Moderate consumption of freeze-dried blueberry powder increased net bone calcium retention compared with no treatment in healthy postmenopausal women: a randomized crossover trial.

BACKGROUND: Preclinical studies suggest that blueberry consumption is associated with improved bone health. OBJECTIVES: We conducted a blueberry dose-response study in ovariectomized (OVX)-rats that informed a study in postmenopausal women using the urinary appearance of calcium (Ca) tracers from prelabeled bone to reflect changes in bone balance. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner compared with no treatment. METHODS: OVX rats were fed 4 doses of blueberry powder (2.5%, 5%, 10%, and 15%) in randomized order to determine bone 45Ca retention. Fourteen healthy, nonosteoporotic women ≥4 y past menopause were dosed with 50 nCi of 41Ca, a long-lived radioisotope, and equilibrated for 5 mo to allow 41Ca deposition in bone. Following a 6-wk baseline period, participants were assigned to a random sequence of 3 6-wk interventions, a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries incorporated into food and beverage products. Urinary 41Ca:Ca ratio was measured by accelerator mass spectrometry. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures analysis of variance. RESULTS: In both OVX rats and postmenopausal women, blueberry interventions benefited net bone calcium balance at lower but not at higher doses. In women, net bone calcium retention increased by 6% with the low (95% CI: 2.50, 8.60; P < 0.01) and 4% with the medium (95% CI: 0.96, 7.90; P < 0.05) dose compared with no treatment. Urinary excretion of hippuric acid increased dose-dependently with blueberry consumption. No significant relationships were found between bone resorption biomarkers, 25-hydroxyvitamin D, and interventions. CONCLUSIONS: Moderate consumption (<1 cup/d) of blueberries may be an effective strategy to attenuate bone loss in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT02630797.

Soluble corn fiber increases bone calcium retention in postmenopausal women in a dose-dependent manner: a randomized crossover trial.

BACKGROUND: Dietary soluble corn fiber (SCF) significantly improves calcium absorption in adolescents and the bone strength and architecture in rodent models. OBJECTIVE: In this study, we aimed to determine the skeletal benefits of SCF in postmenopausal women. DESIGN: We used our novel technology of determining bone calcium retention by following the urinary appearance of (41)Ca, a rare long-lived radioisotope, from prelabeled bone to rapidly and sensitively evaluate the effectiveness of SCF in reducing bone loss. A randomized-order, crossover, double-blinded trial was performed in 14 healthy postmenopausal women to compare doses of 0, 10, and 20 g fiber from SCF/d for 50 d. RESULTS: A dose-response effect was shown with 10 and 20 g fiber from SCF/d, whereby bone calcium retention was improved by 4.8% (P < 0.05) and 7% (P < 0.04), respectively. The bone turnover biomarkers N-terminal telopeptide and osteocalcin were not changed by the interventions; however, a significant increase in bone-specific alkaline phosphatase, which is a bone-formation marker, was detected between 0 and 20 g fiber from SCF/d (8%; P = 0.035). CONCLUSION: Daily SCF consumption significantly increased bone calcium retention in postmenopausal women, which improved the bone calcium balance by an estimated 50 mg/d. This study was registered at clinicaltrials.gov as NCT02416947.

Effect of Hesperidin With and Without a Calcium (Calcilock) Supplement on Bone Health in Postmenopausal Women.

CONTEXT: Citrus fruits contain unique flavanones. One of the most abundant of the flavanones, hesperidin, has been shown to prevent bone loss in ovariectomized rats. OBJECTIVE: The objective of the study was to measure the effect of hesperidin with or without calcium supplementation on bone calcium retention in postmenopausal women. DESIGN: The study was a double-blind, placebo-controlled, randomized-order crossover design of 500 g hesperidin with or without 500 mg calcium supplement in 12 healthy postmenopausal women. Bone calcium retention was determined from urinary excretion of the rare isotope, (41)Ca, from bone. RESULTS: Calcium plus hesperidin, but not hesperidin alone, improved bone calcium retention by 5.5% (P < .04). CONCLUSION: Calcium supplementation (Calcilock), in combination with hesperidin, is effective at preserving bone in postmenopausal women.

Impact of equol-producing capacity and soy-isoflavone profiles of supplements on bone calcium retention in postmenopausal women: a randomized crossover trial.

