Category Archives: Supplements

Flavonoids Associated with Increased Bone Density in Women

Abstract

Associations between dietary flavonoid intakes and bone health in a Scottish population.

Flavonoids are bioactive polyphenols found particularly in fruit and vegetables, but little is known about their role in bone health in humans. The aim of this observational study was to investigate whether dietary flavonoid intake was associated with bone mineral density (BMD) and bone resorption in a large group of perimenopausal Scottish women. Over 3000 women completed a food frequency questionnaire as part of an osteoporosis screening study. The diets were analyzed for flavonoid intake using a food composition database. BMD was measured at the femoral neck (FN) and lumbar spine (LS) by dual-energy X-ray absorptiometry (DXA). Free pyridinoline (PYD) and deoxypyridinoline (DPD) were measured by high-performance liquid chromatography (HPLC) in second early morning fasted urine samples. The mean flavonoid intake of the diet was 307 ±199 mg/d. The catechin family contributed the most to flavonoid intakes (55%), and the flavones the least (<1%). Associations were found between energy-adjusted total flavonoid intakes and BMD at the FN and LS (FN r = 0.054, LS r = 0.036, p ≤ .05). Annual percent change in BMD was associated with intakes of procyanidins and catechins (p ≤ .05), and flavanones were negatively associated with bone-resorption markers (PYD r = -0.049, DPD r = -0.057, p ≤ .001). These associations were still seen after adjusting for confounders. It is concluded that dietary flavonoid intakes are associated with BMD, supporting the evidence from animal and cellular studies.

Hardcastle AC, Aucott L, Reid DM, Macdonald HM
J. Bone Miner. Res. May 2011
PMID: 21541996

Review: Acid-Producing Diets May be Protective When Calcium is High

Abstract

The acid-ash hypothesis revisited: a reassessment of the impact of dietary acidity on bone.

The acid-ash hypothesis states that when there are excess blood protons, bone is eroded to provide alkali to buffer the net acidity and maintain physiologic pH. There is concern that with the typical Western diet, we are permanently in a state of net endogenous acid production, which is gradually reducing bone. While it is clear that a high acid-producing diet generates increased urinary acid and calcium excretion, the effect of diet does not always have the expected results on BMD, fracture risk and markers of bone formation and resorption, suggesting that other factors are influencing the effect of acid/alkali loading on bone. High dietary protein, sodium and phosphorus intake, all of which are necessary for bone formation, were thought to be net acid forming and contribute to low BMD and fracture risk, but appear under certain conditions to be beneficial, with the effect of protein being driven by calcium repletion. Dietary salt can increase short-term markers of bone resorption but may also trigger 1,25(OH)2D synthesis to increase calcium absorption; with low calcium intake, salt intake may be inversely correlated with BMD but with high calcium intake, salt intake was positively correlated with BMD. With respect to the effect of phosphorus, the data are conflicting. Inclusion of an analysis of calcium intake may help to reconcile the contradictory results seen in many of the studies of bone. The acid-ash hypothesis could, therefore, be amended to state that with an acid-producing diet and low calcium intake, bone is eroded to provide alkali to buffer excess protons but where calcium intake is high the acid-producing diet may be protective.

Nicoll R, McLaren Howard J
J. Bone Miner. Metab. Feb 2014
PMID: 24557632

High-Protein Short-Term Diets are Not Detrimental to Bone

Abstract

Calcium homeostasis and bone metabolic responses to high-protein diets during energy deficit in healthy young adults: a randomized controlled trial.

Although consuming dietary protein above current recommendations during energy deficit (ED) preserves lean body mass, concerns have been raised regarding the effects of high-protein diets on bone health. The objective was to determine whether calcium homeostasis and bone turnover are affected by high-protein diets during weight maintenance (WM) and ED.

In a randomized, parallel-design, controlled trial of 32 men and 7 women, volunteers were assigned diets providing protein at 0.8 [Recommended Dietary Allowance (RDA)], 1.6 (2 × RDA), or 2.4 (3 × RDA) g · kg(-1) · d(-1) for 31 d. Ten days of WM preceded 21 d of ED, during which total daily ED was 40%, achieved by reduced dietary energy intake (∼30%) and increased physical activity (∼10%). The macronutrient composition (protein g · kg(-1) · d(-1) and % fat) was held constant from WM to ED. Calcium absorption (ratio of (44)Ca to (42)Ca) and circulating indexes of bone turnover were determined at day 8 (WM) and day 29 (ED).
Regardless of energy state, mean (±SEM) urinary pH was lower (P < 0.05) at 2 × RDA (6.28 ± 0.05) and 3 × RDA (6.23 ± 0.06) than at the RDA (6.54 ± 0.06). However, protein had no effect on either urinary calcium excretion (P > 0.05) or the amount of calcium retained (P > 0.05). ED decreased serum insulin-like growth factor I concentrations and increased serum tartrate-resistant acid phosphatase and 25-hydroxyvitamin D concentrations (P < 0.01). Remaining markers of bone turnover and whole-body bone mineral density and content were not affected by either the protein level or ED (P > 0.05).
These data demonstrate that short-term consumption of high-protein diets does not disrupt calcium homeostasis and is not detrimental to skeletal integrity.

