151
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Abstract
Nutrition plays a major role in the development and maintenance of bone structures resistant to usual mechanical loadings. In addition to calcium in the presence of an adequate vitamin D supply, proteins represent a key nutrient for bone health, and thereby in the prevention of osteoporosis. In sharp opposition to experimental and clinical evidence, it has been alleged that proteins, particularly those from animal sources, might be deleterious for bone health by inducing chronic metabolic acidosis which in turn would be responsible for increased calciuria and accelerated mineral dissolution. This claim is based on an hypothesis that artificially assembles various notions, including in vitro observations on the physical-chemical property of apatite crystal, short term human studies on the calciuric response to increased protein intakes, as well as retrospective inter-ethnic comparisons on the prevalence of hip fractures. The main purpose of this review is to analyze the evidence that refutes a relation of causality between the elements of this putative patho-physiological "cascade" that purports that animal proteins are causally associated with an increased incidence of osteoporotic fractures. In contrast, many experimental and clinical published data concur to indicate that low protein intake negatively affects bone health. Thus, selective deficiency in dietary proteins causes marked deterioration in bone mass, micro architecture and strength, the hallmark of osteoporosis. In the elderly, low protein intakes are often observed in patients with hip fracture. In these patients intervention study after orthopedic management demonstrates that protein supplementation as given in the form of casein, attenuates post-fracture bone loss, increases muscles strength, reduces medical complications and hospital stay. In agreement with both experimental and clinical intervention studies, large prospective epidemiologic observations indicate that relatively high protein intakes, including those from animal sources are associated with increased bone mineral mass and reduced incidence of osteoporotic fractures. As to the increased calciuria that can be observed in response to an augmentation in either animal or vegetal proteins it can be explained by a stimulation of the intestinal calcium absorption. Dietary proteins also enhance IGF-1, a factor that exerts positive activity on skeletal development and bone formation. Consequently, dietary proteins are as essential as calcium and vitamin D for bone health and osteoporosis prevention. Furthermore, there is no consistent evidence for superiority of vegetal over animal proteins on calcium metabolism, bone loss prevention and risk reduction of fragility fractures.
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Affiliation(s)
- Jean-Philippe Bonjour
- Service of Bone Diseases, University Hospital, Rue Micheli-Du-Crest, 1211 Geneva, Switzerland.
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152
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Doyle L, Jewell C, Mullen A, Nugent AP, Roche HM, Cashman KD. Effect of dietary supplementation with conjugated linoleic acid on markers of calcium and bone metabolism in healthy adult men. Eur J Clin Nutr 2005; 59:432-40. [PMID: 15674313 DOI: 10.1038/sj.ejcn.1602093] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Conjugated linoleic acid (CLA) has been shown to positively influence calcium and bone metabolism in experimental animals and cells in culture, but there are limited human data available. OBJECTIVE To investigate the effect of CLA supplementation on biomarkers of calcium and bone metabolism in healthy adult males. DESIGN The study consisted of a double-blind, placebo-controlled trial in which 60 healthy adult males (aged 39-64 y) were randomly assigned to receive daily either 3.0 g CLA isomer blend (50:50% cis-9,trans-11:trans-10,cis-12 isomers) or a palm/bean oil blend (placebo) for 8 weeks. Urine and blood samples were collected at weeks 0 and 8 and were analysed for biomarkers of calcium and bone metabolism. RESULTS Supplementation with CLA or placebo for 8 weeks had no significant effects on markers of bone formation (serum osteocalcin and bone-specific alkaline phosphatase) or bone resorption (serum C-telopeptide-related fraction of type 1 collagen degradation products, urinary N-telopeptide-related fraction of type 1 collagen degradation products, urinary pyridinoline and deoxypyridinoline), or on serum or urinary calcium levels. Baseline levels of these biochemical parameters were similar in both groups of subjects. While the placebo had no effect, CLA supplementation resulted in a three-fold increase (P<0.00001) in cis-9,trans-11 CLA isomer in total plasma lipids. CONCLUSION Under the conditions tested in this double-blind, placebo-controlled trial in adult men, a CLA supplement of mixed isomers did not affect markers of calcium or bone metabolism. Further investigation of the effects of CLA on calcium and bone metabolism in other gender- and age-groups is warranted.
