- Fermentation of calcium-fortified soya milk does not appear to enhance acute calcium absorption in osteopenic post-menopausal women. [Randomized Controlled Trial]
- BJBr J Nutr 2011; 105(2):282-6
- Ageing women may choose to drink soya milk to reduce menopausal symptoms. As fermentation enriches soya milk with isoflavone aglycones, its beneficial qualities may improve. To reduce osteoporotic ri…
Ageing women may choose to drink soya milk to reduce menopausal symptoms. As fermentation enriches soya milk with isoflavone aglycones, its beneficial qualities may improve. To reduce osteoporotic risk, however, soya milk must be Ca enriched, and it is not known how fermentation affects Ca bioavailability. A randomised crossover pilot study was undertaken to compare the Ca absorption of fortified soya milk with that of fermented and fortified soya milk in twelve Australian osteopenic post-menopausal women. The fortified soya milk was inoculated with Lactobacillus acidophilus American Type Culture Collection (ATCC) 4962 and fermented for 24 h at 37°C. Ca absorption from soya milk samples was measured using a single isotope radiocalcium method. Participants had a mean age of 54·8 (sd 12·3) years, with mean BMI of 26·5 (sd 5·5) kg/m2 and subnormal to normal serum 25-hydroxyvitamin D (mean 62·5 (sd 19·1) nmol/l). Participants consumed 185 kBq of 45Ca in 44 mg of Ca carrier. The mean fractional Ca absorption (α) from soya milk and fermented soya milk was 0·64 (sd 0·23) and 0·71 (sd 0·29), respectively, a difference not of statistical significance (P = 0·122). Although fermentation of soya milk may provide other health benefits, fermentation had little effect on acute Ca absorption.
- Calcium absorption in Australian osteopenic post-menopausal women: an acute comparative study of fortified soymilk to cows' milk. [Randomized Controlled Trial]
- APAsia Pac J Clin Nutr 2010; 19(2):243-9
- Calcium loss after menopause increases the risk of osteoporosis in aging women. Soymilk is often consumed to reduce menopausal symptoms, although in its native form, it contains significantly less ca…
Calcium loss after menopause increases the risk of osteoporosis in aging women. Soymilk is often consumed to reduce menopausal symptoms, although in its native form, it contains significantly less calcium than cow's milk. Moreover, when calcium is added as a fortificant, it may not be absorbed efficiently. This study compares calcium absorption from soymilk fortified with a proprietary phosphate of calcium versus absorption from cow's milk. Preliminary studies compared methods for labelling the calcium fortificant either before or after its addition to soymilk. It was established that fortificant labelled after it was added to soymilk had a tracer distribution pattern very similar to that shown by fortificant labelled before adding to soymilk, provided a heat treatment (90?C for 30 min) was applied. This method was therefore used for further bioavailability studies. Calcium absorption from fortified soy milk compared to cow's milk was examined using a randomised single-blind acute cross-over design study in 12 osteopenic post-menopausal women aged (mean +/- SD) 56.7+/-5.3 years, with a body mass index of 26.5+/-5.6 kg/m2. Participants consumed 20 mL of test milk labelled after addition of fortificant with 185 kBq of 45Ca in 44 mg of calcium carrier, allowing the determination of the hourly fractional calcium absorption rate (alpha) using a single isotope radiocalcium test. The mean hourly fractional calcium absorption from fortified soymilk was found to be comparable to that of cows' milk: alpha = 0.65+/-0.19 and alpha =0.66+/-0.22, p>0.05, respectively.
