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High Omega-6 to Omega-3 Ratio is Associated with Lower Bone Density

Abstract

Ratio of n-6 to n-3 fatty acids and bone mineral density in older adults: the Rancho Bernardo Study.

Several lines of evidence suggest that n-3 fatty acids reduce the risk of some chronic diseases, including heart disease, diabetes, and cancer. Other research, mainly in animals, also suggests a role in bone health.
We aimed to investigate the association between the ratio of dietary n-6 to n-3 fatty acids and bone mineral density (BMD) in 1532 community-dwelling men and women aged 45-90 y.
Between 1988 and 1992, dietary data were obtained through self-administered food-frequency questionnaires, and BMD was measured at the hip and spine with the use of dual-energy X-ray absorptiometry. A medical history was obtained and current medication use was validated. Age- and multiple-adjusted linear regression analyses were performed.
There was a significant inverse association between the ratio of dietary linoleic acid to alpha-linolenic acid and BMD at the hip in 642 men, 564 women not using hormone therapy, and 326 women using hormone therapy; these results were independent of age, body mass index, and lifestyle factors. An increasing ratio of total dietary n-6 to n-3 fatty acids was also significantly and independently associated with lower BMD at the hip in all women and at the spine in women not using hormone therapy.
A higher ratio of n-6 to n-3 fatty acids is associated with lower BMD at the hip in both sexes. These findings suggest that the relative amounts of dietary polyunsaturated fatty acids may play a vital role in preserving skeletal integrity in older age.

Weiss LA, Barrett-Connor E, von Mühlen D
Am. J. Clin. Nutr. Apr 2005
PMID: 15817874 | Free Full Text

Review: Studies on GLA, Omega 3, and Other Fatty Acids

Abstract

Polyunsaturated fatty acids: biochemical, nutritional and epigenetic properties.

Dietary polyunsaturated fatty acids (PUFA) have effects on diverse physiological processes impacting normal health and chronic diseases, such as the regulation of plasma lipid levels, cardiovascular and immune function, insulin action and neuronal development and visual function. Ingestion of PUFA will lead to their distribution to virtually every cell in the body with effects on membrane composition and function, eicosanoid synthesis, cellular signaling and regulation of gene expression. Cell specific lipid metabolism, as well as the expression of fatty acid-regulated transcription factors, likely play an important role in determining how cells respond to changes in PUFA composition. This review will focus on recent advances on the essentiality of these molecules and on their interplay in cell physiology, leading to new perspective in different therapeutic fields.

Benatti P, Peluso G, Nicolai R, Calvani M
J Am Coll Nutr Aug 2004
PMID: 15310732 | Free Full Text

This article reviewed, among many others, the study from EPA + GLA Increases Bone Density in Elderly Women:

In a single-blind, randomized study, Kruger et al. [174] tested the interactions between calcium and DGLA + EPA in osteoporotic or osteopenic women. All of the women were living in the same institution for the elderly and fed the same low-calcium, non-vitamin D enriched foods, and had similar amounts of sunlight. Subjects were randomly assigned to DGLA + EPA or coconut oil (placebo group); in addition, all received 600 mg/day of calcium. Markers of bone formation/degradation and bone mineral density (BMD) were measured at baseline, 6, 12 and 18 months. At 18 months, osteocalcin and deoxypyridinoline levels fell significantly in both groups, indicating a decrease in bone turnover, whereas bone specific ALP rose indicating beneficial effects of calcium given to all the patients. Lumbar and femoral BMD, in contrast, showed different results in the two groups. Over the first 18 months, lumbar spine density remained the same in the treatment group, but decreased 3.2% in the placebo group. Femoral bone density increased 1.3% in the treatment group, but decreased 2.1% in the placebo group. During the second period of 18 months with all patients now on active treatment, lumbar spine density increased 3.1% in patients who remained on active treatment, and 2.3% in patients who switched from placebo to active treatment; femoral BMD in the latter group showed an increase of 4.7%.

 

Vitamin K1 or K2 (MK-4) Does Not Increase Bone Density in Healthy Postmenopausal Women

Abstract

Vitamin K treatment reduces undercarboxylated osteocalcin but does not alter bone turnover, density, or geometry in healthy postmenopausal North American women.

