Absorción mineral y retención ósea en ratas normales en crecimiento por el consumo de un yogur experimental reducido en lactosa que contiene galactooligosacáridos (GOS) / Mineral absorption and bone retention in normal growing rats by consumption of an experimental lactose-reduced yogurt containing galactooligosaccharides (GOS)

Introducción: Los GOS son prebióticos naturales presentes en la leche materna que pue-den obtenerse enzimáticamente a partir de la lactosa de leche de vaca durante la fabricación de yogur. El producto lácteo resultante será reducido en lactosa y contendrá prebióticos y bacterias potencialmente probióticas. Sin embargo, mantendrá la baja relación Ca/Pi que aporta la leche de vaca, lo que podría alterar el remodelamiento óseo y la mineralización. Objetivo: comparar si un yogur reducido en lactosa que contiene GOS (YE) ofrece ventajas adicionales respecto de un yogur regular sin GOS (YR) sobre las absorciones (Abs) de Ca y Pi, retención y calidad ósea durante el crecimiento normal. Al destete, ratas machos fueron divididas en 3 grupos alimentados con AIN ́93-G (C), YE o YR durante 28 días. Resultados: YE mostró el mayor aumento de lactobacilos fecales; producción de ácidos grasos de cadena corta especialmente p, profundidad de las criptas colónicas y menor pH cecal. El %AbsCa y %AbsPi aumentó en el siguiente órden: YE> YR> C (p < 0,05). El contenido de Ca y Pi en fémur, la densidad y contenido mineral óseos y los parámetros biomecánicos fueron similares en YE y C, mientras que YR mostró valores significativa-mente menores (p < 0,05). Conclusiones: YE aumentó las Abs y biodisponibilidad de minerales, alcanzando la retención y calidad ósea de C. El aumento en las Abs observado en YR no logró obtener la retención y calidad ósea de C. Conclusión: YE habría contrarrestado el efecto negativo del mayor aporte de Pi de la leche de vaca y sería una buena estrategia para lograr el pico de masa ósea y calidad del hueso adecuados, especialmente en individuos intolerantes a la lactosa. (AU)

Breast milk contains an optimal calcium/phosphate (Ca/Pi) ratio and GOS. These natural prebiotics can be enzymatically produced via cow's milk lactose inyogurt manufacture. This milk product is low in lactose and contains prebiotics and potentially probiotic bacteria but maintains a low Ca/Pi ratio that could alter bone remodeling and mineralization. We evaluated if a lactose-reduced yogurt containing GOS (YE) offers additional advantages over regular yogurt without GOS (YR) on Ca and Pi absorption (Abs), bone retention and quality during normal growth. Weaning male rats were divided into 3 groups fed AIN'93-G (C), YE or YR for 28 days. Results: YE showed the highest increase in fecal lactobacilli; short-chain fatty acids production, especially propionate and butyrate; intestine crypt depth, and the lowest cecal pH. AbsCa% and AbsPi% increased in this order: YE> YR> C (p <0.05). Ca and Pi content in femur, bone density and mineral content, and biomechanical parameters were similar in YE and C, while YR showed the significantly lowest value (p < 0.05). Conclusions: YE increased mineral Abs reaching the retention and bone quality of C. Although YR increased Abs, bone retention and quality did not achieve C values. Seemingly, YE compensated for the negative effect of the higher Pi supply and would be a good strategy to achieve adequate peak bone mass and bone quality, especially in lactose intolerant individuals. (AU)

Calcium Bioavailability in the Soluble and Insoluble Fibers Extracted from Opuntia ficus indica at Different Maturity Stages in Growing Rats.