- Determination of Vitamin D-dependent calcium absorption by 45Ca gavage in the rat. [Journal Article]
- JSJ Steroid Biochem Mol Biol 2007; 103(3-5):517-20
- Precise determination of Vitamin D-dependent intestinal calcium absorption in longitudinal studies is problematic. We have assessed Vitamin D-dependent intestinal calcium absorption by (45)Ca gavage.…
Precise determination of Vitamin D-dependent intestinal calcium absorption in longitudinal studies is problematic. We have assessed Vitamin D-dependent intestinal calcium absorption by (45)Ca gavage. Rats were gavaged with a 1mL solution containing (45)Ca (CaCl(2), 9.3MBq/mL) maintained at 37 degrees C. Total Ca concentration of the gavage fluid was optimised by comparing the absorption curves for fluids made up to 0.025, 2.025, 4.025 and 40.025 mmol/L with (40)CaCl(2). The effect of varying dietary Ca on fractional Ca absorption was determined in rats fed semi-synthetic diets containing either 0.05%, 0.2%, 0.4% or 1.0% Ca for 50 days. Serum 1,25 dihydroxyvitamin D (1,25D) was determined by radioimmunoassay. Total gavage Ca of 0.025 mmol/L achieved the highest peak fractional absorption and was adopted for all future experiments. Fifty days after allocation to the diets both fractional Ca absorption and 1,25D were highest in rats fed 0.05% Ca and lowest in those fed 1.0% Ca (absorption, P<0.05 and 1,25D, P<0.05). There was a strong logarithmic relationship between 1,25D and fractional Ca absorption (R(2) 0.69, P<0.001). Weekly repetition of the procedure did not cause a fall in haematocrit over 7 weeks. Radiocalcium ((45)Ca) absorption by gavage provides a simple measure of Vitamin D-dependent Ca absorption for repetitive use in longitudinal studies.
- Effect of low intensity laser irradiation on surgically created bony defects in rats. [Journal Article]
- JOJ Oral Rehabil 2006; 33(8):619-924
- Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in …
Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.
- Radiofrequency-induced carcinogenesis: cellular calcium homeostasis changes as a triggering factor. [Journal Article]
- IJInt J Radiat Biol 2005; 81(3):205-9
- The aim was to study the effects of radiofrequency (Rf) in a mice strain characterized by age-determined carcinogenesis of lymphatic tissues. Mice were treated with a 1?h/week Rf exposure for 4 month…
The aim was to study the effects of radiofrequency (Rf) in a mice strain characterized by age-determined carcinogenesis of lymphatic tissues. Mice were treated with a 1?h/week Rf exposure for 4 months. A group submitted to sham exposure was used as control animals. The evolution of carcinogenesis was followed up to 18 months. The maximal life span of control mice was about 24 months. All dead animals were clinically and histologically examined to give an age-determined comparative quantification of the evolving carcinogenesis. A radiocalcium tracer method permitted the evaluation of Rf effects on transmembrane transport of extracellular calcium at 1 and 24 h after exposure. The determination of induced lipid peroxidation completed this second study. The findings show that Rf provoked an earlier general lymphocyte cell infiltration, formation of lymphoblastic ascites and extranodal tumours of different histological types, as well as an increased early mortality. The results suggest that in Rf-exposed mice, carcinogenesis may be induced earlier and with different pathological forms than in control animals. The modifications in cellular calcium homeostasis and the age-determined thymus involution appear to be important factors involved in this carcinogenesis process.
- Does the response of bone mass to calcium supplements depend on calcium absorption efficiency? [Journal Article]
- EJEur J Endocrinol 2004; 151(6):759-63
- CONCLUSIONS: These results support our earlier studies which suggest that poor calcium absorption limits the response of bone to calcium supplements.
- Effect of age on calcium absorption in postmenopausal women. [Journal Article]
- AJAm J Clin Nutr 2004; 80(4):998-1002
- CONCLUSIONS: A late age-related decrease in calcium absorption is seen in postmenopausal women in addition to the decline that occurs at menopause. This decrease could be due to a decline in either the active calcium transport or diffusion component of the calcium absorption system.
