Measurement of net acid excretion by use of paper strips

OBJECTIVE: Net endogenous acid production, reflected in the steady state as net acid excretion (NAE), is implicated in bone loss because it is positively associated with urinary calcium loss. Protein is one of the main sources of dietary acid load, whereas fruit and vegetables provide alkaline potassium salts that counteract the dietary acid load. This study investigated whether a pH paper strip measurement of overnight (i.e., first void) urine would reflect 24-h NAE, measured as excretion rates of titratable acid minus bicarbonate plus ammonium. METHODS: Twenty-three subjects collected 24-h urine in two parts: day (approximately 7 am to 11 pm) and overnight (approximately 11 pm to 7 am). At first void, subjects recorded pH using paper strips. Subjects recorded intake and 20 subjects provided fasting urine collected from 7 to 9 am. RESULTS: The pH paper strip measurements of first void urine was significantly correlated with 24-h titratable acid minus bicarbonate (r = -0.466, P < 0.025) but not with 24-h NAE. We examined the association of dietary protein, potassium, protein:potassium ratio, and sodium with NAE, with fasting morning urinary calcium excretion, an indirect measurement of bone loss, and with urinary cross-links, a direct measurement of bone resorption. Of these, only sodium intake (measured as 24-h urine excretion) and urine potassium:sodium ratio showed a significant relation (with fasting calcium excretion). CONCLUSIONS: We did not find that the first void urine pH by paper strip measurement provided an index of daily net endogenous acid production as reflected in 24-h NAE. In our sample of young adults, daily sodium intake positively correlated with bone resorption, as reflected in fasting urine calcium, whereas daily NAE did not.     

Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium

OBJECTIVE: To estimate cross-sectional and long-term dietary sodium intakes and sources in Finland, and to evaluate the validity of 48-h recall to assess sodium intake. DESIGN: Cross-sectional dietary surveys and food availability data (Food Balance Sheets). SETTING: Dietary surveys were carried out in Finland in 1992, 1997 and 2002. Food availability data were collected from 1980 to 1999. SUBJECTS: A stratified random sample was drawn from the population register. The total number of participants in the three dietary surveys was 6730. In the subsample for urine collection, the number of participants was 879. INTERVENTIONS: Nutrient intakes were estimated on the basis of a 3-day food diary in 1992, a 24-h recall in 1997 and a 48-h recall in 2002. The 24-h urinary excretion of sodium was used to validate sodium intake. In addition, salt intake was estimated based on Food Balance Sheets. RESULTS: Sodium intake has slowly decreased since the early 1980s. Reported daily sodium intake correlated significantly with sodium excretion. CONCLUSIONS: Sodium intake has decreased during the last two decades, but is still higher than the recommended daily intake. Sodium intake estimation based on dietary surveys and food availability data is a valid method provided that the food composition database is up to date and of good quality. SPONSORSHIP: All surveys were funded by the National Public Health Institute in Finland and the Ministry of Social Affairs and Health.     

Day-to-day and within-day variation in urinary iodine excretion.