Childhood and adolescence are crucial stages of life for bone health. Therefore, an adequate calcium intake and a healthy life style constitute the main strategies to prevent the risk of osteoporosis-related fractures during adulthood. It has been demonstrated that inclusion of indigestible carbohydrates in foods can help improve calcium absorption in growing stages. The objective of this study was to evaluate the effect of supplementation of soluble and insoluble fibers extracted from O. ficus indica cladodes on calcium bioavailability. Male Wistar rats 4-week old were fed diets added with soluble and insoluble fibers extracted from O. ficus indica cladodes at early and late maturity stages, as the only source of calcium. The mineral content, bone mineral density (BMD), physical, microstructural, and biomechanical properties of rat femurs were determined. The bones of rats fed with diets containing a soluble fiber extracted from O. ficus indica at early and late maturity stages exhibited better bone properties (resistance to fracture, microarchitecture, and calcium content) than control rats and rats fed with an insoluble fiber from O. ficusindica cladodes at both maturity stages. As expected, based on these results, the BMD values were higher in adolescent and pubertal rats fed with a diet containing the O. ficus indica soluble fiber. These results demonstrate that the soluble fiber from O. ficus indica cladodes is indeed a valuable source of bioavailable calcium, which contributes to improve physical, densitometric, biomechanical, and microstructural properties of bone in growing rats.

Calcium Bioavailability of Opuntia ficus-indica Cladodes in an Ovariectomized Rat Model of Postmenopausal Bone Loss.

Osteoporosis is a disease of the skeletal system characterized by low bone mass and bone weakening, which increase the risk of fracture. This disease is associated with menopause because hypoestrogenism induces the maturation and activation of osteoclasts. In addition, a low dietary intake of calcium leads to low bone mineral density and postmenopausal osteoporosis. The objectives of this work were to determine calcium bioavailability of Opuntia ficus-indica cladodes at a late maturity stage and to assess its contribution in improving bone health in an ovariectomized rat model. Two-month-old Wistar female rats (n = 35) were used and distributed in seven experimental groups: (i) control group (Crtl), (ii) sham group (SH), (iii) ovariectomized group (OVX), (iv) ovariectomized group supplemented with calcium citrate (CCa), (v) ovariectomized group supplemented with O. ficus-indica powder (NI), (vi) ovariectomized group supplemented with soluble fiber from O. ficus-indica (FS) and (vii) ovariectomized group supplemented with insoluble fiber from O. ficus-indica (FI). Our results showed that calcium in the soluble fiber of O. ficus-indica is bioavailable and contributes to improve the physical, densitometric, biomechanical and microstructural properties of bones in ovariectomized rats. These findings indicated that O. ficus-indica cladodes at a late maturity stage represent a good source of bioavailable calcium and consumption of these cladodes might be beneficial for the prevention of osteoporosis and other bone diseases.

Effect of Adding a Galacto-Oligosaccharides/Fructo-Oligosaccharides (GOS/FOS®) Mixture to a Normal and Low Calcium Diet, on Calcium Absorption and Bone Health in Ovariectomy-Induced Osteopenic Rats.

Menopause is associated with bone loss. Prebiotics increase Ca, inorganic phosphorus (Pi), and Mg absorption, improving bone health. These increases would supply an extra amount of minerals, decreasing bone resorption and possibly reversing ovariectomy-induced bone loss. The present experimental study sought to evaluate the effect of adding a prebiotic GOS/FOS® mixture to a normal or a low Ca diet on Ca, Pi, and Mg absorption, in osteopenic rats. Four groups of n = 8 rats each were OVX, and 8 rats were SHAM operated. All rats were fed a commercial diet for 45 days. They were then fed one of the following diet for 45 days: C-0.5%: SHAM fed AIN 93 M containing 0.5%Ca; O-0.5% and O-0.3%: OVX rats fed AIN 93 M, containing 0.5% or 0.3%Ca, respectively; GF-0.5% and GF-0.3%: OVX rats fed AIN 93 M, containing 0.5% or 0.3%Ca+ 2.5% GOS/FOS®, respectively. At the end of the experimental time point, Ca, P, and MgAbs% was significantly higher in GF-0.5% and GF-0.3% as compared to the remaining groups (p < 0.01). Irrespective of diet Ca content, CTX decreased whereas femur Ca and P content, tibia BV/TV and GPC.Th, lumbar spine and proximal tibia BMD, bone strength, bone stiffness, and elastic modulus increased in the GF-0.5% and GF-0.3% groups as compared to O-0.5% and O-0.3%, respectively (p < 0.05). This prebiotic mixture would be a useful tool to prevent the increase in bone loss associated with menopause and aging.

