Suppressing Growth Hormone to Extend Longevity in Mice

It should not be a surprise to see suppression of growth hormone in mammals result in extended healthy life spans. After all, the present record holder for the Mprize for mouse longevity involved gene engineering of a growth hormone deficient breed. Here researchers demonstrate benefits in a mouse breed used for Alzheimer's research, as it develops accelerated degeneration of the brain: "people sometimes take growth hormone, believing it will be the fountain of youth. ... Many older people have been taking growth hormone to rejuvenate themselves. These results strongly suggest that growth hormone, when given to middle aged and older people, may be hazardous. ... The scientists studied the compound MZ-5-156, a 'growth hormone-releasing hormone (GHRH) antagonist.' They conducted their research in the SAMP8 mouse model, a strain engineered for studies of the aging process. Overall, the researchers found that MZ-5-156 had positive effects on oxidative stress in the brain, improving cognition, telomerase activity (the actions of an enzyme which protects DNA material) and life span, while decreasing tumor activity. MZ-5-156, like many GHRH antagonists, inhibited several human cancers, including prostate, breast, brain and lung cancers. It also had positive effects on learning, and is linked to improvements in short-term memory. The antioxidant actions led to less oxidative stress, reversing cognitive impairment in the aging mouse."



It's really ironic and instructive that many of the early fads in the life extension community later actually turn out to shorten life rather than lengthen it.

The prime example would the early fad for mega-doses of the antioxidant vitamins ACE, which mega-studies clearly show shorten life:

"Bottom line: on average supplements increase an ordinary adult’s chance of dying by 7%. While selenium reduces death rates by 0.2%, beta carotene increases them by 9%, vitamin C and E by 6%, and vitamin A by 20%."

Another example, I fear, is the recent transhumanist fad for the paleo-diet. I've looked into this and concluded the evidence is null at best, and negative at worst. The low-carb approach has been tried via the Atkins diet, and on balance, the evidence actually suggests a low-carb diet shortens life:

"A Swedish prospective study with a follow-up of approximately 10 years came to the results that the people eating most similar to Atkins diet had a hazard ratio of 1.2 for all-cause mortality compared to controls, and a hazard ratio of 1.4 for cardiovascular mortality."

The lesson is that any non-standard supplement or diet can just as easily shorten life as lengthen it, all other things being equal, and you should be very wary of following fads without strong positive evidence.

Posted by: zarzuelazen at December 24th, 2010 11:51 PM

Post a comment; thoughtful, considered opinions are valued. New comments can be edited for a few minutes following submission. Comments incorporating ad hominem attacks, advertising, and other forms of inappropriate behavior are likely to be deleted.

Note that there is a comment feed for those who like to keep up with conversations.