OBJECTIVE: To examine the day-to-day and within-day variation in urinary iodine excretion and the day-to-day variation in iodine intake. DESIGN: Collection of consecutive 24-h urine samples and casual urine samples over 24h. SETTING: The study population consisted of highly motivated subjects from our Institute. SUBJECTS: Study 1: Ten healthy subjects (seven females and three males) aged 30-46 y. Study 2: Twenty-two healthy subjects (9 males and 13 females) aged 30-55 y. METHODS: Study 1: 24-h urine samples were collected for four consecutive days. Study 2: Each urine voided over 24 h was collected into separate containers. In both studies dietary records were kept. MAIN OUTCOME MEASURES: Twenty-four-hour urinary iodine excretion, 24-h urinary iodine excretion estimated as I/Cr*24 h Cr and as a concentration in casual urine samples. RESULTS: Study 1: Both iodine excreted in 24-h urine and iodine intake varied from day-to-day. Iodine excretion correlated with iodine intake (=-0.46, P=0.01). Iodine intake (mean 89 +/- 6.5 microg/d) was not significantly different from iodine excretion (mean 95 +/- 5.3 microg/d). Study 2: Twenty-four hour iodine excretion estimated as I/Cr*24 h Cr from the morning urine sample was significantly lower than actual 24-h iodine excretion, whereas 24-h iodine excretion estimated as I/Cr*24 h Cr from the first sample after the morning sample and the last sample before the subjects went to bed was not significantly different from actual 24-h iodine excretion. Twenty-four-hour urine excretion estimated as a concentration was lower than actual 24-h iodine excretion in casual urine taken at any time of the day. CONCLUSIONS: For determination of iodine status in an individual, more than one 24-h urine sample must be used. The use of the I/Cr ratio in casual urine samples is a usable measure of iodine status if corrected for the age- and sex-adjusted 24-h creatinine excretion. Further, the study suggests that fasting morning urine samples would underestimate iodine status in this population.     

人群两次24小时尿量及食盐摄入量关联性分析

  目的   分析两次24 h尿量和尿盐排出量, 探讨24 h尿用于评估群体和个体食盐摄入量的价值。   方法   于2013-2014年在山东省和江苏省4个项目县, 采用多阶段整群随机抽样的方法, 抽取18~69岁调查对象进行问卷调查并收集间隔1 d两次24 h尿液, 比较两次24 h尿量的差异, 从个体和群体两个层面分析两次24 h尿盐排出量的差异。   结果   1 288名研究对象年龄为(42.3±14.0)岁, 男性626名(48.6%)。24 h平均尿量为(1 462±437)ml, 第1次24 h尿量(1 427±488)ml低于第2次24 h尿量(1 498±552)ml(t=-4.439, P < 0.001)。调查对象每日食盐摄入量为(9.8±3.3)g, 男性每日食盐摄入量(10.1±3.5)g高于女性(9.5±3.1)g(t=3.09, P=0.002), 不同年龄组人群每日食盐摄入量差异有统计学意义(F=7.57, P < 0.001), 1 136名(88.2%)研究对象每日食盐摄入量高于推荐值。从个体层面比较, 调查对象两次24 h尿盐排出量绝对差异 < 1 g, 人数为279(21.7%), 而有48.5%的调查对象差异 > 3 g。从群体层面比较, 调查对象两次24 h尿盐排出量分别为(9.9±4.1)g和(9.7±4.0)g, 差异无统计学意义(P=0.102), 两次24 h尿盐排出量的组内相关系数为0.508(95% CI:0.451~0.559)。   结论   本研究结果提示24 h尿钠能较好评估人群食盐摄入量, 但不能准确反映个体食盐摄入量。     

Self-Reported Taste Preference Can Be a Proxy for Daily Sodium Intake in Middle-Aged Japanese Adults

Reducing dietary salt intake remains a challenging issue in the management of chronic disease. Taste preference is suspected to be an important proxy index of daily sodium consumption. This study examined the difference in daily sodium intake according to self-reported taste preference for miso soup as representative of homemade cooking in middle-aged urban Japanese adults. Among 896 candidates randomly selected from examinees of cancer screening provided by the National Cancer Center, Japan, 143 men and women participated in this cross-sectional study. During the period from May 2007 through April 2008, participants provided a food frequency questionnaire, which included information on taste preference and dietary behaviors, a weighed food record over 4 consecutive days, a simultaneous 24-hour urine collection, and a sample of miso soup as it is usually prepared in the home. Mean 24-hour urinary sodium excretion and daily sodium intake were compared according to the self-reported taste preference for miso soup. Taste preference was significantly associated with both 24-hour urinary sodium excretion (trend P<0.01) and daily sodium intake (trend P=0.01), with a corresponding regression coefficient per 1 rank preference increment of 403 mg and 315 mg/day, respectively. The observed association between preference and urinary excretion was attenuated by further adjustment for discretionary salt-related behaviors. These findings suggest that self-reported taste preference for homemade cooking is a defining feature of daily sodium intake through discretionary salt-related dietary behaviors. A reduction in daily sodium consumption per 1 rank light preference was estimated to equate to approximately 1 g salt/day.     