Effect of a mixture of GOS/FOS® on calcium absorption and retention during recovery from protein malnutrition: experimental model in growing rats.

INTRODUCTION: During growth, protein deprivation impairs epiphyseal growth plate (EGP) height, bone volume (BV) and endochondral ossification. During catch-up growth, Ca availability becomes essential to ensure the extra amount needed to achieve optimal peak bone mass and strength. GOS and FOS improve mineral absorption in the colon. PURPOSE: The effect of a mixture of GOS/FOS® 9:1 added to a 0.5 %Ca (NCa) and a 0.3 %Ca (LCa) diets on Ca, P and Mg absorptions and bone mineralization, density and structure using an experimental model of growing rats recovering from early protein malnutrition was investigated. METHODS: To induce protein malnutrition, rats were fed a low protein diet: 4 % (LPD) during 1 week and then were randomly assigned to recovery groups (R) until day 50 (T = 50) as follows: R0.5 %: NCa; RP0.5 %: NCa + 5.3 % GOS/FOS®; R0.3 %: LCa and RP0.3 %: LCa + 5.3 % GOS/FOS®. Control groups received the 0.5 %Ca or 0.3 %Ca diet from weaning until day 40 or 50. RESULTS: Body weight and length increased in C groups throughout the study; both were arrested in all R during LPD consumption and increased immediately after re-feeding. Independently of dietary Ca content, LS counts, ß-glucosidase and Ca, P and Mg absorption increased, whereas cecum pH, ß-glucuronidase, urease and tryptophanase decreased in RP0.5 %: and RP0.3 %: as compared to the other studied groups (p < 0.01). Prebiotic consumption decreased CTX levels and increased femur Ca, Mg and P contents, total skeleton bone mineral content, proximal tibia and spine BMD, BV, EGP height and hypertrophic zone thickness, stiffness and elastic modulus as compared to recovery groups fed the prebiotic-free diets. CONCLUSION: Under the present experimental conditions, GOS/FOS® mixture induced colonic positive effects, which increased Ca, P and Mg absorption. Thus, consuming the prebiotic-containing diet resulted in an extra amount of minerals that improved bone development in growing rats recovering from protein malnutrition.

Effect of a combination GOS/FOS® prebiotic mixture and interaction with calcium intake on mineral absorption and bone parameters in growing rats.

AIM: Increasing calcium intake is the most effective strategy for avoiding Ca deficit. However, if intake remains inadequate, improving Ca absorption becomes an important tool to optimize Ca homeostasis and bone health. PURPOSE: The effect of a mixture of GOS/FOS(®) 9:1 added to a normal- or low-Ca diets on Ca absorption and bone mineralization, density and structure was investigated, in a model of growing rats. Several colonic parameters to help support the findings were also evaluated. RESULTS: Weanling Wistar rats received one of the four experimental AIN-93G diets: C5: 0.5% Ca; C3: 0.3% Ca; P5: 0.5% Ca + 5.3% GOS/FOS(®); P3: 0.3% Ca + 5.3% GOS/FOS(®) until 50 days (T = 50). At T = 50, lactobacillus and cecum weights were higher, whereas cecum pH was lower in P5 and P3 versus C5 and C3 (p < 0.001). At T = 50, fecal Ca, Mg and P were lower and their absorptions (mg/dL) were higher in P5 and P3 versus C5 and C3, respectively (p < 0.05). Ca, Mg and P absorption % was higher in P5 and P3 versus C5 and C3 (p < 0.001). Femur Ca and P content, bone mineral content, trabecular bone mineral density, tibia length, bone volume, osteoblast surface, stiffness and elastic modulus were higher in P5 and P3 versus C5 and C3 (p < 0.05). Despite the lower Ca content, P3 group reached similar values than C5 in all these latter parameters. CONCLUSIONS: Supplementing diets with the GOS/FOS(®) mixture increased bone mineralization, density and structure due to an increase in Ca, P and Mg absorptions. Thus, this prebiotic mixture may help to improve bone development in a period of high calcium requirements.