Cao JJ, Pasiakos SM, Margolis LM, Sauter ER…
Am. J. Clin. Nutr. Feb 2014
PMID: 24284444

Review: Protein Benefits for Bone may Require Calcium

Abstract

Dietary protein is beneficial to bone health under conditions of adequate calcium intake: an update on clinical research.

To underscore recent clinical studies, which evaluate the association between dietary protein and bone health.
Epidemiologic studies show greater protein intake to be beneficial to bone health in adults. In addition, randomized controlled trials show that protein’s positive effect on bone health is augmented by increased calcium intake. The relation between dietary protein and fracture risk is unclear. Dietary protein may positively impact bone health by increasing muscle mass, increasing calcium absorption, suppressing parathyroid hormone, and augmenting insulin-like growth factor 1 production; but the effects of other factors that contribute to this association, such as dietary protein dose and timing response, require further research.
The positive effects of protein intake on bone health may only be beneficial under conditions of adequate calcium intake. Dietary protein’s relation with fracture risk requires further investigation.

Mangano KM, Sahni S, Kerstetter JE
Curr Opin Clin Nutr Metab Care Jan 2014
PMID: 24316688

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, but not Chloride, Increases Bone Density in Postmenopausal Women

Abstract

Partial neutralization of the acidogenic Western diet with potassium citrate increases bone mass in postmenopausal women with osteopenia.

Chronic acid loads are an obligate consequence of the high animal/grain protein content of the Western diet. The effect of this diet-induced metabolic acidosis on bone mass is controversial. In a randomized, prospective, controlled, double-blind trial, 161 postmenopausal women (age 58.6 +/- 4.8 yr) with low bone mass (T score -1 to -4) were randomly assigned to 30 mEq of oral potassium (K) citrate (Kcitrate) or 30 mEq of K chloride (KCl) daily. The primary end point was the intergroup difference in mean percentage change in bone mineral density (BMD) at lumbar spine (L2 through L4) after 12 mo. Compared with the women who received KCl, women who received Kcitrate exhibited an intergroup increase in BMD (+/-SE) of 1.87 +/- 0.50% at L2 through L4 (P < 0.001), of 1.39 +/- 0.48% (P < 0.001) at femoral neck, and of 1.98 +/- 0.51% (P < 0.001) at total hip. Significant secondary end point intragroup changes also were found: Kcitrate increased L2 through L4 BMD significantly from baseline at months 3, 9, and 12 and reached a month 12 increase of 0.89 +/- 0.30% (P < 0.05), whereas the KCl arm showed a decreased L2 through L4 BMD by -0.98 +/- 0.38% (P < 0.05), significant only at month 12. Intergroup differences for distal radius and total body were NS. The Kcitrate-treated group demonstrated a sustained and significant reduction in urinary calcium excretion and a significant increase in urinary citrate excretion, with increased citrate excretion indicative of sustained systemic alkalization. Urinary bone resorption marker excretion rates were significantly reduced by Kcitrate, and for deoxypyridinoline, the intergroup difference was significant. Urinary net acid excretion correlated inversely and significantly with the change in BMD in a subset of patients. Large and significant reductions in BP were observed for both K supplements during the entire 12 mo. Bone mass can be increased significantly in postmenopausal women with osteopenia by increasing their daily alkali intake as citrate, and the effect is independent of reported skeletal effects of K.

Jehle S, Zanetti A, Muser J, Hulter HN…
J. Am. Soc. Nephrol. Nov 2006
PMID: 17035614 | Free Full Text

Despite more than 70 yr of sustained interest in the possibility that chronic metabolic acidosis might decrease bone mass, central questions regarding the effect of acid-base alterations on human bone physiology and pathophysiology remain unanswered (4,27,28). First, does chronic metabolic acidosis of any magnitude decrease bone mass? Second, does the low-grade chronic metabolic acidosis that is induced by the acidogenic Western diet result in osteoporosis? Third, can neutralization of dietary acid result in increased bone mass in normal humans or those with osteopenia?

Indirect support for a possible role of chronic metabolic acidosis to reduce bone mass comes from small, uncontrolled studies in humans with nonazotemic renal disease (distal renal tubular acidosis [29,30]). Chronic dietary acid loads were shown to result in significant and reversible negative calcium balance (6), and experimental increases in animal protein intake or its chief acidogenic constituent, methionine, within the range that is characteristic of the Western diet were shown to cause both negative calcium balance and increased systemic acid load (31,32). Compatible with and strongly supportive of these observations, short-term neutralization of endogenous acid production by oral ingestion of bicarbonate for 7 to 18 d in both postmenopausal women and young healthy adults resulted in calcium retention and—on the basis of analysis of bone markers—in inhibition of bone resorption (13,14).

