Kcal vs. protein (was: [Re: Which calories?])

[Guest guest]

Hi all,

Here you have a reference that points just in another direction

regarding the issue of calories from carbs or protein. Of course,

one have to have in mind this strain of mice had a renal disease,

but it's worth reading it

http://www.pnas.org/cgi/reprint/83/15/5659

Take a look at this extract:

" It was also of interest that the diet that promoted the very

longest life and the greatest increase in maximum life span in

these relatively short-lived mice was the diet of very high

carbohydrate, low fat, normal protein composition. However,

this diet exhibited the greatly beneficial effect only when

fed as a calorie-restricted diet. The diets higher in fat and

higher in protein permitted the increasing of longevity and life

span when fed in restricted amounts, but the calorie restriction

did not produce as much life extension when the diets

had a high fat or high protein content as it did when the diet

had a very high proportion of carbohydrates. "

Cheers.

Willie.

> Early studies showing lifespan increase with protein restriction

> created controversy concerning whether these benefits were simply

> another example of CRAN. This issue was apparently resolved by a

paper

> that appeared in the JOURNAL OF NUTRITION Vol.116, p.641-654

(1986),

> authored by Weindruch, Roy Walford, Suzzane Fligiel and

> Guthrie. Since Weindruch (who got his Ph.D. under Walford) is

listed

> first, he may deserve the most responsibility for this study. These

> data illustrate a study of the effect of combining protein

restriction

> with CRAN.

>

> Mean and maximum lifespan for 6 cohorts of mice under 6 dietary

> protocols can be summarized by the following table (RES =

Restriction):

>

> MEAN MAXIMUM

> (months) (months)

>

> (1) ad lib diet 27 35

>

> (2) 25% RES after weaning (day 21) 33 40

>

> (3) 55% RES after weaning (day 21) 42-43 51

>

> (4) 55% RES before weaning (day 7) 42-43 51

>

> (5) 55% RES after weaning (day 21) 40 48-49

> with gradual protein RES

>

> (6) 65% RES after weaning (day 21) 45 53

>

> Maximum lifespan was taken as the mean life span of the longest-

lived

> 10% in each group.

>

> Mice in cohorts (3), (4), (5) and (6) all had 35% casein (milk

> protein) in their diets. But the mice on gradual protein

restriction

> received 35% casein from weaning until 4 months, 25% casein at 4-12

> months, 20% casein at 12-24 months and 15% casein from 24 months

until

> death. Calories lost from protein restriction were compensated for

by

> carbohydrate in an equal mixture of sucrose and corn starch. The

> authors make the statement that " Mice restricted in both calorie

and

> protein intake exhibited shorter mean and maximum lifespans (~5%)

than

> did mice fed the same number of calories of a high protein diet. "

>

> http://www.benbest.com/calories/cran95.html

>

> Thanks,

> Kat.

>

>

> > There might be an even greater degree of confusion **IF** it

turns

> > out (as I hypothesize - fwiw wmnbm) that marked restriction of

fat OR

> > marked restriction of protein each result in a substantial

extension

> > of maximal lifespan - while moderate restriction of both at the

same

> > time, amounting to the same total number of calories, has only a

> > minor effect. In this case should we choose to restrict

protein, or

> > fat?