Effect of dietary calcium (Ca) on body composition and Ca metabolism during growth in genetically obese (ß) male rats.

INTRODUCTION: Obese ß rats may be a suitable model to evaluate the association between calcium intake (CaI) and obesity during growth. OBJECTIVE: The present study comparatively evaluated Ca absorption and retention, and changes in body composition in spontaneously genetically obese (ß) male rats fed three different dietary Ca levels: high 0.9% (HCa); normal: 0.5% (NCa); low: 0.2% (LCa). METHODS: Pregnant rats were fed isocaloric diets which varied in Ca content only. Male pups continued feeding the same maternal diet until postnatal day 60. The percentage of Apparent Ca absorption (CaA %), Ca balance (CaB), body composition, glucose, triglycerides (TGL), and insulin levels were evaluated. RESULTS: Food consumption and body weight (BW) were higher in Group LCa than in Groups NCa and HCa (p < 0.01); no differences were observed between the latter two groups. Group LCa presented the highest body fat, liver weight, perigonadal and retroperitoneal fat (p < 0.05); conversely, body ashes and total skeleton bone mineral content were significantly lower compared with animals in both the NCa (p < 0.01) and HCa groups (p < 0.01). CaB (mg/day) reached a plateau at the highest CaI (mg/day) value (r = 0.985, p < 0.001). CaA%, serum glucose, insulin, and TGL levels rose as CaI decreased (p < 0.01). CONCLUSIONS: Although further studies are required, low Ca consumption in this strain of rats could modulate BW inducing changes in several lipid metabolism parameters, which in turn lead to an increase in body fat.

Lactose malabsorption, calcium intake, and bone mass in children and adolescents.

OBJECTIVES: The objective of the present study was to evaluate the calcium intake and bone mass in children and early adolescents in accordance with their absorption capacity to lactose. PATIENTS AND METHODS: A transversal study was conducted on a sample composed of 76 individuals. Lactose malabsorption status was determined with hydrogen breath test. The hydrogen breath test was applied using 2  g of lactose per kilogram of weight up to a maximum of 50  g. A hydrogen increment ≥20  pm in relation to fasting was used to characterize lactose malabsorption. Two 24-hour recalls were applied for the evaluation of food consumption. Bone mineral content and bone mineral density were evaluated in the lumbar spine by dual-energy x-ray absorptiometry. RESULTS: The prevalence of lactose malabsorption was 61.8%. The participants were divided into 2 groups: lactose malabsorbers (n = 47) and lactose absorbers (n = 29). There was no statistically significant difference (P > 0.05) between the groups with respect to the intake of total calcium, milk calcium, milk, cheese, yogurt, ice cream, and calcium density of the diet. Additionally, there was no difference with respect to the bone mineral content and the bone mineral density of the lumbar spine. Independent from lactose absorption capacity, it was observed that the majority of the children and early adolescents showed calcium intake lower than the recommended value. CONCLUSIONS: There was no relation among lactose malabsorption and bone densities, bone mineral content, or calcium intake within the present study.