Effects of an oxalate load on urinary oxalate excretion in calcium stone formers.

OBJECTIVE: To investigate the oxalate intake and the effect of an oxalate load on urinary oxalate excretion in calcium stone-forming (CSF) patients. DESIGN: Prospective study. SETTING: University-affiliated outpatient Renal Lithiasis Unit. Patients and controls: Seventy (70) CSF and 41 healthy subjects (HS) collected a 24-hour urine sample and were submitted to a 3-day dietary record to determine mean oxalate (Ox), calcium (Ca) and vitamin C intake. Fifty-eight (58) CSF patients were randomly selected to receive milk (N = 28) or dark (N = 30) chocolate as an oxalate load. INTERVENTION: Administration of either milk (94 mg Ox + 430 mg Ca) or dark chocolate (94 mg Ox + 26 mg Ca) for 3 days. A 24-hour urine sample was obtained before and after the load to determine calcium, oxalate, sodium, potassium, urea, and creatinine. MAIN OUTCOME MEASURE: Oxalate intake and excretion. RESULTS: CSF patients presented mean Ox intake of 98 +/- 137 mg/d, similar to that of HS (108 +/- 139 mg/d). Mean Ox and vitamin C intake was directly correlated with Ox excretion only in CSF. The consumption of dark chocolate induced a significant increase in mean urinary Ox (36 +/- 14 versus 30 +/- 10 mg/24 hr) not observed in the milk chocolate group. Thus, a 2-fold increase in Ox intake in this population of CSF patients produced a significant 20% increase in oxaluria, not observed when Ca was consumed simultaneously. CONCLUSION: The present study suggests that even small increases in Ox intake affect oxalate excretion and the mitigation of urinary oxalate increase by Ca consumption reinforces that Ca and Ox intakes for CSF patients should be in balance. Further studies are necessary to assess whether or not a 20% increase in oxaluria will lead to a higher risk of stone formation.     

A method to assess sodium intake in populations

Dietary sodium measurement in populations has severe limitations whether assessment is based on urinary excretion or on food intake methods. We have validated a simple instrument to determine total dietary sodium intake of populations in a pilot study of 10 women, 20 to 36 years old. Sodium intake determined by means of the sodium measurement instrument was correlated with sodium intake from food analysis, sodium intake calculated from food composition tables, and measurement of 24-hour urinary sodium excretion. Sodium values obtained with the instrument are based on regression equations, which incorporate information as follows: an average measure of 7 days' actual table salt use, the average sodium contribution of 17 high-sodium foods from a food frequency checklist maintained for 7 days, a calculation of drinking water sodium, and measurements of height and weight to establish 24-hour energy needs, a surrogate estimate of sodium found in all foods not included in the food frequency checklist. Participants were studied for 16 days: 7 consecutive days on either a 2,000-mg or a 3,500-mg sodium diet, 2 days' adjustment, and 7 days' crossover. Participants were allowed to select foods from a diverse menu, eat at fast-food restaurants, and consume alcohol if desired. Mean of 7-day sodium intake obtained with the instrument was significantly correlated with mean of 7-day sodium intake determined by food analysis (r = .80), from food composition tables (r = .62), and from urinary excretion (r = .56).     

Does dietary recall adequately assess sodium, potassium, and calcium intake in hypertensive patients?

