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Higher IGF-1, Increased Lifespan for men


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#1 Matt

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Posted 28 May 2008 - 05:35 PM


Most CRers want lower IGF-1, however I don't believe there would be increased mortality with low IGF-1 in CRers for many reasons which I might go into later. What do you think?
http://jcem.endojour...2007-1633v1.pdf

http://www.scienceda...80527084252.htm
ScienceDaily (May 28, 2008) — Elderly men with higher activity of the hormone IGF-1--or insulin-growth factor 1--appear to have greater life expectancy and reduced cardiovascular risk, according to a new study.
IGF-1 is a hormone similar in molecular structure to insulin. It is released from the liver and plays an important role in childhood growth and continues to have anabolic effects in adults.

In this study, researchers evaluated 376 healthy elderly men between the ages of 73 and 94 years. A serum sample was taken from each subject at the beginning of the study and researchers were contacted about the status of the participants over a period of eight years.

Subjects with the lowest IGF-1 function had a significantly higher mortality rate than subjects with the highest IGF-1 bioactivity. These results were especially significant in individuals who have a high risk to die from cardiovascular complications.

These new findings come as a result of a new form of testing for IGF-bioactivity. Researchers in this study used a new method, a bioassay, to measure the function of IGF-1 in the blood. Compared to commonly used methods to measure IGF-1, the IGF-1 bioassay gives more information about the actual function (bioactivity) of circulating IGF-1 in the body.

"The bioassay allowed us to more clearly see the association between high circulating IGF-1 bioactivity and extended survival," said Michael Brugts, MD, of the Erasmus Medical Center in Rotterdam, The Netherlands and lead author of the study. "Interestingly, we could not find such a relationship when IGF-1 in blood was measured with the more commonly used methods."

Immunoassays, commonly used previously to determine IGF-1 circulation levels, remove certain proteins that interfere with accurate measurements. Recent studies however have found that these proteins are important modulators of IGF-1 bioactivity. The bioassay used in this study does not disregard or remove this protein, thus enabling researchers to have a more accurate understanding of IGF-1 function.

Determination of IGF-1 function using the bioassay opens the possibility to gather new insights about the functions of IGF-1 in the body, said Brugts.

Edited by Matt, 28 May 2008 - 05:42 PM.


#2 FunkOdyssey

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Posted 28 May 2008 - 06:50 PM

Probably correlation and not causation (supplementing with growth hormone would not have the same effect as naturally high levels which are an indicator of good health and younger biological age).

Edited by FunkOdyssey, 28 May 2008 - 06:50 PM.


#3 VictorBjoerk

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Posted 28 May 2008 - 07:24 PM

isn't a diet high in sugar associated with high IGF-levels so wouldn't the men who eat more sugar have more IGF than the others?Is this really a good thing?
Or is it just that the biologically younger and healthier men of the group have naturally higher IGF levels?

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#4 rhodan

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Posted 28 May 2008 - 08:05 PM

This study indicates that intermittent fasting (IF) results in better (lower) than CR levels of blood glucose and insulin.

And in addition, IF gives a higher IGF-1 level than CR and even than control (Ad libidum) :

Posted Image

Edited by rhodan, 28 May 2008 - 08:05 PM.


#5 Guest_Kismet_*

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Posted 29 May 2008 - 02:05 PM

However, there are no studies that consistently show IF is superior to or at least as good as CR, not even in rodents. So far I've only seen mixed results about IF, with strain-specific influence on maximum life span :-/
Besides IF being quite an abrupt change is in stark contrast to the CR "slow-induction of restriction" philosophy, which is (afaik) based on some studies showing that a sudden calorie restriction diminished some/all (?) benefits of CR.

Thus it is premature to assume IF does anything, though, it is promising.

#6 niner

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Posted 30 May 2008 - 05:16 AM

However, there are no studies that consistently show IF is superior to or at least as good as CR, not even in rodents.
[...]
Thus it is premature to assume IF does anything, though, it is promising.

There is a very old study from Spain showing that IF in humans is much better than ad Lib., so I don't think it's premature to think that IF does something.

#7 Guest_Kismet_*

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Posted 30 May 2008 - 10:00 AM

I'll have a look at that study (if I can find it), but you could give me more of a hint as to its title.

#8 edward

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Posted 03 June 2008 - 01:56 AM

That study is an interesting one and is one of my reasons for interest in IF. http://www.pnas.org/...ull/100/10/6216... There is another variable in these CR and IF studies, macronutrient composition which may in and of itself influence IGF-1 levels, life extension etc... Add in CRing this Macronutrient profile by 60% or restricting it every other day and you have other things at work. The NIH-07 diet that the rats were fed (whether it was restricted CR, given every other day IF or Ad Lib, or their PF mimicking the slightly lower calories consumed by the IF mice) may not be ideal (for mice, of course not for humans but definitely for mice it may be a pro aging diet, so therefore any method for restricting such a diet may be an improvement) http://www.ehponline...3/rao-full.html

This NIH-07 diet is 24% protein, 5% fat, and 3.5% fiber and 67.5% carbohydrates. For humans obviously this would not be a great diet, at least a 20% fat intake in humans has been shown to be beneficial in terms of appetite satiation, not to mention getting the fatty acids we need. Most CRs try to "Zone" their macro nutrients. No I'm not going to plug low carb here ;)

But forget humans for awhile we are talking rats apparently 5% fat is bare minimum for them, so even they may need a little bit more fat, so CRing this at 60% puts them below the bare minimum they actually need to survive well (ie not true CR because their nutritional bases are not covered). Furthermore there is evidence http://www.ehponline...3/rao-full.html that rats may need a protein percentage more along the lines of 15% so restricting this in some way may be beneficial in and of itself...

