• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.480-487
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• 1997

The present study was designed to examine how Ca intake contributes to the increase of peak bone mass with growing female rats. Weaned rats were fed experimental diets consisting in five levels of Ca; very low(0.1%), low(0.2%), moderate(0.5%), high(1.0%) and very high(1.5%) for 4, 8 and 12 weeks. Bone growth, metabolism and Ca metabolism were determined. As for the rats fed for 4 weeks, the bone weight, length and breaking force and bone metabolism were not significantly affected by dietary Ca levels, whereas the current intakes of Ca were observed to have significantly affected the rats fed for 8 or 12 weeks with regard to the bone weight, length and breaking force and bone metabolism. The bone ash and Ca contents of the rats were affected by dietary Ca levels for the total period of feeding. It is suggested that dietary Ca itself affected the mineralization process either during the growth or later, although the resulting bone mass is not a linear function of dietary Ca content.

• Journal of Nutrition and Health
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• v.31 no.6
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• pp.1039-1048
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• 1998

It has been reported that boron may be beneficial for optimal calcium metabolism and, thus, optimal bone metabolism. Therefore, we designed a study to determine the effect of boron supplementation on Ca and bone metabolism in rats. The rats of 80-l40g body weight were given a control(0ug), 5$\mu\textrm{g}$, 10$\mu\textrm{g}$, 20$\mu\textrm{g}$, 40$\mu\textrm{g}$, or 80$\mu\textrm{g}$ boron supplement per Is diet for 4-weeks. The results are summarized as follows. There were no differences in total food intake and weight gain among the experimental groups. fecal Ca excretion, urinary Ca excretion, apparent Ca absorption, Ca retention, serum alkaline phosphatase activity, and urinary hydroxyproline were not affected by boron supplementation. There was no difference in serum creatinine. Whereas, urinary creatinine excretion was increased with increasing boron supplementation, and conse-quently creatinine clearance was increased with boron supplementation. No differences were found in length, weight, density, Ca content of femur and scapular. The findings suggest that boron supplementation was not effective in Ca and bone metabolism in growing rats fed normal Ca diet. (Korean J Nutrition 31(6) : 1039-1048, 1998)

• Food Science of Animal Resources
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• v.33 no.4
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• pp.515-521
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• 2013

In this study, we examined the effects of organic types of calcium derived from oyster shell (OS-Ca) and nano-calcium (Nano-Ca) on the bio-availability and physiological responses associated with bone health in ovariectomised rats. Increased body weight, which is one of the physiological effects of ovary removal, was significantly recovered by Nano-Ca treatment (p<0.05). The reduced calcium level in the liver in ovariectomised rat was increased significantly with OS-Ca and Nano-Ca treatment (p<0.05), suggesting improved calcium bio-availability. Alkaline phosphatase (ALP), osteocalcin, and deoxypyridinoline (DPD) were analysed as biochemical markers of bone metabolism and health in the presence or absence of OSCa and Nano-Ca. ALP, osteocalcin, and DPD levels increased following ovary removal and tended to decrease after treatment with Nano-Ca, indicating that Nano-Ca induces favourable bone metabolism. This result was reflected in the recovery of bone mineral density (BMD) and bone mineral content (BMC) of the femur after Nano-Ca treatment following ovary removal. Taken together, our data show that the tested calcium treatments, especially using Nano-Ca, enhanced the bioavailability or absorption of calcium and positively affected bone metabolism in ovariectomised rats.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.78-88
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• 2015

Purpose: The objective of this study is to review researches regarding factors that potentially affect adolescent calcium (Ca) metabolism, and to suggest a potential modeling approach for optimizing gastrointestinal Ca absorption and peak bone mass. Background: Optimal gastrointestinal Ca absorption is a key to maximizing peak bone mass in adolescents. Urine Ca excretion in adolescents rises only after bone accretion is saturated, indicating that higher intestinal Ca absorption and bone retention is necessary to ensure maximum bone accretion. Hence, maximizing peak bone mass is possible by controlling the factors influencing gastrointestinal Ca absorption and bone accretion. However, a mechanism that explains the unique adolescent Ca metabolism has not yet been elucidated. Review: Dietary factors that enhance gastrointestinal Ca absorption may increase the available Ca pool usable for bone accretion, and a specific hormone may direct optimal Ca utilization to maximize peak bone mass. IGF-1 is an endocrine hormone whose levels peak during adolescence and increase fractional Ca absorption and bone Ca accretion. Prebiotics, generally obtained from dietary sources, have been reported to exert a beneficial effect on Ca absorption via microbiota activity. We selected and reviewed three candidates that could be used to propose a comprehensive Ca metabolic model for optimal Ca absorption and peak bone mass in adolescents. Modeling: Modeling has been used to investigate Ca metabolism and its regulators. Herein, we reviewed previous Ca modeling studies. Based on this review, we proposed a method for developing a comprehensive model that includes regulatory effectors of IGF-1 and prebiotics.