[…]

This study establishes that bone mass can be increased significantly in postmenopausal women with osteopenia by increasing their daily alkali intake as Kcitrate and that this effect is independent of reported in vitro skeletal effects of co-administered K. The magnitude of the effect is large, and the safety profile was found to be excellent, albeit based on a limited sample size. The results strongly support the thesis that neutralization of the modern Western diet will promote skeletal health. The associated BP effects of the K supplement provide additional incentive to move forward with controlled outcome trials using long-term Kcitrate treatment.

Potassium Citrate or Fruits + Veggies, No Benefit Over 2 Years

Abstract

Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial.

Alkali provision may explain why fruit and vegetables benefit bone health.
We aimed to determine the effects of alkali-providing potassium citrate (double-blind) and fruit and vegetable intake (single-blind) on bone turnover over 2 y.
We conducted a randomized placebo-controlled trial in 276 postmenopausal women (aged 55-65 y). Women were randomly assigned to 4 groups: high-dose potassium citrate (55.5 mEq/d), low-dose potassium citrate (18.5 mEq/d), placebo, and 300 g additional fruit and vegetables/d (equivalent of 18.5 mEq alkali). Serum and fasted urine for bone markers were collected at baseline and at 3, 6, 12, 18, and 24 mo. An additional urine sample was collected at 4-6 wk. Bone mineral density (BMD) was measured at baseline and 2 y.
Repeated-measures ANOVA showed no difference between groups for urinary free deoxypyridinoline cross-links relative to creatinine (fDPD/Cr), serum N-terminal propeptide of type 1 collagen, or beta C-terminal telopeptide, although, at 4-6 wk, fDPD/Cr was lower in the high-dose potassium citrate group (P = 0.04). Mean +/- SD spine BMD loss in the placebo group (1.8 +/- 3.9%) did not differ significantly from that in the treatment groups (2.1 +/- 3.2%; P = 0.88). Hip BMD loss in the placebo and low-dose potassium citrate groups was 1.3 +/- 2.3% and 2.2 +/- 2.3%, respectively (P = 0.14).
Two-year potassium citrate supplementation does not reduce bone turnover or increase BMD in healthy postmenopausal women, which suggests that alkali provision does not explain any long-term benefit of fruit and vegetable intake on bone.

Macdonald HM, Black AJ, Aucott L, Duthie G…
Am. J. Clin. Nutr. Aug 2008
PMID: 18689384 | Free Full Text

In summary, neither potassium citrate at 18.5 or 55.6 mEq/d nor 300 g self-selected fruit and vegetables/d influenced bone turnover or prevented BMD loss over 2 y in healthy postmenopausal women. Further work is required to investigate whether particular fruit and vegetables are important and how much of each is optimal for bone health.

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 Increases Bone Density and Volume in Adults

Abstract

Effect of potassium citrate on bone density, microarchitecture, and fracture risk in healthy older adults without osteoporosis: a randomized controlled trial.

The acid load imposed by a modern diet may play an important role in the pathophysiology of osteoporosis. Our objective was to evaluate the skeletal efficacy and safety and the effect on fracture prediction of K-citrate to neutralize diet-induced acid loads.
We conducted a randomized, double-blind, placebo-controlled trial at a teaching hospital.
Subjects included 201 elderly (>65 yr old) healthy men and women (t-score of -0.6 at lumbar spine).
Intervention was 60 mEq of K-citrate daily or placebo by mouth. All subjects received calcium and vitamin D.
The primary outcome was change in areal bone mineral density (aBMD) at the lumbar spine by dual-energy x-ray absorptiometry after 24 months. Secondary endpoints included changes in volumetric density and microarchitectural parameters by high-resolution peripheral quantitative computed tomography in both radii and both tibiae and fracture risk assessment by FRAX (Switzerland).
K-citrate increased aBMD at lumbar spine from baseline by 1.7 ± 1.5% [95% confidence interval (CI) = 1.0-2.3, P < 0.001] net of placebo after 24 months. High-resolution peripheral quantitative computed tomography-measured trabecular densities increased at nondominant tibia (1.3 ± 1.3%, CI = 0.7-1.9, P < 0.001) and nondominant radius (2.0 ± 2.0%, CI = 1.4-2.7, P < 0.001). At nondominant radius, trabecular bone volume/tissue volume increased by 0.9 ± 0.8%, (CI = 0.1-1.7), trabecular thickness by 1.5 ± 1.6% (CI = 0.7-2.3), and trabecular number by 1.9 ± 1.8% (CI = 0.7-3.1, for all, P < 0.05). K-citrate diminished fracture prediction score by FRAX significantly in both sexes.
Among a group of healthy elderly persons without osteoporosis, treatment with K-citrate for 24 months resulted in a significant increase in aBMD and volumetric BMD at several sites tested, while also improving bone microarchitecture. Based on the effect on fracture prediction, an effect on future fractures by K-citrate is possible.

Jehle S, Hulter HN, Krapf R
J. Clin. Endocrinol. Metab. Jan 2013
PMID: 23162100

Despite the conflicting evidence for the acid load theory, potassium or citrate nonetheless appear to increase bone density. How it does that is debated.

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