Prebióticos y su efecto en la biod sponibilidad del calcio / Prebiotics and their effect on calcium bioavailability

En la búsqueda de medidas de prevención de enfermedades crónicas no trasmisibles, se piensa en los prebióticos como una forma efectiva, saludable y relativamente barata para la optimización de la absorción de Ca. El aumento de la expectativa de vida de la población y el incremento de enfermedades como la osteoporosis traen graves consecuencias a la salud del individuo, acarreando importantes desembolsos económicos. En esta revisión se condensa el conocimiento presente sobre el efecto fisiológico del consumo de carbohidratos prebióticos y su posible interferencia en la biodisponibilidad del Ca, como también las posibilidades de su empleo en estrategias para combatir las deficiencias del mineral. Se elaboró una recopilación de los estudios originales realizados con mayor impacto en el tema, dando preferencia a los publicados en los últimos 6 años. Utilizamos las bases de datos PubMed, Lilacs e SciELO, usando las palabras claves calcio, prebióticos e probióticos.

The increased life expectancy and prevalence of non-communicable chronic diseases have serious health and economic consequences on the population. Among the useful tools for preventing osteoporosis, prebiotics are thought to be an effective, healthy and relatively cheap way of optimizing calcium absorption. The objective of this review was to summarize the present knowledge on the physiological effects of prebiotic carbohydrate consumption and its possible interference with calcium bioavailability. The possibility of using prebiotics to fight calcium deficiency was also assessed. The keywords calcium, prebiotics and probiotics were used to search the PubMed, Lilacs and SciELO databases for the most significant original studies on the subject published in the last 6 years.

[Adolescents do not lose bone mineral density postpartum: comparative study with adult women]. / Las adolescentes no pierden densidad mineral ósea en el posparto: estudio comparativo con adultas.

OBJECTIVE: To analyze the pattern of bone mineral density (BMD), serum concentrations of estradiol and calcium levels, dietary calcium, body mass index (BMI), and lactation in adolescents and adult women at 15, 90, and 365 postpartum days (ppd). MATERIAL AND METHODS: A prospective cohort study was conducted of 33 adolescents and 39 adult women. Anthropometric and dietetic evaluations were performed, as well as evaluations of bone mineral density in L2-L4 and femur neck. Estradiol concentrations and calcium serum levels were determined. RESULTS: L2-L4 BMD increased by 16% in adolescents, and 3% in adult women from day 15 to 365 ppd. While age was associated with this change (ß=13.779, EE=3.5, p=0.001), lactation was not (ß=-0.705, EE=0.647, p=0.283). The adult women had a higher L2-L4 BMD at 15, 90, and 635 ppd (1.151 vs 0.978 g/cm², 1.195 vs 1.070 g/cm², 1.195 vs 1.123 g/cm², respectively) (p<0.003). CONCLUSIONS: Adolescents' BMD increased three times more than that of adult women. For all women, BMD was dependent of age and independent of lactation.

Las adolescentes no pierden densidad mineral ósea en el posparto: estudio comparativo con adultas / Adolescents do not lose bone mineral density postpartum: comparative study with adult women

OBJETIVO: Analizar el patrón de la densidad mineral ósea (DMO), calcio y estradiol séricos, consumo de calcio, índice de masa corporal (IMC) y lactancia en adolescentes y adultas a 15, 90 y 365 días posparto (dpp). MATERIAL Y MÉTODOS: Cohorte prospectivo en 33 adolescentes y 39 adultas con evaluación antropométrica, dietética y ósea en L2-L4 y cuello de fémur; bioquímica con estradiol y calcio séricos. RESULTADOS: Las adolescentes aumentaron de los 15 a los 365 dpp 16 por ciento su DMO de L2-L4, las adultas 3 por ciento. La edad se asoció a este cambio (β=13.779, EE=3.5, p=0.001); la lactancia no se asoció (β=-0.705, EE=0.647, p=0.283). Las adultas presentaron mayor DMO de L2-L4 a 15, 90 y 365 dpp respectivamente (1.151vs 0.978g/cm², 1.195vs1.070g/cm², 1.195vs1.123g/cm², p<0.003). CONCLUSIONES: Las adolescentes incrementaron su DMO tres veces más que las adultas. El cambio en la DMO fue dependiente de la edad e independiente de la práctica de lactancia.