• Journal of Nutrition and Health
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• v.30 no.7
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• pp.813-824
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• 1997

This study was designed to investigate the effect of dietary calcium and phosphate levels on calcium and bone metabolism in rats. The rats were divided into six groups and each of the groups was fed diets with different Ca/P ratios. The experimental periods were 5 weeks . There was no significant different difference in dietary intake, body weight gain, and organ weight among the groups with different calcium and phosphate intake levels. Fecal calcium excretion was not significantly different among the groups, but urinary calcium excretion was increased by the increase in Ca/P ratio. Fecal phosphate excretion was not different but urinary phosphate excretion was increased by the increase in dietary phosphate intake. There was no significant difference in serum alkaline phophatase activity and urinary hydroxyproline levels were not significantly different among the groups. The low calcium-high phosphate(0.25Ca-1.2% P) group showed the lowest total calcium content in femur and scapula. This may be due to it having the lowest Ca/P ratio among groups. The low calcium-high phosphate(0.2%Ca-1.2%P) group showed that mandible is almost lost and osteolyzed Harversian canal was expanded in femur. Results suggest that phosphate intake affects calcium and bone metabolism more with inadequate calcium nutrition that with adequate calcium intake. Thus , for normal bone growth and metabolism , adequate calcium intake and/or high Ca/P ratio are important.

• Journal of Nutrition and Health
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• v.31 no.4
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• pp.716-728
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• 1998

To investigate the effect of dietary Ca levels on metabolic changes of Ca and skeleton in postmenopausal women, 10-month-old ovariectomized female rats were compared with 2 month old rats. The rats were fed either 0.2% or 1.2% Ca diets for 16 weeks. Food intake and weight gain as higher in rats fed high Ca diets and in ovariectomized rats. Apparent Ca absorption as higher, and Ca balance was lower in the low Ca groups. Vertebrae density was higher in old rats or those fed a high Ca diets. The old rats and ovariectomized rats showed decreased bone formation, increased bone resorption and kidney function deterioration resulting in increased urinary Ca excretion. Contradictory to the above observation, old rats and ovariectomized rats still showed higher bone mass and bone ash content. Therefore aging was not fully onging in 10-month-old rats. Bone weights, mineral contents, and mineral/wt ratio were lower in ovariectomized rats. Dietary Ca level did not affect urinary Ca excretion, urinary protein excretion, GFR, serum alkaline phosphatase, or urinary hydroxyporline excretion. This means that dietary Ca level did not influence kidney function or bone turnover. However Ca content and the ash content of femur, 4th vertebra, and scapula were increased in high Ca groups. Therefore, it is considered that decreased bone formation and accelerated bone resorption may account for the increased osteoporotic risk in women in menopause after middle age. However, Ca metabolism can be improved and bone components can be maintained if Ca is supplemented.

• Journal of Nutrition and Health
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• v.28 no.5
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• pp.434-441
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• 1995

The model rats with postmenopausal osteoporosis were comparatively observed with regard to the effects of bovine ash and calcium phosphate on calcium metabolism. The modelling design involved the five week-old week-old female SD-strain rats ovariectomized and fed a low-Ca diet(20% casein, 0.06% Ca and 0.38% P) for three weeks. The rats were divided into five groups, one of which was fed the low-Ca diet(basal), and the rest of which were divided into five groups, one of which was fed the low-Ca diet(basal), and the rest of which were fed four kinds of Ca-supplemental diets(20% protein, 1.06% Ca and 0.8% P) for three weeks. The Ca-suplements diets contained two kinds of Ca sources, bovine bone ash(BBA) or calcium phosphate, tribasic [Ca3(PO4)2] and two kinds of protein sources, casein or isolated soy protein(ISP). The model rats of postmenopausal osteoporosis fed basal diet showed a significant decrease in Ca utilization in reference to serum Ca concentration, breaking force of bone, Ca and P contents of bone, and Ca absorption and retention. However, the supply of Ca for three weeks demonstrated the improved utilization of Ca. One step further, BBA was more effective than calcium phosphate in improving Ca utilization in ISP-fed groups. On the other hand, no significant difference was seen in casein-fed groups. It is to conclude that BBA could be more effective in accelerating Ca utilization under vulnerable dietary or physiological conditions such as vegetable protein intake and osteoprosis.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1266-1271
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• 2007

