Diet-induced acidosis and alkali supplementation.

Western diet, high in protein-rich foods and poor in vegetables, is likely to be responsible for the development of a moderate acid excess leading to metabolism deregulation and the onset or worsening of chronic disturbances. Available findings seem to suggest that diets with high protein/vegetables ratio are likely to induce the development of calcium lithiasis, especially in predisposed subjects. Moreover, some evidence supports the hypothesis of bone metabolism worsening and enhanced bone loss following acid-genic diet consumption although available literature seems to lack direct and conclusive evidence demonstrating pathological bone loss. According to other evidences, diet-induced acidosis is likely to induce or accelerate muscle wasting or sarcopenia, especially among elderlies. Furthermore, recent epidemiological findings highlight a specific role of dietary acid load in glucose metabolism deregulation and insulin resistance. The aim of this review is to investigate the role of acid-genic diets in the development of the mentioned metabolic disorders focusing on the possible clinical improvements exerted by alkali supplementation.

The intake of yam (Dioscorea bulbifera Linn) attenuated the hyperglycemia and the bone fragility in female diabetic rats.

INTRODUCTION: Diabetic patients have a higher risk to osteoporotic fractures. Foods, such as yam, to oppose hyperglycemia, has been used to treatment of diabetes. OBJECTIVE: The goal was assess the role of Brazilian yam (Dioscorea bulbifera) on glycemia and bone parameters of female diabetic rats. METHODS: Female Wistar rats with 3 months age were allocated in three groups. Control group (C, n = 6), treated with normal fat diet. Diabetic rats treated with high-fat diet without (DM, n = 8) and with (DMY, n = 8) liofilized yam flour. After 5 weeks of the experiment, serum glucose and insulin, pancreas mass, number and area of pancreas islets were quantified. And femur parameters were analyzed by dual-energy X-ray absorptiometry (DXA) and computed tomography (CT). RESULTS: Differences were considered significant if P<0.05. Diabetic groups showed lower (P < 0.05): femur and pancreas mass, area of the pancreatic islets and insulin. However, DMY showed lower (-10%, P < 0.05) concentrations of glucose to DM group. Femur, by DXA, showed lower bone mineral density, content and area in the DM group. While the DMY group showed greater (+27%, P < 0.05) radiodensity of femoral head when compared to DM group. DISCUSSION: Brazilian yam flour supplement did not fix a defect, but alleviated the consequences of the experimental diabetic disease. It showed results to control the rise in blood glucose levels in diabetic rats, suggesting protection in oxidative agents and postpone harm in the bone. CONCLUSION: Considering all the findings of the present study, our results suggest that yam flour does act producing benefits in the experimental diabetes.

Introducción: Los pacientes diabéticos tienen un mayor riesgo de fracturas osteoporóticas. Los alimentos, como el ñame, para oponerse a la hiperglucemia, se ha utilizado para el tratamiento de la diabetes. Objetivos: El objetivo era evaluar el papel de ñame brasileño (Dioscorea bulbifera) sobre la glucemia y el hueso parámetros de ratas diabéticas hembra. Métodos: Ratas Wistar hembra con 3 meses de edad fueron asignados en tres grupos. El grupo de control (C, n = 6), tratados con dieta normal de la grasa. Las ratas diabéticas tratadas con dieta alta en grasas y sin (DM, n = 8) y con (DMY, n = 8) harina de ñame liofilizado. Después se cuantificaron 5 semanas del experimento, la glucosa y la insulina en suero, la masa páncreas, el número y el área de islotes del páncreas. Y los parámetros de fémur fueron analizados por absorciometría de rayos X de energía dual (DXA) y la tomografía computarizada (CT). Resultados: Las diferencias se consideraron significativas si P < 0,05. Grupos diabéticos mostraron menor (P < 0,05): el fémur y la masa páncreas, el área de los islotes pancreáticos y la insulina. Sin embargo, DMY mostró inferior (-10%, P < 0,05) concentraciones de glucosa al grupo DM. Fémur, por DXA, mostró menor densidad mineral ósea, el contenido y el área en el grupo de DM. Mientras que el grupo DMY mostró mayor (27%, P < 0,05) radiodensidad de la cabeza femoral en comparación con el grupo de DM. Discusión: Suplemento de harina de ñame brasileña no fijó un defecto, pero alivia las consecuencias de la enfermedad diabética experimental. Se mostró resultados para controlar el aumento de los niveles de glucosa en sangre en ratas diabéticas, lo que sugiere la protección en agentes oxidantes y posponer daño en el hueso. Conclusión: Teniendo en cuenta todos los resultados de este estudio, nuestros resultados sugieren que la harina de ñame actúa de producir beneficios en la diabetes experimental.