OBJECTIVE: To analyze the pattern of bone mineral density (BMD), serum concentrations of estradiol and calcium levels, dietary calcium, body mass index (BMI), and lactation in adolescents and adult women at 15, 90, and 365 postpartum days (ppd). MATERIAL AND METHODS: A prospective cohort study was conducted of 33 adolescents and 39 adult women. Anthropometric and dietetic evaluations were performed, as well as evaluations of bone mineral density in L2-L4 and femur neck. Estradiol concentrations and calcium serum levels were determined. RESULTS: L2-L4 BMD increased by 16 percent in adolescents, and 3 percent in adult women from day 15 to 365 ppd. While age was associated with this change (β=13.779, EE=3.5, p=0.001), lactation was not (β=-0.705, EE=0.647, p=0.283). The adult women had a higher L2-L4 BMD at 15, 90, and 635 ppd (1.151 vs 0.978g/cm², 1.195 vs 1.070g/cm², 1.195 vs 1.123g/cm², respectively) (p<0.003). CONCLUSIONS: Adolescents' BMD increased three times more than that of adult women. For all women, BMD was dependent of age and independent of lactation.

[Calciotropic actions of parathyroid hormone and vitamin D-endocrine system]. / Acciones calciotrópicas de la hormona paratiroidea y del sistema endocrino de la vitamina D.

Parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)zD] participate in systemic regulation of calcium homeostasis through endocrine effects mediated via the specific receptors PTHR1 and VDR, expressed in bone, kidney, intestine and parathyroid glands. In bone, both hormones PTH and 1,25-(OH)2D promote calcium release into the circulation; however, they also have anabolic effects in this tissue. In kidney, PTH controls 1,25-(OH)2D synthesis, and together both hormones stimulate calcium reabsorption. The most important calciotropic action of 1,25-(OH)2D is stimulation of intestinal calcium absorption. In the parathyroid glands, 1,25-(OH)2D regulates PTH synthesis through a negative feedback mechanism, while modulating the gland growth. Finally, a general overview of the maternal adaptations regarding calcium homeostasis during pregnancy and lactation is presented.

[Bioavailability of dietary calcium]. / Biodisponibilidade do cálcio dietético.

Dietary calcium (Ca) is fundamental to the bone's health. Both the purport and the element bioavailability in the food need to be considered. The purpose of this work was to summarize the factors involved in Ca absorption and point out the sources with higher bioavailability. Ca is mostly absorbed in the jejunum and low pH seems to favor its absorption, which is higher during growth, gestation/lactation and Ca and phosphorus (P) deficiency, and lower with aging. The richest and best-absorbed Ca source is cow's milk and its derivatives. Other foods show high Ca concentrations but variable bioavailability: foods rich in phytates and oxalates show a smaller absorption and carbohydrate-rich foods show higher absorption. Since Ca bioavailability in other animal's milk, soymilk and some vegetables is closer to that in cow's milk, adequate amounts of these foods could be used as an alternative.

Biodisponibilidade do cálcio dietético / Bioavailability of dietary calcium / Bioavailability of dietary calcium

O cálcio (Ca) dietético é fundamental para a saúde óssea. Tanto o teor como a biodisponibilidade do elemento nos alimentos devem ser considerados. Este artigo objetiva sumarizar os fatores envolvidos na absorção e destacar os alimentos com melhor disponibilidade do Ca. Este é absorvido principalmente no jejuno e o pH baixo parece favorecer sua absorção, que é maior no crescimento, na gestação/lactação e na carência de Ca ou fósforo (P), e menor no envelhecimento. As maiores fontes, e com melhor absorção, são os laticínios bovinos. Outros alimentos apresentam concentrações elevadas de Ca, mas com biodisponibilidade variável: os ricos em ácidos oxálico e fítico apresentariam uma menor absorção, enquanto que os ricos em carboidratos teriam uma absorção maior. Por apresentarem uma biodisponibilidade do Ca mais próxima da do leite bovino, o leite de outros animais, o de soja enriquecido e alguns vegetais, em quantidades adequadas, poderiam ser usados como alternativas a este.

