Tag Archives: in vivo

High-Protein + Adequate Calcium is Better for Maintaining Bone Than Normal-Protein Diets in Rats

Abstract

Effects of the amount and source of dietary protein on bone status in rats.

This study examined the effects of the dietary amount and source of protein on bone status in rats. 140 male Wistar rats aged 8 weeks were randomly allocated to 4 groups (n = 35) fed normal-protein (NP, 10% richness) or high-protein (HP, 45% richness) diets based on whey protein (WP) or soy protein (SP) sources for 12 weeks. Plasma urea was 46% higher for the HP compared to the NP diet (p < 0.001). Urinary calcium was 65% higher for the HP compared to the NP and 60% higher for the WP compared to the SP diets (all, p < 0.001). Urinary pH was 8% more acidic in the HP compared to the NP diet (p < 0.001) and 4% in the WP compared to the SP diet (p < 0.01). The plasma osteocalcin concentration was 19% higher for the NP compared to the HP (p < 0.05) and 25% for the SP compared to the WP diets (p < 0.01). Femur ash, metaphyseal and diaphyseal cross-sectional, trabecular and cortical areas were 3% higher in the HP compared to the NP diet (all, p < 0.05). Femur diaphyseal periosteal and endocortical perimeters were also 3% higher in the HP compared to the NP diet (both, p < 0.01). Groups fed the SP diet showed 2% higher femur ash percentage, 7% higher calcium content (both, p < 0.001), and 3% higher diaphyseal cortical area and thickness (both, p < 0.05) than those fed the WP diet. Some interactions were found, such as the greater effects of the SP diet on decreasing the higher plasma urea concentration promoted by the intake of the HP diet (p < 0.001). Under adequate Ca intake, HP diets could better maintain bone properties than NP diets, even with increasing some acidity markers, which could be reduced by the intake of SP sources.

Nebot E, Erben RG, Porres JM, Femia P…
Food Funct Apr 2014
PMID: 24531397

High-Protein Meat Diet has No Adverse Effects on Bone in Postmenopausal Women

Abstract

A diet high in meat protein and potential renal acid load increases fractional calcium absorption and urinary calcium excretion without affecting markers of bone resorption or formation in postmenopausal women.

Our objective in this study was to determine the effects of a high-protein and high-potential renal acid load (PRAL) diet on calcium (Ca) absorption and retention and markers of bone metabolism. In a randomized crossover design, 16 postmenopausal women consumed 2 diets: 1 with low protein and low PRAL (LPLP; total protein: 61 g/d; PRAL: -48 mEq/d) and 1 with high protein and high PRAL (HPHP; total protein: 118 g/d; PRAL: 33 mEq/d) for 7 wk each separated by a 1-wk break. Ca absorption was measured by whole body scintillation counting of radio-labeled (47)Ca. Compared with the LPLP diet, the HPHP diet increased participants’ serum IGF-I concentrations (P < 0.0001), decreased serum intact PTH concentrations (P < 0.001), and increased fractional (47)Ca absorption (mean ± pooled SD: 22.3 vs. 26.5 ± 5.4%; P < 0.05) and urinary Ca excretion (156 vs. 203 ± 63 mg/d; P = 0.005). The net difference between the amount of Ca absorbed and excreted in urine did not differ between 2 diet periods (55 vs. 28 ± 51 mg/d). The dietary treatments did not affect other markers of bone metabolism. In summary, a diet high in protein and PRAL increases the fractional absorption of dietary Ca, which partially compensates for increased urinary Ca, in postmenopausal women. The increased IGF-I and decreased PTH concentrations in serum, with no change in biomarkers of bone resorption or formation, indicate a high-protein diet has no adverse effects on bone health.

Cao JJ, Johnson LK, Hunt JR
J. Nutr. Mar 2011
PMID: 21248199 | Free Full Text

The present study detected no change in potential biomarkers of osteoclast activity, such as blood TRAP, CTX, and sRANKL and urinary DPD, or biomarkers of osteoblast activity, such as blood OPG and OC. The observed changes in IGF-I and PTH were apparently insufficient to elicit detectable changes in biomarkers of osteoclast or osteoblast activity.

Many epidemiological observations have shown that long-term protein intakes are positively associated with bone mineral density (9, 11, 13, 53). Several recent meta-analyses have concluded that protein is beneficial to bone health (54) and protein-induced acid load does not promote skeletal bone mineral loss or contribute to the development of osteoporosis (55, 56). The results from this study are in agreement with those findings.

