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Potassium is an essential nutrient of concern according to recent Dietary Guidelines for Americans Advisory Committees, with less than 3% of the population meeting the current adequate intake (AI) level of 4700mg/d. Increases in potassium intake have been linked to improvements in cardiovascular and other metabolic health outcomes. Blood pressure (BP) is currently the primary criterion for determining potassium requirements. In this clinical trial, we assessed the effects of increasing potassium intake on BP and microcirculation (endothelial function). Thirty pre-hypertensive-to-hypertensive (Systolic BP ≥ 120mmHg) 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 potassium interventions including a basal diet (control) of 2300mg/d(~60mmol/d), and three periods of an additional 1000mg/d(3300mg/d(~85mmol/d) total) of potassium in the form of potatoes (baked, boiled, or pan-heated with no additional fat), French fries, or a potassium gluconate supplement. Each intervention period was separated by two or more weeks of wash out. Blood pressure was measured in triplicate using manual auscultation on days 1, 4, 6, 8, 11, 13, 15, 16, and 17 of each intervention. Microvascular and endothelial function were assessed via thermal hyperemia, utilizing laser Doppler flowmetry (LDF), at baseline and at the end of each intervention. Results for differences in both SBP and DBP ± SE were assessed at the end treatment (average of day 15, 16, and 17 measurements) using a mixed model with repeated measures and Dunnett adjustment (P < 0.05), with no significant differences among groups (control: 128.7 ± 2.1/ 83.6 ± 1.6, French fries: 127.7 ± 2.2/ 83.7 ± 1.6, potatoes: 127.6 ± 2.3/ 85.1 ± 1.6, supplement: 128.0 ± 2.2/ 83.7 ± 1.7). Utilizing the same statistical analysis, there were also no significant differences in endothelial function (measured as percent of cutaneous vascular conductance max (%CVCmax) ± SE) among groups (control: 87.4 ± 1.5%, French Fries: 87.7 ± 1.4%, potatoes: 88.3 ± 1.1%, supplement: 88.9 ± 1.0%). In this small, controlled feeding study of short duration, increased potassium from potatoes or supplement achieved 70% of recommended intakes, but had no significant benefit to blood pressure or microvascular function in men and women with higher cardiometabolic risk.

Introduction: Hypertension is a major risk factor for CVD affecting 34% of American adults. High sodium (Na) intake is identified as a modifiable risk factor for high blood pressure, but our ability to assess Na intake is poor. The gold standard is to measure Na excretion in a 24h urine collection, but this is burdensome. An alternative method is to predict 24h Na excretion from a spot urine sample. However, we do not know how well predicted 24h Na excretion reflects intake, the true outcome of interest, or the ideal time to collect a spot urine sample. These gaps can only be filled using a controlled feeding study in which intake is known and timing of urine collections is controlled. Hypothesis: We hypothesized that, with currently available equations, 24h Na excretion predicted from spot urine samples will not accurately reflect intake. Methods: This is a secondary analysis of a randomized, multi-phase, crossover, full-feeding trial in healthy adults ( n = 39, aged 29.7 ± 11.2 y). Data from the two control phases were used in which dietary intake and testing conditions were identical. Participants ate three meals in a clinic setting and spot urine samples were collected every 2 hours as part of a 24h collection. Urine samples were analyzed for sodium, potassium, and creatinine. The INTERSALT equations were used to predict 24h Na excretion from each of the 9 spot urine samples collected. Predicted 24h Na excretion values were compared with observed 24h excretion and known dietary intake using repeated measures ANOVA. Intra-class correlations for each timed spot urine sample were calculated to determine the variability in average spot urine Na excretion between the two control phases. Results: Predicted 24h Na excretion using the spot urines at hour 10, 12, overnight, and early morning collection were not significantly different from observed 24h Na excretion (all p ≥ 0.21). However, predicted 24h Na excretion underestimates observed 24h Na excretion by about >600 mg. Importantly, all predicted 24h excretions as well as observed 24h excretion were significantly lower than intake by >1000 mg (all p < 0.001). Intraclass correlations were significant at hour 0, 2, 8, 12, and evening/overnight (all p < 0.05), suggesting low day-to-day variability in Na excretion at these times. Conclusions: Regardless of time of spot urine collection, predicted 24h Na excretion is lower than Na intake, suggesting currently-available equations do not provide adequate estimates of Na intake. The next step is to develop equations to accurately predict Na intake from a controlled feeding study model using spot urine samples collected at a time when Na excretion is consistent from day to day. These improved equations could be used to implement effective dietary interventions to reduce blood pressure and CVD risk.

Prebiotics and phytoestrogens have sparked great interest because evidence indicates that the consumption of these dietary constituents leads to lower cholesterol levels and inhibition of postmenopausal bone loss. The aim of this study was to determine the effect of both a prebiotic (Synergy) and a phytoestrogen (genistein) on bone and blood lipid levels in an animal model of postmenopausal women.A 4-week feeding study was conducted in 5-month-old ovariectomized (OVX) Sprague-Dawley rats to examine the effect of genistein, Synergy (a prebiotic), and genistein and Synergy combined on bone density and strength, calcium metabolism, and lipid biomarkers. There were six treatment groups: sham control, OVX control, OVX rats receiving daily estradiol injections, and OVX rats receiving an AIN-93M diet supplement with 200 ppm genistein, with 5% Synergy or with 200 ppm genistein and 5% Synergy combined.The rats receiving genistein had significantly lower total serum cholesterol concentrations than OVX rats in the control group (17%), OVX rats receiving daily estradiol injections (14%), and OVX rats fed the 5% Synergy diet (19%). Consumption of Synergy improved calcium absorption efficiency (41%) compared with nonconsumption (OVX control). Sham control rats had a significantly higher femoral bone density, as determined by underwater weighing, than did the rats in all of the OVX groups. Genistein consumption restored total and trabecular bone mineral density at the distal femur similar to the levels of sham rats.Genistein supplementation imparts modest heart health benefits and improves bone geometry at the distal femur, and prebiotic consumption (Synergy) results in improved calcium utilization strength in ovariectomized rats, but the combination produced no synergistic effects.