Low vitamin K status is associated with low BMD and increased fracture risk. Additionally, a specific menaquinone, menatetrenone (MK4), may reduce fracture risk. However, whether vitamin K plays a role in the skeletal health of North American women remains unclear. Moreover, various K vitamers (e.g., phylloquinone and MK4) may have differing skeletal effects. The objective of this study was to evaluate the impact of phylloquinone or MK4 treatment on markers of skeletal turnover and BMD in nonosteoporotic, postmenopausal, North American women. In this double-blind, placebo-controlled study, 381 postmenopausal women received phylloquinone (1 mg daily), MK4 (45 mg daily), or placebo for 12 mo. All participants received daily calcium and vitamin D(3) supplementation. Serum bone-specific alkaline phosphatase (BSALP) and n-telopeptide of type 1 collagen (NTX) were measured at baseline and 1, 3, 6, and 12 mo. Lumbar spine and proximal femur BMD and proximal femur geometry were measured by DXA at baseline and 6 and 12 mo. At baseline, the three treatment groups did not differ in demographics or study endpoints. Compliance with calcium, phylloquinone, and MK4 treatment was 93%, 93%, and 87%, respectively. Phylloquinone and MK4 treatment reduced serum undercarboxylated osteocalcin but did not alter BSALP or NTX. No effect of phylloquinone or MK4 on lumbar spine or proximal femur BMD or proximal femur geometric parameters was observed. This study does not support a role for vitamin K supplementation in osteoporosis prevention among healthy, postmenopausal, North American women receiving calcium and vitamin D supplementation.

Binkley N, Harke J, Krueger D, Engelke J…
J. Bone Miner. Res. Jun 2009
PMID: 19113922 | Free Full Text

Vitamin K1 500mcg No Benefit for Bone Density Over 3 Years

Abstract

Effect of vitamin K supplementation on bone loss in elderly men and women.

Vitamin K has been implicated in bone health, primarily in observational studies. However, little is known about the role of phylloquinone supplementation on prevention of bone loss in men and women.
The objective of this study was to determine the effect of 3-yr phylloquinone supplementation on change in bone mineral density (BMD) of the femoral neck bone in older men and women who were calcium and vitamin D replete.
In this 3-yr, double-blind, controlled trial, 452 men and women (60-80 yr) were randomized equally to receive a multivitamin that contained either 500 mug/d or no phylloquinone plus a daily calcium (600 mg elemental calcium) and vitamin D (400 IU) supplement.
Measurements of the femoral neck, spine (L2-L4), and total-body BMD, bone turnover, and vitamins K and D status were measured every 6-12 months. Intent-to-treat analysis was used to compare change in measures in 401 participants who completed the trial.
There were no differences in changes in BMD measurements at any of the anatomical sites measured between the two groups. The group that received the phylloquinone supplement had significantly higher phylloquinone and significantly lower percent undercarboxylated osteocalcin concentrations compared with the group that did not receive phylloquinone. No other biochemical measures differed between the two groups.
Phylloquinone supplementation in a dose attainable in the diet does not confer any additional benefit for bone health at the spine or hip when taken with recommended amounts of calcium and vitamin D.

Booth SL, Dallal G, Shea MK, Gundberg C…
J. Clin. Endocrinol. Metab. Apr 2008
PMID: 18252784 | Free Full Text

Review: Vitamin K1 Cost Effectiveness for Osteoporosis

Abstract

Vitamin K to prevent fractures in older women: systematic review and economic evaluation.

