I have been skeptical of Michael Sherman’s high
estimate of protein requirements. They appear to
greatly exceed those recommended by Walford. Also,
they would almost seem to put CR out of my reach, so I
don’t want to believe them.

Below are some of Michael’s past postings on the
subject,
which Michael was kind enough to send to me. They
include a response from Walford to Michael’s views.

After reading the postings, I still question Michael’s
reasoning and basically agree with Walford. However,
as a result of reading the exchange, I have decided to
substantially raise my protein intake. I hope this
post will encourage you in your CR endeavors,
regardless of the protein level you are able to
achieve.

BRIAN’S SUMMARY
Michael extrapolates from data in a nutrition text,
and comes to the conclusion that CRers may need much
higher than the RDA for protein. Otherwise, we may
suffer a negative nitrogen balance and waste away.
He suggests 155 grams for a 150 pound person, which
is far more than most of us at that weight probably
get,
and is over 2.5 times the RDA (around 60g).

Michael notes that this higher protein requirement
seems to be supported by Walford's text, but not by
his popular books. A chart is given of one study in
the text, that appears to show a definite advantage in
consuming a high level of protein.

Walford responded to Michael's comments, that most of
the advantage from increased protein was with the
middle level of protein(22%). On this basis, he made
the "conservative" recommendation of high-end RDA for
protein. He dismissed the nutrition book, in his
colorful way, as being “out to lunch on CR.”

BRIAN’S COMMENT:

Even with the low level of protein, 10% of calories,
the CR animals handily outlasted the AL animals. 10%
of a CR level of 1800 calories would be 180 calories,
or 45 grams of protein @4cal./g. Even the vegans
among us could manage that pretty well. This would
seem to indicate that even on a low level of protein,
CR did not jeopardize the health of the animals.

At a protein level of 22% of calories, additional
benefits of CR were achieved, according to Walford.
This would amount to around 99 grams of protein, for
1800
calories. This is over 1.5 times the RDA. (The
Anti-
aging Plan recommended “10 or 20 percent above the
RDA.”)
This is well within the reach of an omnivore or an
ovo-lacto,
but a bit of a stretch for a vegan.

The maximum life span appears to occur with protein
at
50% of calories. For the 1800 calorie diet again,
this would amount to around 225 grams of protein.
I'm
not sure that any of us can manage that, even if we
eat steak and eggs with every meal.

BRIAN’S CONCLUSION:

Don't despair if you are not getting more than double
the
RDA of protein. You are apparently still getting
many
benefits from CR, without jeopardizing your health.

If you can pack in enough protein to get 1.5 times
the RDA,
you appear to get additional benefit from CR.

If you can heroically consume 225 grams of protein in
a 150 pound body, you may outlast us all. You will
apparently not be harmed. The final study compares
the effect of protein levels on various body
functions,
including kidney function. Kidney function was not
adversely
affected by protein level, as is claimed by some
vegans.
The only effect on the kidneys came from CR, which
delayed
the decline in function.

MICHAEL’S POSTINGS:

ATTACHMENT part 2 message/rfc822
From: "Michael Sherman"
Subject: Re: [CR] Protein
Date: Mon, 1 Nov 1999 01:35:00 -0700

I think its time to inject some hard, cold numbers
into this protein discussion. I have discovered
what
I think is solid evidence that CR people need to eat
more protein than the standard RDAs, and more than
is
recommended by Walford. This data comes
from Modern Nutrition in Health and Disease, 8th
ed.,
1994, Ch. 1, pp. 24-29. The faulty reasoning below
is
my own.

Background: Minimal required levels of protein
intake for adults
are determined by nitrogen balance experiments.
Researchers
carefully account for all sources of N loss (urine,
feces, dermal, semen, etc.) and then measure how
much N intake is required so that the N loss exactly
matches intake (no, I don't know how they keep track
of semen loss!). The mean protein requirement is
computed for a large number of subjects on a per-kg
of body weight basis, then the RDA per kg is set to
cover
two standard deviations above the mean. This is
then
applied to the average body weight person to produce
the RDA per day.

The 1989 RDA (from the US Food and Nutrition
Board) is: 0.8g/kg BW. This applies to adult males
and
non-pregnant, non-lactating adult females. Based
on average weight people, the recommendation is
further
fuzzed into a single daily recommendation of about
60g/day for men and 50g/day for women.

But don't pull out your calculator just yet. In the
discussion on computing protein requirements, the
book says
Nitrogen balance is also affected by energy
intake. ... N balance becomes progressively more
negative as energy intake is reduced below the
needs of the body. ... A direct relationship
exists between energy intake and N balance from
negative at low-energy levels to positive at
excessive intakes of energy.
A table then shows measured requirements varying by
a factor of two over a calorie intake range from
57 cal/kg (RDA would be 0.5g/kg) to 40 cal/kg
(RDA would be 1.02g/kg).

