The Value of Late Onset CR

From what I have seen, most of the benefits will still be gained if done later in life.  This makes sense to me since a lot of the declines in health and pathologies occur at those later periods.  MR had a stickied thread on a CR forum about studies on late life onset of CR in mice and the talks you (matt) posted showing the age where CR beats out fitness seem to fit along these lines.

"The study, appearing this week in the Proceedings of the National
Academy of Sciences (news - web sites), showed that mice at the
relatively advanced age of 19 months that were placed on a restricted
calorie diet lived 42 percent longer than litter mates who continued
to eat a standard diet."

"Spindler said that while older mice that go on a diet do live longer
than those that don't, they still don't live as long as mice that
have been on restricted diets for a lifetime. He said mice put on
low-calorie diets just after birth have been known to live up to four
years, almost twice as long as normal mice and months longer than the
aged mice in the new study."

He was 41 when he died (123 human years). He wasn't CR'd until the latter part of his life either... equiv to around 50-60 year old human.

An interesting article from 2004, and a more recent paper:

http://www.imminst.o...=0

Proc Natl Acad Sci U S A. 2004 Apr 13;101(15):5524-9. Epub 2004 Mar 25. Links
Temporal linkage between the phenotypic and genomic responses to caloric restriction.Dhahbi JM, Kim HJ, Mote PL, Beaver RJ, Spindler SR.
BioMarker Pharmaceuticals, Incorporated, 900 East Hamilton Avenue, Campbell, CA 95008, USA.

Caloric restriction (CR), the consumption of fewer calories while avoiding malnutrition, decelerates the rate of aging and the development of age-related diseases. CR has been viewed as less effective in older animals and as acting incrementally to slow or prevent age-related changes in gene expression. Here we demonstrate that CR initiated in 19-month-old mice begins within 2 months to increase the mean time to death by 42% and increase mean and maximum lifespans by 4.7 (P = 0.000017) and 6.0 months (P = 0.000056), respectively. The rate of age-associated mortality was decreased 3.1-fold. Between the first and second breakpoints in the CR survival curve (between 21 and 31 months of age), tumors as a cause of death decreased from 80% to 67% (P = 0.012). Genome-wide microarray analysis of hepatic RNA from old control mice switched to CR for 2, 4, and 8 weeks showed a rapid and progressive shift toward the gene expression profile produced by long-term CR. This shift took place in the time frame required to induce the health and longevity effects of CR. Shifting from long-term CR to a control diet, which returns animals to the control rate of aging, reversed 90% of the gene expression effects of long-term CR within 8 weeks. These results suggest a cause-and-effect relationship between the rate of aging and the CR-associated gene expression biomarkers. Therefore, therapeutics mimicking the gene-expression biomarkers of CR may reproduce its physiological effects.

PMID: 15044709 [PubMed - indexed for MEDLINE]

Edited by Matt, 10 December 2009 - 06:39 PM.