Re: Study says restrict protein, not calories

[Guest guest]

Correction, the CR group tested had been CRONing an average of 7 years.

>

> Study shows IGF-1 (insulin-like growth factor-1), is not reduced by CR

> in humans as it is in animals. Humans on 6-year CR show IGF-1 levels

> similiar to the regular sedentary population. Comparing the CR group

> to a vegetarian group shows lower IGF-1 in vegetarians.

>

> Dave

>

>

>

> Link:

>

> http://www.sciencedaily.com/releases/2008/09/080924151018.htm

>

>

> Text:

>

> Differences Between People And Animals On Calorie Restriction

>

> ScienceDaily (Sep. 26, 2008) — Calorie restriction, a diet that is low

> in calories and high in nutrition, may not be as effective at

> extending life in people as it is in rodents, according to scientists

> at Washington University School of Medicine in St. Louis.

>

> Previous research had shown that laboratory animals given 30 percent

> to 50 percent less food can live up to 50 percent longer. Because of

> those findings, some people have adopted calorie restriction in the

> hope that they can lengthen their lives. But the new research suggests

> the diet may not have the desired effect unless people on calorie

> restriction also pay attention to their protein intake.

>

> In an article published online this month in the journal Aging Cell,

> investigators point to a discrepancy between humans and animals on

> calorie restriction. In the majority of the animal models of

> longevity, extended lifespan involves pathways related to a growth

> factor called IGF-1 (insulin-like growth factor-1), which is produced

> primarily in the liver. Production is stimulated by growth hormone and

> can be reduced by fasting or by insensitivity to growth hormone. In

> calorie-restricted animals, levels of circulating IGF-1 decline

> between 30 percent and 40 percent.

>

> " We looked at IGF-1 in humans doing calorie restriction, " says first

> author Luigi Fontana, M.D., Ph.D., assistant professor of medicine at

> Washington University and an investigator at the Istituto Superiore di

> Sanità in Rome, Italy. " For years, we have been following a cohort of

> people from the CR Society who have been on long-term calorie

> restriction. We found no difference in IGF-1 levels between people on

> calorie restriction and those who are not. "

>

> The CR Society members, who call themselves CRONies (Calorie

> Restriction with Optimal Nutrition), had been on a calorie-restriction

> diet for an average of seven years when Fontana did the measurements,

> but their IGF-1 levels were virtually identical to sedentary people

> who ate a standard, Western diet.

>

> Because calorie restriction is linked to extraordinary increases in

> maximal lifespan in rats and mice, Fontana and colleagues at

> Washington University, including principal investigator O.

> Holloszy, M.D., professor of medicine, have been involved in a

> scientific study that compares calorie restriction to exercise and

> measures many biological factors linked to longevity and health.

> Called the CALERIE study (Comprehensive Assessment of the Long term

> Effects of Reducing Intake of Energy), the project randomly divided 48

> people into three groups: Eighteen cut their caloric intake by 25

> percent for one year. Another 18 started exercising to increase their

> energy expenditure by 25 percent for a year. A third group of 10

> people didn't change anything.

>

> At the end of that year, the investigators measured IGF-1 levels in

> all three groups. Again they found no reductions in the group on

> calorie restriction.

>

> " That was puzzling because it was the first time we hadn't seen

> agreement between mice and rats on calorie restriction and humans on

> calorie restriction, " Fontana explains. " But we know there are two

> major influences on IGF-1 levels: calorie intake and protein intake.

> So we decided to look at the influence of protein. "

>

> Again, Fontana had a ready-made study group. His team has been

> following a population of strict vegans for several years. They tend

> to eat less protein than the CRONies from the CR Society, so he

> compared IGF-1 levels between the two groups.

