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Restrict Protein, Not Just Calories, to Prolong Life

Thursday, February 17, 2011

Dr. Gabe Mirkin's Fitness and Health E-Zine
February 20, 2011

Restrict Protein, Not Just Calories, to Prolong Life

Recent research show that protein restriction may be far
more effective than calorie restriction in prolonging the lives of
humans. Many studies show that restricting calories prolongs the
lives of yeast, worms, spiders, flies, insects, rats and probably
monkeys. Humans who severely restrict calories have long-life
characteristics, such as low cholesterol and blood pressure and
hearts that are more than 15 years younger than those of other
North Americans their age (Experimental Gerontology, August 2007).
However, most of the test group of humans who restrict
calories do not have a drop in a hormone called Insulin-Like
Growth Factor-1 (IGF-1) that appears necessary for living a long
time. High blood levels of IGF-1 are associated with premature
aging and diseases of aging such as diabetes and cancer.
IGF-1 levels are lower than normal in worms, flies and mice on
restricted-calorie diets, but not in humans. This week a report
shows that IGF-1 shortens life by increasing cell DNA genetic
damage, and causes cancer by blocking apoptosis that causes cancer
cells to kill themselves before they destroy their host (Science
Translational Medicine, February 16, 2011).
Luigi Fontana, a professor of medicine at Washington
University in St Louis, noticed that most calorie-restricting
humans eat high levels of protein, about 1.7 grams per kilogram of
body weight/day. This is more than the US government-recommended
intake of 0.8 g/kg/day, and even higher than the 1.2 g/kg/day that
the average American eats. Dr. Fontana asked humans on calorie
restricted diets to reduce their intake of protein to 0.95 g/kg/day.
After just three weeks of reduced protein intake, their IGF-1 levels
dropped markedly (Aging Cell, September, 2008).
Among the calorie-restricting humans, vegans have lower
levels of IGF-1 than meat-eaters (Rejuvenation Research, February
2007). Strict vegans also have significantly lower IGF-1 levels
than people who restrict just calories, even if they are heavier
and have more body fat. Strict vegans take in about 10 percent of
their calories from protein, whereas those on calorie restriction
tended to get 24 percent of calories from protein. Other data
show that diets lower in protein might protect against some
cancers. So restricting protein may be more important than
restricting calories.
If fruit flies and rodents are fed special diets that
restrict protein, they can eat as many calories as they want and
still live longer (Nature, December 2009). This suggests that as
long as you are not overweight, you may not need to restrict
calories. Instead, restrict only protein which is far easier to do.
Furthermore, you can probably eat all the fruits and
vegetables you want and not restrict calories as long as you
restrict protein. That's very good news because it is far easier
to restrict protein than it is to restrict all foods. The only way
that you can restrict calories and still remain healthy is to eat
a diet based on vegetables. It now appears that you extend your
life far more by reducing protein that you would by restricting
just calories.
www.DrMirkin.com
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  Member Comments About This Blog Post:

SNIC23 7/27/2013 8:52PM

    Very interesting! I believe that it is recommended that we consume far more protein than is necessary/healthy for our bodies.

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CHANETC 2/17/2011 9:16PM

    JUNEPA-The recommendation seems to be 10% of your daily calories from protein and 5% is probably sufficient. From Dr.Mirkin's article the recommendation was based on you body weight:
"Luigi Fontana, a professor of medicine at Washington University in St Louis, noticed that most calorie-restricting humans eat high levels of protein, about 1.7 grams per kilogram of body weight/day. This is more than the US government-recommended intake of 0.8 g/kg/day, and even higher than the 1.2 g/kg/day that
the average American eats. Dr. Fontana asked humans on calorie restricted diets to reduce their intake of protein to 0.95 g/kg/day. After just three weeks of reduced protein intake, their IGF-1 levels dropped markedly (Aging Cell, September, 2008)."
DrMirkin.com

Comment edited on: 2/17/2011 9:18:19 PM

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JUNEPA 2/17/2011 8:45PM

    I found restricting simple carbs greatly improved my diet, and once I did that I always had to work hard to get the protein in without getting to much fat (animal protein sources ) or carbs (vegetable sources) at the end of the day, using the Spark nutrition tracking system (I am not currently tracking, but did track for about 6 months every day last year) Spark recommends 15% protein, for me about 75 grams, are you saying 15 grams is enough?

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GIANT-STEPS 2/17/2011 5:04PM

  Our actual protein requirements are much lower than most people think. Current recommendations are based on outdated and flawed research and assumptions. There is no point in our lives when we grow and build muscle faster than when we are babies and human breast milk only gets 10% of its calories from protein. Calves grow much faster than humans and their milk gets 40% of its calories from protein. Rats mature even faster and have yet a higher percentage of protein.
When tested humans maintained their nitrogen balance (meaning they didn't loose muscle) on energy sufficient diets with as little as 5% protein. Doubling to 10% was suggested as a safety margin. Many diets recommend 2-3 times as much protein.

Even most vegans get more than 10% of their calories from protein. It is necessary to live on mostly fruit for protein to be this low.

For all intents and purposes it is nearly impossible to be protein deficient on an energy sufficient diet. There are people in starving 3rd world countries who are protein deficient but they are also starving. When someone is starving protein can do them a lot of good but for us adding protein is a liability.

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