Low mineral intake is associated with high systolic blood pressure in the Third and Fourth National Health and Nutrition Examination Surveys: could we all be right?

Analysis of the first National Health and Nutrition Examination Survey (NHANES) in 1984 revealed that a dietary pattern low in mineral intake, specifically calcium, potassium, and magnesium, was associated with hypertension in American adults. Using more recent survey data from NHANES III and NHANES IV, we re-examined the validity of this relationship. Blood pressure (BP) and nutrient intake data from 10,033 adult participants in NHANES III and 2311 adults in NHANES IV revealed findings similar to those of the earlier analysis, demonstrating that the association between inadequate mineral consumption and higher BP is valid and has persisted over two decades. Exploring this relationship further, we separated untreated hypertensive persons by hypertension type (systolic, diastolic, or both), and observed that the BP effect of low mineral intake was most pronounced in those with only systolic hypertension. We also observed that sodium intake was significantly lower in the systolic hypertension group and significantly higher in the diastolic hypertension group compared with the other groups. The nutrient pattern in the combined hypertension group was similar to that of the normotensive group. These findings may help to explain the inconsistent responses generally observed in dietary intervention studies, and they highlight the possible importance of tailored nutritional recommendations for hypertension based on hypertension category and individual dietary practices. Although randomized controlled trials are needed to characterize further the relationship between nutrient intake and hypertension type, these findings indicate that dietary management of hypertension may be more effective if the focus is on the overall nutritional profile rather than single-nutrient intake as currently recommended for most patients.

Symptoms of postpartum depression and breastfeeding.

Despite important health benefits, the presence of depressive symptoms may decrease the prevalence of breastfeeding. The current study assessed the relationship between depressive symptoms and breastfeeding at 6 and 12 weeks postpartum. Participants were recruited from a cohort completing a clinical trial of calcium for prevention of preeclampsia. At 6 weeks postpartum, the Edinburgh Postnatal Depression Scale (EPDS) was completed by mail. At 12 weeks postpartum, the EPDS was completed at an outpatient visit. There was an inverse relationship between depressive symptoms and breastfeeding at 6 weeks postpartum (P<.001) but not at 12 weeks. This relationship persisted even after controlling for prior history of depression, increased life stress, and current psychoactive medication. The results suggest that depressive symptoms early in the postpartum period may lower the prevalence of breastfeeding.

The significance of duration and amount of sodium reduction intervention in normotensive and hypertensive individuals: a meta-analysis.

The purpose of this meta-analysis was to establish the time for achievement of maximal blood pressure (BP) efficacy of a sodium reduction (SR) intervention and the relation between the amount of SR and the BP response in individuals with hypertension and normal BP. Relevant studies were retrieved from a pool of 167 randomized controlled trials (RCTs) published in the period 1973-2010 and integrated in meta-analyses. Fifteen relevant RCTs were included in the maximal efficacy analysis. After initiation of sodium reduction (range: 55-118 mmol/d), there were no significant differences in systolic blood pressure (SBP) or diastolic blood pressure (DBP) between measurements at weeks 1 and 2 (∆SBP: -0.18 mmHg/∆DBP: 0.12 mmHg), weeks 1 and 4 (∆SBP: -0.50 mmHg/∆DBP: 0.35 mmHg), weeks 2 and 4 (∆SBP: -0.20 mmHg/∆DBP: -0.10 mmHg), weeks 2 and 6 (∆SBP: -0.50 mmHg/∆DBP: -0.42 mmHg), and weeks 4 and 6 (∆SBP: 0.39 mmHg/∆DBP: -0.22 mmHg). Eight relevant RCTs were included in the dose-response analysis, which showed that within the established usual range of sodium intake [<248 mmol/d (5700 mg/d)], there was no relation between the amount of SR (range: 136-188 mmol) and BP outcome in normotensive populations [∆SBP: 0.99 mm Hg (95% CI: -2.12, 4.10 mm Hg), [corrected] P = 0.53; ∆DBP: -0.49 mm Hg (95% CI: -4.0, 3.03), P = 0.79]. In contrast, prehypertensive and hypertensive populations showed a significant dose-response relation (range of sodium reduction: 77-140 mmol/d) [∆SBP: 6.87 mmHg (95% CI: 5.61, 8.12, P < 0.00001); ∆DBP: 3.61 mmHg (95% CI: 2.83, 4.39, P < 0.00001)]. Consequently, the importance of kinetic and dynamic properties of sodium reduction, as well as baseline BP, should probably be considered when establishing a policy of sodium reduction.

