WHAT’S THE BEST DIET FOR OUR PLANET?

The nev­erend­ing del­uge of in­for­ma­tion about our food choices can be baf­fling. So should we all be­come ve­gan, or can we re­ally have our steak and eat it?

BBC Earth (Asia) - - Front Page - WORDS BY JOSH GAB­BATISS

Diet can be a con­tentious is­sue, sub­ject to the forces of per­sonal ethics, re­li­gious be­liefs and health con­cerns. But when it comes to the en­vi­ron­ment, for many peo­ple it’s an open-and-shut case. “The ev­i­dence is all there, you just need to look for it,” my ve­gan friend told me re­cently, with the kind of sanc­ti­mo­nious air that puts some peo­ple off ve­g­an­ism al­to­gether.

The thing is, although I’m not a ve­gan my­self, I sus­pect he’s prob­a­bly right. While I’m quite sure this is not the stated aim of most ve­g­ans, ab­stain­ing from an­i­mal prod­ucts does seem to give you the moral high ground in the en­vi­ron­men­tal stakes. I’ve watched Cowspiracy, I know the deal. At the same time, I’ll ad­mit to be­ing a lit­tle put off by how self-as­sured some peo­ple seem in their di­etary choices. Sel­dom does all the ev­i­dence point in one di­rec­tion, and when con­sid­er­ing some­thing as mul­ti­fac­eted as the global food sys­tem, per­haps it’s un­wise to gen­er­alise.

In re­cent years, sci­en­tists and the pub­lic have be­come in­creas­ingly aware that the food we eat can have neg­a­tive im­pacts on the planet. With this in mind, it’s worth ask­ing – whichever side of the fence you’re on – whether the ev­i­dence re­ally is ‘all there’, and whether there ex­ists a diet that is ob­jec­tively best for the en­vi­ron­ment.

This is not a straight­for­ward is­sue. Ac­cord­ing to fig­ures from the Con­sul­ta­tive Group on In­ter­na­tional Agri­cul­tural Re­search (CGIAR), one-third of our green­house gas emis­sions come from agri­cul­ture. But that’s just one fac­tor. Our food sys­tem is also the lead­ing cause of de­for­esta­tion, land use change and bio­di­ver­sity loss in the world. Then there’s over­fish­ing, pol­lu­tion, ground­wa­ter de­ple­tion, ex­ces­sive fer­tiliser use and pes­ti­cides to con­tend with as well. With all th­ese is­sues to con­sider, a ‘sus­tain­able’ diet might mean dif­fer­ent things de­pend­ing on who you talk to. How­ever, cer­tain trends cut through the noise – most no­tably, an em­pha­sis on more plant-based di­ets.

The idea that veg­e­tar­i­an­ism is good for the planet is rel­a­tively new. Back in 1971, a vi­sion­ary

book by Frances Moore Lappé en­ti­tled Diet For A

Small Planet sug­gested that world hunger could be re­me­di­ated if less em­pha­sis was placed on meat in West­ern di­ets. Her recipes for spinach lasagne and soy burg­ers caused a stir at the time, but skip for­ward 46 years and of­fi­cial guide­lines ev­ery­where from the Netherlands to the US em­pha­sise lower meat con­sump­tion for a healthy body and a healthy planet. Veg­e­tar­i­an­ism has gone main­stream. In a re­port from the US-based 2015 Di­etary Guide­lines Ad­vi­sory Com­mit­tee, the authors con­cluded: “Con­sis­tent ev­i­dence in­di­cates that, in gen­eral, a di­etary pat­tern that is higher in plant-based foods … and lower in an­i­mal-based foods is more health pro­mot­ing and is as­so­ci­ated with lesser en­vi­ron­men­tal im­pact than is the cur­rent av­er­age US diet.”

