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  1. #1
    Usuari@ expert@ Avatar de sujal
    Fecha de ingreso
    marzo-2006
    Ubicación
    Guadalajara
    Mensajes
    8.690

    Exceso proteínas y osteoporosis


    Cross-cultural association between dietary animal protein and hip fracture: a hypothesis.Abelow BJ, Holford TR, Insogna KL.
    1992 Jan;50(1):14-8.
    Abelow BJ, Holford TR, Insogna KL.

    Yale University School of Medicine, New Haven, Connecticut 06510.

    Age-adjusted female hip fracture incidence has been noted to be higher in industrialized countries than in nonindustrialized countries. A possible explanation that has received little attention is that elevated metabolic acid production associated with a high animal protein diet might lead to chronic bone buffering and bone dissolution. In an attempt to examine this hypothesis, cross-cultural variations in animal protein consumption and hip fracture incidence were examined. When female fracture rates derived from 34 published studies in 16 countries were regressed against estimates of dietary animal protein, a strong, positive association was found. This association could not plausibly be explained by either dietary dietary calcium or total caloric intake. Recent studies suggest that the animal protein-hip fracture association could have a biologically tenable basis. We conclude that further study of the metabolic acid-osteoporosis hypothesis is warranted.

    PMID: 1739864 [PubMed - indexed for MEDLINE]

    http://www.ncbi.nlm.nih.gov/sites/en...RVAbstractPlus

  2. #2
    Usuari@ expert@ Avatar de sujal
    Fecha de ingreso
    marzo-2006
    Ubicación
    Guadalajara
    Mensajes
    8.690
    A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women.
    2001 Jan;73(1):118-22.
    Sellmeyer DE, Stone KL, Sebastian A, Cummings SR

    Study of Osteoporotic Fractures Research Group.Sellmeyer DE, Stone KL, Sebastian A, Cummings SR.

    Division of Endocrinology, the General Clinical Research Center, and the Department of Epidemiology and Biostatistics, University of California, San Francisco, USA. dsellmeyer@psg.ucsf.edu

    BACKGROUND: Different sources of dietary protein may have different effects on bone metabolism. Animal foods provide predominantly acid precursors, whereas protein in vegetable foods is accompanied by base precursors not found in animal foods. Imbalance between dietary acid and base precursors leads to a chronic net dietary acid load that may have adverse consequences on bone. OBJECTIVE: We wanted to test the hypothesis that a high dietary ratio of animal to vegetable foods, quantified by protein content, increases bone loss and the risk of fracture. DESIGN: This was a prospective cohort study with a mean (+/-SD) of 7.0+/-1.5 y of follow-up of 1035 community-dwelling white women aged >65 y. Protein intake was measured by using a food-frequency questionnaire and bone mineral density was measured by dual-energy X-ray absorptiometry. RESULTS: Bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake. Women with a high ratio had a higher rate of bone loss at the femoral neck than did those with a low ratio (P = 0.02) and a greater risk of hip fracture (relative risk = 3.7, P = 0.04). These associations were unaffected by adjustment for age, weight, estrogen use, tobacco use, exercise, total calcium intake, and total protein intake. CONCLUSIONS: Elderly women with a high dietary ratio of animal to vegetable protein intake have more rapid femoral neck bone loss and a greater risk of hip fracture than do those with a low ratio. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture. This possibility should be confirmed in other prospective studies and tested in a randomized trial.

    PMID: 11124760 [PubMed - indexed for MEDLINE]

    http://www.ncbi.nlm.nih.gov/sites/en...RVAbstractPlus

  3. #3
    Usuari@ expert@ Avatar de sujal
    Fecha de ingreso
    marzo-2006
    Ubicación
    Guadalajara
    Mensajes
    8.690
    Protein consumption and bone fractures in women.
    1996 Mar 1;143(5):472-9.
    Feskanich D, Willett WC, Stampfer MJ, Colditz GA.

    Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.

