Low urine pH and acid excretion do not predict bone fractures or the loss of bone mineral density: a prospective cohort study Dietary acid load, kidney function, osteoporosis, and risk of fractures in elderly men and women Neutralization of Western diet inhibits bone resorption independently of K intake and reduces cortisol secretion in humans. Partial neutralization of the acidogenic Western diet with potassium citrate increases bone mass in postmenopausal women with osteopenia. Long-term protein intake and dietary potential renal acid load are associated with bone modeling and remodeling at the proximal radius in healthy children. Effect of fruit on net acid and urinary calcium excretion in an acute feeding trial of women. More acidic dietary acid-base load is associated with reduced calcaneal broadband ultrasound attenuation in women but not in men: results from the EPIC-Norfolk cohort study. Renal response to acute acid loadingAn organ physiological approach The effects of a low-sodium base-producing diet including red meat compared with a high-carbohydrate, low-fat diet on bone turnover markers in women aged 45-75 years. Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study. 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. A new fluoride preparation for the prevention of postmenopausal osteoporosis: calcium monofluorophosphate. Dietary acid load and risk of hypertension: the Rotterdam Study. Quality of diet and potential renal acid load as risk factors for reduced bone density in elderly women. Calcium, gamma-linolenic acid and eicosapentaenoic acid supplementation in senile osteoporosis Decreasing the Linoleic Acid to α-Linolenic Acid Diet Ratio Increases Eicosapentaenoic Acid in Erythrocytes in Adults Potassium bicarbonate attenuates the urinary nitrogen excretion that accompanies an increase in dietary protein and may promote calcium absorption.
Background The acid-ash hypothesis , the alkaline diet , and related products are marketed to the general public . Websites , lay literature , and direct mail marketing encourage people to measure their urine pH to assess their health status and their risk of osteoporosis . The objectives of this study were to determine whether 1 ) low urine pH , or 2 ) acid excretion in urine [ sulfate + chloride + 1.8x phosphate + organic acids ] minus [ sodium + potassium + 2x calcium + 2x magnesium mEq ] in fasting morning urine predict : a ) fragility fractures ; and b ) five-year change of bone mineral density ( BMD ) in adults . Methods Design : Cohort study : the prospect i ve population -based Canadian Multicentre Osteoporosis Study .  Multiple logistic regression was used to examine associations between acid excretion ( urine pH and urine acid excretion ) in fasting morning with the incidence of fractures ( 6804 person years ) . Multiple linear regression was used to examine associations between acid excretion with changes in BMD over 5-years at three sites : lumbar spine , femoral neck , and total hip ( n = 651 ) . Potential confounders controlled included : age , gender , family history of osteoporosis , physical activity , smoking , calcium intake , vitamin D status , estrogen status , medications , renal function , urine creatinine , body mass index , and change of body mass index . Results There were no associations between either urine pH or acid excretion and either the incidence of fractures or change of BMD after adjustment for confounders . Conclusion Urine pH and urine acid excretion do not predict osteoporosis risk Summary Because kidney dysfunction reduces the ability to excrete dietary acid excess , we hypothesized that underlying kidney function may have confounded the mixed studies linking dietary acid load with the risk of osteoporosis and fractures in the community . In a relatively large survey of elderly men and women , we report that dietary acid load did neither associate with DEXA-estimated bone mineral density nor with fracture risk . Underlying kidney function did not modify these null findings . Our results do not support the dietary acid-base hypothesis of bone loss . Introduction Impaired renal function reduces the ability to excrete dietary acid excess . We here investigate the association between dietary acid load and bone mineral density ( BMD ) , osteoporosis , and fracture risk by renal function status . Methods An observational study was conducted in 861 community-dwelling 70-year-old men and women ( 49 % men ) with complete dietary data from the Prospect i ve Investigation of the Vasculature in Uppsala Seniors ( PIVUS ) . The exposure was dietary acid load as estimated from 7-day food records by the net endogenous acid production ( NEAP ) and potential renal acid load ( PRAL ) algorithms . Renal function assessed by cystatin C estimated glomerular filtration rate was reduced in 21 % of the individuals . Study outcomes were BMD and osteoporosis state ( assessed by DEXA ) and time to fracture ( median follow-up of 9.2 years ) . Results In cross-section , dietary acid load had no significant associations with BMD or with the diagnosis of osteoporosis . During follow-up , 131 fractures were vali date d. Neither NEAP ( adjusted hazard ratios ( HR ) ( 95 % confidence interval ( CI ) ) , 1.01 ( 0.85–1.21 ) , per 1 SD increment ) nor PRAL ( adjusted HR ( 95 % CI ) , 1.07 ( 0.88–1.30 ) , per 1 SD increment ) associated with fracture risk . Further multivariate adjustment for kidney function or stratification by the presence of kidney disease did not modify these null associations . Conclusions The hypothesis that dietary acid load associates with reduced BMD or increased fracture risk was not supported by this study in community-dwelling elderly individuals . Renal function did not influence on this null finding A  Western-type diet  is associated with osteoporosis and calcium nephrolithiasis . On the basis of observations that calcium retention and inhibition of bone resorption result from alkali administration , it is assumed that the acid load inherent in this diet is responsible for increased bone resorption and calcium loss from bone . However , it is not known whether the dietary acid load acts directly or indirectly ( i.e. , via endocrine changes ) on bone metabolism . It is also unclear whether alkali administration affects bone resorption/calcium balance directly or whether alkali-induced calcium retention is dependent on the cation ( i.e. , potassium ) supplied with administered base . The effects of neutralization of dietary acid load ( equimolar amounts of NaHCO(3 ) and KHCO(3 ) substituted for NaCl and KCl ) in nine healthy subjects ( 6 men , 3 women ) under metabolic balance conditions on calcium balance , bone markers , and endocrine systems relevant to bone [ glucocorticoid secretion , IGF-1 , parathyroid hormone (PTH)/1,25(OH)(2 ) vitamin D and thyroid hormones ] were studied . Neutralization for 7 days induced a significant cumulative calcium retention ( 10.7 + /- 0.4 mmol ) and significantly reduced the urinary excretion of deoxypyridinoline , pyridinoline , and n-telopeptide . Mean daily plasma cortisol decreased from 264 + /- 45 to 232 + /- 43 nmol/l ( P = 0.032 ) , and urinary excretion of tetrahydrocortisol ( THF ) decreased from 2,410 + /- 210 to 2,098 + /- 190 microg/24 h ( P = 0.027 ) . No significant effect was found on free IGF-1 , PTH/1,25(OH)(2 ) vitamin D , or thyroid hormones . An acidogenic Western diet results in mild metabolic acidosis in association with a state of cortisol excess , altered divalent ion metabolism , and increased bone resorptive indices . Acidosis-induced increases in cortisol secretion and plasma concentration may play a role in mild acidosis-induced alterations in bone metabolism and possibly in osteoporosis associated with an acidogenic Western diet 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 r and omized , prospect i ve , controlled , double-blind trial , 161 postmenopausal women ( age 58.6 + /- 4.8 yr ) with low bone mass ( T score -1 to -4 ) were r and omly 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 BACKGROUND Protein and alkalizing minerals are increasingly described as playing a major role in influencing bone status , not only in the elderly but also in children and adolescents . OBJECTIVE We examined whether the long-term dietary protein intake and diet net acid load are associated with bone status in children . DESIGN In a prospect i ve study design in 229 healthy children and adolescents aged 6 - 18 y , long-term dietary intakes were calculated from 3-d weighed dietary records that were collected yearly over the 4-y period before a one-time bone analysis . Dietary acid load was characterized as potential renal acid load ( PRAL ) by using an algorithm including dietary protein , phosphorus , magnesium , and potassium . Proximal forearm bone variables were measured by peripheral quantitative computed tomography . RESULTS After adjustment for age , sex , and energy intake and control for forearm muscularity , BMI , growth velocity , and pubertal development , we observed that long-term  dietary protein intake  was significantly positively associated with periosteal circumference ( P < 0.01 ) , which reflected bone modeling , and with cortical area ( P < 0.001 ) , bone mineral content ( P < 0.01 ) , and polar strength strain index ( P < 0.0001 ) , which reflected a combination of modeling and remodeling . Children with a higher dietary PRAL had significantly less