Th­ese are not empty words. Study after study has demon­strated the ben­e­fi­cial ef­fects of a plant-based diet for the en­vi­ron­ment. A pa­per pub­lished last year in

Pro­ceed­ings Of The Na­tional Academy Of Sciences

con­cluded that a mass switch to veg­e­tar­i­an­ism would bring down food-re­lated green­house gas emis­sions by a whop­ping 63 per cent, while even just stick­ing to global health guide­lines re­gard­ing meat con­sump­tion (so lay­ing off the burg­ers a bit) would be enough to re­duce emis­sions by 29 per cent.

As for ve­g­an­ism, it does seem to be edg­ing ahead in the planet-sav­ing stakes. Many of the is­sues that arise from farm­ing live­stock for meat – meth­ane emis­sions from an­i­mal di­ges­tion, pol­lu­tion from farms, en­ergy-in­ten­sive feeds – also ap­ply to the dairy and egg in­dus­tries. If wide­spread ve­g­an­ism was en­acted, that 63 per cent re­duc­tion in emis­sions shoots up to 70 per cent.

IN DE­FENCE OF CARNIVORES

Th­ese seem like hard fig­ures to ig­nore, and yet ig­nored they are by the vast ma­jor­ity of peo­ple. While plant-based di­ets have now been nor­malised in a way that was prob­a­bly unimag­in­able in Lappé’s day, prac­tis­ing veg­e­tar­i­ans and ve­g­ans are still rel­a­tively thin on the ground. It’s thought only 2 per cent of the UK pop­u­la­tion is veg­e­tar­ian, and less than 1 per cent is ve­gan.

But stop the press! Maybe cut­ting out an­i­mal prod­ucts en­tirely, or even nearly en­tirely, isn’t nec­es­sar­ily the way to go. There have been stud­ies pub­lished in rep­utable jour­nals which sug­gest that vegeta­bles may not be our sole sal­va­tion. Back in 2015, a par­tic­u­lar pa­per caused a me­dia firestorm when its lead au­thor, Prof Paul Fis­chbeck of Carnegie Mel­lon Univer­sity, made the dec­la­ra­tion that “eat­ing let­tuce is over three times worse in green­house gas emis­sions than eat­ing ba­con”. “LET­TUCE WORSE THAN BA­CON” screamed the head­lines, as com­men­ta­tors smugly ob­served that

“While plant­based di­ets have now been

nor­malised, veg­e­tar­i­ans and ve­g­ans are still rel­a­tively thin on the ground”

veg­e­tar­i­an­ism isn’t all it’s cracked up to be.

Other re­search has sug­gested that at least some de­gree of car­nivory could be ben­e­fi­cial. A re­cent anal­y­sis of 10 dis­tinct di­ets, each with a dif­fer­ent ra­tio of meat and an­i­mal prod­ucts, saw ve­g­an­ism rel­e­gated to fifth po­si­tion when it came to max­imis­ing sus­tain­able land use, be­low dif­fer­ent de­grees of veg­e­tar­i­an­ism and om­nivory. This comes as a blow to ve­g­ans who tend to as­sume, un­der­stand­ably, that due to the well-doc­u­mented prob­lems with live­stock farm­ing, their diet plan au­to­mat­i­cally places them in the top spot.

THE DEVIL IN THE DE­TAIL

How can re­searchers come to such dif­fer­ent

con­clu­sions? Well, the short an­swer is be­cause they’re try­ing to an­swer a com­pli­cated ques­tion. To work out the best diet for the planet, sci­en­tists tally up the en­vi­ron­men­tal costs of the pro­duc­tion, trans­porta­tion and mar­ket­ing of foods, and then com­pare the op­tions. Yet there are many such costs in­volved, and there­fore many po­ten­tial met­rics. Some re­searchers com­pletely ig­nore cer­tain as­pects, such as the amount of food that is wasted, while oth­ers place more em­pha­sis on as­pects that they deem to be most rel­e­vant.

For ex­am­ple, there is no ques­tion that red meat pro­duces far more emis­sions than veg­etable pro­tein sources like lentils and beans – around 13 times more, in fact. But if you’re fo­cus­ing on land use, then cows and sheep start to make a lot of sense. Live­stock, and food for live­stock, can be farmed on land that’s un­suit­able for hu­man crops, so if that land can be put to good use it will im­prove the ef­fi­ciency of food pro­duc­tion in a given area.