>

> " The vegans had significantly less circulating IGF-1, even if they

> were heavier and had more body fat than CRONies, " he says. " Protein in

> the diet seemed to correlate with the lower levels of IGF-1. The

> strict vegans took in about 10 percent of their total calories from

> protein, whereas those on calorie restriction tended to get about 23

> or 24 percent of calories from protein. "

>

> The investigators wanted to take one more look at the relationship

> between dietary protein and IGF-1, so Fontana asked a group of CRONies

> to eat less protein for a few weeks. He says it was not easy to cut

> protein because those on calorie restriction have to do a lot of

> calculating and juggling to ensure they take in very few calories and

> still get adequate nutrition. Increasing dietary protein is one way

> many CRONies guard against becoming malnourished.

>

> " But six of them agreed to lower their protein intake, " Fontana

> explains, " and after three weeks their circulating IGF-1 declined

> dramatically. "

>

> Previous research from Fontana's group had found that a diet lower in

> protein might protect against some cancers. These more recent findings

> suggest lowering protein also might be important to longevity. Fontana

> admits his evidence is preliminary, but the findings suggest that when

> people adjust their diets to improve health and lengthen life, they

> should control not only calories and fat but also keep an eye on

protein.

>

> Fontana isn't proposing radical low-protein diets. Instead, he is

> suggesting the current recommended daily allowance (RDA) for protein,

> which is 0.82 grams of protein per kilogram of body weight, or about

> 56 grams of protein for an average, adult man and 46 grams for an

> average, adult woman. Most people, including CRONies, consume much

> more protein than the RDA recommendation.

>

> " It's much easier to restrict protein than to restrict calories, " he

> says. " If our research is on the right track, maybe humans don't need

> to be so calorie restricted. Limiting protein intake to .7 or .8 grams

> per kilogram per day might be more effective. That's just a

> hypothesis. We have to confirm it in future studies. "

>

> Until then, Fontana suggests people might want to look at protein

> consumption and tailor it to RDA recommendations. Traditionally, he

> says, nutritionists have not worried about people eating too much

> protein, but these findings suggest perhaps they should.

>

> Journal references:

>

> 1. Fontana et al. Long-term effects of calorie or protein

> restriction on serum IGF-1 and IGFBP-3 concentration in humans. Aging

> Cell, 2008; 7 (5): 681 DOI: 10.1111/j.1474-9726.2008.00417.x

> 2. Fontana L, Klein S, Holloszy JO. Long-term low-protein,

> low-calorie diet and endurance exercise modulate metabolic factors

> associated with cancer risk. American Journal of Clinical Nutrition,

> vol. 84; pp. 1456-1462, Dec. 2006

>

[Guest guest]

Fontana explains. " But we know there are two

> major influences on IGF-1 levels: calorie intake and protein intake.

> So we decided to look at the influence of protein. "

He forgot two of the biggest influences on IGF-1 levels: age and

exercise!

(The FASEB Journal. 2007;21:922.13)