Estimated healthcare savings associated with adequate dairy food intake.

Medical literature that has coalesced during the past two to three decades has identified adequate intake of nutrients from dairy foods as a common factor in the reduction of the disease burden of several common medical conditions. These include obesity, hypertension, type 2 diabetes, osteoporosis, kidney stones, certain outcomes of pregnancy, and some cancers. Treatment of these disorders, particularly cardiovascular, consumes a significant portion of the United States' healthcare budget. Drawing on accumulated data from prospective longitudinal studies and randomized controlled trials, this article summarizes the evidence of the net benefits of increased dairy food intake on these conditions, their outcomes, and their costs. Estimated improvements in outcomes were combined with available data on annual costs of the respective disorders. From the calculated annual impact, we generated first-year and fifth-year healthcare cost savings that would accrue if adult Americans simply increased their intake of dairy foods to the currently recommended 3 to 4 servings/d. Using conservative estimates of potential benefit, we project first-year savings of approximately 26 billion dollars and 5-year cumulative savings in excess of 200 billion dollars.

Blood pressure and mesenteric resistance arterial function after spaceflight.

Ground studies indicate that spaceflight may diminish vascular contraction. To examine that possibility, vascular function was measured in spontaneously hypertensive rats immediately after an 18-day shuttle flight. Isolated mesenteric resistance arterial responses to cumulative additions of norepinephrine, acetylcholine, and sodium nitroprusside were measured using wire myography within 17 h of landing. After flight, maximal contraction to norepinephrine was attenuated (P < 0.001) as was relaxation to acetylcholine (P < 0.001) and sodium nitroprusside (P < 0.05). At high concentrations, acetylcholine caused vascular contraction in vessels from flight animals but not in vessels from vivarium control animals (P < 0.05). The results are consistent with data from ground studies and indicate that spaceflight causes both endothelial-dependent and endothelial-independent alterations in vascular function. The resulting decrement in vascular function may contribute to orthostatic intolerance after spaceflight.

Calcium metabolism and cardiovascular function after spaceflight.

To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P < 0.001), elevated parathyroid hormone levels (P < 0.001), reduced calcitonin levels (P < 0.05), unchanged 1,25(OH)(2)D(3) levels, and elevated skull (P < 0.01) and reduced femur bone mineral density. Basal and thrombin-stimulated platelet free calcium (intracellular calcium concentration) were also reduced (P < 0.05). There was a tendency for indirect systolic BP to be reduced in conscious flight animals (P = 0.057). However, mean arterial pressure was elevated (P < 0.001) after anesthesia. Dietary calcium altered all aspects of calcium metabolism (P < 0.001), as well as BP (P < 0.001), but the only interaction with flight was a relatively greater increase in ionized calcium in flight animals fed low- compared with high-calcium diets (P < 0.05). The results indicate that 1) flight-induced disruptions of calcium metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

Adequate nutrient intake can reduce cardiovascular disease risk in African Americans.

Cardiovascular disease kills nearly as many Americans each year as the next seven leading causes of death combined. The prevalence of cardiovascular disease and most of its associated risk factors is markedly higher and increasing more rapidly among African Americans than in any other racial or ethnic group. Improving these statistics may be simply a matter of improving diet quality. In recent years, a substantial and growing body of evidence has revealed that dietary patterns complete in all food groups, including nutrient-rich dairy products, are essential for preventing and reducing cardiovascular disease and the conditions that contribute to it. Several cardiovascular risk factors, including hypertension, insulin resistance syndrome, and obesity, have been shown to be positively influenced by dietary patterns that include adequate intake of dairy products. The benefits of nutrient-rich dietary patterns have been specifically tested in randomized, controlled trials emphasizing African American populations. These studies demonstrated proportionally greater benefits for African Americans without evidence of adverse effects such as symptoms of lactose intolerance. As currently promoted for the prevention of certain cancers and osteoporosis, regular consumption of diets that meet recommended nutrient intake levels might also be the most effective approach for reducing cardiovascular disease risk in African Americans.