In conclusion, in postmenopausal women, a diet high in both protein and PRAL increased Ca absorption, at least partially compensating for an increase in urinary excretion. No change in either bone resorption or formation biomarkers was observed, indicating that a high-protein diet is not detrimental. However, the increased serum IGF-I combined with decreased serum PTH concentrations suggest that a high-protein diet could be beneficial to bone health.

Potassium Bicarbonate Decreases Resorption and Increases Bone Formation in Postmenopausal Women

Abstract

Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate.

In normal subjects, a low level of metabolic acidosis and positive acid balance (the production of more acid than is excreted) are typically present and correlate in degree with the amount of endogenous acid produced by the metabolism of foods in ordinary diets abundant in protein. Over a lifetime, the counteraction of retained endogenous acid by base mobilized from the skeleton may contribute to the decrease in bone mass that occurs normally with aging.
To test that possibility, we administered potassium bicarbonate to 18 postmenopausal women who were given a constant diet (652 mg [16 mmol] of calcium and 96 g of protein per 60 kg of body weight). The potassium bicarbonate was given orally for 18 days in doses (60 to 120 mmol per day) that nearly completely neutralized the endogenous acid.
During the administration of potassium bicarbonate, the calcium and phosphorus balance became less negative or more positive–that is, less was excreted in comparison with the amount ingested (mean [+/- SD] change in calcium balance, +56 +/- 76 mg [1.4 +/- 1.9 mmol] per day per 60 kg; P = 0.009; change in phosphorus balance, +47 +/- 64 mg [1.5 +/- 2.1 mmol] per day per 60 kg; P = 0.007) because of reductions in urinary calcium and phosphorus excretion. The changes in calcium and phosphorus balance were positively correlated (P < 0.001). Serum osteocalcin concentrations increased from 5.5 +/- 2.8 to 6.1 +/- 2.8 ng per milliliter (P < 0.001), and urinary hydroxyproline excretion decreased from 28.9 +/- 12.3 to 26.7 +/- 10.8 mg per day (220 +/- 94 to 204 +/- 82 mumol per day; P = 0.05). Net renal acid excretion decreased from 70.9 +/- 10.1 to 12.8 +/- 21.8 mmol per day, indicating nearly complete neutralization of endogenous acid.
In postmenopausal women, the oral administration of potassium bicarbonate at a dose sufficient to neutralize endogenous acid improves calcium and phosphorus balance, reduces bone resorption, and increases the rate of bone formation.

Sebastian A, Harris ST, Ottaway JH, Todd KM…
N. Engl. J. Med. Jun 1994
PMID: 8190153 | Free Full Text

Potassium Citrate Increases Calcium Levels in Adults

Abstract

Potassium citrate supplementation results in sustained improvement in calcium balance in older men and women.

The dietary acid load created by the typical Western diet may adversely impact the skeleton by disrupting calcium metabolism. Whether neutralizing dietary acid with alkaline potassium salts results in sustained improvements in calcium balance remains controversial. In this randomized, double-blind, placebo-controlled study, 52 men and women (mean age 65.2 ± 6.2 years) were randomly assigned to potassium citrate 60 mmol/d, 90 mmol/d, or placebo daily with measurements of bone turnover markers, net acid excretion, and calcium metabolism, including intestinal fractional calcium absorption and calcium balance, obtained at baseline and at 6 months. At 6 months, net acid excretion was significantly lower in both treatment groups compared to placebo and it was negative, meaning subjects’ dietary acid was completely neutralized (-11.3 mmol/d on 60 mmol/d; -29.5 mmol/d on 90 mmol/d, p < 0.001 compared to placebo). At 6 months, 24-hour urine calcium was significantly reduced in persons taking potassium citrate 60 mmol/d (-46 ± 15.9 mg/d) and 90 mmol/d (-59 ± 31.6 mg/d) compared with placebo (p < 0.01). Fractional calcium absorption was not changed by potassium citrate supplementation. Net calcium balance was significantly improved in participants taking potassium citrate 90 mmol/d compared to placebo (142 ± 80 mg/d on 90 mmol/d versus -80 ± 54 mg/d on placebo; p = 0.02). Calcium balance was also improved on potassium citrate 60 mmol/d, but this did not reach statistical significance (p = 0.18). Serum C-telopeptide decreased significantly in both potassium citrate groups compared to placebo (-34.6 ± 39.1 ng/L on 90 mmol/d, p = 0.05; -71.6 ± 40.7 ng/L on 60 mmol/d, p = 0.02) whereas bone-specific alkaline phosphatase did not change. Intact parathyroid hormone was significantly decreased in the 90 mmol/d group (p = 0.01). Readily available, safe, and easily administered in an oral form, potassium citrate has the potential to improve skeletal health. Longer-term trials with definitive outcomes such as bone density and fracture are needed.

