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OBJECTIVES: Preclinical studies suggest that blueberry consumption is associated with improved bone health. This study quantified changes in urinary excretion of the long-lived calcium radioisotope (41)Ca to assess the dose-response effect of blueberries on bone loss in postmenopausal women. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner. METHODS: Healthy women at least 4 years past menopause were dosed with 50 nCi of (41)Ca and completed a 5-mo equilibration period for (41)Ca deposition in bone followed by a 6-wk control period. Subsequently, participants were assigned to a random sequence of 3 intervention periods, each corresponding to a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries. The blueberry powder was incorporated into granola bars, spread, and drinks consumed daily for 6 wk, followed by a 6-wk washout period. Urinary (41)Ca: Ca ratio was measured by accelerator mass spectrometry in 24-h urine collected weekly during intervention and every 3 wk during washout. Serum 25-hydroxyvitamin D and calcium concentrations were assessed prior to each intervention. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures ANOVA. RESULTS: Fourteen healthy, non-osteoporotic (mean bone mineral density t-score: −1.33) women completed the study. Net bone calcium retention increased by 6% in the low (P

OBJECTIVES: Accurate estimates of sodium (Na) intake are critical for advancing our understanding of Na and cardiovascular disease. The aim of this study was to utilize data from a controlled feeding study to assess the agreement between estimated 24hUNa, calculated from several timed spot urine collections, and known Na intake. METHODS: This secondary analysis used data from the control phase of a potassium intervention study in normotensive men and women (n = 39) to avoid the potential confounding factor of dietary potassium manipulation. Participants followed the controlled diet containing on average 3463 mg Na/d for 3 days. On day 4, participants ate 3 meals in a clinic setting and collected urine every 2 hours starting with a fasting second void. The 24-hour urine collection was completed with the first morning void the following day. Spot urine samples were analyzed for Na and estimated 24hUNa was calculated from all samples using the INTERSALT and Tanaka equations, and from only the fasting second collection using the Kawasaki equation. The relationship between estimated 24hUNa and Na intake was assessed using Spearman correlations, and agreement between estimated 24hUNa and intake was assessed using Wilcoxon Signed Rank Tests and Bland Altman plots. RESULTS: For all timed spot urine samples, estimated 24hUNa using INTERSALT and Kawasaki were significantly correlated with Na intake (all P 0.05). For all timed spot urine samples, estimated 24hUNa using INTERSALT was significantly different from Na intake (all P

OBJECTIVES: Potassium is an essential nutrient of concern according to recent Dietary Guidelines for Americans Advisory Committees. Current recommendations established by the Institute of Medicine (IOM) are given as an Adequate Intake (AI) of 4700 mg/d, met by less than 3% of the population. Little is known about potassium (K) tissue retention and less is understood on how retention may affect health outcomes. In this clinical trial, we assessed the effects of K intake from potato sources and a K supplement on overall K balance. METHODS: Thirty pre-hypertensive-to-hypertensive (Systolic BP ≥ 120 mmHg) men (N = 15) and women (N = 15) with a mean ± SD age, BMI, and BP (systolic(SBP)/diastolic(DBP)) of 48.2 ± 15 y, 31.4 ± 6.1, and 136.3 ± 11.9/86.1 ± 7.1 mmHg, respectively, were enrolled in a cross-over randomized control diet trial. Participants were assigned to a random order of four 16-day dietary K interventions including a basal diet (control) of 2300 mg/d(∼60 mmol/d), and three periods of an additional 1000 mg/d(3300 mg/d(∼85 mmol/d) total) of K in the form of potatoes (baked, boiled, or pan-heated with no additional fat), French fries, or a K gluconate supplement. Each intervention period was separated by two or more weeks of wash out. Twenty-four hour urine and stool samples were collected throughout each intervention phase, and assessed via ICP-OES for K, sodium (Na), and calcium (Ca) content. Results for differences in mineral balance were assessed as % (%) of intake by 15-day sums as follows: retention = dietary intake – urine + stool losses. RESULTS: Using a mixed model with repeated measures and follow-up contrast analyses, initial analysis shows no significant differences (P > 0.05) in % mineral retention (± SE) for K (control: 28.92 ± 7.19, French fries: 30.37 ± 5.81, potatoes: 26.39 ± 5.11, supplement: 34.52 ± 6.53), Na (control: 23.42 ± 10.34, French fries: 30.37 ± 8.03, potatoes: 20.15 ± 6.86, supplement: 26.47 ± 10.14), or Ca (control: 25.21 ± 11.23, French fries: 16.61 ± 13.47, potatoes: 24.22 ± 4.56, supplement: 31.46 ± 8.22). CONCLUSIONS: Although there appears to be no difference in mineral retention due to source, these findings may challenge the current dogma that K and Na intake are equivalent to urinary output, and raise the question of how retention in various tissues can influence health outcomes. FUNDING SOURCES: The Alliance for Potato Research and Education.