What determines human sodium intake: policy or physiology?

Past and current U.S. sodium and health policy focused on population-wide reductions in sodium intake. Underlying that policy are a number of assumptions that recent scientific publications challenged. The assumptions include the following: 1) that current intakes are excessive; 2) that the "healthy range" must be below current intakes; 3) that sodium intake can be substantially reduced by public policy; 4) that human intake is dictated by the sodium content of the food supply; and 5) that, unlike all other essential nutrients in which a healthy range is defined by a Gaussian distribution, lower sodium intake is always better. Drawing on the most current published evidence, this review addresses each of these long-standing assumptions. Based on worldwide surveys that assessed sodium intake by 24-h urinary sodium measurements, it is now evident that, across 45 societies and 5 decades, humans consume a reproducible, narrow range of sodium: ∼2600­4800 mg/d. This range is independent of the food supply, verifiable in randomized controlled trials, consistent with the physiologic regulators of sodium intake and is not modifiable by public policy interventions. These findings indicate that human sodium intake is controlled by physiology and cannot be modified by public health policies.

Normal range of human dietary sodium intake: a perspective based on 24-hour urinary sodium excretion worldwide.

BACKGROUND: The recommendation to restrict dietary sodium for management of hypertensive cardiovascular disease assumes that sodium intake exceeds physiologic need, that it can be significantly reduced, and that the reduction can be maintained over time. In contrast, neuroscientists have identified neural circuits in vertebrate animals that regulate sodium appetite within a narrow physiologic range. This study further validates our previous report that sodium intake, consistent with the neuroscience, tracks within a narrow range, consistent over time and across cultures. METHODS: Peer-reviewed publications reporting 24-hour urinary sodium excretion (UNaV) in a defined population that were not included in our 2009 publication were identified from the medical literature. These datasets were combined with those in our previous report of worldwide dietary sodium consumption. RESULTS: The new data included 129 surveys, representing 50,060 participants. The mean value and range of 24-hour UNaV in each of these datasets were within 1 SD of our previous estimate. The combined mean and normal range of sodium intake of the 129 datasets were nearly identical to that we previously reported (mean = 158.3±22.5 vs. 162.4±22.4 mmol/d). Merging the previous and new datasets (n = 190) yielded sodium consumption of 159.4±22.3 mmol/d (range = 114-210 mmol/d; 2,622-4,830mg/d). CONCLUSIONS: Human sodium intake, as defined by 24-hour UNaV, is characterized by a narrow range that is remarkably reproducible over at least 5 decades and across 45 countries. As documented here, this range is determined by physiologic needs rather than environmental factors. Future guidelines should be based on this biologically determined range.

Community-based priorities for improving nutrition and physical activity in childhood.

Overweight among America's youth has prompted a large response from foundations, government, and private organizations to support programmatic interventions. The architecture for many of these programs was derived from "experts," whereas the perspective of families, and communities--those most affected and most instrumental in altering behavior--is rarely the driving force. Shaping America's Youth (SAY) was established to assess programs that target nutrition and physical activity and to promote the necessary family and community input. In a 2004 report, SAY documented how community efforts are motivated, funded, structured, and evaluated. It identified discordance between that effort and the opinions of experts. To ensure that the voices of families and communities are integrated into such local and national policies and programs, SAY initiated a unique series of 5-day-long town meetings, input from which was independently statistically analyzed. Across a range of demographics, the results indicated that participants perceive the barriers and solutions similarly. There was broad agreement that the family has primary responsibility, starting with a need to focus on improved quality and duration of family time directed at nutrition and activity. Concurrently they identified needed actions from external sources, including clear and consistent nutrition information; ready access to healthy foods; and a built environment that promotes physical activity. Rather than one-dimensional or governmental solutions, they expressed a need for community-based partnerships integrating health care, education, environment, government, and business. Although this citizen-engagement process did not identify specific actions, it defined basic steps that communities must integrate into future approaches.