Moseley KF, Weaver CM, Appel L, Sebastian A…
J. Bone Miner. Res. Mar 2013
PMID: 22991267

Potassium Citrate Reduces Resorption in Postmenopausal Women

Abstract

Effects of potassium citrate supplementation on bone metabolism.

Western diets rich in animal protein result in long-term acid loading that, despite corresponding increases in net renal acid excretion, may induce a chronic state of acidemia. This may have deleterious effects on both the kidney and bone, by increasing the risk of calcium stone in the former and leading to chemical dissolution of mineral alkaline salts in the latter. Whereas supplementation with alkaline citrate has been shown to reduce stone recurrences, its effect on bone turnover has received less attention. The aim of the present study was to evaluate whether potassium citrate favorably affects bone turnover markers in postmenopausal females with low bone density. Thirty women, aged 58 +/- 8.1 years, were enrolled and studied on basal conditions and after a 3-month course of potassium citrate supplementation (0.08-0.1 g/kg b.w. daily). Twenty-two women concluded the study while 8 withdrew. Twenty-four age-matched healthy women were taken as control cases. All were evaluated for electrolyte and acid-base balance-related parameters, bone turnover, markers and renal function. A significant decrease in net acid excretion was observed upon citrate supplementation, and this was paralleled by a significant decrease of urinary deoxypyridinolines, hydroxyproline-to-creatinine ratios, and, to a lesser extent, serum osteocalcin. Percent variations of urine citrate were inversely related to those of deoxypyridinolines and hydroxyproline. No change in these chemistries occurred in the control group. Our results suggest that treatment with an alkaline salt, such as potassium citrate, can reduce bone resorption thereby contrasting the potential adverse effects caused by chronic acidemia of protein-rich diets.

Marangella M, Di Stefano M, Casalis S, Berutti S…
Calcif. Tissue Int. Apr 2004
PMID: 15255069

Bicarbonate, but Not Potassium, Decreases Resorption

Abstract

Treatment with potassium bicarbonate lowers calcium excretion and bone resorption in older men and women.

Bicarbonate has been implicated in bone health in older subjects on acid-producing diets in short-term studies.
The objective of this study was to determine the effects of potassium bicarbonate and its components on changes in bone resorption and calcium excretion over 3 months in older men and women. Design, Participants, and Intervention: In this double-blind, controlled trial, 171 men and women age 50 and older were randomized to receive placebo or 67.5 mmol/d of potassium bicarbonate, sodium bicarbonate, or potassium chloride for 3 months. All subjects received calcium (600 mg of calcium as triphosphate) and 525 IU of vitamin D(3) daily.
Twenty-four-hour urinary N-telopeptide and calcium were measured at entry and after 3 months. Changes in these measures were compared across treatment groups in the 162 participants included in the analyses.
Bicarbonate affected the study outcomes, whereas potassium did not; the two bicarbonate groups and the two no bicarbonate groups were therefore combined. Subjects taking bicarbonate had significant reductions in urinary N-telopeptide and calcium excretion, when compared with subjects taking no bicarbonate (both before and after adjustment for baseline laboratory value, sex, and changes in urinary sodium and potassium; P = 0.001 for both, adjusted). Potassium supplementation did not significantly affect N-telopeptide or calcium excretion.
Bicarbonate, but not potassium, had a favorable effect on bone resorption and calcium excretion. This suggests that increasing the alkali content of the diet may attenuate bone loss in healthy older adults.