- A longitudinal study of bone-related biochemical changes at the menopause. [Journal Article]
- CEClin Endocrinol (Oxf) 2004; 61(1):123-30
- CONCLUSIONS: We conclude that the menopausal rise in calculated serum ionized calcium without fall in PTH, indicates a change in PTH set-point, and that the falls in gastrointestinal absorption and renal tubular reabsorption of calcium reflect the loss of an oestrogen action at these two sites. Although these changes are sufficient to explain the rise in calcium requirement at the menopause, the association of high bone resorption with normal serum PTH suggests also an increased sensitivity of bone to the action of parathyroid hormone. There is significant 'tracking' of many variables across the menopause despite very significant changes in their absolute values.
- The effects of age and other variables on serum parathyroid hormone in postmenopausal women attending an osteoporosis center. [Journal Article]
- JCJ Clin Endocrinol Metab 2004; 89(4):1646-9
- It has been known for many years that serum PTH rises with age, and it has been suggested that this rise may contribute to bone loss in postmenopausal women. It has been variously attributed to decli…
It has been known for many years that serum PTH rises with age, and it has been suggested that this rise may contribute to bone loss in postmenopausal women. It has been variously attributed to declining renal function, declining calcium absorption efficiency, and declining serum 25-hydroxyvitamin D [25(OH)D] levels. We studied the effects of age, weight, renal function, radiocalcium absorption, serum ionized calcium, and serum 25(OH)D on serum PTH levels in 918 postmenopausal women attending an osteoporosis center. On simple linear regression, serum PTH was a positive function of age (P = 0.003) and weight (P < 0.001) and an inverse function of serum 25(OH)D (P < 0.001) and serum ionized calcium (P = 0.002). On stepwise regression, serum 25(OH)D was the most significant (negative) determinant of serum PTH, followed in decreasing order of significance by serum ionized calcium (negative) and body weight and age (positive). Serum PTH was not related to radiocalcium absorption. The reciprocal relation between serum PTH and serum 25(OH)D could not be explained by the serum concentration of 1,25-dihydroxyvitamin D, which did not change with age. After adjustment for serum ionized calcium, body weight, and age, the rise in serum PTH appeared to start when serum 25(OH)D fell less than 80 nmol/liter.
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- Radiocalcium absorption is reduced in postmenopausal women with vertebral and most types of peripheral fractures. [Journal Article]
- OIOsteoporos Int 2004; 15(1):27-31
- Intestinal calcium absorption accounts for 60% of the variance in calcium balance and is therefore a potentially very important determinant of bone status. Whether measured by the balance technique o…
Intestinal calcium absorption accounts for 60% of the variance in calcium balance and is therefore a potentially very important determinant of bone status. Whether measured by the balance technique or with radiocalcium, it is known to be significantly reduced in postmenopausal women with vertebral and hip fractures. By contrast, there is very little information about calcium absorption in other types of postmenopausal fracture. We now report a series of 549 untreated, Caucasian postmenopausal women in whom we recorded prevalent fractures, measured radiocalcium absorption, and obtained radiographs of the lateral thoracic and lumbar spine. Of these women, 172 had no prevalent fractures, showed normal spine radiographs, and served as controls; 72 had one or more peripheral fractures but normal spine radiographs; 147 had one or more wedged or crushed vertebrae but no peripheral fractures; and 158 had a history of peripheral fracture and one or more fractured vertebrae. Age-adjusted radiocalcium absorption was significantly lower in the two groups with spinal fractures than in the controls ( P<0.001) but not in the group with peripheral fractures only. It was also lower in the cases with more than two spinal fractures than in those with two or less (P<0.001). In respect of peripheral fractures, the greatest age-adjusted absorption deficit was found in fractures of the humerus (35%) followed by hip (32%), spine (21%), wrist (19%), and rib 17% (all significant but not significantly different from each other). Lesser deficits in tibia, ankle and foot fractures were not significant but type 2 errors could not be excluded. We conclude that impaired calcium absorption is particularly associated with those fractures for which osteoporosis is a significant risk factor.