Dietary calcium (Ca) is fundamental to the bone's health. Both the purport and the element bioavailability in the food need to be considered. The purpose of this work was to summarize the factors involved in Ca absorption and point out the sources with higher bioavailability. Ca is mostly absorbed in the jejunum and low pH seems to favor its absorption, which is higher during growth, gestation/lactation and Ca and phosphorus (P) deficiency, and lower with aging. The richest and best-absorbed Ca source is cow's milk and its derivatives. Other foods show high Ca concentrations but variable bioavailability: foods rich in phytates and oxalates show a smaller absorption and carbohydrate-rich foods show higher absorption. Since Ca bioavailability in other animal's milk, soymilk and some vegetables is closer to that in cow's milk, adequate amounts of these foods could be used as an alternative.

Formulation and sensory evaluation of Prosopis alba (Algarrobo) pulp cookies with increased iron and calcium dialyzabilities.

Prosopis alba (algarrobo) is an important indigenous specie, which fruits are used as food and feed since ancient times. Cookies containing algarrobo pulp (AP) with increased iron and calcium availabilities were formulated and sensory evaluated. AP is preferred as food ingredient because of its high sugar content and pleasant flavour. Formulated cookies mean proximal composition was 8.9 g/100 g protein, 7.2 g/100 g dietary fiber, 25 g/100 g total sugar, and 18.5 g/100 g crude fat with iron and calcium contents 30 ppm and 340 ppm, respectively. Ascorbic (AA) and citric (CA) acids at different mM acid: mM Fe were added in order to increase mineral availabilities being evaluated by an in vitro method. Those ratios were 5:1 and 10:1 for AA:Fe whereas for CA:Fe were 50:1 and 100:1 and combinations of them. After chosen the best AA:Fe and CA:Fe ratios (5:1 and 50:1, respectively), sensory evaluation with trained sensory panel and a consumer acceptability test with one hundred and seventy untrained judges were carried out. Acceptability test showed that 77.65% of the people (< 25 years old 41.76%, 25-50 years old 20.00% and > 50 years old 15.89%) tasting final formulated cookies indicated that they "like very much" or "moderately like" and there were not consumers rejecting them.

Calcium absorption from corn tortilla is relatively high and is dependent upon calcium content and liming in Mexican women.

Corn tortillas are the staple food of Mexico. During their preparation, calcium is added to the tortillas; therefore, tortillas are the main source of calcium for a large proportion of the population. The bioavailability of calcium from lime-treated tortillas in humans is not known. The objectives of the present study were to determine calcium absorption from corn tortilla, to determine the effect of lime treatment on calcium absorption from corn tortilla, and to compare calcium absorption from tortilla prepared with a commercial corn flour and tortillas prepared with the traditional lime treatment at home. Nonpregnant, nonlactating women (n = 9) were administered 3 different treatments: 1) 180 g of corn tortilla prepared from corn flour with no lime treatment (CF), 2) 180 g of corn tortilla prepared from lime-treated commercial corn flour (LTCCF), or 3) 180 g of corn tortillas prepared from lime-treated home-prepared corn flour (LTHCF). Calcium absorption was measured using an established dual-tracer stable isotope technique. Calcium absorption of CF, LTCCF, and LTHCF was (mean +/- SD): 44 +/- 3.2, 32 +/- 4.4, and 30 +/- 2.4%, respectively; the fractional calcium absorption from CF differed from that of either LTCCF or LTHCF (P < 0.01). The total amount of calcium absorbed per treatment was higher in LTHCF (98.10 mg +/- 21.7) than in LTCCF (59.9 mg +/- 23.7, P < 0.001) and CF (3.78 mg +/- 0.9, P < 0.0.001). In conclusion, calcium absorption from corn tortillas is high and dependent on calcium concentration. The addition of calcium during lime treatment increases calcium concentration and total calcium absorption.