Physiological and nutritional aspects of post-exercise recovery: specific recommendations for female athletes.

Gender-based differences in the physiological response to exercise have been studied extensively for the last four decades, and yet the study of post-exercise, gender-specific recovery has only been developing in more recent years. This review of the literature aims to present the current state of knowledge in this field, focusing on some of the most pertinent aspects of physiological recovery in female athletes and how metabolic, thermoregulatory, or inflammation and repair processes may differ from those observed in male athletes. Scientific investigations on the effect of gender on substrate utilization during exercise have yielded conflicting results. Factors contributing to the lack of agreement between studies include differences in subject dietary or training status, exercise intensity or duration, as well as the variations in ovarian hormone concentrations between different menstrual cycle phases in female subjects, as all are known to affect substrate metabolism during sub-maximal exercise. If greater fatty acid mobilization occurs in females during prolonged exercise compared with males, the inverse is observed during the recovery phase. This could explain why, despite mobilizing lipids to a greater extent than males during exercise, females lose less fat mass than their male counterparts over the course of a physical training programme. Where nutritional strategies are concerned, no difference appears between males and females in their capacity to replenish glycogen stores; optimal timing for carbohydrate intake does not differ between genders, and athletes must consume carbohydrates as soon as possible after exercise in order to maximize glycogen store repletion. While lipid intake should be limited in the immediate post-exercise period in order to favour carbohydrate and protein intake, in the scope of the athlete's general diet, lipid intake should be maintained at an adequate level (30%). This is particularly important for females specializing in long-duration events. With protein balance, it has been shown that a negative nitrogen balance is more often observed in female athletes than in male athletes. It is therefore especially important to ensure that this remains the case during periods of caloric restriction, especially when working with female athletes showing a tendency to limit their caloric intake on a daily basis. In the post-exercise period, females display lower thermolytic capacities than males. Therefore, the use of cooling recovery methods following exercise, such as cold water immersion or the use of a cooling vest, appear particularly beneficial for female athletes. In addition, a greater decrease in arterial blood pressure is observed after exercise in females than in males. Given that the return to homeostasis after a brief intense exercise appears linked to maintaining good venous return, it is conceivable that female athletes would find a greater advantage to active recovery modes than males. This article reviews some of the major gender differences in the metabolic, inflammatory and thermoregulatory response to exercise and its subsequent recovery. Particular attention is given to the identification of which recovery strategies may be the most pertinent to the design of training programmes for athletic females, in order to optimize the physiological adaptations sought for improving performance and maintaining health.

Bone metabolism and disease--K/DOQI impact on nurses and dietitians.

Earlier monitoring and treatment of elevated phosphorus and PTH prior to initiation of dialysis may prevent the development of bone disease. We can no longer be complacent or content with patients having a calcium-phosphorus product of 70 or phosphorus of 6.0. When we strive for the recommended optimal levels and goals and work toward these new goals we will improve our patient outcomes. We must be vigilant and have an increased intensity of focus on bone metabolism as part of the total patient care. The entire team serves to provide ongoing education and encouragement throughout the continuum of care with the CKD client.

Nutrición y osteoporosis / No disponible

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Chemical and biomechanical characterization of hyperhomocysteinemic bone disease in an animal model.