    Dietary protein increases urinary calcium losses and has been associated with higher rates of hip fracture in cross-cultural studies. However, the relation between protein and risk of osteoporotic bone fractures among individuals has not been examined in detail. In this prospective study, usual dietary intake was measured in 1980 in a cohort of 85,900 women, aged 35-59 years, who were participants in the Nurses' Health Study. A mailed food frequency questionnaire was used and incident hip (n = 234) and distal forearm (n = 1,628) fractures were identified by self-report during the following 12 years. Information on other factors related to osteoporosis, including obesity, use of postmenopausal estrogen, smoking, and physical activity, was collected on biennial questionnaires. Dietary measures were updated in 1984 and 1986. Protein was associated with an increased risk of forearm fracture (relative risk (RR) = 1.22, 95% confidence interval (Cl) 1.04-1.43, p for trend = 0.01) for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day. A similar increase in risk was observed for animal protein, but no association was found for consumption of vegetable protein. Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture (RR = 1.23, 95% Cl 1.01-1.50) compared with women who ate red meat less than once per week. Recall of teenage diet did not reveal any increased risk of forearm fracture for women with higher consumption of animal protein or red meat during this earlier period of life. No association was observed between adult protein intake and the incidence of hip fractures, though power to assess this association was low.

    PMID: 8610662 [PubMed - indexed for MEDLINE]

    http://www.ncbi.nlm.nih.gov/sites/en...RVAbstractPlus

  4. #4
    Usuari@ expert@ Avatar de sujal
    Fecha de ingreso
    marzo-2006
    Ubicación
    Guadalajara
    Mensajes
    8.690

    Mito proteico.... veamos



    Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity.(1999)

    McCarty MF.

    Nutrition 21/AMBI, San Diego, CA, USA.

    Amino acids modulate the secretion of both insulin and glucagon; the composition of dietary protein therefore has the potential to influence the balance of glucagon and insulin activity. Soy protein, as well as many other vegan proteins, are higher in non-essential amino acids than most animal-derived food proteins, and as a result should preferentially favor glucagon production. Acting on hepatocytes, glucagon promotes (and insulin inhibits) cAMP-dependent mechanisms that down-regulate lipogenic enzymes and cholesterol synthesis, while up-regulating hepatic LDL receptors and production of the IGF-I antagonist IGFBP-1. The insulin-sensitizing properties of many vegan diets--high in fiber, low in saturated fat--should amplify these effects by down-regulating insulin secretion. Additionally, the relatively low essential amino acid content of some vegan diets may decrease hepatic IGF-I synthesis. Thus, diets featuring vegan proteins can be expected to lower elevated serum lipid levels, promote weight loss, and decrease circulating IGF-I activity. The latter effect should impede cancer induction (as is seen in animal studies with soy protein), lessen neutrophil-mediated inflammatory damage, and slow growth and maturation in children. In fact, vegans tend to have low serum lipids, lean physiques, shorter stature, later puberty, and decreased risk for certain prominent 'Western' cancers; a vegan diet has documented clinical efficacy in rheumatoid arthritis. Low-fat vegan diets may be especially protective in regard to cancers linked to insulin resistance--namely, breast and colon cancer--as well as prostate cancer; conversely, the high IGF-I activity associated with heavy ingestion of animal products may be largely responsible for the epidemic of 'Western' cancers in wealthy societies. Increased phytochemical intake is also likely to contribute to the reduction of cancer risk in vegans. Regression of coronary stenoses has been documented during low-fat vegan diets coupled with exercise training; such regimens also tend to markedly improve diabetic control and lower elevated blood pressure. Risk of many other degenerative disorders may be decreased in vegans, although reduced growth factor activity may be responsible for an increased risk of hemorrhagic stroke. By altering the glucagon/insulin balance, it is conceivable that supplemental intakes of key non-essential amino acids could enable omnivores to enjoy some of the health advantages of a vegan diet. An unnecessarily high intake of essential amino acids--either in the absolute sense or relative to total dietary protein--may prove to be as grave a risk factor for 'Western' degenerative diseases as is excessive fat intake.

    PMID: 10687887 [PubMed - indexed for MEDLINE]

    http://www.ncbi.nlm.nih.gov/pubmed/1...med.Pubmed_Res

    (Se agradecería una traducción de este artículo)

  5. #5
    PETW/(No L7s)
    Fecha de ingreso
    diciembre-2008
    Mensajes
    2.029
    A ver si mañana puedo traducirlo, Sujal.

  6. #6

  7. #7
    PETW/(No L7s)
    Fecha de ingreso
    diciembre-2008
    Mensajes
    2.029
    Las proteínas veganas pueden reducir el riesgo de padecer cáncer, obesidad y enfermedades cardiovasculares, ya que estimulan el aumento de la actividad del glucagón. .(1999)

    McCarty MF.

    Nutrición 21/AMBI, San Diego, CA, EE.UU.