To determine the clinical and cost-effectiveness of vitamin K in preventing osteoporotic fractures in postmenopausal women.
Searches were conducted in May 2007 in MEDLINE, MEDLINE In-Process, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, BIOSIS, CINAHL, DARE, NHS EED and HTA databases, AMED, NRR, Science Citation Index and Current Controlled Trials. The MEDLINE search was updated in March 2009.
Selected studies were assessed and subjected to data extraction and quality assessment using standard methods. Where appropriate, meta-analysis was carried out. A mathematical model was constructed to estimate the cost-effectiveness of vitamin K1.
The electronic literature searches identified 1078 potentially relevant articles. Of these, 14 articles relating to five trials that compared vitamin K with a relevant comparator in postmenopausal women with osteoporosis or osteopenia met the review inclusion criteria. The double-blind ECKO trial compared 5 mg of phylloquinone (vitamin K1) with placebo in Canadian women with osteopenia but without osteoporosis. Four open-label trials used 45 mg of menatetrenone (vitamin K2) in Japanese women with osteoporosis; the comparators were no treatment, etidronate or calcium. The methodological quality of the ECKO trial was good; however, all four menatetrenone trials were poorly reported and three were very small (n < 100 in each group). Phylloquinone was associated with a statistically significant reduction in the risk of clinical fractures relative to placebo [relative risk 0.46, 95% confidence interval (CI) 0.22 to 0.99]; morphometric vertebral fractures were not reported. The smaller menatetrenone trials found that menatetrenone was associated with a reduced risk of morphometric vertebral fractures relative to no treatment or calcium; however, the larger Osteoporosis Fracture (OF) study found no evidence of a reduction in vertebral fracture risk. The three smaller trials found no significant difference between treatment groups in non-vertebral fracture incidence. In the ECKO trial, phylloquinone was not associated with an increase in adverse events. In the menatetrenone trials, adverse event reporting was generally poor; however, in the OF study, menatetrenone was associated with a significantly higher incidence of skin and skin appendage lesions. No published economic evaluations of vitamin K were found and a mathematical model was thus constructed to estimate the cost-effectiveness of vitamin K1. Comparators were alendronate, risedronate and strontium ranelate. Vitamin K1 and alendronate were markedly more cost-effective than either risedronate or strontium ranelate. The base-case results favoured vitamin K1, but this relied on many assumptions, particularly on the efficacy of preventing hip and vertebral fractures. Calculation of the expected value of sampled information was conducted assuming a randomised controlled trial of 5 years’ duration comparing alendronate with vitamin K1. The costs incurred in obtaining updated efficacy data from a trial with 2000 women per arm were estimated to be a cost-effective use of resources.
There is currently large uncertainty over whether vitamin K1 is more cost-effective than alendronate; further research is required. It is unlikely that the present prescribing policy (i.e. alendronate as first-line treatment) would be altered.

Stevenson M, Lloyd-Jones M, Papaioannou D
Health Technol Assess Sep 2009
PMID: 19818211 | Free Full Text

This is a huge 158 page report. The reason they used K1 instead of K2 was:Vitamin K to prevent fractures in older women: systematic review and economic evaluation

No formal evaluation of vitamin K2 has been undertaken for a number of reasons. This intervention is currently not permitted as a food supplement in the EU because there is no evidence for its independent role in health26 and the price of the intervention is unknown. Additionally, the fracture efficacy data have wide confidence intervals, all of which spanned unity, and the only large (n > 1500 patients per arm) RCT reported a RR of 1.01 for vitamin K2 compared with calcium or no active intervention.

 

 

Vitamin K2 (MK-4) Prevents Glucocorticoid Bone Loss

Abstract

Vitamin K2 inhibits glucocorticoid-induced bone loss partly by preventing the reduction of osteoprotegerin (OPG).

We have recently demonstrated that glucocorticoid (GC) suppresses bone formation and enhances bone resorption, with resultant bone loss. This altered bone turnover is not due to the action of parathyroid hormone (PTH), but appears to be related to the suppression of osteoprotegerin (OPG). As vitamin K2 (menatetrenone) has been used for the treatment of osteoporosis, the present study was carried out to evaluate the effect of vitamin K2 on GC-induced bone loss. Twenty patients with chronic glomerulonephritis treated with GC for the first time were chosen for this study. Ten patients received GC alone (group A) and the other 10 patients each received 15 mg of vitamin K2 per day in addition to GC (group B). Markers of bone metabolism, including serum OPG, osteocalcin (OC), bone-specific alkaline phosphatase activity (BAP), PTH, tartrate-resistant acid phosphatase (TRAP), and bone mineral density (BMD), were measured before and during the treatment. OPG was significantly decreased in group A (P < 0.001), while no significant change was seen in group B. TRAP was markedly increased in both groups, more particularly in group A (P < 0.01). PTH was decreased in group A, but was increased in group B. OC was decreased at month 1 but subsequently increased until month 12 in both groups. BAP had decreased at month 3 in group A (P < 0.05), but not in group B. BMD of the lumbar spine was significantly reduced after 6 months (P < 0.01), and 12 months (P < 0.001) of treatment in group A, whereas there was no remarkable change in group B. The present study demonstrated that the inhibition exerted by vitamin K2 of the reduction in OPG induced by GC may, at least in part, play a role in the prevention and treatment of GC-induced bone loss.