OBJECTIVE: A diet low in sodium, high in potassium, and high in calcium is recommended to lower blood pressure. However, compliance with this diet is poor, probably because of dietary intake underestimation. Therefore, we compared electrolyte intake as estimated from dietary recall with a 24-h urinary excretion. METHODS: Thirty-six patients (26 men and 10 women) with a mean age of 46 +/- 8 y participated in the study. All participants had essential hypertension and were on no drug therapy (n = 20) or non-diuretic monotherapy (n = 16). Patients were instructed to consume a low-sodium (50 mmol/d), high-potassium (supplementation with 30 to 60 mmol/d), and high-calcium (1000 mg/d) diet. Compliance with the diet was assessed at baseline and then 1, 2, and 3 mo after starting the diet. Sodium, potassium, and calcium intakes were carefully estimated from patients' dietary recall and 24-h urinary collection. RESULTS: Estimated sodium intake significantly correlated with 24-h urinary excretion (R = 0.43 P < 0.001). However, estimated sodium intake was lower than urinary sodium excretion by 34% at baseline and by 47% after 3 mo of dieting (P < 0.05). Estimated potassium intake correlated with 24-h urinary excretion. Estimated calcium intake significantly increased from 933 +/- 83 mg/d to 1029 +/- 171 mg/d (P < 0.05). Calcium intake derived from patients' recall far exceeded and only slightly correlated with 24-h urinary excretion (R = 0.23, P < 0.01). CONCLUSIONS: Patients tend to underestimate their sodium intake by 30% to 50%; therefore, urinary sodium excretion is more accurate to assess sodium intake. Thus, 24-h urinary sodium excretion should be used in clinical practice and in clinical trials, especially when dietary non-compliance is suspected.     

Feasibility of outpatient electrolyte balance studies.

Clinical studies requiring controlled electrolyte balance have traditionally been conducted in an inpatient (IP), metabolic ward setting. The purpose of this study was to test the feasibility of performing such studies in an outpatient (OP) clinical research setting. Focusing on sodium (Na) and potassium (K) balance, we retrospectively compared 28 subjects studied as OP vs 25 studied as IP on our metabolic ward. We assessed their adherence to our metabolic diets and their compliance with serial 24-hr urine collections. Dietary compliance was assessed by checksheet and urinary Na excretion; urine collection accuracy was determined by serial 24-hr creatinine excretion. The diets for both studies contained a low Na phase (10 mEq) and a high Na phase (200 mEq for IP and 250 mEq for OP), each lasting 1 week. When in balance on the low Na diet, 24-hr Na excretion was 4.6 +/? 0.7 mEq for OP and 13.4 +/? 2.2 mEq for IP, indicating excellent compliance with the low salt diet. Na excretion on the high Na diet was 184.5 +/? 7.4 mEq for OP and 195.3 +/? 9.6 mEq for IP. These values were not significantly different from each other; however, the OP were significantly less than their diet of 250 mEq Na (p less than 0.05). This difference may have been due to dermal Na losses. K excretion was also similar in the two groups. There was no significant difference in the reproducibility of individual multiple urinary creatinine measurements in OP vs IP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feasibility of outpatient electrolyte balance studies

Clinical studies requiring controlled electrolyte balance have traditionally been conducted in an inpatient (IP), metabolic ward setting. The purpose of this study was to test the feasibility of performing such studies in an outpatient (OP) clinical research setting. Focusing on sodium (Na) and potassium (K) balance, we retrospectively compared 28 subjects studied as OP vs 25 studied as IP on our metabolic ward. We assessed their adherence to our metabolic diets and their compliance with serial 24-hr urine collections. Dietary compliance was assessed by checksheet and urinary Na excretion; urine collection accuracy was determined by serial 24-hr creatinine excretion. The diets for both studies contained a low Na phase (10 mEq) and a high Na phase (200 mEq for IP and 250 mEq for OP), each lasting 1 week. When in balance on the low Na diet, 24-hr Na excretion was 4.6 +/- 0.7 mEq for OP and 13.4 +/- 2.2 mEq for IP, indicating excellent compliance with the low salt diet. Na excretion on the high Na diet was 184.5 +/- 7.4 mEq for OP and 195.3 +/- 9.6 mEq for IP. These values were not significantly different from each other; however, the OP were significantly less than their diet of 250 mEq Na (p less than 0.05). This difference may have been due to dermal Na losses. K excretion was also similar in the two groups. There was no significant difference in the reproducibility of individual multiple urinary creatinine measurements in OP vs IP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Measuring Population Sodium Intake: A Review of Methods