cortical area ( P < 0.05 ) and bone mineral content ( P < 0.01 ) . Long-term calcium intake had no significant effect on any bone variable . CONCLUSIONS Long-term dietary protein intake appears to act anabolically on diaphyseal bone strength during growth , and this may be negated , at least partly , if dietary PRAL is high , ie , if the intake of alkalizing minerals is low OBJECTIVE Consumption of fruits and vegetables has been implicated in lowering net acid excretion ( NAE ) , but few studies have directly examined NAE and urinary calcium effects . Further , there is no evidence that only fresh fruits and vegetables must be consumed for a beneficial effect on bone . METHODS A crossover , acute-load study was design ed to investigate whether processed fruit was as effective as fresh fruit in reducing NAE and protein-induced hypercalciuria .  Fifteen women completed three dietary treatments on three different mornings . A fasting urine sample was collected before consuming one of the following three isocaloric high-protein treatments : control , fresh apples , and processed applesauce . The serving size for the applesauce treatment was 2.5 times that for fresh apples . Urine was collected at baseline ( 0 h ) and at 1.5 , 3.0 , and 4.5 h. RESULTS Compared with baseline , NAE increased after control treatment but decreased after fresh or processed apple treatment ( P = 0.041 ) . Calcium excretion increased with all treatments by 3 h ; however , the increase was less for fresh apple and applesauce ( P = 0.024 ) . CONCLUSIONS In an acute feeding model , fruit intake reduced NAE and urinary calcium excretion . Processed fruit appears to be effective , although a larger serving size was needed than with fresh fruit BACKGROUND Dietary patterns that promote mild metabolic acidosis may have a negative effect on  bone density .  OBJECTIVE We investigated the relation between a measure of  dietary acid-base load , potential renal acid load ( PRAL ) , and calcaneal broadb and ultrasound attenuation ( BUA ) after adjustment for confounders and also compared the results with different estimates of acid-base load . DESIGN A cross-sectional study was conducted in 14 563 men and women aged 42 - 82 y living in Norfolk , United Kingdom , in which measures of calcaneal BUA  and dietary PRAL were estimated by using the European Prospect i ve Investigation into Cancer and Nutrition Norfolk ( EPIC-Norfolk ) food-frequency question naire . RESULTS A more acidic dietary intake ( high PRAL ) was significantly associated with lower calcaneal BUA in women but not in men ; there was a difference of approximately 2 % in BUA between the highest and lowest quintiles of PRAL , independent of age , body mass index , smoking habit , physical activity , diagnosed osteoporosis , and history of fracture , and ( in women ) hormone replacement therapy . No relation was observed between history of fracture or incident fracture and PRAL . Those with the greatest PRAL had higher intakes of meat , fish , eggs , and cereal and cereal products and lower intakes of fruit and vegetables , tea , and coffee . CONCLUSION PRAL was inversely associated with bone ultrasound measures in women , but the magnitude of the association was relatively small compared with other known risk factors . Further longitudinal studies are required to establish whether , in the long term , these small effects are important in overall fracture risk in population Objective : In previous studies of the renal response to acute NH 4 Cl acidosis no correlation was found between systemic acid – base status and the traditionally used quantity , renal net acid excretion ( NAE ) . If NAE is to be considered a physiologically meaningful quantity then this is surprising , as the extracellular acid – base status would be expected to be the key physiological trigger for renal NAE . The object of this study was to investigate the renal response to acute non‐carbonic acid loading using a quantitative organ physiological approach . Material and Methods : Five‐h NH 4 Cl loading studies were performed in 10 healthy men using a r and omized , placebo‐controlled , crossover design . Arterialized capillary blood , serum and urine were collected hourly during the loading studies for the measurement of electrolytes and acid – base status . Concentrations of non‐metabolizable base ( NB ) and acid ( NA ) were calculated from measured concentrations of non‐metabolizable ions according to Kildeberg . Results : In the steady state ( placebo ) the rate of renal excretion of NA ( = −NB ) was close to zero , indicating that the net extrarenal input of NA ( endogeneous production , gastrointestinal absorption , skeletal release , etc . ) was likewise about zero . An inverse correlation was found between blood pH and the rate of renal excretion of NA . Only a small amount of the acid load ( ≈8 % ) was excreted during the 5‐h study period and this was accompanied by massive calciuria , indicating that mobilization of NB from bone contributed substantially to the current net extrarenal NA input . Conclusion : From a physiological point of view , NB can be regarded as the actual substrate for renal acid – base control , and measurement of renal turnover of NB may give a more precise description of renal acid – base metabolism during acid loading than previously described methods A r and omised , parallel- design dietary intervention study was conducted in women ( aged 45 - 75 years ) with prehypertension or stage 1 hypertension . The aim was to compare the effects on bone turnover of a low-Na base-producing ( LNAB ) Dietary Approaches to Stop Hypertension (DASH)-type diet ( including six serves lean red meat/week ) with a high-carbohydrate low-fat ( HCLF ) diet with a higher acid load ( both > 800 mg dietary Ca/d ) . Fasting serum bone markers ( baseline and week 14 ) and 24 h urinary electrolyte excretion ( baseline , weeks 4 , 8 , 12 and 14 ) were measured . After the intervention period , the LNAB group ( n 46 ) had a fall of 26 ( sem 6 ) % ( P < 0.0001 ) in urinary Na , an increase in K excretion ( 6.8 ( sem 3.6 ) mmol/d ; P = 0.07 ) and , compared with the HCLF group ( n 49 ) , a greater reduction in urinary Ca excretion by 0.7 ( sem 0.3 ) mmol/d . Serum 25-hydroxyvitamin D , intact parathyroid hormone and osteocalcin did not change , and both groups had a similar increase of 23 ( sem 5 ) % ( P < 0.0001 ) in C-terminal telopeptide of type I collagen . The HCLF group had an 11 ( sem 4 ) % increase ( P = 0.003 ) in N-terminal propeptide , type I procollagen , which could indicate an increased rate of bone turnover . The fall in urinary Ca with the lower-Na lower-acid load diet is likely to have long-term beneficial effects on bone . As bone resorption was not different between the two dietary patterns with relatively high Ca intake , the effect on bone health of a dietary pattern with a lower acid load warrants further study on a lower Ca intake Excess dietary proteins and " acid ash " diets have been suspected to increase the risk of osteoporosis , but experimental and epidemiological evidence is mixed . We aim ed to determine whether the association between protein intake and the overall acid-base equilibrium of the diet ( as renal net acid excretion [ RNAE ] estimate ) and fracture risk vary according to calcium intake . During an average of 8.37 + /- 1.73 yr of follow-up , 2408 women reported a fracture ( excluding high-impact trauma ) among 36,217 postmenopausal women from the E3N prospect i ve study . We used Cox regression models to study the interaction between calcium and , respectively , proteins and RNAE , from the 1993 dietary question naire for fracture risk determination , adjusting for potential confounders . There was no overall association between fracture risk and total protein or RNAE . However , in the lowest quartile of calcium ( < 400 mg/1000 kcal ) , high protein intake was associated with a significant increased fracture risk ( RR = 1.51 for highest versus lowest quartile ; 95 % CI , 1.17 - 1.94 ) . An increasing fracture risk with increasing animal protein intake was also observed ( trend , p < 0.0001 ) . A similar pattern of interaction for fracture risk was observed between RNAE and calcium . In this Western population of postmenopausal women with normal to high protein intake and fairly high calcium intake , there was no overall association between total protein or RNAE and fracture risk . However , there was some evidence that high protein-high acid ash diets were associated with an increased risk of fracture when calcium intake was low ( < 400 mg/1000 kcal ) 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 r and omized 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 Fifty-six postmenopausal women aged 52.4 + /- 6.7 years ( SD ) were treated for 12 months with L-glutamine calcium monofluorophosphate . Each patient received four tablets/day , providing a total dose of 20 mg of fluoride and 600 mg of elemental calcium .  Bone mineral density was measured at baseline and after 6 and 12 months of treatment by dual photon absorptiometry of the distal forearm . At these times , serum levels of alkaline phosphatase and osteocalcin , and urinary concentrations of hydroxyproline and calcium , were also assayed . Results were compared with a control group of 50 untreated postmenopausal women with similar clinical characteristics . Forty-nine patients completed the study .  