BACKGROUND: Postmenopausal estrogen depletion is a major contributing factor to bone loss. Soy isoflavones have variable effects on the prevention of postmenopausal bone loss, which is possibly related to the specific isoflavone content or the variable equol-producing capacity of individuals. OBJECTIVE: We aimed to determine the effects of the content of isoflavones in a soy supplement and the equol-producing ability of the individual on postmenopausal bone calcium retention. DESIGN: The study was a blinded, randomized, crossover intervention trial in 24 postmenopausal women who were prescreened for their ability to convert daidzein to equol. Women were equilibrated with (41)Ca before the intervention. Interventions were 5 soy isoflavone oral supplements (2 doses of a genistein-rich soy supplement and 3 doses of mixed isoflavones in various proportions) and a bisphosphonate (risedronate). Each intervention was given sequentially for 50 d followed by a 50-d washout period. The percentage of bone calcium retention was determined from the change in urinary (41)Ca:calcium. RESULTS: Interventions that ranged from 52 to 220 mg total isoflavones/d increased bone calcium retention between 3.4% and 7.6% (P < 0.05), which was a moderate effect compared with that of risedronate at 15.3% (95% CI: 7.1%, 22.7%; P = 0.0014). The most-effective soy intervention delivered 105.23 mg total isoflavones/d as genistein, daidzein, and glycitein in their natural ratios and increased bone calcium retention by 7.6% (95% CI: 4.9%, 10.2%; P < 0.0001). Genistein, at 52.85 mg/d, increased bone calcium retention by 3.4% (95% CI: 0.5%, 6.2%; P = 0.029); but there was no benefit at higher amounts (113.52 mg/d). There was no difference (P = 0.5) in bone calcium retention between equol producers and nonproducers. CONCLUSION: Soy isoflavones, although not as potent as risedronate, are effective bone-preserving agents in postmenopausal women regardless of their equol-producing status, and mixed isoflavones in their natural ratios are more effective than enriched genistein. This trial was registered at clinicaltrials.gov as NCT00244907.

A Bayesian approach to an interlaboratory comparison.

Interlaboratory comparisons are an important check of the quality of a measurement technique. In this paper we examine the accelerator mass spectrometry (AMS) measurement of 41Ca, an unstable isotope of calcium that has emerged as a valuable tracer for a variety of studies. We use a Bayesian framework to explore the quality and consistency of the AMS measurements made by Lawrence Livermore National Laboratory (LLNL) and the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). This framework should be generalizable to other interlaboratory comparisons. The laboratories measured 47 samples, with each lab measuring an aliquot of each sample. The Bayesian approach allowed us to derive a probability distribution for four parameters reflecting the quality of the data, and to then address the following questions: (1) are the results from the two labs consistent? (2) are the uncertainties quoted by the two labs reasonable? We find that any consistent offset between the two labs is negligible, and that the uncertainties may be slightly underestimated.

Applying accelerator mass spectrometry for low-level detection of complex engineered nanoparticles in biological media.

Complex engineered nanoparticles (CENPs), which have different core and surface components, are being developed for medicinal, pharmaceutical and industrial applications. One of the key challenges for environmental health and safety assessments of CENPs is to identify and quantity their transformations in biological environments. This study reports the effects of in vivo exposure of citrate-coated nanoalumina with different rare isotope labels on each component. This CENP was dosed to the rat and accelerator mass spectrometry (AMS) was used to quantify (26)Al, (14)C, and their ratio in the dosing material and tissue samples. For CENPs detected in the liver, the rare isotope ratio, (14)C/(26)Al, was 87% of the dosing material's ratio. The citrate coating on the nanoalumina in the liver was stable or, if it degraded, its metabolites were incorporated with nearby tissues. However, in brain and bone where little alumina was detected, the rare isotope ratio greatly exceeded that of the dosing material. Therefore, in the animal, citrate dissociated from CENPs and redistributed to brain and bone. Tracking both the core and surface components by AMS presents a new approach for characterizing transformations of CENPs components in biological milieu or environments.

Ultra-trace analysis of 41Ca in urine by accelerator mass spectrometry: an inter-laboratory comparison.

A 41Ca interlaboratory comparison between Lawrence Livermore National Laboratory (LLNL) and the Purdue Rare Isotope Laboratory (PRIME Lab) has been completed. Analysis of the ratios assayed by accelerator mass spectrometry (AMS) shows that there is no statistically significant difference in the ratios. Further, Bayesian analysis shows that the uncertainties reported by both facilities are correct with the possibility of a slight under-estimation by one laboratory. Finally, the chemistry procedures used by the two facilities to produce CaF2 for the cesium sputter ion source are robust and don't yield any significant differences in the final result.

Calcium isolation from large-volume human urine samples for 41Ca analysis by accelerator mass spectrometry.

Calcium oxalate precipitation is the first step in preparation of biological samples for (41)Ca analysis by accelerator mass spectrometry. A simplified protocol for large-volume human urine samples was characterized, with statistically significant increases in ion current and decreases in interference. This large-volume assay minimizes cost and effort and maximizes time after (41)Ca administration during which human samples, collected over a lifetime, provide (41)Ca:Ca ratios that are significantly above background.

Interpretation of 41Ca data using compartmental modeling in post-menopausal women.