Calcium homeostasis during pregnancy and lactation in Brazilian women with low calcium intakes: a longitudinal study.

BACKGROUND: Physiologic adjustments in calcium homeostasis during pregnancy and lactation in women with marginal calcium intakes have not been described. OBJECTIVE: The objective was to examine longitudinal changes in various aspects of calcium homeostasis during pregnancy and lactation in 9 healthy Brazilian women who habitually consumed approximately 500 mg Ca/d. DESIGN: Calcium homeostasis was assessed at 3 time points: 10-12 (early pregnancy, EP) and 34-36 (late pregnancy, LP) wk of pregnancy and 7-8 wk postpartum (early lactation, EL). At each time point, the following variables were measured: dietary calcium intake with a 3-d weighed food record, 24-h urinary calcium excretion (UCa), intestinal calcium absorption (%CaAbs) via administration of stable calcium isotopes with a breakfast meal, serum 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin-like growth factor I (IGF-I), and biochemical markers of bone turnover. RESULTS: Dietary calcium did not change during the study. %CaAbs increased from 69.7 +/- 5.4% ( +/- SEM) during EP to 87.6 +/- 4.5% during LP (P < 0.05) and returned to 65.1 +/- 6.2% during EL. Compared with EP, UCa decreased 22% during LP and 68% during EL (P < 0.05). The net mean change in calcium retention was 212 mg/d during LP and 182 mg/d during EL. Several significant associations were found between the main outcome variables (%CaAbs, UCa, and markers of bone turnover) and serum hormones, especially IGF-I and PTH. CONCLUSIONS: Calcium homeostasis appears to be attained by a more efficient intestinal calcium absorption during pregnancy and by renal calcium conservation during both pregnancy and lactation. IGF-I and PTH seem to play major roles in the adjustment of calcium metabolism during pregnancy and lactation.

A protective effect of dietary calcium against acute waterborne cadmium uptake in rainbow trout.

The present study examined the interactions between elevated dietary calcium (as ionic Ca2+ in the form of CaCl2 x 2H2O) and acute waterborne Cd exposure (50 microg/l as CdNO3 for 3 h) on whole body uptake and internal distribution of newly accumulated Cd, Ca2+, and Na+ in juvenile rainbow trout (Oncorhynchus mykiss). Fish were fed with three diets 20 (control), 30 and 60 mg Ca2+/g food: for 7 days before fluxes were measured with radiotracers over a 3h period. The two elevated Ca2+ diets reduced the whole body uptake of both Ca2+ and Cd by >50% and similarly reduced the internalization of both newly accumulated metals in most tissues, effects which reflect the shared branchial uptake route for Ca2+ and Cd. As the Ca2+ concentrations of the fluid phases of the stomach and intestinal contents were greatly elevated by the experimental diets, increased gastrointestinal Ca2+ uptake likely caused the down-regulation of the branchial Ca2+ (and Cd) uptake pathway. Waterborne Na+ uptake and internal distribution were not affected. While plasma Ca2+ surged after the first two feedings of the 60 mg Ca2+/g diet, internal homeostasis was quickly restored. Total Ca2+, Na+, and Cl- levels in tissues were not affected by diets. While dietary Ca2+ protected against waterborne Cd uptake, it did not protect against the relative inhibition of waterborne Ca2+ uptake caused by waterborne Cd. Acute exposure to 50 microg/l Cd reduced the uptake and internalization of newly accumulated Ca2+ (but not Na+) by 70% or more, regardless of diet. Since elevated dietary Ca2+ reduces waterborne Cd uptake, fish eating a Ca(2+)-rich invertebrate diet may be more protected against waterborne Cd toxicity in a field situation.