Sasaki N, Kusano E, Takahashi H, Ando Y…
J. Bone Miner. Metab. 2005
PMID: 15616893 | Free Full Text

The dose in the abstract is wrong. They used 15mg three times per day. That is 45mg per day and the same as the prescription dose used in Japan.

The patients were randomly divided into two groups before treatment. Informed consent was obtained from all subjects. Ten patients (6 men, and 2 premenopausal and 2 postmenopausal women ) received GC alone (group A) and the other 10 patients (6 men and 2 premenopausal and 2 postmenopausal women) each received 15 mg of vitamin K2 (menatetrenone; Glakay; Eisai, Tokyo, Japan) three times per day in addition to GC (group B) during the study period. The profiles of the patients are shown in Table 1. Renal function was normal in all subjects (serum Cr level 1.2mg/dl). There were no significant differences between the two groups in age, body mass index, or dose of GC (Table 1), or in various serum and urinary biochemical parameters at baseline (Table 2).

 

Vitamin K1 and MK-4 Stimulate Osteoblasts and Inhibit Osteoclasts In Vitro

Abstract

Vitamin K stimulates osteoblastogenesis and inhibits osteoclastogenesis in human bone marrow cell culture.

Accumulating evidence indicates that menaquinone-4 (MK-4), a vitamin K(2) with four isoprene units, inhibits osteoclastogenesis in murine bone marrow culture, but the reason for this inhibition is not yet clear, especially in human bone marrow culture. To clarify the inhibitory mechanism, we investigated the differentiation of colony-forming-unit fibroblasts (CFU-Fs) and osteoclasts in human bone marrow culture, to learn whether the enhancement of the differentiation of CFU-Fs from progenitor cells might relate to inhibition of osteoclast formation. Human bone marrow cells were grown in alpha-minimal essential medium with horse serum in the presence of MK-4 until adherent cells formed colonies (CFU-Fs). Colonies that stained positive for alkaline phosphatase activity (CFU-F/ALP(+)) were considered to have osteogenic potential. MK-4 stimulated the number of CFU-F/ALP(+) colonies in the presence or absence of dexamethasone. The stimulation was also seen in vitamin K(1) treatment. These cells had the ability to mineralize in the presence of alpha-glycerophosphate. In contrast, both MK-4 and vitamin K(1) inhibited 1,25 dihydroxyvitamin D(3)-induced osteoclast formation and increased stromal cell formation in human bone marrow culture. These stromal cells expressed ALP and Cbfa1. Moreover, both types of vitamin K treatment decreased the expression of receptor activator of nuclear factor kappaB ligand/osteoclast differentiation factor (RANKL/ODF) and enhanced the expression of osteoprotegerin/osteoclast inhibitory factor (OPG/OCIF) in the stromal cells. The effective concentrations were 1.0 microM and 10 microM for the expression of RANKL/ODF and OPG/OCIF respectively. Vitamin K might stimulate osteoblastogenesis in bone marrow cells, regulating osteoclastogenesis through the expression of RANKL/ODF more than through that of OPG/OCIF.

Koshihara Y, Hoshi K, Okawara R, Ishibashi H…
J. Endocrinol. Mar 2003
PMID: 12630919 | Free Full Text

Review: Vitamin K and Bone Health 1998-2008

Abstract

Update on the role of vitamin K in skeletal health.

A protective role for vitamin K in bone health has been suggested based on its role as an enzymatic cofactor. In observational studies, vitamin K insufficiency is generally associated with lower bone mass and increased hip fracture risk. However, these findings are not supported in randomized controlled trials (RCT) of phylloquinone (vitamin K(1)) supplementation and bone loss at the hip in the elderly. This suggests that increased vegetable and legume intakes may simultaneously improve measures of vitamin K status and skeletal health, even though the mechanisms underlying these improvements may be independent of each other. Menaquinone-4 (vitamin K(2)), when given at pharmacological doses, appears to protect against fracture risk and bone loss at the spine. However, there are emerging data that suggest the efficacy of vitamin K supplementation on bone loss is inconclusive.