This study examined effects of calcium supplemented milk on bone loss in ovariectomized rats. Twenty four Sprague-Dawley female rats, 7 weeks-old, were divided into 4 groups, ovariectomized and fed diets containing: 1) control, no Ca supplemented milk, 2) ovx 1, Ca carbonate supplemented milk, 3) ovx 2, ionized Ca supplemented milk, and 4) ovx 3, nano Ca supplemented milk. All rats were fed 1 ml of milk containing 20 mg supplemented Ca. After 18 wk feeding, body weight gain and food efficiency ratio were significantly different between ovx 1 and ovx 3. Serum concentration of calcium and phosphorus were not different among groups. However, there was a significant difference in calcium content of dry femoral weight in ovx 3 compared with the control and ovx 2. In addition, femoral bone mineral density ($g/cm^2$) was significantly greater in ovx 3 than in other groups (p<0.05). The ovx 3 group showed the highest stiffness (N/mm), maximum energy (N) in femur and trabecular bone area (%). The present study indicated that nano Ca supplementation in milk may be an effective way to enhance bone calcium metabolism for ovariectomized rats.

• Journal of Nutrition and Health
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• v.25 no.7
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• pp.569-577
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• 1992

To study the effects of the age and the dietary protein content on Ca metabolism male rats of 1 month 6 month 12 month of age were fed experimental diets containing 5%, 15% or 50% casein for 4 weeks. Food and ca intake were higher in old rats and in high protein groups. The weight ash and Ca contents of femur and tibia were higher in old rats. The higher dietary protein level resulted in higher skeletal weigh ash and Ca contents. But high protein diet(50% casein) lead to reduced bone mineral density(ash/dry bone weight) and Ca density(Ca/dry bone weight) in 1 month old rats. Low protein diet(5% casein) on the other hand reduced the bone growth even though the bone density was higher in this group. The ill effect of low protein diet was not evident in 12 month old rats. Glomerular filteration rate(GFR) and urinary Ca excretionincreased with age and with dietary protein level especially in 12 month old rats. Serum immunoreactive parathyroid hormone(iPTH) level tended to be higher in aged rats but was not affected by dietary protein level except 1 month old rats where 50% protein group showed significantly higher value. This study showed that the dietary protein level seemed to have different effect on Ca metabo-lism in rats of different age., The low bone density in the high protein group of growing rats may be due to the higher iPTH level and increased urinary Ca. The dietary protein level however had no effects on the bone composition in aged rats even though the higher urinary Ca excretion. In conclusion this study suggests that high protein intake from young may lead to less peak bone mass and to increase the bone loss in later years, which would increase the risk for osteporosis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.677-684
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• 1999

This study has dealt the effect of Ca regulating hormones and dietary Ca levels on Ca metabolism. Animals(BALB/c mice) were divided into three dietary groups(high and medium Ca and Ca free) and hormones including parathyroid hormone(PTH), calcitonin(CT), cholecalciferol(Vit D) were i.p. injected. After feeding experimental diets for five weeks, mice were anaethetized and sacrificed by heart puncture. We found that femur growth of mouse was slightly increased by high dietary Ca without showing statistical significance comparing to low dietary Ca group. The combination of PTH and CT showed the same effect when dietary Ca was high. At the same time, total mineral retention in bone was most affected by dietary Ca. In general, high Ca diet elevated Ca level in the serum. When dietary Ca was low, PTH stimulated Ca release from the bone into the serum, which was shown to be inhibited by CT treatment. Comparing to the control, PTH, Vit D and CT together tended to inhibit serum Ca level at high and medium dietary Ca. PTH and Vit D inhibited Ca reserve in the liver at all dietary levels of Ca. Both PTH and Vit D stimulated bone Ca retention when dietary Ca was low, but this effect was reversed when dietary Ca was high. When PTH, Vit D and CT were administered together, bone Ca level was greatly enhanced at low dietary Ca than at high dietary Ca, which suggests that these hormonal cooperation is needed for proper bone density maintenance especially when dietary minerals are not sufficient.