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Affiliation(s)
- L Doyle
- Department of Food and Nutritional Sciences, University College, Cork, Ireland
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153
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Abstract
High-protein (HP) weight-loss diets have existed in the United States for decades, although their popularity has recently surged as obesity has become more common. Despite their widespread use, valid concerns exist that HP diets may induce clinically important alterations in renal function and health. HP consumption has been found, under various conditions, to lead to glomerular hyperfiltration and hyperemia; acceleration of chronic kidney disease (CKD); increased proteinuria; diuresis, natriuresis, and kaliuresis with associated blood pressure changes; increased risk for nephrolithiasis; and various metabolic alterations. Unfortunately, a comprehensive understanding of the implications of HP diets is limited by the lack of a universally accepted definition for HP intake, a paucity of rigorous long-term human interventional studies that necessitate relying on short-term or fairly circumstantial evidence, and sparse data on the effects of HP consumption in obese individuals. In addition, matters are further complicated because the renal impact HP diets for limited periods is most likely different than that for more chronic consumption. Nevertheless, although there are no clear renal-related contraindications to HP diets in individuals with healthy kidney function, the theoretical risks should be reviewed carefully with the patient. In contrast, HP diets have the potential for significant harm in individuals with CKD and should be avoided if possible. Because CKD is often a silent disease, all individuals should undergo a screening serum creatinine measurement and urinary dipstick test for proteinuria before the initiation of such a diet.
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Affiliation(s)
- Allon N Friedman
- Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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154
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Svetkey LP, Erlinger TP, Vollmer WM, Feldstein A, Cooper LS, Appel LJ, Ard JD, Elmer PJ, Harsha D, Stevens VJ. Effect of lifestyle modifications on blood pressure by race, sex, hypertension status, and age. J Hum Hypertens 2005; 19:21-31. [PMID: 15385946 DOI: 10.1038/sj.jhh.1001770] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recommendations for control of high blood pressure (BP) emphasize lifestyle modification, including weight loss, reduced sodium intake, increased physical activity, and limited alcohol consumption. The Dietary Approaches to Stop Hypertension (DASH) dietary pattern also lowers BP. The PREMIER randomized trial tested multicomponent lifestyle interventions on BP in demographic and clinical subgroups. Participants with above-optimal BP through stage 1 hypertension were randomized to an Advice Only group or one of two behavioural interventions that implement established recommendations (Est) or established recommendations plus DASH diet (Est plus DASH). The primary outcome was change in systolic BP at 6 months. The study population was 810 individuals with an average age of 50 years, 62% women, 34% African American (AA), 95% overweight/obese, and 38% hypertensive. Participants in all the three groups made lifestyle changes. Mean net reductions in systolic (S) BP in the Est intervention were 1.2 mmHg in AA women, 6.0 in AA men, 4.5 in non-AA women, and 4.2 in non-AA men. The mean effects of the Est Plus DASH intervention were 2.1, 4.6, 4.2, and 5.7 mmHg in the four race-sex subgroups, respectively. BP changes were consistently greater in hypertensives than in nonhypertensives, although interaction tests were nonsignificant. The Est intervention caused statistically significant BP reductions in individuals over and under age 50. The Est Plus DASH intervention lowered BP in both age groups, and significantly more so in older individuals. In conclusion, diverse groups of people can adopt multiple lifestyle changes that can lead to improved BP control and reduced CVD risk.
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Affiliation(s)
- L P Svetkey
- Duke Hypertension Center and the Sarah W Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27710, USA.
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155
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Abstract
Osteoporosis and low bone mass are currently estimated to be a major public health threat. Adequate nutrition plays a major role in the prevention and treatment of osteoporosis; the micronutrients of greatest importance are calcium and vitamin D. Calcium has been shown to have beneficial effects on bone mass at all ages, although the results are not always consistent. Higher doses than the current US recommendation (600 IU) of vitamin D in the elderly (age > or = 65 y) may actually be required for optimal bone health (800-1000 IU/d). The elderly can clearly benefit from increased vitamin D intakes; however, the potential importance of vitamin D in peak bone mass is just being investigated. Vitamin D has been related to falls, with supplementation reducing the number of falls. There are clear fracture benefits demonstrated in randomized clinical trials of calcium and vitamin D supplementation. The other micronutrient needs for optimizing bone health can be easily met by a healthy diet that is high in fruits and vegetables to ensure adequate intakes for magnesium, potassium, vitamin C, vitamin K, and other potentially important nutrients. Healthcare professionals need to be aware of the importance of adequate calcium and vitamin D intakes (easily monitored by serum 25(OH)D) for optimal bone health, as well as the prevention of falls and fractures. In addition, a healthy diet that includes 5 servings a day of fruits and vegetables should optimize the intake of micronutrients required for bone health.