Bone mineral density in the treated patients showed a significant increase after 6 months in comparison with both baseline ( p < 0.01 ) and controls ( p < 0.01 ) . After 12 months no significant further increase in bone mineral density was detected . In the control group , a significant decrease of bone mineral density was observed at this time ( p < 0.01 ) . After 6 months , serum osteocalcin levels were significantly increased in the treated group ( p < 0.01 vs. basal and controls ) . The other biochemical parameters did not show any significant variations . After 12 months , all the biochemical parameters evaluated , with the exception of serum alkaline phosphatase , were significantly different in comparison with the control group ( p < 0.01 ) . Osteocalcin levels also increased in comparison with the basal value ( p < 0.01 ) . Adverse effects were mild . However , seven patients stopped the treatment before the 6th month because of gastrointestinal complaints . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND Mild metabolic acidosis , which can be caused by diet , may result in elevated blood pressure ( BP ) . DESIGN The analyses included 2241 participants aged ≥55 y who were free of hypertension at baseline ( 1990 - 1993 ) and who had complete dietary and BP data .  Dietary data were obtained from a 170-item food-frequency question naire . We used 2 measures to characterize dietary acid load : ( 1 )  potential renal acid load ( PRAL ) by using an algorithm including protein , phosphorus , potassium , calcium , and magnesium , and ( 2 ) estimated  net endogenous acid production ( NEAP ) based on protein and potassium . HRs for 6-y incidence of hypertension were obtained in tertiles of PRAL and NEAP with adjustment for age , sex , BMI , smoking , education , and intakes of alcohol , fiber , and total energy . RESULTS We identified 1113 incident cases of hypertension during 8707 person-years of follow-up .  The median dietary acid load ranged from -14.6 to 19.9 mEq/d across categories of PRAL . Hypertension risk was not significantly associated with dietary acid load . The multivariate HRs ( 95 % CIs ) in consecutive tertiles of PRAL were 1.00 ( reference ) , 1.01 ( 0.87 , 1.17 ) , and 1.02 ( 0.88 , 1.18 ) ( P trend = 0.83 ) . The median dietary acid loads were 30.4 , 36.7 , and 43.7 mEq/d , respectively , in consecutive tertiles of NEAP . Corresponding HRs for NEAP were 1.00 ( reference ) , 0.92 ( 0.80 , 1.07 ) , and 0.94 ( 0.81 , 1.10 ) ( P-trend = 0.46 ) . CONCLUSION The findings from this prospect i ve cohort study provided no evidence of an association between dietary acid load and risk of hypertension in older adults BACKGROUND Bone mineral density ( BMD ) may be influenced by the general dietary pattern and the potential renal acid load ( PRAL ) . METHODS We compared the dietary intake ( estimated using the European Prospect i ve Investigation into Cancer and nutrition question naire ) of 497 community-living women ( 60 years of age and older ) grouped according to tertiles of baseline total , trabecular and cortical BMD estimated using tibial peripheral quantitative computed tomography ( pQCT ) , and of BMD variation over 6 years . RESULTS None of the nutrients taken into account nor PRAL was associated with total BMD , with the exception that the intake of polyunsaturated fatty acids ( PUFA ) was slightly higher among women with the highest total BMD . Similar results were found for trabecular BMD . Cortical BMD was associated with serum 25-OH vitamin D ( 38.8 , 43.2 , and 49.5 nmol/L in the first , second , and third tertiles , respectively ; P=0.042 ) . In the longitudinal analysis , a lower BMI was associated with greater loss of total BMD , while lower serum 25-OH vitamin D at baseline was associated with smaller loss of cortical BMD . CONCLUSIONS We found no relationship between dietary acid load and BMD . We also confirmed the role of well-recognized risk factor for osteoporosis Recent animal work suggests that gamma-linolenic acid ( GLA ) and eicosapentaenoic acid ( EPA ) enhance calcium absorption , reduce excretion and increase calcium deposition in bone . A pilot study was set up to test the interactions between calcium and GLA+EPA in humans . Sixty-five women ( mean age 79.5 ) , taking a background diet low in calcium , were r and omly assigned to GLA+EPA or coconut oil placebo capsules ; in addition , all received 600 mg/day calcium as the carbonate . Markers of bone formation/degradation and bone mineral density ( BMD ) were measured at baseline , 6 , 12 and 18 months . Twenty-one patients were continued on treatment for a second period of 18 months , after which BMD ( 36 months ) was measured . At 18 months , osteocalcin and deoxypyridinoline levels