Monkeys live longer after eating lighter: study

July 9, 2009
Courtesy Science
and World Science staff

A 20-year study on rhe­sus mon­keys sug­gests that slashing ca­lorie in­take slows the ag­ing pro­cess and leads to long­er life spans, pos­sibly in hu­mans al­so, re­search­ers say.

Pre­vi­ous stud­ies with yeast, worms, flies, and ro­dents have sug­gested that this kind of “ca­lor­ic re­stric­tion” – a re­duc­tion of about 30 per­cent, and very dif­fer­ent from mal­nu­tri­tion – can lead to such health ben­e­fits in some mam­mals. But giv­en the many par­al­lels be­tween rhe­sus mon­keys and hu­mans, this study sug­gests that these ben­e­fits might oc­cur in hu­mans as well, ac­cord­ing to the sci­en­tists.

Calorie-restric­ted mon­key "Can­to." (Cour­tesy Sci­ence)

Ricki Col­man at the Wis­con­sin Na­tional Pri­mate Re­search Cen­ter and col­leagues be­gan the study in 1989 by as­sign­ing adult rhe­sus mon­keys, each be­tween age sev­en and 14, to ei­ther a ca­lor­ic re­stric­tion group or a con­trol group.

Once the mon­keys were as­signed, the re­search­ers be­gan re­duc­ing the di­ets of mon­keys in the ca­lor­ic re­stric­tion group by 10 per­cent every three months un­til they reached the de­sired 30 per­cent cut­back.

At the end of the stu­dy, 37 per­cent of the con­trol group had died of age-re­lat­ed causes while only 13 per­cent of the ca­lor­ic-re­stric­tion group had, they found. This find­ing means that the con­trol mon­keys ex­pe­ri­enced a death rate from age-re­lat­ed con­di­tions such as di­a­be­tes, can­cer, car­di­o­vas­cu­lar dis­ease, and brain at­ro­phy three times that of the ca­lor­ic re­stric­tion group.

Any mon­key that died during the study un­der­went a com­plete nec­rop­sy by a board-certified path­ol­o­gist, so that age-re­lat­ed deaths could be dis­tin­guished from oth­er un­re­lat­ed con­di­tions, the re­search­ers not­ed.

The find­ings are to ap­pear in the July 10 is­sue of the re­search jour­nal Sci­ence.

A study in the No­vem­ber 2007 is­sue of the jour­nal An­nals of the New York Acad­e­my of Sci­ences reached si­m­i­lar con­clu­sions about the ben­e­fits of ca­lor­ic re­stric­tion by com­par­ing Amer­i­cans with some Jap­a­nese popula­t­ions with tra­di­tion­ally spare di­ets.