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Affiliation(s)
- Jeri W Nieves
- Clinical Research and Regional Bone Centers, Helen Hayes Hospital, West Haverstraw, NY, USA
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156
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Wigertz K, Palacios C, Jackman LA, Martin BR, McCabe LD, McCabe GP, Peacock M, Pratt JH, Weaver CM. Racial differences in calcium retention in response to dietary salt in adolescent girls. Am J Clin Nutr 2005; 81:845-50. [PMID: 15817862 DOI: 10.1093/ajcn/81.4.845] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Sodium is an important determinant of urinary calcium excretion, and race is an important determinant of calcium retention. The effect of dietary sodium on calcium retention and the influence of race have not been studied in adolescence, the life stage during which peak bone mass is accrued. OBJECTIVE The study reported here was undertaken to compare racial differences in calcium retention as a function of dietary salt intake. DESIGN A total of 35 adolescent girls (22 black and 13 white) participated in two 20-d metabolic summer camps, separated by 2 wk, that simulated a free-living environment. The effect of changes in dietary sodium on calcium retention was tested in a randomized-order, crossover design with 2 concentrations of sodium-1.30 g/d (57 mmol/d) and 3.86 g/d (168 mmol/d)-and a constant calcium intake of 815 mg/d (20 mmol/d). RESULTS Both race and sodium intake significantly affected calcium retention (P < 0.01). Calcium retention was significantly greater in black girls than in white girls, regardless of dietary sodium intake (P < 0.001). The high-sodium diet significantly reduced calcium retention in both whites and blacks (P < 0.01), primarily through a decrease in net calcium absorption. Black girls excreted significantly less calcium in the urine than did white girls, regardless of diet (P < 0.05). CONCLUSIONS Calcium retention is significantly greater in black girls than in white girls but is significantly reduced in girls of both races in response to salt loading.
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Affiliation(s)
- Karin Wigertz
- Departments of Foods and Nutrition and of Statistics, Purdue University, West Lafayette, IN, USA
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157
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Macdonald HM, New SA, Fraser WD, Campbell MK, Reid DM. Low dietary potassium intakes and high dietary estimates of net endogenous acid production are associated with low bone mineral density in premenopausal women and increased markers of bone resorption in postmenopausal women. Am J Clin Nutr 2005; 81:923-33. [PMID: 15817873 DOI: 10.1093/ajcn/81.4.923] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The Western diet may be a risk factor for osteoporosis. Excess acid generated from high protein intakes increases calcium excretion and bone resorption. Fruit and vegetable intake could balance this excess acidity by providing alkaline salts of potassium. Algorithms based on dietary intakes of key nutrients can be used to approximate net endogenous acid production (NEAP) and to explore the association between dietary acidity and bone health. OBJECTIVE We investigated the relation between dietary potassium and protein, NEAP (with an algorithm including the ratio of protein to potassium intake), and potential renal acid load (with an algorithm including dietary protein, phosphorous, potassium, magnesium, and calcium) and markers of bone health. DESIGN Measurements of bone mineral density (BMD) (n = 3226) and urinary bone resorption markers (n = 2929) at the lumbar spine and femoral neck were performed in perimenopausal and early postmenopausal women aged 54.9 +/- 2.2 y (x +/- SD) in 1997-1999. BMD (g/cm(2)), free pyridinoline (fPYD), and free deoxypyridinoline (fDPD) were expressed relative to creatinine. Dietary intake was assessed with a food-frequency questionnaire. RESULTS Comparison of the highest with the lowest quartile of potassium intake or the lowest with the highest NEAP showed a 6-8% increase in fPYD/creatinine and fDPD/creatinine. A difference of 8% in BMD was observed between the highest and lowest quartiles of potassium intake in the premenopausal group (n = 337). CONCLUSIONS Dietary potassium, an indicator of NEAP and fruit and vegetable intake, may exert a modest influence on markers of bone health, which over a lifetime may contribute to a decreased risk of osteoporosis.