fell significantly in both groups , indicating a decrease in bone turnover , whereas bone specific alkaline phosphatase rose indicating beneficial effects of calcium given to all the patients . Lumbar and femoral BMD , in contrast , showed different effects 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 % . This pilot controlled study suggests that GLA and EPA have beneficial effects on bone in this group of elderly patients , and that they are safe to administer for prolonged periods of time The n-6/n-3 fatty acid ( FA ) ratio has increased in the Western-style diet to ~10–15:1 during the last century , which may have contributed to the rise in cardiovascular disease ( CVD ) . Prior studies have evaluated the effects on CVD risk factors of manipulating the levels of n-6 and n-3 FA using food and supplements or investigated the metabolic fate of linoleic acid ( LNA ) and α-linolenic acid ( ALA ) by varying the n-6/n-3 ratios . However , no previous studies have investigated the potential interaction between diet ratios and supplementation with eicosapentaenoic acid ( EPA , 20:5n-3 ) and docosahexaenoic acid ( DHA , 22:6n-3 ) . We used a factorial design approach with adults ( n = 24 ) in a controlled feeding trial to compare the accretion of EPA and DHA into red blood cell membranes ( RBC ) by adding a direct source ( algal oil supplement ) of EPA and DHA in a diet with a 10:1 versus 2:1 ratio of n-6/n-3 FA . Subjects were r and omized into 8-week crossover diet sequences and each subject consumed three of four diets [ 10:1 , 10:1 plus supplement ( 10:1 + S ) , 2:1 and 2:1 + S ] . LNA and ALA intakes were 9.4 and 7.7 % , and 1.0 and 3.0 % during the low and high ALA diets , respectively . Compared to the Western-style 10:1 diet , the 2:1 diet increased EPA by 60 % ( P < 0.0001 ) in RBC membranes without the direct EPA source and a 34 % increase ( P = 0.027 ) was observed with the 10:1 + S diet ; however , DHA levels increased in both diet ratios only with a direct DHA source . Shifting towards a 2:1 diet is a valid alternative to taking EPA-containing supplements CONTEXT Protein is an essential component of muscle and bone . However , the acidic byproducts of protein metabolism may have a negative impact on the musculoskeletal system , particularly in older individuals with declining renal function . OBJECTIVE We sought to determine whether adding an alkaline salt , potassium bicarbonate ( KHCO3 ) , allows protein to have a more favorable net impact on intermediary indices of muscle and bone conservation than it does in the usual acidic environment . DESIGN We conducted a 41-d r and omized , placebo-controlled , double-blind study of KHCO3 or placebo with a 16-d phase-in and two successive 10-d metabolic diets containing low ( 0.5 g/kg ) or high ( 1.5 g/kg ) protein in r and om order with a 5-d washout between diets . SETTING The study was conducted in a metabolic research unit . PARTICIPANTS Nineteen healthy subjects ages 54 - 82 yr participated . INTERVENTION KHCO3 ( up to 90 mmol/d ) or placebo was administered for 41 d. MAIN OUTCOME MEASURES We measured 24-h urinary nitrogen excretion , IGF-I , 24-h urinary calcium excretion , and fractional calcium absorption . RESULTS KHCO3 reduced the rise in urinary nitrogen excretion that accompanied an increase in protein intake ( P = 0.015 ) and was associated with higher IGF-I levels on the low-protein diet ( P = 0.027 ) with a similar trend on the high-protein diet ( P = 0.050 ) . KHCO3 was also associated with higher fractional calcium absorption on the low-protein diet ( P = 0.041 ) with a similar trend on the high-protein diet ( P = 0.064 ) . CONCLUSIONS In older adults , KHCO3 attenuates the protein-induced rise in urinary nitrogen excretion , and this may be mediated by IGF-I. KHCO3 may also promote calcium absorption independent of the dietary protein content
Urine calcium excretion rates were consistent with osteoporosis development ; however calcium balance studies did not demonstrate loss of whole body calcium with higher net acid excretion .
No study revealed a biologic mechanism functioning at physiological pH. Finally , r and omized studies did not provide evidence for an adverse role of phosphate , milk , and grain foods in osteoporosis .
Conclusions A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health
Background Modern diets have been suggested to increase systemic acid load and net acid excretion .
In response , alkaline diets and products are marketed to avoid or counteract this acid , help the body regulate its pH to prevent and cure disease .
The objective of this systematic review was to evaluate causal relationships between dietary acid load and osteoporosis using Hill 's criteria .