© 2007 FASEB This Article

Influences of Lifelong Exercise and Mild (8%) Caloric Restriction on

IGF-1 and Heat Shock Proteins in the Plantaris of the Aging Fischer-

344 Rat

Jong-Hee Kim1, Hyo-Bum Kwak1, Christiaan Leeuwenburgh2 and M

Lawler1

1 Health and Kinesiology, Texas A & M University, 158 Read Building,

College Station, TX, 77843,

2 Aging and Geriatric, University of Florida, 1329 SW 16th Street,

Gainesville, 32610

ABSTRACT

A major characteristic of aging skeletal muscle is reduction of

muscle mass called sarcopenia caused by reductions in fiber number

and cross-sectional area. Increased oxidative stress and impaired

stress-response may contribute to sarcopenia with aging. Insulin like

growth factor-1 (IGF-1) and heat shock proteins (HSPs) are important

anti-atrophy agents involved in regulating cell growth,

differentiation, and cell survival. Our purpose was to identify the

effect of 8%CR and lifelong exercise on IGF-1 and HSP signaling

(HSP90, HSP70, HSF-1 HSP25, phosphorylated HSP25 [p-HSP25]) in the

Fischer-344 rat plantaris. We divided male Fischer-344 rats at 11

weeks into four groups: young fed ad libitum until 6 mo. old (YAL,

n=12); fed ad libitum until 24 mo. old (OAL, n=11); 8% caloric

restriction to 24 mo of age (OCR, n=12); wheel running 24 mo. with 8%

caloric restriction (OExCR, n=12). IGF-1 protein expression decreased

(–57%) in OAL as compared to 6AL. Lifelong exercise but not 8%CR

resulted in a significant increase (+51%) in IGF-1 compared with

24AL. Age, 8%CR, and lifelong exercise had no effect on HSP90, HSP70,

and HSF-1 levels. However, HSP25 (–46%) and p-HSP25 (–25%) levels

were lower in OAL compared to YAL rats, while 8%CR and OExCR resulted

in significantly greater for both HSP25 (123%, 50%) and p-HSP25 (50%,

108%), respectively. Our results indicate that lifelong wheel running

exercise combined with mild caloric restriction could confer

protection against muscle sarcopenia via IGF-1 and HSP25 signaling

pathways.

Supported by a grant from NIH R01 AG17994

http://www.fasebj.org/cgi/content/meeting_abstract/21/6/A1311-a

> >

> > Study shows IGF-1 (insulin-like growth factor-1), is not reduced

by CR

> > in humans as it is in animals. Humans on 6-year CR show IGF-1

levels

> > similiar to the regular sedentary population. Comparing the CR

group

> > to a vegetarian group shows lower IGF-1 in vegetarians.

> >

> > Dave

> >

> >

> >

> > Link:

> >

> > http://www.sciencedaily.com/releases/2008/09/080924151018.htm

> >

> >

> > Text:

> >

> > Differences Between People And Animals On Calorie Restriction

> >

> > ScienceDaily (Sep. 26, 2008) — Calorie restriction, a diet that

is low

> > in calories and high in nutrition, may not be as effective at

> > extending life in people as it is in rodents, according to

scientists

> > at Washington University School of Medicine in St. Louis.

> >

> > Previous research had shown that laboratory animals given 30

percent

> > to 50 percent less food can live up to 50 percent longer. Because

of

> > those findings, some people have adopted calorie restriction in

the

> > hope that they can lengthen their lives. But the new research

suggests

> > the diet may not have the desired effect unless people on calorie

> > restriction also pay attention to their protein intake.

> >

> > In an article published online this month in the journal Aging

Cell,

> > investigators point to a discrepancy between humans and animals on

> > calorie restriction. In the majority of the animal models of

> > longevity, extended lifespan involves pathways related to a growth

> > factor called IGF-1 (insulin-like growth factor-1), which is

produced

> > primarily in the liver. Production is stimulated by growth

hormone and

> > can be reduced by fasting or by insensitivity to growth hormone.

In

> > calorie-restricted animals, levels of circulating IGF-1 decline

> > between 30 percent and 40 percent.

> >

> > " We looked at IGF-1 in humans doing calorie restriction, " says

first

> > author Luigi Fontana, M.D., Ph.D., assistant professor of

medicine at

> > Washington University and an investigator at the Istituto

Superiore di

> > Sanità in Rome, Italy. " For years, we have been following a

cohort of

> > people from the CR Society who have been on long-term calorie

> > restriction. We found no difference in IGF-1 levels between

people on

> > calorie restriction and those who are not. "

> >

> > The CR Society members, who call themselves CRONies (Calorie

> > Restriction with Optimal Nutrition), had been on a calorie-

restriction

> > diet for an average of seven years when Fontana did the

measurements,

> > but their IGF-1 levels were virtually identical to sedentary

people

> > who ate a standard, Western diet.

> >

> > Because calorie restriction is linked to extraordinary increases

in

> > maximal lifespan in rats and mice, Fontana and colleagues at

> > Washington University, including principal investigator O.

> > Holloszy, M.D., professor of medicine, have been involved in a

> > scientific study that compares calorie restriction to exercise and

> > measures many biological factors linked to longevity and health.

