Post by GP
"The digestion of protein releases acids that the body usually neutralizes
with calcium and other buffering agents in the blood."
"Il nostro organismo infatti è tendenzialmente basico e, per mantenerlo
tale, occorre curare l'alimentazione dando preferenza ad alimenti
alcalinizzanti (frutta e verdura)."
" ....i cereali (anch'essi molto acidificanti a parte il miglio)..."
Se sono vere queste affermazioni (chiedo lumi) il remoto rischi di rompersi
il polsopotrebbe diminuire ulteriormente
Mi rispondo da solo:
The accusation is that high protein intakes cause calcium to 'leech' from
bones, thus causing bone-thinning. A review of the research in this area
shows that high protein intake, in the presence of alkalinising fruit and
vegetable intake and adequate calcium intake, either has no adverse affect
on bone mass or has a positive affect on bone mass (51).
High-carb advocates are quick to point out that meat increases the acid load
in the body, claiming this will lead to bone thinning. They are strangely
silent when it comes to pointing out that grains also increase the acid load
in the body (57). Those attacking low-carb diets like to portray them as
`unbalanced' diets, consisting of huge amounts of animal protein and little
Don't believe them! Alkalinising low-carbohydrate vegetables and small
servings of low-glycemic fruits are a perfect compliment to animal protein
in a low-carb diet. Dr. Robert Atkins, invariably mentioned by those
attacking low-carb diets, repeatedly recommended the consumption of fruits
and (especially) vegetables in his writings. Paleolithic nutrition (my
favoured approach to low-carb eating) is by its very nature a diet high not
only in animal protein but low-carbohydrate plant foods.
Studies have shown high levels of protein and calcium to act synergistically
in increasing bone mineral density (BMD). Higher protein intake was
significantly associated with a favorable change in total-body BMD in
elderly subjects supplemented with calcium and vitamin D. In this 3 year
study, a placebo group not receiving the supplements did not experience such
favourable changes (52).
The message here is to consume a well-rounded diet that includes whole-food
sources of protein, and alkalinising plant foods. A calcium and vitamin D
supplement may well be warranted for those at risk of, and wishing to
prevent, bone thinning.
A recent study from Denmark examined the effects of a six-month high-protein
diet vs a low-protein diet in 65 overweight adults. No adverse effects on
bone mineral content were seen in the high-protein group, who lost almost
twice as much weight as the low-protein group (53).
A study with women 55-69 years of age showed that as the consumption of
animal protein increased, the incidence of hip fracture decreased (54).
Another study showed significantly lower calcium absorption in women
consuming the lowest-fat, highest-fiber diets, compared to those eating the
highest-fat, lowest-fiber diets (55).
For over 2 million years, humans were hunter-gatherers. Through their
research, paleontologists have determined what the hunter-gatherers ate -
and it wasn't pasta, rice cakes and low-fat cookies! (56) The
hunter-gatherers ate a diet rich in animal protein. Far from being delicate
and fracture-prone, their remains show skeletal structures that were more
robust than those of modern man.
The hunter-gatherers consumed mainly meat, and a wide variety of wild plant
foods - nuts, seeds, and alkaline fruits and vegetables. Grain consumption
was either non-existent or minimal. The widespread consumption of grains in
the human diet is a relatively recent phenomenon, dating back 10,000 years.
Grains and legumes contain 'anti-nutrients' such as phytates, which act to
intefere with the body's absorption of vital minerals, particularly iron and
zinc (which is essential for healthy bone formation) (58,59). As mentioned,
grains also increase the acid load in the body.
We can see that a low-carbohydrate, high fat, high protein diet is a far
better choice for building strong bones than a low-fat, high-carbohydrate
diet. It ensures adequate intake of protein; it replaces acid-forming,
phytate-containing grains and legumes with alkalinising fruits and
vegetables; and the fat content of such a diet assists the absorption of
fat-soluble bone-building vitamins like Vitamin D and K.
51 Massey LK. Does Excess Dietary Protein Adversely Affect Bone? Symposium
Overview. Journal of Nutrition, June 1998; 128 (6): 1048-1050
52 Dawson-Hughes B, Harris SS. Calcium intake influences the association of
protein intake with rates of bone loss in elderly men and women. American
Journal of Clinical Nutrition, April 2002; 75 (4): 773-779.
53 Astrup A., et al. The Effect of Protein Intake on Bone Mineralisation: A
Randomised Controlled 6-Months Trial in Overweight Subjects. The American
Journal of Clinical Nutrition 2002; 75 (2s): abstract 16.
54 Munger R.G, et al. Prospective study of dietary protein intake and risk
of hip fracture in postmenopausal women. American Journal of Clinical
Nutrition, 1999; 69: 147-152.
55 Wolf R.L, et al. Factors associated with calcium absorption efficiency in
pre- and perimenopausal women. American Journal of Clinical Nutrition, 2000;
56 Cordain L, et al. Plant-animal subsistence ratios and macronutrient
energy estimations in worldwide hunter-gatherer diets, American Journal of
Clinical Nutrition, March 2000; 71 (3): 682-692.
57 Barzel US, K. Massey LK. Excess Dietary Protein Can Adversely Affect
Bone. Journal of Nutrition. 128: 1051-1053.
58 Hallberg L, et al. Iron absorption in man: ascorbic acid and
dose-dependent inhibition by phytate. American Journal of Clinical
Nutrition; 49: 140-144.
59 Lönnerdal B. Dietary Factors Influencing Zinc Absorption. Journal of
Nutrition, 2000; 130: 1378S-1383S.