Shea MK, Booth SL
Nutr. Rev. Oct 2008
PMID: 18826451 | Free Full Text

This is a great review of the different forms of Vitamin K and their benefits for bone. The full study includes a table listing many studies dated from 1998 to 2008 with their outcomes. I highly recommend reading the full text.

MK-4 in doses of 45 mg/d is used as a pharmacological treatment for osteoporosis in Japan, so there are numerous randomized control studies that have assessed the efficacy of MK-4 supplementation on skeletal health. Such doses cannot be attained from the diet, regardless of the form of vitamin K consumed. Phylloquinone from the diet is converted to MK-4 in certain tissues, including bone, but the proportion of phylloquinone that is converted is not known and no dose-dependent data are available for this conversion.

[…]

As reviewed in an earlier volume of this journal,60 studies indicate a therapeutic dose (45 mg/day) of MK-4 has a beneficial effect on spine or metacarpal BMD and fracture61–76 (Table 2). There is also improvement in bone turnover, as measured by circulating markers of bone formation and bone resorption, in response to MK-4 supplementation studies.71,72,76,77 In a separate systematic review and analysis of randomized clinical trials assessing the influence of vitamin K supplementation on hip fracture, Cockayne et al.78 concluded that supplementation with MK-4 for longer than 6 months reduces risk for hip and vertebral fracture. Included in that analysis were 12 studies that used daily doses of 45 mg/d of MK-4. As discussed by the authors, several of the studies used for the meta-analysis lacked sufficient sample size,64–66,70,73,79 were non-placebo-controlled intervention trials,70–74,76,77,80 and/or used concurrent treatment with calcium and/or vitamin D.62,69,75,76

It was subsequently disclosed that a large unpublished surveillance study conducted in Japan (n > 3000) did not find a protective effect of MK-4 supplementation (45 mg/day) on bone loss and fracture in the elderly, and that inclusion of this study may have altered the results of the meta-analysis.81 More recently, two placebo-controlled studies with large sample sizes reported no protective effect of 45 mg/d of MK-4 on hip BMD.59,67 Prior to these two publications, the majority of MK-4 supplementation studies did not report hip BMD as an outcome (Table 2). Given the heterogeneous quality of the studies used and considering the null findings of more recent, larger, placebo-controlled trials and unpublished surveillance data, prior systematic reviews and meta-analyses may need to be revisited.

 

Vitamin K1 and K2 Reversed Bone Loss in Obese Mice

Abstract

Vitamin K1 (phylloquinone) and K2 (menaquinone-4) supplementation improves bone formation in a high-fat diet-induced obese mice.

Several reports suggest that obesity is a risk factor for osteoporosis. Vitamin K plays an important role in improving bone metabolism. This study examined the effects of vitamin K1 and vitamin K2 supplementation on the biochemical markers of bone turnover and morphological microstructure of the bones by using an obese mouse model. Four-week-old C57BL/6J male mice were fed a 10% fat normal diet group or a 45% kcal high-fat diet group, with or without 200 mg/1000 g vitamin K1 (Normal diet + K1, high-fat diet + K1) and 200 mg/1000 g vitamin K2 (Normal diet + K2, high-fat diet + K2) for 12 weeks. Serum levels of osteocalcin were higher in the high-fat diet + K2 group than in the high-fat diet group. Serum OPG level of the high-fat diet group, high-fat diet + K1 group, and high-fat diet + K2 group was 2.31 ± 0.31 ng/ml, 2.35 ± 0.12 ng/ml, and 2.90 ± 0.11 ng/ml, respectively. Serum level of RANKL in the high-fat diet group was significantly higher than that in the high-fat diet + K1 group and high-fat diet + K2 group (p<0.05). Vitamin K supplementation seems to tend to prevent bone loss in high-fat diet induced obese state. These findings suggest that vitamin K supplementation reversed the high fat diet induced bone deterioration by modulating osteoblast and osteoclast activities and prevent bone loss in a high-fat diet-induced obese mice.