As for the idea that let­tuce is worse for the en­vi­ron­ment than ba­con, the re­searchers had opted to an­a­lyse emis­sions on a per calo­rie ba­sis. This seems an un­fair com­par­i­son. After all, no one is sug­gest­ing that veg­e­tar­i­ans re­place two rash­ers of ba­con at break­fast with the 3.3kg of let­tuce it would take to match them, calo­rie-wise. But what Fis­chbeck and his col­leagues wanted to em­pha­sise was the need to con­sider foods on their in­di­vid­ual merit, rather than as­sum­ing that just be­cause you have cho­sen diet A or diet B, you are au­to­mat­i­cally sav­ing the world.

VA­RI­ETY IS THE SPICE OF LIFE

This is a good point. There is an aw­ful lot of va­ri­ety in green cre­den­tials, even within food groups. Beef

and lamb pro­duce far more emis­sions than pork, which in turn pro­duces more than chicken. As for fish, the vari­a­tion in im­pact is enor­mous, so di­verse are the means by which dif­fer­ent species are caught or farmed and the lev­els of threat they are all un­der in dif­fer­ent parts of the world.

Fruits and vegeta­bles are even more com­pli­cated. Ro­bust pro­duce that can be grown in fields, such as cab­bage and pota­toes, re­sult in rel­a­tively low green­house gas pro­duc­tion, but if a plant re­quires in­tense re­frig­er­a­tion, or has to be grown in a hot house, alarm bells be­gin to ring. Sim­i­larly, vegeta­bles which must be flown great dis­tances be­fore they ar­rive on your plate come with a size­able emis­sions price tag. That’s be­fore you even con­sider the huge quan­ti­ties of wa­ter needed to grow citrus fruits, or the pes­ti­cides that are pumped into banana plan­ta­tions. Green­house gases, though the most widely used mea­sure of im­pact, only tell one side of a far more com­pli­cated story, and those who opt for more plant-based di­ets must be wary of re­plac­ing the an­i­mal parts of their diet with plants that cause harm in other ways.

The fact is, whichever la­bel you choose to de­fine your­self – ve­gan, veg­e­tar­ian, pesc­etar­ian or om­ni­vore – there’s no room for com­pla­cency. Ul­ti­mately, the choices you make about your food are just as im­por­tant as the diet tribe you be­long to.

FU­TURE FARM­ING

Another layer of com­plex­ity is the va­ri­ety of farm­ing strate­gies in use. Rather than de­mon­is­ing meat, some ar­gue, poli­cies could en­sure that live­stock farm­ing is more ef­fi­cient and pro­duces fewer green­house gases. This may sound a lit­tle too good to be true, but sci­en­tists have sug­gested that by sim­ply sup­ple­ment­ing the graz­ing di­ets of cat­tle and sheep with higher qual­ity feeds, emis­sions from live­stock farm­ing could be re­duced by nearly a quar­ter in the next two decades. So rel­a­tively sim­ple changes can make a dif­fer­ence, but when con­sid­er­ing the scale of our food sys­tem’s im­pact on the planet, some­thing big­ger might be nec­es­sary. In­dus­trial agri­cul­ture has been our go-to sys­tem for some time, but the overuse of pow­er­ful chem­i­cal pes­ti­cides and fer­tilis­ers is re­sult­ing in de­graded ecosys­tems that are ul­ti­mately un­sus­tain­able.

