Protein bioavailability?

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Protein bioavailability?

Postby boardn10 » Fri Nov 21, 2008 4:15 pm

Does anyone know the most bioavailable protein? I haven't read the most recent research but I always understood soy to be right up there with anything of an animal source!? I ask because this came up with someone else I know with Lyme disease who advised to eat lots of eggs since they are the so called 'perfect' protein.

-Rich
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Re: Protein bioavailability?

Postby JeffN » Fri Nov 21, 2008 4:23 pm

boardn10 wrote:Does anyone know the most bioavailable protein? I haven't read the most recent research but I always understood soy to be right up there with anything of an animal source!? I ask because this came up with someone else I know with Lyme disease who advised to eat lots of eggs since they are the so called 'perfect' protein.

-Rich


What would you want something to be the most "bio-available" when more of it is not good.

The current research on CR-ON is showing that the most available proteins are also the ones that rise IGF-1 the most, which in turn, may increase the growth rates of cancer.

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IGF-1

Postby JeffN » Fri Nov 21, 2008 4:46 pm

Here is the study, along with a private conversation with one of the participants, of which, due to the conversation having been private, I will just quote the main points. The study is public.

""Q. How often do you and (...) test for IGF-1, monthly?

We have tested IGF-1 about every 3 months since 2003. We test it along with the IGF binding proteins 1, 2 and 3, insulin, T3 and the VAP test.

We wanted to see how total protein fared against the above battery of tests as well as individual protein concentrates including whey, brewers yeast, soy protein isolate, nonfat yogurt, kefir. and a mixture of individual amino acids. The results were frightening -- each one of these substances sent IGF-1 significantly higher -- independent of total calorie intake.

The goal was to customize our CR diet to produce IGF-1 in the lower third of the reference range and to get IGFBP1, which is an indicator of SIRT1 activity, glucagon activity, etc., at the high end of the reference range.

This is consistent with the downregulation of energy availability and of anabolic activity that is shown in long-lived CR animals.

I have found, however, that protein absorbability makes a greater difference in IGF-I (and the binding proteins) than total protein, if the protein is from vegetables and grains, beans (this does not mean concentrates), and fruits.""


The Study...

Luigi Fontana, Edward P. Weiss, Dennis T. Villareal, Samuel Klein, John O. Holloszy. "Long-term effects of calorie or protein restriction onserum IGF-1 and IGFBP-3 concentration in humans." *Aging Cell. *(2008) Doi: 10.1111/j.1474-9726.2008.00417.x


ABSTRACT
Reduced function mutations in the insulin/IGF-I signaling pathway increase maximal lifespan and health span in many species. Calorie restriction (CR) decreases serum IGF-1 concentration by ~40%, protects against cancer and slows aging in rodents. However, the long-term effects of CR with adequate nutrition on circulating IGF-1 levels in humans are unknown. Here we report data from two long-term CR studies (1 and 6 years) showing that severe CR without malnutrition did not change IGF-1 and IGF-1 : IGFBP-3 ratio levels in humans. In contrast, total and free IGF-1 concentrations were significantly lower in moderately protein-restricted individuals. Reducing protein intake from an average of 1.67 g kg−1 of body weight per day to 0.95 g kg−1 of body weight per day for 3 weeks in six volunteers practicing CR resulted in a reduction in serum IGF-1 from 194 ng mL−1 to 152 ng mL−1. These findings demonstrate that, unlike in rodents, long-term severe CR does not reduce serum IGF-1 concentration and IGF-1 : IGFBP-3 ratio in humans. In addition, our data provide evidence that protein intake is a key determinant of circulating IGF-1 levels in humans, and suggest that reduced protein intake may become an important component of anticancer and anti-aging dietary interventions.

Some other interesting points from the "conversation"...

"One of the most telling comparisons in the study was between our high-protein CR group and a cohort of ad-lib vegans. The CR Society group ate an average of 1772 calorie per day while the vegans ate 1980 calories per day. However, The CR group ate an average of 23.5% of total calories in protein while the vegans ate 9.6 percent protein. The excess protein eaten by our group was enough to completely nullify CR's IGF-I lowering effect."


I am hoping to have one (or two) of these researchers at the Sept 09 McDougall Advanced Weekend.

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Postby landog » Fri Nov 21, 2008 6:19 pm

What did Jeff just say???

If anyone can interpret, I'd be grateful.

Thanks,
-dig
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Postby JeffN » Fri Nov 21, 2008 7:15 pm

landog wrote:What did Jeff just say???

If anyone can interpret, I'd be grateful.

Thanks,
-dig


HI,

Sorry! :)

Read this McDougall newsletter and especially the parts about IGF-1

http://www.drmcdougall.com/misc/2005nl/ ... 0pusoy.htm

Elevated IGF-1 levels in adults can increase the growth rate of cancer. Even isolated plant proteins (like soy) can raise IGF-1 levels. We want lower IGF-1 levels especially as we get older.

The above studies showed that higher "total" protein levels raised IGF-1, and so keeping "total" protein levels low, was important.

In addition, the vegan low protein diet, produced lower IGF-1 levels than the low protein calorie restricted diet. In other words, the vegan lower protein diet, which was lower in protein than the low protein calorie restricted diet, produced lower IGF-1 levels. So, based on that one marker, the vegan diet that was not calorie restricted did better than the calorie restricted diet.

Also, when the diet was made up of proteins of higher availability, even if the total protein of the diet was low, it raised IGF-1 levels.

So, the take home message from this is keep your total protein low and choose proteins which are less bio-available, which are plant proteins. Just more support to follow the program. :)

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