Drastic Diet May Extend Human Life, Study Finds

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Drastic diet may extend human life, study finds

Nov. 15, 2007

Special to World Science

 

Eating little may help people live longer, a study has found, of­fer­

ing sup­port for an idea that has tan­ta­lized sci­en­tists for dec­ades.

 

Re­search­ers have long known that cut­ting an­i­mals' food supply to near-

starva­t­ion lev­els gives them—for rea­sons still un­clear—long­er lives

and health­i­er old age. Stud­ies have found that in hu­mans, too,

sharply re­duced eat­ing is as­so­ci­at­ed with health­i­er ag­ing, as long as

nu­tri­tion­al ba­lance is main­tained.

 

Less food on the plate could mean a longer life, researchers say.

(Courtesy pdphoto.org)

 

But wheth­er this prac­tice could ac­tu­ally length­en our lives has re­

mained un­cer­tain.

 

Some sci­en­tists have ar­gued that it's doubt­ful, be­cause hu­mans al­

ready live un­usu­ally long. Only one small past study in hu­mans of­

fered weak ev­i­dence that peo­ple eat­ing less lived long­er, ac­cord­ing

to its au­thors, who were al­so in­volved in the new re­search.

 

The new study is the first to probe the claim by com­par­ing hu­man

popula­t­ions, wrote the Amer­i­can and Jap­a­nese sci­en­tists in a re­port

on their find­ings.

 

More­o­ver, they added, it's " the first study that has shown ex­tend­ed

av­er­age and max­i­mum life span in a hu­man popula­t­ion that is po­ten­

tially due to " re­duced eat­ing. The prac­tice is known as ca­lor­ic re­

stric­tion.

 

The re­search­ers stud­ied res­i­dents of the Jap­a­nese is­land of Ok­i­nawa,

known through much of the last cent­ury both for ex­cep­tion­ally long-

lived in­hab­i­tants and for very spare, though bal­anced di­et­s. The in­

vest­i­gat­ors said they found ev­i­dence that the two things are at least

par­tially re­lat­ed.

 

Al­though that con­clu­sion might seem ob­vi­ous to some—given the past re­

search—the sci­en­tists wrote that to reach it, they had to ac­count for

some fac­tors that had ham­pered sys­tem­at­ic anal­y­sis. For one, Oki­na­wan

di­ets have changed, be­com­ing richer since about the end of the 1960s.

Al­so, it was­n't clear how to best as­sess his­tor­i­cal di­e­tary in­take

and com­pare it to that of oth­er popula­t­ions.

 

The find­ings, by Brad­ley Will­cox of the Pa­cif­ic Health Re­search In­sti­

tute and John A. Burns School of Med­i­cine in Hon­o­lu­lu and col­leagues,

ap­pear in the No­vem­ber is­sue of the re­search jour­nal An­nals of the

New York Acad­e­my of Sci­ences.

 

An­i­mal tests have found that the ex­treme di­et­ing of ca­lor­ic re­stric­

tion en­tails cut­ting some 40 per­cent of calo­ries to get the strongest

life-extending ef­fects. An­i­mals placed on such reg­i­mens live up to 40

per­cent long­er than nor­mal, as long as the di­et re­mains nu­tri­tionally

bal­anced. (Some sci­en­tists pro­pose—a­gain based mostly on an­i­mal test­s—

that tak­ing a sub­stance called res­ver­a­trol may rep­li­ca­te ca­lor­ic re­

stric­tion's ben­e­fits, with­out the un­pleas­ant­ness.)

 

Will­cox and col­leagues found that at least from the mid-20th cen­tu­ry

through the 1960s, the Oki­na­wan di­et was about 11 per­cent short of

what would nor­mally be rec­om­mended to main­tain body weight. As of

1995, the av­er­age Oki­na­wan lived about five years long­er than the av­

er­age Amer­i­can, and about 18 months more than the av­er­age Jap­a­nese.

 

The is­landers' spar­tan di­ets may have been a leg­a­cy of " pe­ri­odic crop

fail­ures that oc­curred in Oki­na­wa in the early 20th cen­tu­ry and a

long his­to­ry of mar­gin­al food sup­ply, " the re­search­ers wrote.

 

The study had some weak­nesses, they added; for in­stance, it could­n't

rule out that Oki­na­wans lived long­er be­cause of the types of nu­tri­

ents they ate, rath­er than the amount. None­the­less, the " ten­ta­tive "

find­ings fit with a broad ar­ray of an­i­mal stud­ies, and point to a

need for still more re­search, Will­cox and col­leagues wrote.

 

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