Re: Resveratrol supplementation does not extend lifespan in ad libitum-fed rodents.
On Jul 11, 5:46 am, François Rose <fr.r...@free.fr> wrote:
> On Jul 11, 6:14 am, Olafur Pall Olafsson <olafurp...@yahoo.com> wrote:
>
>
>
> > On Jul 10, 11:01 pm, François Rose <fr.r...@free.fr> wrote:
>
> > > On Jul 10, 12:59 pm, François Rose <fr.r...@free.fr> wrote:
>
> > > > > > François Rose
> > > > > > PS to rs1000: just curious, when you wrote "So they published it
> > > > > > afterall....
> > > > > > did you mean that the authors were possibly a bit reluctant to publish
> > > > > > these results (because the resveratrol life extending effect was not
> > > > > > seen in normal diet and CR diet animals)?
>
> > > > François Rose- Hide quoted text -
>
> > > > - Show quoted text -
>
> > > Thanks, Jay, for the copy of the full text
>
> > Thanks for the report Francois.
>
> > > MAX LIFESPAN (= mean of the final 20% mice !!!!!!!!!!)
> > > standard diet (regardless resveratrol):139 +/- 1 weeks
> > > every other day feeding (without RSV):144
> > > every other day feeding (with low dose RSV((100 mg/kg of
> > > food)(7.6 ± 0.2 mg/kg/day which equals 1.27mg/kg/day for a human (I
> > > have to divide by 6 because the animals were mice):147 weeks
>
> > Your calculations are not very accurate. Dividing by 7,3 rather than 6
> > should give more accurate numbers since the metabolism of mice is
> > approximately 7,3 times faster than that of humans. This would give a
> > dose of:
> > 7,6mg/kg / 7,3 = 1,0mg/kg for humans if one calculates the dose based
> > on the amount per body weight. You can also see that your number is
> > suspiciously high if you calculate the dose based on the amount per kg
> > of food given in the full text. As you report the dose was 100mg/kg
> > food. Usually this is on a dry weight basis. On a dry weight basis a
> > 70kg adult human eats roughly 500g of food daily which gives about
> > 50mg per day or 50mg/70kg = 0,71mg/kg body weight of resveratrol. This
> > is even further from your number of 1,27mg/kg/day than what I get
> > using the conversion factor of 7,3. To see how I estimated that a 70kg
> > adult human eats roughly 500g of food daily on a dry weight basis see
> > the last post in this discussion:http://tinyurl.com/5ryqad
>
> > > every other day feeding (with high dose RSV (400 mg/kg of
> > > food)(30.4 ± 0.6 mg/kg/day which equals 5mg/kg/day for a human):143
> > > weeks
>
> > Using a conversion factor of 7,3 the numbers for the high dose
> > resveratrol group amount to:
> > 30,4mg/kg / 7,3 = 4,2mg/kg body weight daily for humans if one
> > calculates the dose based on the amount per body weight, and
> > 400mg/kg x 0,5kg / 70kg = 2,9mg/kg body weight daily for a 70kg human
> > if one calculates the dose based on the amount per kg of food given.- Hide quoted text -
>
> > - Show quoted text -
>
> Thanks for the correction, Olafur
> I wasn't sure about my calculations; that's why I wrote them so that
> I
> could be corrected.
> I don't not know yet very well the conversion and I got to work more
> on
> this.
> Thanks for the link
>
> I say it once again because I think it is an important point, IMO:this
> study really casts doubt upon the use of high dose resveratrol
> (regarding life extending effect AND health span)
>
> François
Yo cannot use relative metabolic rates alone except as a starting
point for safe dosage. Mice, rats and humans all differ significantly
in the rate and amount of glucuronidation and sulfonation bin the
intestines and liver. Humans are much more efficient at this than
rodents, so the amount of free resveratrol in the blood is
significantly lower than in rodents at metabolically equivalent
doses. I've seen it estimated that the metabolic rate and the
glucoronidation rate cancel out, so mouse and human dose per kg should
be about the same. One would have to compare blood serum levels of
resveratrol over time to get an idea. Even then, there is speculation
that the metabolic by-products of resveratrol are also active.
The most extensive human trials were with a formulation (and hence
more bio-available form) of resveratrol, SRT501, by Sirtris. They
used 2.5 and 5 gram doses for dealing with disease. I wonder if
they've published data on blood-serum levels?
rjk3@my-deja.c…
ironjustice