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Affiliation(s)
- Helen M Macdonald
- Department of Medicine and Therapeutics, University of Aberdeen, Medical School Buildings, Aberdeen, United Kingdom.
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158
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Abstract
BACKGROUND Dietary potassium intake (K) lowers urinary calcium (Ca) excretion and, in short-term studies, may improve Ca balance. PURPOSE Our objective was to assess K effects on the Ca economy under steady-state conditions. DESIGN 8-day, inpatient metabolic studies of nitrogen, phosphorus, and Ca balance, combined with dual isotopic Ca tracer kinetics studies. Study diet matched to prestudy nutrient intakes. SUBJECTS 191 single women studied from 1-5 times at approximately 5-year intervals, for a total of 644 inpatient studies. Median age at time of study: 50.2 yrs; 301 studies were performed postmenopausally without hormone replacement; 343 were either premenopausal or postmenopausal but on estrogen replacement therapy. RESULTS Dietary K was highly significantly associated with urinary Ca excretion, with a coefficient of -0.0109 mmol urine Ca/mmol diet K. However, dietary K was negatively correlated with dual-tracer Ca absorption (coefficient for Ca absorption fraction: -0.00094/mmol dietary K), and was not associated with urine Ca after adjustment for Ca absorption. CONCLUSION While a high K diet (i.e., one rich in fruits, vegetables, and dairy products) has multiple health benefits and clearly lowers urine Ca, it does not seem to exert any appreciable net influence on the Ca economy, largely because the reduced calciuria is offset by reduction of intestinal absorption. We note, however, that since the high K intakes in our studies come more from milk and meat than from fruits and vegetables, we cannot exclude a possible balance effect for different food sources of K.
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Affiliation(s)
- Karen Rafferty
- Creighton University, Osteoporosis Research Center, Omaha, Nebraska 68131, USA.
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159
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Natri AM, Kärkkäinen MUM, Ruusunen M, Puolanne E, Lamberg-Allardt C. A 7-week reduction in salt intake does not contribute to markers of bone metabolism in young healthy subjects. Eur J Clin Nutr 2005; 59:311-7. [PMID: 15674316 DOI: 10.1038/sj.ejcn.1602074] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Sodium intake increases urinary calcium excretion and may thus lead to negative calcium balance and bone loss. OBJECTIVE We hypothesised that reducing sodium intake would reduce urinary calcium excretion and have a beneficial influence in bone metabolism. DESIGN A total of 29 subjects, 14 males and 15 females, were divided into two study groups. One group (low-sodium group (LS)) reduced sodium intake for 7 weeks by substituting low-salt alternatives for the most important dietary sources of sodium. The other group, serving as a control group (C), was given the same food items in the form of normally salted alternatives. Fasting serum samples as well as 24-h urine samples were obtained in the beginning and at the end of the study. Urinary sodium, urinary calcium, urinary creatinine, serum calcium, serum phosphate, serum creatinine, serum parathyroid hormone (s-PTH), serum C-terminal telopeptides of Type-I collagen and serum bone alkaline phosphatase (s-B-ALP) were analysed. RESULTS The LS group showed a significant decline (P = 0.001) in urinary sodium/creatinine ratio without a significant effect on urinary calcium/creatinine ratio. In the LS group, s-PTH increased (P = 0.03). The C group showed an increase in s-PTH (P = 0.05) and in s-B-ALP, but no differences were observed between the study groups in the changes of serum markers of calcium and bone metabolism. CONCLUSIONS We have shown that reducing the sodium intake of young, healthy people with adequate calcium intake over a 7-week period does not affect the markers of bone metabolism.