The point I am making is that perhaps all the conflicting IF studies may have something to do with Macronutrient differences in what the rats were fed.

Edited by edward, 03 June 2008 - 02:02 AM.


#9 niner

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Posted 03 June 2008 - 03:50 AM

I'll have a look at that study (if I can find it), but you could give me more of a hint as to its title.

There's a lot of literature out there; go to Pubmed and enter "intermittent fasting" (with the double quotes) as the target of the search, then click the 'go' button. This brings up 75 hits.

Here's a historical reference from 1946!
Carlson AJ, Hoelzel F. Apparent prolongation of the life span of rats by intermittent fasting. J Nutr 1946;31:363–75.

And here's the Spanish study. Upon looking at this, I have to take back what I said; it's not exactly IF because the feeding on alternate days was not ad lib. In my notes (below) I called it "intermittent CR", not intermittent fasting, so I must have just gotten confused. I guess I should start either IF or CR to protect my brain...

Valejo EA, La dieta del hambre a dias alternos en la alimentacion de los viejos. Rev Clin Exp. 1957; 63: 25-31. (The alternate-day hunger diet in the feeding of the elderly.) An actual clinical study of Intermittent CR in humans. 60 residents of home for elderly, avg age 72. Half got 2300 Cal/d, other half alternated days between the same 2300 Cal diet and one with only 885 Cal, avging 1593/d for 3 y. Overall nutritional plan was not v. good, but CR group spent half as many days in infirmary, and only half as many died.

#10 kismet

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Posted 06 June 2008 - 07:14 PM

Yeah, I went through lots of those IF abstracts and some full studies I found on pubmed and even found the study you mentioned on imminst (but I was unable to answer as I had some problems w/ my account...)

However, it is quite hard to figure out whether 'intermittent fasting' or 'intermittent feeding' mentioned in the abstracts is CR w/ intermittent fasting or really ad lib IF.
Regardless there are some really promising rodent studies using IF w/ an ad lib diet.

#11 edward

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Posted 06 June 2008 - 08:39 PM

Yeah, I went through lots of those IF abstracts and some full studies I found on pubmed and even found the study you mentioned on imminst (but I was unable to answer as I had some problems w/ my account...)

However, it is quite hard to figure out whether 'intermittent fasting' or 'intermittent feeding' mentioned in the abstracts is CR w/ intermittent fasting or really ad lib IF.
Regardless there are some really promising rodent studies using IF w/ an ad lib diet.


If the subject used is a Rodent then implementing an IF regime (of every other day feeding) will yield an animal that (obviously) eats nothing when food is deprived and eats roughly TWICE as much when food is provided, thats just how Rodents are (apparently at first the rodents are eating a little less than the ad lib rodents but over time they end up eating the same total calories as rodents on ad lib all the time they just eat twice as much during the eat period). So the IF in these abstracts really is ad lib IF not a trick to restrict calories.

#12 Mixter

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Posted 23 June 2008 - 08:20 PM

One problem in that study is the increased beta-Hydroxybutyrate
(lower right in the graphic), which is a ketone body in the brain...
high ketone bodies in the long term lead to nasty AGEs...

So unless for a shorter weight-loss boost, ketosis is a bad
thing for longevity due to AGE formation (methylglyoxal), which
probably means, intermittent fasting is ok as long as blood
sugar levels are kept at a minimum, maybe with honey
sweetened tea and vegetablel snacks, etc...

#13 InquilineKea

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Posted 22 June 2011 - 08:23 PM

Well, anabolic hormones usually decline with age. So CRONites would be expected to have lower levels when young, but higher levels when old (it's the same thing with testosterone). Even though IGF-1 is horrible horrible shit.

Anyways, I just got an IGF-I test and got 200 ng/mL. Is this good or bad for a late teen? Reference range is 158 - 497. To me, though, "good" means VERY low. I wish my insulin and glucose levels could be as low as my triglyceride levels *shrug*

The weird thing with IGF-1, though, is that it does DECLINE with age, unlike almost all the other horrible biomarkers we know about. And CR might attenuate its decline, which could partially mitigate the effect of CR. That being said, IGF-1 maybe isn't as horrible as glucose/insulin are then.

http://www.sciencedi...096637407001335

EDIT: just looked it up. I'm below 50th percentile, but still closer to 50th percentile than 2.5th percentile *sigh*. I love it how the lower limit for the reference range corresponds to the 50th percentile in 40-year olds.

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Edited by InquilineKea, 22 June 2011 - 08:35 PM.


#14 albedo

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Posted 18 August 2012 - 03:08 PM

At 57 I have IGF-1 240 ng/mL (ref: 81-225) and trying to reduce it by lowering protein intake, increasing exercise and lowering calories. Is this the right order? Should I focus on something else?

#15 zorba990

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Posted 18 August 2012 - 05:21 PM

At 57 I have IGF-1 240 ng/mL (ref: 81-225) and trying to reduce it by lowering protein intake, increasing exercise and lowering calories. Is this the right order? Should I focus on something else?


I wonder between Bill Bixby and Lou Ferigno who had the higher igf-1 levels? Maybe igf-II is the thing to look at?
http://connection.eb...-pca-than-igf-i

#16 albedo

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Posted 19 August 2012 - 08:01 AM

Good thought zorba990 and thank you for the reference. I did not know about this and never tested for IGF-II. I wonder what is the relationship between the two factors.

Edited by albedo, 19 August 2012 - 08:02 AM.





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