BACKGROUND: Classical homocystinuria is an autosomal recessive disorder caused by cystathionine beta-synthase (CBS) deficiency and characterized by distinctive alterations of bone growth and skeletal development. Skeletal changes include a reduction in bone density, making it a potentially attractive model for the study of idiopathic osteoporosis. METHODS: To investigate this aspect of hyperhomocysteinemia, we supplemented developing chicks (n = 8) with 0.6% dl-homocysteine (hCySH) for the first 8 weeks of life in comparison to controls (n = 10), and studied biochemical, biomechanical and morphologic effects of this nutritional intervention. RESULTS: hCySH-fed animals grew faster and had longer tibiae at the end of the study. Plasma levels of hCySH, methionine, cystathionine, and inorganic sulfate were higher, but calcium, phosphate, and other indices of osteoblast metabolism were not different. Radiographs of the lower limbs showed generalized osteopenia and accelerated epiphyseal ossification with distinct metaphyseal and suprametaphyseal lucencies similar to those found in human homocystinurics. Although biomechanical testing of the tibiae, including maximal load to failure and bone stiffness, indicated stronger bone, strength was proportional to the increased length and cortical thickness in the hCySH-supplemented group. Bone ash weights and IR-spectroscopy of cortical bone showed no difference in mineral content, but there were higher Ca2+/PO4(3-) and lower Ca2+/CO3(2-) molar ratios than in controls. Mineral crystallization was unchanged. CONCLUSION: In this chick model, hyperhomocysteinemia causes greater radial and longitudinal bone growth, despite normal indices of bone formation. Although there is also evidence for an abnormal matrix and altered bone composition, our finding of normal biomechanical bone strength, once corrected for altered morphometry, suggests that any increase in the risk of long bone fracture in human hyperhomocysteinemic disease is small. We also conclude that the hCySH-supplemented chick is a promising model for study of the connective tissue abnormalities associated with homocystinuria and an important alternative model to the CBS knock-out mouse.

Omega-3 polyunsaturated fatty acids and skeletal health.

This minireview on skeletal biology describes the actions of prostaglandins and cytokines involved in the local regulation of bone metabolism, it documents the role of lipids in bone biology, and it presents relationships between fatty acids and other factors that impact skeletal metabolism. The data presented herein show consistent and reproducible beneficial effects of omega-3 (n-3) fatty acids on bone metabolism and bone/joint diseases. Polyunsaturated fatty acids modulate eicosanoid biosynthesis in numerous tissues and cell types, alter signal transduction, and influence gene expression. These effects have not been explored in the skeletal system. Future research on n-3 fatty acids in bone biology should focus on the following two aspects. First, the further elucidation of how n-3 fatty acids alter biochemical and molecular processes involved in bone modeling and bone cell differentiation, and second, the evaluation of the potential pharmaceutical applications of these nutraceutical fatty acids in maintaining bone mineral status and controlling inflammatory bone/joint diseases.

Vitamin D metabolites in plasma of cows fed a prepartum low-calcium diet for prevention of parturient hypocalcemia.

Our objective was to characterize changes in vitamin D metabolites of plasma in Jersey cows fed a prepartum low-calcium diet. Eight cows were fed a high-calcium diet (80 g/day) and eight were fed a low-calcium diet (8 g/day) at least 14 days before parturition. Calcium concentrations in plasma decreased after initiation of feeding either diet, but cows fed low-calcium diet tended to have lower prepartum calcium and phosphorus and greater peripartal calcium in plasma. Hydroxyproline in plasma was greater during peripartal period in cows fed low-calcium diet. Prepartum 1,25-dihydroxyvitamin D in plasma tended to be greater in cows fed low calcium. Increases in 1,25-dihydroxyvitamin D were only 2 and 3 days after initiation of the low-calcium diet; during the first 2 days after parturition, however, 1,25-dihydroxyvitamin D tended to be lower in those cows fed low calcium. As parturition neared, 24,25-dihydroxyvitamin D tended to be lower in cows fed the low calcium-diet. Usual early postpartum changes in calcium phosphorus, magnesium, 1,25-dihydroxyvitamin D, and hydroxyproline were seen during first few days after initiation of feeding low calcium. Thus, we propose that the preventative action of the low-calcium diet is associated with preparation of the calcium homeostatic mechanism several days before the calcium demand of initiation of lactation.

Osteopenia of prematurity: the cause and possible treatment.

By photon absorptiometry, extrauterine bone mineralization in low-birth-weight infants fed a standard commercial formula lags significantly behind intrauterine bone mineralization. In the present study, infants of 28- to 32-week and 33- to 35-week gestational age were studied. The calcium content in a standard formula was increased to provide a daily calcium intake of 220 to 250 mg/kg/day. Phosphate intake was 110 to 125 mg/kg/day. Extrauterine bone mineralization by photon absorptiometry appeared to approximate the intrauterine bone mineralization rate.