    Los aminoácidos modulan la secreción tanto de la insulina como del glucagón; por lo tanto, la composición de las proteínas alimenticias puede influir en el equilibrio de la actividad del glucagón y la insulina. La proteína de soja, así como muchas otras proteínas veganas, tiene más aminoácidos no esenciales que la mayoría de proteínas animales, y en consecuencia, debería favorcer principamente la producción de glucagón. Al actuar sobre los hepatocitos, el glucagón estimula (y la insulina dificulta) los mecanismos dependientes de campo que reducen los enzimas lipogénicos y la síntesis del colesterol, mientras que incrementan los receptores hepáticos de LDL y la producción de la antagonista IGFBP-1 del IGF-I. Las propiedades que sensibilizan a la insulina presentes en muchas dietas veganas (altas en fibra y bajas en grasas saturadas) aumentarían estos efectos al reducir la secreción de insulina. Además, el contenido relativamente bajo de aminoácidos esenciales de algunas dietas veganas puede aumentar la síntesis del IGF-I del hígado. Por tanto, se espera que las dietas que incluyen proteínas veganas disminuyan los niveles elevados de lípidos en suero, estimulen la pérdida de peso y reduzcan la actividad circulatoria IGF-I. Este último efecto debería impedir la inducción del cáncer (como se ha comprobado en estudios con animales y proteína de soja), reducir el daño inflamatorio mediado por los neutrófilos y ralentizar el crecimiento y la maduración en los niños. De hecho, los veganos tienden a tener pocos lípidos en suero, una constitución delgada, una estatura menor, una pubertad tardía y menos riesgo de padecer ciertos cánceres frecuentes en occidente. Se ha documentado que una dieta vegana tiene una eficacia clínica en la artritis reumatoide. Las dietas veganas bajas en grasas pueden proteger sobre todo de los cánceres asociados a la resistancia a la insulina, es decir, el de mama y el de colon, así como el de próstata. En cambio, la alta actividad del IGF-I asociada con una gran ingesta de productos animales puede ser la máxima responsable de la epidemia de cánceres en las sociedades ricas de occidente. También es probable que un aumento de la ingesta fitoquímica contribuya a la reducción del riesgo de padecer cáncer entre los veganos. Se ha documentado la regresión de las estenosis coronarias en dietas veganas bajas en grasas combinadas con la práctica de ejercicio. Dichas dietas también tienden a mejorar notablemente el control de la diabetes y a disminuir la presión alta. El riesgo de padecer otras muchos desórdenes degenerativos puede disminuir en los veganos, aunque es posible que una reducción de la actividad del factor de crecimiento sea el responsable de un aumento del riesgo de padecer una apoplejía hemorrágica. Al alterar el equilibrio entre el glucagón y la insulina, es posible que la ingesta de suplementos de aminoácidos no esenciales por parte de los omnívoros les permita disfrutar de algunas de las ventajas para la salud de una dieta vegana. Una ingesta innecesariamente alta de aminoácidos esenciales, ya sea en sentido absoluto o relacionado con las proteínas alimenticias totales, puede ser un factor de riesgo tan grave de padecer enfermedades degenerativas occidentales como lo es una ingesta excesiva de grasas.

    PMID: 10687887 [PubMed - indexed for MEDLINE]

    http://www.ncbi.nlm.nih.gov/pubmed/1...med.Pubmed_Res

  8. #8
    Usuari@ expert@ Avatar de aaaxxx
    Fecha de ingreso
    abril-2008
    Mensajes
    11.894
    glucagón???? jajaaaaaaaaa. sí, de eso doy fe

  9. #9
    PETW/(No L7s)
    Fecha de ingreso
    diciembre-2008
    Mensajes
    2.029
    Cita Iniciado por aaaxxx Ver mensaje
    glucagón???? jajaaaaaaaaa. sí, de eso doy fe
    Pues no veas escribiéndolo.

  10. #10
    Usuari@ expert@ Avatar de sujal
    Fecha de ingreso
    marzo-2006
    Ubicación
    Guadalajara
    Mensajes
    8.690

    Una ingesta innecesariamente alta de aminoácidos esenciales, ya sea en sentido absoluto o relacionado con las proteínas alimenticias totales, puede ser un factor de riesgo tan grave de padecer enfermedades degenerativas occidentales como lo es una ingesta excesiva de grasas.
    Muchas gracias Velveteen, te estoy muy agradecido.

 

 
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