Now I personally weigh about 57 kg and eat about
1750 cal/day. This is not particularly low for a CR
diet, yet at 31 cal/kg is way off the chart.
Fortunately the
data were fairly linear at that end, so I extended
the table with a ruler and came up with a
requirement
of 1.5g/kg! That is near double the US RDA of
0.8g/kg
and would put my daily requirement for protein at
87g, which
is about what I eat.

For your own use, try this formula:

RDA protein (g/day) = 3.22 BWInKg - .055
totalCalsPerDay

So if you weigh 70 kg and eat 1800 cal/day, your
protein RDA
is 3.22 * 70 - 0.055 * 1800 = 126 g/day. The above
formula
is a linear fit to the low end of the data in Table
1-6, pg 24.
(But this isn't the final formula, read on ...)

This is as far as I could get with Modern Nutrition
in Health
and Disease. However, I still think this is an
underestimate,
because:
(1) Protein requirements are higher for lean body
mass
than for fat, and
(2) these experiments would have been done on
people of
normal body fat content, and
(3) CR people have lower-than-normal body fat.
If we assume that normal people have 20% body fat,
the
above formula can be rewritten in terms of lean body
weight (LBW):

RDA protein (g/day) = 4.03 LBWInKg - .055
totalCalsPerDay

Now if a CR person has 10% body fat, then a 70kg
1800 cal/day
person requires 4.03 * (0.9*70) - (0.055 * 1800) =
155 g/day.
That would be 34% of calories from protein, which
seems very
high. My own requirement by this formula would then
be 108g/day,
meaning that 25% of my calories should come from
protein.

If the above isn't enough to convince you to eat
more
protein than normal people, let me close with a few
choice
quotes from The Retardation of Aging and Disease by
Dietary
Restriction, by Weindruch and Walford:

The average LS [lifespan] of rats on DR increased
as the amount
of protein in the diet increased suggesting that
the
effects of DR on LS may be enhanced by diets high
in protein
content. (pg 54) ... epithelial ... adrenal and
thyroid
tumor morbidity were ... inversely related to
dietary protein
... In short, both LS and tumor data suggest that
high
protein diets accentuated the benefits of DR in
Ross' colony.
(pg 81) [the extremely restricted rats that did
best were on
a 51% calories-from-protein diet!]

... the inhibition of skin tumors was greater for
mice
energy-restricted only via carbohydrates ... This
finding
accords with our view that the strongest effects
of DR
follows the use of isonutrient diets [by which
they
mean that the *total* amount of protein in a CR
diet should
be the same as an ad-lib diet]. (pg 105)

Despite these comments and many others in the book
stressing
the importance of adequate protein intake, W & W's
recommendations
for people seem to reflect little more than typical
RDAs.
They suggest 0.8 to 1g protein/kg BW per day. (pg
322) They
do not explain how they came to these
recommendations, which
seem not to reflect the requirements for optimal LS
and health
of their experimental rodents.

My analysis above suggests a much higher requirement
of
around 2g/kg BW. I would be very interested in
comments.

sherm

P.S. Essential Amino Acid RDAs, in mg/kg BW:

Isoleucine 10
Leucine 11
Lysine 9
Methionine 14
Phenylalanine 14
Threonine 6
Tryptophan 3
Valine 14

(I do not know if EAA requirements vary with energy
intake the way protein requirements do. But if they
do,
then applying the same reasoning as above would say
these are about a factor of 2 too low for CR
people.)

I believe the definition of "complete protein" would
be one which is not deficient in any of the above
AAs.
An ideal protein would, I think, be one in which all
the EAAs
were represented in the indicated proportions.

The data above come from Modern Nutrition ..., pg
28.




ATTACHMENT part 3 message/rfc822
From: "Michael Sherman"
Subject: protein needs on CR
Date: Sun, 21 Nov 1999 23:20:56 -0700
Organization: Symbolic Dynamics, Inc.

A few weeks ago I posted some information which made
me think that protein needs for CR people might be
higher than for those on higher-energy diets. I've
attached the original post.