Reduction of population sodium intake has been identified as a key initiative for reduction of Non-Communicable Disease. Monitoring of population sodium intake must accompany public health initiatives aimed at sodium reduction. A number of different methods for estimating dietary sodium intake are currently in use. Dietary assessment is time consuming and often under-estimates intake due to under-reporting and difficulties quantifying sodium concentration in recipes, and discretionary salt. Twenty-four hour urinary collection (widely considered to be the most accurate method) is also burdensome and is limited by under-collection and lack of suitable methodology to accurately identify incomplete samples. Spot urine sampling has recently been identified as a convenient and affordable alternative, but remains highly controversial as a means of monitoring population intake. Studies suggest that while spot urinary sodium is a poor predictor of 24-h excretion in individuals, it may provide population estimates adequate for monitoring. Further research is needed into the accuracy and suitability of spot urine collection in different populations as a means of monitoring sodium intake.     

Measuring dietary sodium intake in infancy: a review of available methods

It has been hypothesised that infancy may be a particularly sensitive period with respect to the effect of dietary sodium (salt) intake on later blood pressure. If this is the case, interventions to reduce dietary sodium intake in infancy could have major public health impact by reducing cardiovascular disease in the future. However, research in this area is hampered by difficulties of how to measure dietary sodium intake in infancy. Here we review the literature with an aim to describe different methods that have been used for research purposes, how these have been used and their relative strengths and limitations. We identified five studies that were relevant to our aim. In epidemiological and intervention studies sodium intake in infancy has been assessed via parents using diet diaries, which appear to be feasible and acceptable to parents. In these studies, sodium concentration in breast milk is assumed not to vary from one woman to the next, which may not be correct but has been poorly studied. The gold standard method - 24 h urinary excretion of sodium - was used in only one study and there is debate about the most appropriate way to collect urine for research purposes in infants. None of the studies directly compared different methods for determining infant dietary sodium intake. We conclude that research is required to determine the best methods of estimating dietary sodium intake in infants in different research contexts.     

Sodium and potassium excretion in a sample of normotensive and hypertensive persons in eastern Finland.

A 24-hour urine collection was carried out during a cardiovascular survey in eastern Finland. The study population comprised 148 hypertensive subjects in a random sample of the middle-aged population and 86 normotensive controls. The mean sodium excretion was 197 mmol/24h in both normotensive and hypertensive men, 179 mmol/24h in normotensive women, and 174 mmol/24h in hypertensive women. There were no significant differences in potassium excretion rate or in sodium: potassium molar ratio between the normotensive and the hypertensive among either men or women. There was no statistically significant correlation between blood pressure level and sodium or potassium excretion or sodium: potassium molar ratio. One in four of the subjects reported that they usually added salt to their food before tasting it. The results of this study show that the average level of salt intake in a Finnish population is high, and so is the sodium: potassium molar ratio. Although there was no correlation between sodium excretion and blood pressure levels, it is known that in this population the average blood pressure level is high and cardiovascular disease extremely frequent.     