> > Called the CALERIE study (Comprehensive Assessment of the Long

term

> > Effects of Reducing Intake of Energy), the project randomly

divided 48

> > people into three groups: Eighteen cut their caloric intake by 25

> > percent for one year. Another 18 started exercising to increase

their

> > energy expenditure by 25 percent for a year. A third group of 10

> > people didn't change anything.

> >

> > At the end of that year, the investigators measured IGF-1 levels

in

> > all three groups. Again they found no reductions in the group on

> > calorie restriction.

> >

> > " That was puzzling because it was the first time we hadn't seen

> > agreement between mice and rats on calorie restriction and humans

on

> > calorie restriction, " Fontana explains. " But we know there are two

> > major influences on IGF-1 levels: calorie intake and protein

intake.

> > So we decided to look at the influence of protein. "

> >

> > Again, Fontana had a ready-made study group. His team has been

> > following a population of strict vegans for several years. They

tend

> > to eat less protein than the CRONies from the CR Society, so he

> > compared IGF-1 levels between the two groups.

> >

> > " The vegans had significantly less circulating IGF-1, even if they

> > were heavier and had more body fat than CRONies, " he

says. " Protein in

> > the diet seemed to correlate with the lower levels of IGF-1. The

> > strict vegans took in about 10 percent of their total calories

from

> > protein, whereas those on calorie restriction tended to get about

23

> > or 24 percent of calories from protein. "

> >

> > The investigators wanted to take one more look at the relationship

> > between dietary protein and IGF-1, so Fontana asked a group of

CRONies

> > to eat less protein for a few weeks. He says it was not easy to

cut

> > protein because those on calorie restriction have to do a lot of

> > calculating and juggling to ensure they take in very few calories

and

> > still get adequate nutrition. Increasing dietary protein is one

way

> > many CRONies guard against becoming malnourished.

> >

> > " But six of them agreed to lower their protein intake, " Fontana

> > explains, " and after three weeks their circulating IGF-1 declined

> > dramatically. "

> >

> > Previous research from Fontana's group had found that a diet

lower in

> > protein might protect against some cancers. These more recent

findings

> > suggest lowering protein also might be important to longevity.

Fontana

> > admits his evidence is preliminary, but the findings suggest that

when

> > people adjust their diets to improve health and lengthen life,

they

> > should control not only calories and fat but also keep an eye on

> protein.

> >

> > Fontana isn't proposing radical low-protein diets. Instead, he is

> > suggesting the current recommended daily allowance (RDA) for

protein,

> > which is 0.82 grams of protein per kilogram of body weight, or

about

> > 56 grams of protein for an average, adult man and 46 grams for an

> > average, adult woman. Most people, including CRONies, consume much

> > more protein than the RDA recommendation.

> >

> > " It's much easier to restrict protein than to restrict calories, "

he

> > says. " If our research is on the right track, maybe humans don't

need

> > to be so calorie restricted. Limiting protein intake to .7 or .8

grams

> > per kilogram per day might be more effective. That's just a

> > hypothesis. We have to confirm it in future studies. "

> >

> > Until then, Fontana suggests people might want to look at protein

> > consumption and tailor it to RDA recommendations. Traditionally,

he

> > says, nutritionists have not worried about people eating too much

> > protein, but these findings suggest perhaps they should.

> >

> > Journal references:

> >

> > 1. Fontana et al. Long-term effects of calorie or protein

> > restriction on serum IGF-1 and IGFBP-3 concentration in humans.

Aging

> > Cell, 2008; 7 (5): 681 DOI: 10.1111/j.1474-9726.2008.00417.x

> > 2. Fontana L, Klein S, Holloszy JO. Long-term low-protein,

> > low-calorie diet and endurance exercise modulate metabolic factors

> > associated with cancer risk. American Journal of Clinical

Nutrition,

> > vol. 84; pp. 1456-1462, Dec. 2006

> >

>