Part of my reasoning came from my interpretation of
Weindruch & Walford's book The Retardation of Aging
...,
so I asked for a comment from Walford. Here is part
of what I wrote and then his response:

<SOME REITERATION OF MICHAEL’S ARGUMENT SNIPPED>

Walford replied:

First: looking at Table 2.4 in the
Weindruch/Walford book, study 7, one
observes that the shortest LSs were at 8% casein;
but there wasn't much
difference between 21% casein and 51%. In fact, 21%
gave the longest
MLS, better than both 30% and 51%.
Looking also at Study 9, 10% casein was shortest,
and 51% better than --
but not much better --than 20%. With regard to
tumor incidence, the stated
comparison is between the 51% casein and the 8%
casein. So the higher
protein seems better but only when compared with a
very low protein
intake. The intermediate ranges might be even
better.

Second: none of the material in Modern Nutrition in
Health and Disease was
derived from long-term CR studies in either rodents
or humans, and may not
be directly applicable since CR is (probably) a
different metabolic state
than either controls, short-term fasting, or
starvation. There are by
now over 3,000 papers in the literature on CR but
you will hardly find it
mentioned in that standard (or any other nutrition)
text. The
nutrition community is still "out to lunch" on this
issue.

Third: the Biospherians were on 10-14% cals from
protein, 10% fat, the
rest carbohydrates, including lots of bananas (high
GI index) and sweet
potatoes; had BMI's averaging around 20 (i.e., good
but higher than a
lot of persons on the Internet CR list) -- but had
health risk
factors (blood sugar, lipids, etc) somewhat better
than what seems
the averages in the Internet group.

Interpretation: you can stir all this together,
including your own
arguments about protein levels (which make perfect
sense in their
own right) and what you come out with is that a
very low calorie
diet will almost certainly retard aging and disease
(far better than
any combination of supplements or other measures)
and increase
maximum LS, so long as the nutrients are within a
certain quality
range. Beyond that, it's argumentative.

So in the Weindruch/Walford book we took the
conservative approach of
merely recommending the (upper range) of the RDA's
at that time for
protein intake.

<SOME REITERATION OF MICHAEL’S ARGUMENT SNIPPED>


But that isn't what Ross' data shows. In fact, to
my surprise, it shows
what we are constantly told studies don't show:
that MACRONUTRIENT
COMPOSITION CAN INFLUENCE MAX LS, and that the
higher the protein, the
longer the LS.

Ross and Bras (1973), "Influence of protein
under-and overnutrition on
spontaneous tumor prevalence in the rat." J Nutr
103: 944-63.

Turning to their table 2, we find that there is
improved max LS in BOTH the
Cr AND the ad lib groups, correlated postiively with
protein intake.

DAY SURVIVORSHIP
AD LIB CR
PRO:10% 22% 51% 10% 22% 51%

900 8 2 6 145 116 149
1000 0 0 1 93 85 122
1200 0 0 0 48 61 91
1300 0 0 0 5 31 59
1400 0 11 24
[No Easter miracles in the rodents]
1500 1 10
1600 0 3

Lest anyone object that what we're really seeing in
the high-pro CRONies is
just adequaate-protein diet, note that the same
results were observed in the
ALers.

Further, Ross' tabkle 10, summarizing all tumor
data, shows taht, again for
boht ALers and CRONies, the highest-protein groups
had the lowest ratios of
malignant to benign tumors, and the lowest
AGE-SPECIFIC tumor rates of all
isocaloric groups: that is, the low-protein group
had fewer cancers only
because they died sooner -- thir rate of tumor
formation was higher.

This is only one study, but they used a lot of
animals (1600), and I know of
no contradictory evidence. Even


Exp Gerontol 1983;18(6):427-35

Differential effects of dietary caloric and protein
restriction in the aging rat.

Davis TA, Bales CW, Beauchene RE

Numerous studies have shown caloric restriction
retards the physiological
decline and increases the
life span of animals. However, in these studies
protein consumption was also
reduced; thus,
whether the beneficial effects were due to caloric
or to protein restriction
is unclear. To examine
independently the effects of caloric and protein
restriction on growth,
renal function, and survival,
caloric restricted male rats were fed 18, 30 or 42
percent casein diets that
provided two-thirds of
the quantity of diet consumed by groups fed 12, 20,
or 28 percent casein
diets ad libitum,
respectively. Hence, caloric restricted groups
consumed the same amount of
protein as their paired
ad libitum fed groups but one-third fewer calories.
The results showed that
caloric restriction
decreased mature body weight, increased the rate of
attaining mature body
weight, retarded the
age-associated decline in renal function, and
increased survival. Protein
restriction had no effect on
mature body weight, decreased maturation rate,
improved renal function, and
decreased survival.
Thus, protein restriction did not contribute to the
survival-promoting
effects of caloric restriction in
rats.

PMID: 6673988, UI: 84182821

.... tends to support the general conclusion.

As I wrote last year (though without knowledge of
the MAX LS difference!!):
CRONed animals live longer in the Zone :).

-Michael



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