Calcium-41 (t(1/2) = 10(5) years) can be used after a single dose to follow calcium metabolism over a subject's lifetime. The aims of this study were to expand a (41)Ca kinetic model and estimate bone resorption in women with stable bone loss, compare the rates with those calculated with classical isotope studies, and to use the model to simulate dynamic changes in urinary (41)Ca:Ca ratios and bone balance for the design and interpretation of (41)Ca studies. Forty-two women >5 years post-menopause were given (41)Ca intravenously. Bone mineral content and bone mineral density of total body were measured by dual-energy X-ray absorptiometry at the beginning of the study. Urine collections were made periodically for up to ~5 years while subjects were free living. Urinary (41)Ca:Ca ratios were measured using accelerator mass spectrometry. The isotope data were analyzed by compartmental modeling. Four compartments were necessary to fit the urinary tracer data and total bone calcium. The final model included pathways for absorption, distribution, urinary excretion, and endogenous excretion and was used to calculate rates of bone turnover. Estimates of bone resorption in a subset of the women (n = 13), studied previously in a 3-week balance and full kinetic study with (45)Ca, agreed with those using (41)Ca methodology. Thus, rates of bone resorption can be estimated from (41)Ca urinary data in stable post-menopausal women. The model was used to simulate dynamic changes in urinary (41)Ca:Ca ratios and bone balance, as a result of interventions that perturb calcium metabolism to aid in study design and interpretation.

Pharmacokinetics and tissue distribution of 14C-labeled grape polyphenols in the periphery and the central nervous system following oral administration.

Grape polyphenols confer potential health benefits, including prevention of neurodegenerative diseases. To determine the absorption and tissue distribution of the complex grape polyphenol mixture, (14)C-labeled polyphenols were biosynthesized by grape cell suspension cultures, during co-incubation with radioisotopically labeled sucrose, and fractionated into polyphenolic subfractions. The pharmacokinetics and distribution of grape polyphenols into blood, brain, and peripheral interstitial fluid were determined by tracking the (14)C label. The blood peak (14)C concentration of the fractions ranged from 15 minutes to 4 hours. Absorption and tissue distribution varied greatly between fractions. Concentrations in interstitial fluid were lower than in blood. The amount of residual label in the brain at 24 hours ranged from 0.1% to 1.7% of the dose, depending on the fraction. (14)C label found in the brain tissue and brain microdialysate indicated that grape polyphenols or their metabolites are able to cross the blood-brain barrier. Using (14)C-labeled plant polyphenols it is possible to track the compounds or their metabolic products into any tissue and determine distribution patterns in spite of low concentrations. A central question regarding the potential role of dietary polyphenolics in neurodegenerative research is whether they are bioavailable in the brain. Our observations indicate that some grape-derived polyphenolics do reach the brain, which suggests their potential value for applications in neurodegenerative disorders.

Method for evaluating the potential of C labeled plant polyphenols to cross the blood-brain barrier using accelerator mass spectrometry.

Bioactive compounds in botanicals may be beneficial in preventing age-related neurodegenerative diseases, but for many compounds conventional methods may be inadequate to detect if these compounds cross the blood brain barrier or to track the pharmacokinetics in the brain. By combining a number of unique technologies it has been possible to utilize the power of AMS to study the pharmacokinetics of bioactive compounds in the brain at very low concentrations. (14)C-labeled compounds can be biosynthesized by plant cell suspension cultures co-incubated with radioisotopically-labeled sucrose and isolated and separated into a series of bioactive fractions.To study the pharmacokinetics and tissue distribution of (14)C labeled plant polyphenols, rats were implanted with jugular catheters, subcutaneous ultrafiltration probes and brain microdialysis probes. Labeled fractions were dosed orally. Interstitial fluid (ISF) and brain microdialysate samples were taken in tandem with blood samples. It was often possible to determine (14)C in blood and ISF with a ß-counter. However, brain microdialysate samples (14)C levels on the order of 10(7) atoms/sample required AMS technology. The Brain Microdialysate(AUC)/Serum(AUC) ranged from .021- to .029, with the higher values for the glycoside fractions. By using AMS in combination with traditional methods, it is possible to study uptake by blood, distribution to ISF and determine the amount of a dose which can reach the brain and follow the pharmacokinetics in the brain.

Bone seeking labels as markers for bone turnover: effect of dosing schedule on labeling various bone sites in rats.

Urinary excretion of bone labels can be used to monitor bone resorption. Here we investigate the effects of dosing frequency on label incorporation of various sites when bone turnover was perturbed by ovariectomy. We compared tritiated tetracycline ((3)H-TC) and (45)Ca in two studies. Nine-month-old rats were given single or multiple injections of (3)H-TC and (45)Ca and sacrificed after 7 or 14 days. Six-month-old OVX rats were given (3)H-TC and (41)Ca tracers 1 or 3 months following ovariectomy (OVX + 1 mo or OVX + 3 mo, when bone turnover was higher or lower, respectively) and sacrificed 1 week, 1 month, 3 months, or 6 months postdose. Twenty-four-hour urine pools over 2-4 consecutive days as well as the proximal tibia, femur midshaft, lumbar vertebrae (L1-L4), and remaining skeleton were analyzed for (3)H, (45)Ca, and calcium content. Bone turnover as assessed by urinary (3)H-TC was greater in OVX + 1 mo compared to OVX + 3 mo rats up to 6 months postdose. (45)Ca labeling efficiency (% dose/g Ca) was significantly higher than for (3)H and labeling was higher in trabecular-rich than cortical-rich bone. This study affirms that a single administration of either (3)H-TC or (45)Ca is a useful approach to measuring bone turnover directly. The amount of label incorporation into bone was greater in bone sites that were more metabolically active and in all sites when closer vs farther from OVX.