Dawson-Hughes B, Harris SS, Palermo NJ, Castaneda-Sceppa C…
J. Clin. Endocrinol. Metab. Jan 2009
PMID: 18940881 | Free Full Text

Supplementation with potassium did not significantly alter calcium excretion or markers of bone turnover in this study. This is in contrast to earlier reports of Lemann et al. (19) and Jones et al. (20) who found that increasing potassium intake decreased urinary calcium excretion. The apparently conflicting observation that higher potassium intake is associated with higher BMD in healthy perimenopausal women (21) may result from the fact that potassium-rich diets tend to be alkali-producing, in that they are rich in fruits and vegetables. Treatment with potassium did enhance sodium excretion, as has been documented widely.

In conclusion, we have found that reducing the acidogenicity of the diet into the alkali-producing range with bicarbonate lowers calcium excretion and the bone resorption rate in healthy older men and women consuming rather typical acid-producing American diets. Treatment with 67.5 mmol/d of potassium bicarbonate was safe and well tolerated in this population. Increasing intake of alkali merits further consideration as a safe and low-cost approach to improving skeletal health in older men and women.

Policosanol Prevents Bone Loss in Ovariectomized Rats

Abstract

Policosanol prevents bone loss in ovariectomized rats.

Osteoporosis is characterized by reduced bone mass, abnormal bone architecture and increased fracture risk. Ovariectomy impairs bone mass and metabolism in rats and ovariectomized rats are considered as a suitable model of postmenopausal osteoporosis. Mevalonate is required for producing lipoids that are important in osteoclast activity and thus drugs affecting mevalonate production can prevent bone loss in rodents. Policosanol is a cholesterol-lowering drug isolated from sugar cane wax that inhibits cholesterol biosynthesis through an indirect regulation of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity. The purpose of this study was to determine whether policosanol could prevent bone loss in the bones of ovariectomized rats by comparing its effects with those induced by estradiol. Sprague Dawley female rats were randomly distributed in four groups: a sham-operated group treated with Tween/H2O vehicle and three groups of ovariectomized rats treated with 17beta-estradiol (30 microg/kg/day) or policosanol (50 and 200 mg/kg/day), respectively, for 3 months. At treatment completion the rats were sacrificed, their bones removed and variables of bone resorption and formation were investigated by histomorphometry. Ovariectomy increased trabecular separation but diminished the number and thickness of trabecules. Estradiol and policosanol prevented these effects compared with ovariectomized controls. Both treatments also prevented an increase in the number of osteoclasts and their surface area induced by ovariectomy. Estradiol, but not policosanol, significantly prevented an increase of osteoblast surface area compared with ovariectomized controls. In conclusion, policosanol prevented bone loss and decreased bone resorption in ovariectomized rats, suggesting that it should be potentially useful in preventing bone loss in postmenopausal women.

Noa M, Más R, Mendoza S, Gámez R…
Drugs Exp Clin Res 2004
PMID: 15366788

Cumin Increases Bone Density and Strength in Ovariectomized Rats – Possible SERM

Abstract

Methanolic extract of Cuminum cyminum inhibits ovariectomy-induced bone loss in rats.

Several animal and clinical studies have shown that phytoestrogens, plant-derived estrogenic compounds, can be useful in treating postmenopausal osteoporosis. Phytoestrogens and phytoestrogen-containing plants are currently under active investigation for their role in estrogen-related disorders. The present study deals with anti-osteoporotic evaluation of phytoestrogen-rich plant Cuminum cyminum, commonly known as cumin. Adult Sprague-Dawley rats were bilaterally ovariectomized (OVX) and randomly assigned to 3 groups (10 rats/group). Additional 10 animals were sham operated. OVX and sham control groups were orally administered with vehicle while the other two OVX groups were administered 0.15 mg/kg estradiol and 1 g/kg of methanolic extract of Cuminum cyminum fruits (MCC) in two divided doses for 10 weeks. At the end of the study blood, bones and uteri of the animals were collected. Serum was evaluated for calcium, phosphorus, alkaline phosphatase and tartarate resistant acid phosphatase. Bone density, ash density, mineral content and mechanical strength of bones were evaluated. Scanning electron microscopic (SEM) analysis of bones (tibia) was performed. Results were analyzed using ANOVA and Tukeys multiple comparison test. MCC (1 g/kg, p.o.) significantly reduced urinary calcium excretion and significantly increased calcium content and mechanical strength of bones in comparison to OVX control. It showed greater bone and ash densities and improved microarchitecture of bones in SEM analysis. Unlike estradiol it did not affect body weight gain and weight of atrophic uterus in OVX animals. MCC prevented ovariectomy-induced bone loss in rats with no anabolic effect on atrophic uterus. The osteoprotective effect was comparable with estradiol.