The so­lu­tion to this could be agroe­col­ogy, which op­er­ates un­der the mantra of ‘work­ing with na­ture, rather than against it’, restor­ing bio­di­ver­sity and ecosys­tem func­tions in or­der to en­sure pro­duc­tiv­ity. Th­ese prin­ci­ples are al­ready be­ing put into ac­tion. As

“Ul­ti­mately, the choices you make about your food are just as im­por­tant as the diet tribe you be­long to”

it stands, rice ac­counts for up to a third of our an­nual wa­ter use, but a low-wa­ter agroe­co­log­i­cal method known as Sys­tem of Rice In­ten­si­fi­ca­tion (SRI) is in­creas­ingly be­ing used to pro­duce rice yields up to 50 per cent larger. Wa­ter is only ap­plied to the rice when needed, com­post is used in­stead of chem­i­cal fer­tilis­ers, and farm­ers weed by hand, in­stead of us­ing her­bi­cides. Us­ing this method, Su­mant Ku­mar, a farmer from the In­dian state of Tamil Nadu, has smashed the pre­vi­ous an­nual rice-grow­ing record by an as­ton­ish­ing three tonnes. Whether it in­volves rice, pigs, fish or ap­ples, agroe­col­ogy is about dis­man­tling the cur­rent sys­tem and plac­ing power into the hands of small-scale pro­duc­ers and fam­ily farms. If this is start­ing to sound a bit too ‘eco-war­rior’ for your taste, it’s worth not­ing that even the UN is be­hind this trend. “Mod­ern agri­cul­ture, which be­gan in the 1950s, is more re­source in­ten­sive, very fos­sil fuel de­pen­dent, us­ing fer­tilis­ers, and based on mas­sive pro­duc­tion. This pol­icy has to change,” de­clared UN rep­re­sen­ta­tive Prof Hi­lal Elver back in 2014, ex­plain­ing that it is agroe­col­ogy that holds the key to a sus­tain­able fu­ture.

IN­CON­VE­NIENT TRUTHS

A truly en­vi­ron­men­tally friendly diet re­lies on ma­jor sys­temic changes, but in­di­vid­ual di­ets also need to change. The va­ri­ety of data on of­fer can give the im­pres­sion of flip-flop­ping within the sci­en­tific com­mu­nity, but it’s more in­dica­tive of the sheer com­plex­ity of the sub­ject – not to men­tion the com­pet­ing in­ter­ests of stake­hold­ers in the food in­dus­try. In fact, cer­tain trends are clear.

Head­lines about the evils of let­tuce and ve­g­an­ism

“A truly en­vi­ron­men­tally friendly diet re­lies on ma­jor sys­temic changes, but in­di­vid­ual di­ets also need to change”

sav­ing the world may seem mis­lead­ing, but it would be disin­gen­u­ous to pre­tend that farm­ing an­i­mals isn’t a prob­lem. Peo­ple in the West are eat­ing too much meat, and as coun­tries like China and In­dia be­come wealth­ier, their de­mand for it is in­creas­ing. Dr Ra­jen­dra Pachauri, ex-chair­man of the UN’s In­ter­gov­ern­men­tal Panel on Cli­mate Change called for one meat-free day a week as a way of per­son­ally mak­ing a dif­fer­ence, and this seems like a good place to start. Other sen­si­ble sug­ges­tions in­clude choos­ing fish from sus­tain­able or cer­ti­fied stocks, buy­ing vegeta­bles that store well, and avoid­ing food waste. The kind of mass switch to ve­g­an­ism en­vis­aged by some stud­ies is prob­a­bly un­re­al­is­tic, but rel­a­tively small changes in the way we eat can pro­duce size­able ef­fects. We should be at a stage where sug­ges­tions like Pachauri’s are not con­tro­ver­sial, be­cause while we may not have all the in­for­ma­tion, we cer­tainly have enough to make a dif­fer­ence.

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ABOVE: Shelves groan with food at a Tesco dis­tri­bu­tion plant in Read­ing, UK

RIGHT: Mod­ern West­ern di­ets still con­tain too much meat

BE­LOW: Re­cently, ‘dump­ster divers’ have

put food waste in the spotlight by

sal­vaging ed­i­ble food from skips

BE­LOW: Agroe­col­ogy in­volves work­ing with na­ture and putting con­trol back in the hands of small-scale farm­ers

BE­LOW:

Peo­ple who fol­low veg­e­tar­ian di­ets should still be aware of how their favourite foods af­fect the planet

RIGHT:

Red meats, like beef and lamb, have a greater im­pact on the planet than chicken

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