half a million Europeans, from ten different countries, for well over a decade and a half.

This has allowed researchers to periodically pull all the data together and analyse them for patterns, using the sorts of statistical mathematics that make your brain hurt. We’re not going to go into them here, but take our word for it – they’re very complex and rigorous, and the researchers have gone as far as it’s feasible to go to account for other behaviours like smoking, weight, exercise and so on.

Even then, it has to be said, it’s impossible to do this 100 per cent – these factors may still have had a weak influence on the latest findings.

They also performed a statistical ‘stress tests’ on their results, called a ‘significance’ test, which allowed them to work out whether the results are valid. It’s a slightly unfortunate use of the word ‘significance’, as most people take it to mean ‘important’ – whereas here it just means ‘reliable’.

When stories like this hit the headlines, some tend to trot out the well-worn cliché, ‘there are lies, damned lies… and statistics’, and we wish they’d stop – this is a ‘real’ finding, from a large, well-run study… and it matters.

What did they find?

More than 160g of processed meat

Fortunately, this research is published in an ‘open access’ journal, so you can go and read its findings here, free of charge, if you so wish. However, if you don’t speak science, here are the key findings:

Over an average of nearly 13 years, 26,344 study participants died.
Of these, about 5,500 died of cardiovascular diseases, nearly 10,000 of cancer, about 1,000 of respiratory diseases, 700-odd of digestive tract diseases, and about 9,000 of ‘other causes’.
People who ate more than 160g of processed meat per day (NB, that’s a lot of daily meat) were 18 per cent more likely to die than those who ate between 10 and 20g a day.
The link between red meat and premature death wasn’t statistically significant after the researchers had corrected for possible biases.
There was no link between eating more poultry and an early death.
Those who ate the most processed meat also ate the fewest fruit and vegetables and were more likely to smoke, while men who ate a lot of meat also tended to drink heavily – this is significant, in both senses of the word (see below).
If everyone on the study had eaten 20g of meat or less daily – about a sausage day – then the researchers reckon that overall death rate would have dropped by 3 per cent. We reckon that works out as about 800 deaths (out of a total of just over 26,000) over the study period (using the famous ‘back of an envelope’ method).

What does it all mean?

Firstly, this research emphatically doesn’t mean that meat is ‘bad for you’. What it means is ‘too much processed meat, regularly, over too long a time period’ is bad for you. This is an important distinction, and one that often gets lost in the media hullabaloo over ‘Salami Suicide’ and the like.

And meat is good for you, in moderation. As the researchers write:

A diet rich in meat has several potential nutritional benefits… Meat is rich in protein, iron, zinc and B-vitamins, as well as vitamin A. The bioavailability of iron and folate from meat is higher than from plant products such as grains and leafy green vegetables.

The downside is that it’s also often high in cholesterol and saturated fats, as well as the cancer-linked nasties we discussed above. It’s all about balance.

Secondly, as the authors note,

Meat consumption has increased since World War II. While this increase has long been confined to the Western world, that is, North America, North and Western Europe, and Australia/New Zealand, meat consumption is now also on the rise in other countries, such as China, due to their economic development.

This research is more evidence that growing rates of meat consumption across the world are a contributing to increased levels of disease and premature death, and that this should be taken seriously. We saw only yesterday how the world’s cancer leaders want action to tackle the growing global cancer burden, and earlier in the week how the UK’s health outcomes are sliding down international league tables.

And another thing

But there’s another story here too.

As we noted above, the study showed high levels of processed meat consumption tended to go hand in hand with a diet low in fruit and veg, and with high levels of alcohol consumption and smoking. These are generally behaviours that are found more often in lower income groups, and point to an underlying problem – growing income and health inequality (a point excellently summarised by Ally Fogg in the Guardian earlier this week).

So we think access to good quality, affordable food; information about healthy diets (including properly labelled food); and restrictions on how ‘risky’ foods like processed meat are marketed (particularly to children), are all necessary in these straitened times if we’re to prevent the health gap between top and bottom, mapped out so eloquently by Sir Michael Marmot in 2010, from widening further.

And finally, if you’re someone who enjoys a really ‘meaty’ diet (you know who you are), but your diet contains lots of salami, chorizo, ham and other cured meats, you’d do well to occasionally, maybe, think about swapping these for chicken, fish or (thinking environmentally here) vegetables like beans or lentils. We don’t want to wag fingers, nor apportion blame.

We just want people to be aware of what the evidence says.

And basically, it says ‘everything in moderation’ (except smoking).

But you knew that already.

Henry Scowcroft

Images via Wikimedia Commons

Reference

Rohrmann S., Overvad K., Bueno-de-Mesquita H.B., Jakobsen M.U., Egeberg R., Tjonneland A., Nailler L., Boutron-Ruault M.C., Clavel-Chapelon F. & Krogh V. & (2013). Meat consumption and mortality – results from the European Prospective Investigation into Cancer and Nutrition, BMC Medicine, 11 (1) 63. DOI: 10.1186/1741-7015-11-63

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