Re: Protein Restriction ........... Was: Leucine vs CR Catabolism

[Guest guest]

Methionine is one of the sulfer containing amino acids which are found in higher concentrations in animal protein. It is also a precurser to homocysteine. Rodney <perspect1111@...> wrote: Hi folks:More on protein restriction:"Mitochondrial oxidative stress, aging and caloric restriction: The protein and methionine connection.Pamplona R, Barja G.Department of Basic Medical Sciences, University of Lleida, Lleida 25008, Spain.Caloric restriction (CR) decreases aging rate and mitochondrial ROS (MitROS) production and oxidative stress in rat postmitotic tissues. Low levels of these parameters are also typical traits of long-lived mammals and birds. However, it is not known what dietary components

are responsible for these changes during CR. It was recently observed that 40% protein restriction without strong CR also decreases MitROS generation and oxidative stress. This is interesting because protein restriction also increases maximum longevity (although to a lower extent than CR) and is a much more practicable intervention for humans than CR. Moreover, it was recently found that 80% methionine restriction substituting it for l-glutamate in the diet also decreases MitROS generation in rat liver. Thus, methionine restriction seems to be responsible for the decrease in ROS production observed in caloric restriction. This is interesting because it is known that exactly that procedure of methionine restriction also increases maximum longevity. Moreover, recent data show that methionine levels in tissue proteins negatively correlate with maximum longevity in mammals and birds. All these suggest that lowering of

methionine levels is involved in the control of mitochondrial oxidative stress and vertebrate longevity by at least two different mechanisms: decreasing the sensitivity of proteins to oxidative damage, and lowering of the rate of ROS generation at mitochondria."PMID: 16574059Rodney.>> Hi folks:> > That post was from Tony. It was #13,209. I see it indicated three > amino acids the restriction of which lengthened lifespan even without > the restriction of calories.> > I wonder if this might explain what is happening with the chinese > centenarians - who were eating 11% of their calories as protein - in > the study posted recently?> > Rodney.> > --- In , "Rodney" <perspect1111@> >

wrote:> > >> > Hi Dave:> > > > I remember one study posted here about a year ago which quite > > strongly suggested tryptophan (I believe it was tryptophan) should > > be minimized. But upon investigation it was noted that pretty much > > everything contains it so there wasn't an easy way to minimize it > > apart from reducing overall protein intake.> __________________________________________________

[Guest guest]

Methionine is indeed a precursor to homocysteine. Homocysteine can

then be converted back to methionine in a process (called

remethylation)requiring folic acid and vitamin-B12 as catalyst or it

may be metabolized into cysteine in a process requiring vitamin-B6.

Cysteine is necessary to the synthesis of glutathione, one of our most

important antioxidants. A high blood level of homocysteine has been

found to be highly detrimental to health and is invariably accompanied

by a low level of folic acid.

Regards,

> >

> > >

> > > Hi Dave:

> > >

> > > I remember one study posted here about a year ago which quite

> > > strongly suggested tryptophan (I believe it was tryptophan)

> should

> > > be minimized. But upon investigation it was noted that pretty

> much

> > > everything contains it so there wasn't an easy way to minimize it

> > > apart from reducing overall protein intake.

> >

>

>

>

>

>

>

>

>

[Guest guest]

Hi folks:

This study found the following:

40% caloric restriction extended maximal lifespan by 40%.

40% protein restriction extended maximal lifespan by 20%.

80% methionine restriction extended maximal lifespan by 40%.

Rodney.

[Thanks to the usual source (!) for access to the full text]

> >

> > >

> > > Hi Dave:

> > >

> > > I remember one study posted here about a year ago which quite

> > > strongly suggested tryptophan (I believe it was tryptophan)

> should

> > > be minimized. But upon investigation it was noted that pretty

> much

> > > everything contains it so there wasn't an easy way to minimize

it

> > > apart from reducing overall protein intake.

> >

>