Assessing U.S. Sodium Intake through Dietary Data and Urine Biomarkers

Sodium intake is related to blood pressure, an established risk factor for heart disease and stroke. Reducing intake may save billions in United States health care dollars annually. Efforts targeting sodium reductions make accurate monitoring vital, yet limited information exists on the accuracy of the current data to assess sodium intake in the United States population. In this symposium, new findings were presented on the accuracy of estimating population 24-h urinary excretion of sodium from spot urine specimens or sodium intake from 24-h dietary recalls. Differences in accuracy by sex, BMI, and race were apparent as well as by timing of spot urine collections. Although some published equations appear promising for estimating group means, others are biased. Individual estimates of sodium intake were highly variable and adjustment for within-individual variation in intake is required for estimating population prevalence or percentiles. Estimates indicated United States sodium intake remains high.     

Validez y limitaciones de los métodos para medir la ingesta y la eliminación de sal

High blood pressure (HBP) is the main modifiable cardiovascular risk factor. HBP can be related to high salt intake. To measure intake, not all feeding surveys are comparable and valid. The reference procedure for assessing salt intake consists of measuring the urinary excretion of sodium in urine collected during 24 hours, although alternative methods have been proposed, such as the collection of punctual and timed urine samples. In this review, we analyze which instruments allow the assessment of salt intake and which of them have provided greater validity and reliability through studies of concordance with the elimination of sodium in urine. Current food consumption surveys are inadequate because of their wide variability and relatively low correlation with the elimination of sodium in 24-hour urine. Its main limitation is the need for validation in different population groups. In primary care, salt intake should be assessed by using frequency-of-consumption questionnaires that collect foods with a high salt content, the consumption of preprepared dishes and questions that quantify the addition of salt in the preparation of food or at the table. For the validation of these questionnaires, the standard gold elimination of 24-hour urine sodium adjusted according to creatinine clearance should be used.     

Urinary isoflavone excretion as a compliance measure in a soy intervention among young girls: a pilot study

OBJECTIVE: To investigate the compliance of young girls with a soy intervention. DESIGN: An 8-week dietary intervention and urine sample collection. SETTING: Free-living girls. SUBJECTS: A convenience sample of 8- to 14-y-old girls (20 started and 17 finished the study) recruited through flyers distributed to staff members and previous study participants. INTERVENTION: The girls consumed one daily serving of soymilk, soy nuts, or tofu, completed 3-day food records, kept daily soy intake logs, and collected weekly urine samples. MAIN OUTCOME MEASURES: Compliance with the intervention was evaluated by daily soy intake logs, 3-day food records analyzed by the center's Food Composition and Food Groups Servings Databases, and weekly urinary isoflavone excretion using high-pressure liquid chromatography. The statistical analysis included paired t-tests, analysis of variance, and Spearman's rank-order correlation coefficients. RESULTS: Daily soy intake logs indicated a mean intake of 6.28 servings out of a maximum of 7.0 servings per week. The food records revealed a six-fold increase in isoflavone intake during the study period (P<0.01) which was confirmed by an increase in urinary isoflavone excretion of similar magnitude (23.3-142.1 nmol/mg creatinine, P=0.02). CONCLUSIONS: This study demonstrated the ability of young girls to consume one daily soy serving and the usefulness of urinary isoflavones as a primary compliance measure. The high urinary isoflavone excretion levels detected in girls as compared to adult women suggest less intestinal degradation and/or greater absorption of isoflavones in nonadult populations. This finding requires further investigations into the pharmacokinetics of isoflavones.     

Validity of the Food Frequency Questionnaire—Estimated Intakes of Sodium,Potassium, and Sodium-to-Potassium Ratio for Screening at a Point of Absolute Intake among Middle-Aged and Older Japanese Adults