Shirke SS, Jadhav SR, Jagtap AG
Exp. Biol. Med. (Maywood) Nov 2008
PMID: 18824723

ACE Inhibitor Moexipril Doesn’t Harm Bones in Ovariectomized Rats

Abstract

Impact of antihypertensive therapy on postmenopausal osteoporosis: effects of the angiotensin converting enzyme inhibitor moexipril, 17beta-estradiol and their combination on the ovariectomy-induced cancellous bone loss in young rats.

No data are available on whether angiotensin converting enzyme (ACE) inhibition affects the skeleton, though this might be of clinical relevance when antihypertensive therapy is initiated, particularly in hypertensive women after menopause who typically suffer from a concomitant rapid onset of osteoporosis. In the present study we investigated the effects of the new ACE inhibitor moexipril, 17beta-estradiol and their combination on the bone turnover in ovariectomized Sprague-Dawley rats, an established animal model for studying human postmenopausal osteoporosis.
We studied 119 12-week-old virgin female Sprague-Dawley rats. Seven rats were killed on day 0 as basal controls. The remaining rats were divided into sham-ovariectomy or ovariectomy groups. Vehicle, moexipril at 10 mg/kg per day alone (orally), 17beta-estradiol at 10 mu g/kg per day alone (subcutaneously) or both were administered to both groups immediately after the operation for 14 (short-term effects) or 56 (long-term effects) days. A stereology computer program was used for measurements. Static histomorphometric measurements, using a stereology computer program, were taken on double-fluorescent labeled undecalcified proximal tibial metaphyseal (cancellous bone site) and tibial shaft (cortical bone site) sections.
Ovariectomy induced dramatically cancellous bone loss due to increased bone turnover, with resorption exceeding formation. Moexipril had no effect on the cancellous bone site in either ovariectomized or sham-operated rats. 17beta-Estradiol treatment added extra cancellous bone in the sham-operated rats and prevented cancellous bone loss in the ovariectomized rats by inhibiting bone resorption. The combination of moexipril and 17beta-estradiol gave similar results to those of 17beta-estradiol alone. Comparable results were observed in the cortical bone site.
The results of this study show that ACE inhibition by moexipril has no effect on the skeleton when given alone and that it does not hamper the osteoprotective effects of 17beta-estradiol. These findings are relevant for the use of antihypertensive therapy in postmenopausal women treated or not with hormone replacement therapy.

Stimpel M, Jee WS, Ma Y, Yamamoto N…
J. Hypertens. Dec 1995
PMID: 8903666

Clove Preserves Bone in Ovariectomised Rats

Abstract

Clove (Syzygium aromaticum Linn) extract rich in eugenol and eugenol derivatives shows bone-preserving efficacy.

This study examined the efficacy of hydroalcoholic extract of dried clove buds, which is rich in phenolic compounds namely eugenol and eugenol derivatives (precursors of flavones, isoflavones and flavonoids), on different primary and secondary osteoporotic marker changes in an ovariectomised (OVX) rat model of osteoporosis. Female Wistar rats were randomly divided into three groups: sham-operated control (A), OVX (B) and OVX plus 50% hydroalcoholic extract of dried clove buds for 4 weeks (C). Results indicated that, compared to control, serum alkaline phosphatase (AP; 48.25%, p < 0.01), serum tartrate-resistant acid phosphatase (TRAP; 63.48%, p < 0.01), urinary calcium (14.70%, p < 0.01), urinary phosphate (50.30%, p < 0.01) and urinary creatinine (122.44%, p < 0.01) were significantly altered in OVX rats. All these altered responses were significantly restored (AP: 27.53%, p < 0.01; TRAP: 33.51%, p < 0.01; calcium: 53.15%, p < 0.01; phosphate: 27.49%, p < 0.01; creatinine: 46.40%, p < 0.01) by supplementation with hydroalcoholic extract of dried clove buds. Results of bone density, bone mineral content, bone tensile strength and histological analysis also showed similar trend of results, which supported initial observations of this study. It is proposed that hydroalcoholic extract of dried clove buds has bone-preserving efficacy against hypogonadal osteoporosis.

Karmakar S, Choudhury M, Das AS, Maiti A…
Nat. Prod. Res. 2012
PMID: 21711176