Kim M, Na W, Sohn C
J Clin Biochem Nutr Sep 2013
PMID: 24062608 | Free Full Text

Vitamin K is related to blood coagulation, assisting the promotion of OC carboxylation of γ-glutamic acid, which is produced by osteoblasts, and aiding in bone formation by coupling carboxylated OC with phosphine.(15) Many studies have demonstrated that low intake of vitamin K decreases bone density, and that this is a factor that increases osteoporosis and bone fracture.(16) In the study by Booth et al.,(17) low intake of vitamin K1 led to low bone density, and was a factor for increased risk of bone fracture. When vitamin K1 was administered to human bone marrow culture, osteoclast formation was inhibited.(13) After administering vitamin K2 to osteoblasts, real-time gene expression analysis found that the OC, OPG, and RANKL genes were expressed, demonstrating that vitamin K2 has an influence on osteoblasts and osteoclasts.(18) In addition, vitamin K2 supplementation in patients with osteoporosis necessitated by the administration of glucocorticoids inhibited OPG decrease, and had effects of bone loss prevention.(19) Vitamin K2 supplementation in patients with rheumatoid arthritis accompanied with osteoporosis decreased RANKL levels and inhibited osteoclast activation.(20) Therefore, vitamin K affects bone condition both in healthy adults and in patients with specific diseases.

[…]

The results of the bone density analysis revealed an increase with the vitamin K1 and K2 supplementation in high-fat diets. Studies on the relationship between bone density and vitamin K generally have used dual-energy x-ray absorptiometry or ultrasonic densitometry,(32) but this study used high-resolution 3D micro-CT to analyze the morphologic microstructure of trabecular bone. In the study by Fujikawa et al.,(24) the Tb.N increased when vitamin K2 and calcium were fed to ovariectomized mice, and the Tb.Sp decreased. Yamaguchi et al.,(33) also fed vitamin K2 to ovariectomized rats, and reported that it prevented bone loss. These two studies used osteoporosis-induced animals, and the methods differed from those in this study, in which obesity-induced mice were fed vitamin K supplements. In this study, even though there was no significantly statistical difference in the microstructure analysis between the groups, but BV, Tb.N, and Tb.Sp were seemed to be better in the vitamin K2-supplemented group than those in the HF group, indicating that vitamin K2 may play a role in protecting the structures of trabecular bone.

[…]

The effects of vitamin K1 and K2 supplementation in normal diet on bone metabolism were not statistically significant. However, vitamin K1 and K2 supplementation in a high-fat diet could prevent a decrease in bone density, and vitamin K2 had a greater effect on this parameter. Therefore, vitamin K2 increases OPG, a marker related to bone density and the metabolism of osteoclasts and osteoblasts, and it decreases RANKL, and thus has an influence on bone metabolism. This study has showed the effects of vitamin K on bone density and metabolism in animals, but further studies are needed to determine whether the same holds true for obese humans. Future studies would need to perform bone measurement and biochemical examinations on the bone microstructures and metabolism in humans.

 

High Sodium Causes Loss of Calcium in Rats

Abstract

Calcium metabolism and bone calcium content in normal and oophorectomized rats consuming various levels of saline for 12 months.

The effect of different intakes of salt for 12 mo on bone calcium content and urinary excretion of calcium and hydroxyproline were examined in sham operated and oophorectomized (OX) rats to determine the long term effects of high sodium intake and its interaction with estrogen deficiency. Sham operated (n = 24) and OX (n = 24) rats were divided into groups of six rats in a 2 x 4 design. One group of sham and one of OX rats were given 0, 2, 6 or 18 g/L sodium chloride to drink. Urine samples were collected at 0, 2, 4, 6, 10 and 12 mo for the measurement of sodium, calcium, creatinine and hydroxyproline. At the end of 12 mo, blood was taken for measurement of calcium, albumin, alkaline phosphatase and creatinine and the left femur was removed and analyzed for calcium and phosphate. Body weights of the OX rats were higher than the sham operated controls. At the start of the experiment (10 d after OX) urinary excretions of calcium and hydroxyproline were significantly higher in OX rats. However, after 4-6 mo, they were significantly lower in OX rats. Calcium excretion and hydroxyproline excretion were increased by high salt intake, and there was a significant correlation between sodium and calcium excretion (r = 0.962). Bone calcium content of OX rats was lower than their corresponding sham-operated controls. Sodium intake also had a significant effect on bone calcium content. Multiple regression analysis showed that OX and sodium intake explained 7.6% and 1.5% of the variation in bone calcium content. We conclude that high sodium intake causes increased loss of calcium and reduces bone calcium content in sham-operated as well as OX rats.

Chan EL, Swaminathan R
J. Nutr. Mar 1998
PMID: 9482774 | Free Full Text