Re: Methionine restriction vs CR

[Guest guest]

Hi folks:

" .... the results of the present study strongly support the

possibility that the reduced intake of dietary methionine is the

dietary factor responsible for ..... around half of the increase

in maximum longevity that takes place in [C]R. "

So what accounts for the other half?

Studies, by these same investigators, have previously been posted

here which seemed to say that in their experiments fat and carbs

account for none of the life extension effects of CR. Are they

saying that it appears protein restriction accounts for all of it?

If so then there must be some other amino acid(s), in addition to

MET, that need to be restricted.

Glycine is top of my list of suspects. But I forget now what it was

that put it there.

Or is there some other dietary component, not an amino acid, perhaps

an essential nutrient also, which needs to be restricted to no more

than the RDA? And are amounts less than the RDA (which tends to be

biased to the high side) actually healthier in the case of MET and

this other component?

What is the optimal intake of MET?

In a few years we will probably know all this. I can't wait!

Rodney.

--- In , Al Pater <old542000@...>

wrote:

>

> Hi All,

>

> " In summary, the results of the present study strongly support

the possibility that the reduced intake of dietary methionine is the

dietary factor responsible for the decrease in mitROS generation and

oxidative stress and around half of the increase in maximum

longevity that take place in [C]R. " The below paper is pdf-availed.

>

>

> Caro P, Gómez J, López- M, Sánchez I, Naudí A, Jove M,

Pamplona R, Barja G.

> Forty percent and eighty percent methionine restriction decrease

mitochondrial ROS generation and oxidative stress in rat liver.

> Biogerontology. 2008 Feb 19; [Epub ahead of print]

> PMID: 18283555

>

> Abstract

>

> Dietary restriction (DR) lowers mitochondrial reactive oxygen

species (ROS) generation and oxidative damage and increases maximum

longevity in rodents. Protein restriction (PR) or methionine

restriction (MetR), but not lipid or carbohydrate restriction, also

cause those kinds of changes. However, previous experiments of MetR

were performed only at 80% MetR, and substituting dietary methionine

with glutamate in the diet.

>

> In order to clarify if MetR can be responsible for the lowered ROS

production and oxidative stress induced by standard (40%) DR, Wistar

rats were subjected to 40% or 80% MetR without changing other

dietary components.

>

> It was found that both 40% and 80% MetR decrease mitochondrial ROS

generation and percent free radical leak in rat liver mitochondria,

similarly to what has been previously observed in 40% PR and 40% DR.

The concentration of complexes I and III, apoptosis inducing factor,

oxidative damage to mitochondrial DNA, five different markers of

protein oxidation, glycoxidation or lipoxidation and fatty acid

unsaturation were also lowered.

>

> The results show that 40% isocaloric MetR is enough to decrease

ROS production and oxidative stress in rat liver. This suggests that

the lowered intake of methionine is responsible for the decrease in

oxidative stress observed in DR.

>

> Keywords Mitochondria - Caloric restriction - Aging - Oxygen

radicals - Longevity - Protein damage - Fatty acids - Respiratory

complexes

> ++++++++++++++++++++++++

>

> Table 4 Fatty acid composition of liver mitochondria from

control, 40% and 80% methionine restricted rats.

> ===========================================

> Control 40% MetR 80% MetR

> ===========================================

> 14:0 0.41±0.03 0.34±0.04 0.39±0.03

> 16:0 16.36±0.24 16.22±0.26 15.43±0.23a**,b*

> 16:1n-7 0.70±0.04 0.69±0.06 0.43±0.03a***,b***

> 18:0 20.20±0.41 20.06±0.46 22.07±0.43a**,b**

> 18:1n-9 7.78±0.30 7.61±0.31 6.78±0.35a*

> 18:2n-6 15.85±0.23 17.82±0.45a** 19.84±0.48a***,b**

> 18:3n-3 0.25±0.02 0.17±0.01a** 0.20±0.01a*

> 20:3n-6 0.18±0.01 0.19±0.01 0.14±0.007b*

> 20:4n-6 32.07±0.17 30.38±0.15a*** 27.73±0.46a***,b***

> 22:4n-6 1.55±0.10 1.71±0.14 1.99±0.13a*

> 22:5n-6 0.45±0.02 0.50±0.02 0.50±0.03

> 22:5n-3 0.32±0.02 0.44±0.02a** 0.37±0.02

> 22:6n-3 3.82±0.10 3.82±0.14 4.09±0.08

> ACL 18.53±0.01 18.51±0.01 18.50±0.01

> SFA 36.98±0.51 36.63±0.62 37.90±0.55

> UFA 63.01±0.51 63.36±0.62 62.09±0.55

> MUFA 8.49±0.31 8.31±0.36 7.21±0.38a*,b*

> PUFA 54.51±0.25 55.05±0.42 54.88±0.53

> PUFAn-6 50.11±0.25 50.62±0.49 50.21±0.52

> PUFAn-3 4.40±0.10 4.43±0.15 4.66±0.08

> DBI 202.85±1.26 201.12±1.15 195.77±1.61a**,b**

> PI 186.71±1.14 183.43±1.22 177.61±1.83a***,b**

> ===========================================

> Values are mean±SE from 10 different animals and are expressed

as mol %

> ACL acyl chain length, SFA saturated fatty acids, UFA

unsaturated fatty acids, MUFA monounsaturated fatty acids, PUFA

polyunsaturated fatty acids, DBI double bond index, PI

peroxidizability index

> a Represents significant differences compared to controls,

brepresents significant differences between 40% and 80% MetR groups;

* P < 0.05, ** P < 0.01, *** P < 0.001

>

>

>

>

> ---------------------------------

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