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Affiliation(s)
- A-M Natri
- Department of Applied Chemistry and Microbiology, Division of Nutrition, University of Helsinki, Finland
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160
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Carbone LD, Barrow KD, Bush AJ, Boatright MD, Michelson JA, Pitts KA, Pintea VN, Kang AH, Watsky MA. Effects of a low sodium diet on bone metabolism. J Bone Miner Metab 2005; 23:506-13. [PMID: 16261460 DOI: 10.1007/s00774-005-0621-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2005] [Accepted: 04/13/2005] [Indexed: 10/25/2022]
Abstract
Osteoporosis is a serious public health problem, and dietary interventions may potentially be helpful in preventing this disorder. The purpose of this study was to determine the effects of a low sodium diet on bone metabolism in postmenopausal women. This was a longitudinal study to determine the effects of a low sodium (2-g/day) diet on bone. Forty postmenopausal African-American and Caucasian women were enrolled in a 2-g/day sodium diet for 6 months. Sodium and calcium excretion, bone turnover, and calcitropic hormones (intact parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D) were measured before and 6 months after the intervention. In women who had baseline sodium excretions equal to or greater than the average sodium intake in the United States (> or =3.4 g/day), the low sodium diet resulted in significant decreases in sodium excretion (P = 0.01), in calcium excretion (P = 0.01), and in a biomarker of bone turnover, aminoterminal propeptide of type I collagen (P = 0.04). However, there were no significant changes in calcitropic hormones, including intact PTH (P = 0.97) or 1,25 dihydroxyvitamin D (P = 0.49) with the low sodium diet. These findings suggest that in postmenopausal women with sodium intakes > or =3.4 g/day, a low sodium diet may have benefits for skeletal health.
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Affiliation(s)
- Laura D Carbone
- Department of Medicine, University of Tennessee Health Science Center, 956 Court Avenue, Room G326 Coleman Building, Memphis, TN, 38163, USA.
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161
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Dietary Approaches to Hypertension Management: The DASH Studies. Hypertension 2005. [DOI: 10.1016/b978-0-7216-0258-5.50133-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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162
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McGuire HL, Svetkey LP, Harsha DW, Elmer PJ, Elmer PJ, Appel LJ, Ard JD. Comprehensive lifestyle modification and blood pressure control: a review of the PREMIER trial. J Clin Hypertens (Greenwich) 2004; 6:383-90. [PMID: 15249794 PMCID: PMC8109651 DOI: 10.1111/j.1524-6175.2004.03147.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The PREMIER trial assessed the aggregate effect on blood pressure (BP) of nationally recommended lifestyle modifications in free-living adults with high-normal (stage 1) hypertension. Participants (N=810) were randomized to the advice-only group; the established group (consisting of weight loss, increased physical activity, and reduced sodium and alcohol intake); or the established plus Dietary Approaches to Stop Hypertension (DASH) diet group (consisting of the established interventions in addition to the DASH dietary pattern). The primary outcome was change in systolic BP at 6 months. Net of advice only, mean systolic BP declined by 3.7 mm Hg for members of the established group (p<0.001) and 4.3 mm Hg for the established plus DASH group (p<0.001). The prevalence of hypertension decreased from a baseline of 38% to 17% in the established group (p=0.01) and to 12% in the established plus DASH group (p<0.001) compared with a decrease to 26% in the advice-only group. The PREMIER trial demonstrated that persons with above-optimal BP and stage 1 hypertension can make multiple lifestyle changes leading to better control of BP.
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Affiliation(s)
- Heather L McGuire
- Division of Nephrology, Duke University Medical Center, Durham, NC 27710, USA.
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163
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Bukoski RD. Linkage of Na(+) and Ca(2+) balance: evidence that Na(+) retention preserves Ca(2+) balance and limits bone wasting. J Hypertens 2004; 22:683-5. [PMID: 15126906 DOI: 10.1097/00004872-200404000-00007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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164
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Abstract
Recent data from an ancillary study to the Dietary Approaches to Stop Hypertension (DASH)-Sodium trial suggest that while sodium intake had very little effect on bone metabolism, the DASH diet (over 30 days) significantly reduced markers of bone turnover. This DASH diet-induced reduction in bone turnover, if sustained, may improve bone mineral status.
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Affiliation(s)
- Lorna Doyle
- Department of Food and Nutritional Sciences, University College, Cork, Ireland
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165
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New SA, Francis RM. Understanding, Preventing and Overcoming Osteoporosis. NUTR BULL 2004. [DOI: 10.1111/j.1467-3010.2003.00401.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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