Using Food Frequency Questionnaires (FFQs) to compare dietary references for screening has been in high demand. However, FFQs have been widely used for ranking individuals in a population based on their dietary intake. We determined the validity of sodium (salt equivalent) intake, potassium intake, and sodium-to-potassium (Na/K) ratio obtained using the FFQ for identifying individuals who deviated from the dietary reference intakes (DRIs) measured using multiple 24-h urinary excretion measurements or 12-day weighed food records (WFR). This study included 235 middle-aged subjects. The correlation coefficients (CCs) between the FFQ and WFR estimates were mostly moderate (0.24–0.54); the CCs between the FFQ and 24-h urinary excretion measurements were low or moderate (0.26–0.38). Values of area under the receiver-operating curve (AUC) at the point of DRIs for salt equivalent or potassium were >0.7 with the WFR as the reference standard and 0.60–0.76 with the 24-h urinary excretion as the reference standard. Using both standard measures, the AUC for the Na/K ratio was <0.7. The accuracy of salt equivalent and potassium intake estimation using the FFQ to determine absolute intake point was comparable to that using WFR, allowing for quantified error, but not as good as that of 24-h urinary excretion.     

Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men

BACKGROUND: Low prostate cancer incidence and high soy intake in Asian countries suggest a possible protective effect of soy foods against prostate cancer. The goal of this pilot study was to evaluate the feasibility of a randomized, crossover soy trial among men and to investigate the effects of daily soy intake on serum prostate-specific antigen (PSA) and testosterone levels. METHODS: We randomized 24 men to a high or a low soy diet for 3 months. After a 1-month washout period, the men crossed over to the other treatment. During the high soy diet, the men consumed two daily soy servings; during the low soy diet, they maintained their usual diet. During the entire study each man donated four blood samples and five overnight urine samples. Dietary compliance was assessed by soy calendars, 24-h dietary recalls, and urinary isoflavone excretion measured by high-pressure liquid chromatography with photodiode array detection. Blood samples were analyzed for serum testosterone and PSA by radioimmunoassay. When necessary, variables were log transformed. Two sample t-tests compared the two groups before each study period. Mixed models incorporating the repeated measurements were used to evaluate the effect of the soy diet on urinary isoflavone excretion and serum analytes. RESULTS: Twenty-three men aged 58.7+/-7.2 years completed the study. The compliance with the study regimen was high according to self-reported soy food intake and urinary isoflavone excretion. No significant between-group and within-group differences were detected. During the high soy diet, dietary isoflavone intake and urinary isoflavone excretion increased significantly as compared to the low soy diet. A 14% decline in serum PSA levels (P=0.10), but no change in testosterone (P=0.70), was observed during the high soy diet in contrast to the low soy diet. CONCLUSION: The high adherence as shown by three measures of compliance in this pilot trial demonstrated the feasibility of an intervention based on soy foods among free-living men.     

Correlates of forearm bone mass among women during maximal bone mineralization

The distribution and correlates of bone mass among women ages 20-35 were studied. During young adulthood, bone mass reaches its maximum level and appears to stabilize. Factors that establish the individual's relative position in this plateau period may influence the ultimate expression of bone loss with aging. Mid-distal radial bone mass was measured in a geographically defined population of 86 women in two rural, demographically similar communities in Iowa. The water supplies provided 55 and 375 mg/liter of elemental calcium, generating significantly different mean community dietary calcium intakes of 871 and 1,233 mg/day, respectively. Bone mass was measured by single-beam photon densitometry and correlated with data from physical measurements, medical history, and reported nutritional intake. In evaluating the joint effect of variables in a multiple regression procedure, forearm bone mass was negatively and significantly associated with alcohol consumption (P = 0.0327) and with a first pregnancy prior to age 20 (P = 0.0250). There was a trend for current calcium intake estimated from 24-hr recall to be positively associated with bone mass (P = 0.0816). Because the 24-hr recall is characterized by significant error due to daily variability of an individual's intakes, a more general calcium intake was estimated from food frequency. Women whose estimated intake of calcium from food frequency was greater than 800 mg/day, the Recommended Daily Allowance, had significantly greater bone mass than women whose intake was estimated to be less than 800 mg/day (P = 0.0053). No relationship was observed with oral contraceptive use, parity, breastfeeding practices, smoking behavior, or measures of physical activity.