Com­fort for meat eaters?

Friday - - Living Health -

into car­cino­gens. Red meat is red be­cause of a pro­tein, myo­globin, and the haemoglobin of blood. Th­ese con­tain ‘heme iron’, which, when ox­i­dised by heat, be­comes toxic. Th­ese have been shown to dam­age the cells of the di­ges­tive tract wall, but it isn’t proved that those cells then be­come ma­lig­nant: tu­mour-form­ing.

Another is­sue is het­e­ro­cyclic amines – toxic sub­stances pro­duced when you cook meat – but th­ese are pro­duced when you cook white meat like chicken, too.

Pro­cessed meat is on the dan­ger list be­cause of the com­pounds that come from the salts that are cru­cial in the cur­ing process: the ni­trates and ni­trites. Cooked and pass­ing through the di­ges­tive sys­tem, th­ese turn into a com­pound that is cer­tainly can­cer-form­ing – and this is also present in peo­ple who eat a lot of red meat. The risk fac­tors for those who eat a lot of pro­cessed meat are slightly higher in the sur­veys than they are for peo­ple who eat mainly red meat. But, again, there are wor­ry­ing holes in the re­search. The Span­ish eat twice as much cured meat as peo­ple in Bri­tain, but col­orec­tal can­cer rates there are no higher.

So the search for a cul­prit goes on – with a new idea emerg­ing in the med­i­cal press reg­u­larly. This year the in­ter­est is in car­ni­tine, a harm­less sub­stance in meat of­ten added to en­ergy drinks. US re­searchers an­nounced in April that they be­lieved car­ni­tine was act­ing as a fuel for mi­crobes that pro­duce a com­pound that causes a build-up of plaque in the ar­ter­ies. This throws a new light not on col­orec­tal can­cer but the old the­sis about meat and its role in heart disease.

For the meat eater, only one happy re­sult has emerged from all th­ese in­ves­ti­ga­tions. Re­searchers in China have been fas­ci­nated by the ef­fects of a new meat-heavy diet on peo­ple who tra­di­tion­ally ate very lit­tle. The av­er­age I am a de­voted eater of meats – white, red and pro­cessed. If I go to Spain, I take an ex­tra-large suit­case, stuff­ing it with cured meats on the jour­ney home. And I don’t want to stop. So I turned for sup­port to Pro­fes­sor David Colquhoun, a col­lec­tor of du­bi­ous and con­tra­dic­tory re­search that he ex­poses on his pop­u­lar blog, Im­prob­a­ble Sci­ence. (He is also an em­i­nent phar­ma­col­o­gist at Univer­sity Col­lege, Lon­don.) Colquhoun’s view is that while there are risks ex­posed by some of the long-term stud­ies of diet and red and pro­cessed meat, they are too small to get wound up about.

The big­gest study of all, the Euro­pean Prospec­tive In­ves­ti­ga­tion into Can­cer and Nu­tri­tion, fol­lowed 450,000 peo­ple in 10 coun­tries for 12 years. It con­cluded that there was a “mod­er­ate pos­i­tive as­so­ci­a­tion” be­tween pro­cessed meat con­sump­tion and mor­tal­ity.

But that risk was about one 20th of the risk of smok­ing caus­ing can­cer and so small that you could not, Colquhoun says, ad­e­quately al­low for all the other fac­tors that might blur the re­sults – and those re­sults don’t jus­tify the risk warn­ings. Even if the stud­ies did prove a causal re­la­tion­ship be­tween meat and can­cer, they mean that eat­ing a ham­burger a day short­ens your life ex­pectancy from 80 to 79 years. “Sounds rather small,” com­ments Colquhoun.

“The prob­lem is that it’s hard be­ing an epi­demi­ol­o­gist,” Colquhoun said to me af­ter the car­ni­tine re­search came out. “Com­pe­ti­tion for fund­ing is an in­cen­tive to ex­ag­ger­ate. Peo­ple don’t like pa­pers that don’t come to any solid con­clu­sion – and some sci­en­tists like to get me­dia at­ten­tion.”

Colquhoun’s scep­ti­cism was com­fort­ing. But it did not let me off the hook. There are a host of very good rea­sons to cut out meat eat­ing, as I found while re­search­ing my new book on cheap meat, which was sparked by the UK’s horse­meat scan­dal in Jan­uary. Mod­ern live­stock farm­ing and de­mand for ever-cheaper meat is madly ex­pen­sive on re­sources. It brings huge threats to the en­vi­ron­ment and an ap­palling cost in an­i­mal suf­fer­ing.

But then, as I con­tem­plated a veg­e­tar­ian fu­ture, I was saved by a star­tling piece of re­search done in my own kitchen. I charted one week’s meat con­sump­tion among our fam­ily of four and found that, al­though we ate some meat ev­ery day, in to­tal we ate very lit­tle. A spaghetti Bolog­nese for four of us, with some left­overs, used just 200g of meat, get­ting us into the Har­vard School of Pub­lic Health’s safety zone. And, tak­ing that week’s an­i­mal pro­tein eat­ing and mul­ti­ply­ing by 52, I found we were eat­ing just 25kg of meat a year.

But th­ese are the con­so­la­tions of a wor­ried, middleclass foodie. My diet is not rep­re­sen­ta­tive. To get within the pa­ram­e­ters that the Har­vard School of Pub­lic Health study says will re­duce the disease risks to lev­els near those that veg­e­tar­i­ans en­joy, we need to re­duce our con­sump­tion of the risky meats to just 350g a week – just a cou­ple of sausages and one steak. Or go meat-free two days a week. The great meat feast is over. Alex Ren­ton is the au­thor of Planet Car­ni­vore - Why Cheap Meat Costs the Earth, avail­able on Ama­zon.

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