Review of "Caloric Restriction and Aging"

by Ben Best

Richard Weindruch's article "Caloric Restriction and Aging" appears in in the January 1996 SCIENTIFIC AMERICAN. For anyone who has been reading in this subject area, the article contains few surprises. In my mind the most remarkable thing about the article is that it has appeared in the SCIENTIFIC AMERICAN. This will undoubtedly give public profile and scientific interest a big boost (it probably won't be so easy to omit this subject from nutrition texts in the future). Just demonstrating that aging can be slowed by any means may "whet the appetite" of those who "hunger" for more life & more youth. Even those who would rather not "bite the bullet" and limit their food consumption may be more inspired to look for other ways to achieve the same effect.

The article gives great deference to the idea that Caloric Restriction with Adequate Nutrition (CRAN) has not been proven to extend the lifespan of humans. Scientifically, of course, the lifespan benefits of CRAN are unproven for humans. Nonetheless, given the enormous variety of species on which CRAN has been proven to extend lifespan, such skepticism seems extreme to me -- especially when it could be a matter of life or death I can't afford to "wait and see". Have there been short-lived species in which CRAN has been shown NOT to work (apart from self-destructive species, like salmon)? Why would anyone expect CRAN not to be of benefit only to the most long-lived species -- which are obviously the most difficult to study? Especially when there is no evidence that the effectiveness of CRAN varies inversely with the innate longevity of shorter-lived species.

Dr. Weindruch mentions that CRAN animals stay younger according to 90% of 300 biomarkers of aging. What are the other 10%? He suggests a possible increase in osteoporosis with CRAN, but Dr. Walford suspects a decrease. I'm not sure why this is so difficult to resolve. Dr. Weindruch also suggests that CRAN results in a reduced "ability to withstand stress, such as injury, infection or exposure to extreme temperatures." But then he says that stress-resistance has been little-studied in CRAN animals. I'm not sure why he would have mentioned infection when Dr. Walford has stressed the "robust" result of a stimulation of immune response in CRAN animals. Personally, having practiced CRAN for 2 years I can attest to reduced illness. The last 2 Xmas' may be the only 2 in the last 20 during which I have not caught a cold or flu.

I can attest to increased vulnerability to cold with CRAN -- seals & walrus' are stuffed with fat for reasons of insulation. I can also attest to colder hands & feet -- I now habitually wear two pairs of socks in the wintertime (and I sleep in them). I question, however, that these are symptoms of reduced resistance to stress.