Animal protein & bone strength

[DeniseM]

Is there a difference between animal and vegetable proteins?

This is an excerpt from Dr. Fuhrman’s book Eat For Health (http://www.1shoppingcart.com/app/?Clk=1181074).

Diets too high in animal protein and low in vegetable protein: Meat and other high protein foods leave an acid residue in the blood that leads to bone dissolution. To neutralize this acid load, the body calls on its stores of calcium to provide basic calcium salts. Studies show that people with a high animal protein intake can develop a negative calcium balance, regardless of how much calcium is consumed. An important study demonstrated an increased bone loss and risk of hip fracture in those with a higher ratio of animal protein to vegetable protein. The researchers concluded that an increase in vegetable protein and a decrease in animal protein may decrease the risk of hip fractures in the elderly.1 The recommendations are clear: green vegetables, beans, nuts, and seeds should be the major source of protein. It is important to note that later in life (after age 70), it is crucial to pay more attention to protein intake. At that point, both too much protein and too little protein are unfavorable to bone mass.2

1. Sellmeyer DE, Stone KL, Sebastian A, Cummings SR. A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. Study of Osteoporotic Fractures Research Group. Am J Clin Nutr. 2001;73(1):118-122.

2. Devine A, Dick IM, Islam AF, Dhaliwal SS, Prince RL. Protein consumption is an important predictor of lower limb bone mass in elderly women. Am J Clin Nutr. 2005;81(6):1423-1428.

[mcsblues]

Denise the 'your bones will crumble to dust' scenario is on Mike's list of 'vampire myths' about low carb (from memory right after "your kidneys will explode!:eek::p).

If the best Fuhrman has to offer is one observational study which suggests this possibility in women at 65 (but no randomised trial to put this theory to the test), and another which suggests the more protein (whatever the source) the better when you are 70, then I think he needs to try a bit harder ... don't you?;)

[laughingW]

Sigh. Calcium does go into and out of bone (bones are constantly being broken down and built up; bone problems occur when the breaking-down is going faster than the building-up can keep up). Acid-and-base balance does affect it.

Fuhrman however is making great leaps of opinion, unsupported by data, to single out animal protein.

To add a little depth and context about this vampire myth, see:

Cordain (paleo guy) -

http://www.thepaleodiet.com/nutritional_tools/acid.shtml

John Berardi, a sports nutritionist:

http://www.johnberardi.com/articles/nutrition/bases.htm



A Few Additional Protein Notes
Many doctors, dietitians, and sports nutritionists have come down on animal protein for several reasons including its effect on renal acid load. While it's true that animal protein (especially animal flesh) does produce a high PRAL, I find it interesting that the same "experts" espouse high grain diets. As you can see from the charts above, whole grains are also very acid forming.
Another interesting fact is that while a high protein diet is acid forming, the high protein diet also seems to counteract some of its own acid loading potential.(9) In other words, while protein produces an acid load, it also increases the body's capacity for excreting those acids. None of the other acid producing foods are as effective as protein in doing so. Besides, just like with the other acid-forming foods, all you have to do is consume enough basic foods and supplements to neutralize the acidity.

Conclusions
Just because very few individuals in the sports-nutrition world are talking about acid-base balance doesn't mean that it's not important. Employing a few simple strategies to neutralize your high-acid diet may mean the difference between chronic low-grade acidosis — and the associated muscle wasting, bone loss, and altered hormonal profile — and a healthy, alkaline diet.

[DeniseM]

Thanks, esp for the link to Berardi's explanation.
Denise

[S Bear]

This is peripherally related. It's from a newsletter from Dr Frank Shallenberger about acid and alkaline diets, and relates to the whole bone-loss, acidity issue. I haven't checked the reference. But this info suggests that the purported acidity and leaching created by patterns of food intake pe se is irrelevant.

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You may have heard that as people grow older, and especially when they become sick, their bodies become progressively more acidic. You may have even heard about some new diets on the market called "Acid-Ash" diets. Should you be on one of these diets?

Early in my alternative medical career, someone told me it's the foods we eat that cause this acid accumulation. They said certain foods, known as acid foods, leave an acidic residual when your body metabolizes them. Other foods leave an alkaline (opposite of acid) residual. Therefore, the reason that people become acidic is because they eat too many acid foods and not enough alkaline foods. But is there any truth to this theory?

I don't think so, and here are two reasons why. First, the acid that your body produces comes overwhelmingly from energy metabolism. The amount of acid you produce from the metabolism of acid foods is less than one-half of one percent of the amount of acid produced in normal metabolism. It's just a drop in the bucket.

Second, for two years I monitored the acid production in many people who were avoiding acid foods. I did not find that their acid production was any less than those eating acid foods. Now I have a third reason for doubting this theory.

A meta-analysis of studies on this theory just hit the newsstand recently. A meta-analysis is a review of many studies, and is a very accurate way too analyze data. The authors of the study looked at this theory because proponents of a low-acid food diet say that acidic foods force the kidneys to release excessively acid urine. They also say the main component of these acid foods is phosphoric acid. And when people take in too much phosphoric acid, the body leeches calcium out of the bones to balance it. Calcium has an alkaline effect. The supposed result is that osteoporosis develops from a loss of calcium in the urine. But is it true?

The researchers wanted to find out if phosphoric acid intake causes bone loss in healthy adults. Specifically, the researchers looked at three things. They wanted to know whether or not a diet high in phosphoric acid affected urine calcium loss, overall calcium balance, and markers indicating excessive bone loss.

Here's what they found. They were able to find 12 studies that examined the effects of various levels of dietary phosphoric acid intake. All 12 studies followed a total of 269 subjects. Three of the studies did, in fact, report an increase in the amount of acid excreted in the urine from elevated phosphoric acid intake.

However, this increase in acid urine did not result in a loss of calcium. In fact, the opposite happened! Every one of the studies "demonstrated significant decreases in urine calcium excretion in response to phosphate supplements whether the calcium intake was high or low." And that wasn't all. None of the studies revealed a lower calcium balance from eating high levels of phosphoric acid. According to the authors, "All of the findings from this meta-analysis were contrary to the acid-ash hypothesis. Higher phosphate intakes were associated with decreased urine calcium and increased calcium retention. This meta-analysis did not find evidence that phosphate intake contributes to demineralization of bone or to bone calcium excretion in the urine."

So why didn't eating all that excess phosphoric acid result in calcium loss? Because as much as it was, it was still insignificant next to the amount of acid your body routinely produces from everyday normal metabolism.

REF: Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Phosphate decreases urine calcium and increases calcium balance: a meta-analysis of the osteoporosis acid-ash diet hypothesis. Nutr J. 2009 Sep 15;8:41.

[gman3164]

This sounds like more vegetarian mumbo-jumbo. Are we to believe that plant protein contains more basic amino acids (and less acidic amino acids) than animal protein? Has anyone done a biochemical analysis to investigate this question? I highly doubt it. The Sellmeyer study above was one of several reviewed by Massey back in 2003, and the studies had mixed results (J Nut. 133: 8625-8655). Don't believe a word of it, Denise!