Alexandra Kazaks

Can Dietary Sodium Intake Be Modified by Public Policy

Sodium chloride holds a unique position in the annals of human existence and science (1). For thousands of years, salts high value has made it the foundation of a society, a currency of trade, and cause for wars. Over the past century, sodium chloride has been the subject of intense scientific research to understand its role in human physiology and its impact on health. The latter has focused primarily on salts role in BP regulation, an issue fraught with controversy, as documented a decade ago (2) and still evident in the scientific literature (3,4). Since the first Surgeon Generals Report Healthy People: Promotion and Disease Prevention published in 1979 (5), public health guidelines have recommended that adults consume less salt. This culminated in 2003 with the Institute of Medicine (IOM) Electrolyte DRI Committee targeting 2300 mg/d as the safe upper level of sodium in the diet (6). The 2005 Dietary Guidelines recommended this same level for healthy adults and 1500 mg/d for individuals at risk of hypertension (7). As increasingly more restrictive guidelines have been introduced over the past 30 yr, scientific research has continued to provide new insights regarding the effectiveness and safety of lowering sodium intake. Some, but certainly not all, of the newer data have supported the sodium guidelines (8,9), although the feasibility of their implementation remains in question. It has been assumed that if adults better understood how to reduce sodium in their diets and if more low-sodium foods were available, more individuals would be able to achieve these levels. Public health experts throughout the world have devised strategies targeting greater compliance with the lower sodium recommendations. In the United States (US), a special IOM committee has recently been charged to formulate such strategies (10). Great Britain initiated an intense …

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.

Effect of oral magnesium supplementation on measures of airway resistance and subjective assessment of asthma control and quality of life in men and women with mild to moderate asthma: a randomized placebo controlled trial.

Background: Epidemiological data shows low dietary magnesium(Mg) may be related to incidence and progression of asthma. Objective To determine if long term(6.5 month) treatment with oral Mg would improve asthma control and increase serum measures of Mg status in men and women with mild-to-moderate asthma. Subjects: 55 males and females aged 21 to 55 years with mild to moderate asthma according to the 2002 National Heart, Lung, and Blood Institute(NHLBI) and Asthma Education and Prevention Program(NAEPP) guidelines and who used only beta-agonists or inhaled corticosteroids(ICS) as asthma medications were enrolled. Design: Subjects were randomly assigned to consume 340 mg(170 mg twice a day) of Mg or a placebo for 6.5 months. Measurements: Multiple measures of Mg status including serum, erythrocyte, urine, dietary, ionized and IV Mg were measured. Objective: markers of asthma control were: methacholine challenge test(MCCT) and pulmonary function test(PFT) results. Subjective validated questionnaires on asthma quality of life(AQLQ) and control(ACQ) were completed by participants. Markers of inflammation, including c-reactive protein(CRP) and exhaled nitric oxide(eNO) were determined. Results: The concentration of methacholine required to cause a 20% drop in forced expiratory volume in in minute(FEV1) increased significantly from baseline to month 6 within the Mg group. Peak expiratory flow rate(PEFR) showed a 5.8% predicted improvement over time(P = 0.03) in those consuming the Mg. There was significant improvement in AQLQ mean score units(P < 0.01) and in overall ACQ score only in the Mg group(P = 0.05) after 6.5 months of supplementation. Despite these improvements, there were no significant changes in any of the markers of Mg status. Conclusion: Adults who received oral Mg supplements showed improvement in objective measures of bronchial reactivity to methacholine and PEFR and in subjective measures of asthma control and quality of life.

Weight loss in individuals with metabolic syndrome given DASH diet counseling when provided a low sodium vegetable juice: a randomized controlled trial

BackgroundMetabolic syndrome, a constellation of metabolic risk factors for type 2 diabetes and cardiovascular disease, is one of the fastest growing disease entities in the world. Weight loss is thought to be a key to improving all aspects of metabolic syndrome. Research studies have suggested benefits from diets rich in vegetables and fruits in helping individuals reach and achieve healthy weights.ObjectiveTo evaluate the effects of a ready to serve vegetable juice as part of a calorie-appropriate Dietary Approaches to Stop Hypertension (DASH) diet in an ethnically diverse population of people with Metabolic Syndrome on weight loss and their ability to meet vegetable intake recommendations, and on their clinical characteristics of metabolic syndrome (waist circumference, triglycerides, HDL, fasting blood glucose and blood pressure).A secondary goal was to examine the impact of the vegetable juice on associated parameters, including leptin, vascular adhesion markers, and markers of the oxidative defense system and of oxidative stress.MethodsA prospective 12 week, 3 group (0, 8, or 16 fluid ounces of low sodium vegetable juice) parallel arm randomized controlled trial. Participants were requested to limit their calorie intake to 1600 kcals for women and 1800 kcals for men and were educated on the DASH diet. A total of 81 (22 men & 59 women) participants with Metabolic Syndrome were enrolled into the study. Dietary nutrient and vegetable intake, weight, height, leptin, metabolic syndrome clinical characteristics and related markers of endothelial and cardiovascular health were measured at baseline, 6-, and 12-weeks.ResultsThere were significant group by time interactions when aggregating both groups consuming vegetable juice (8 or 16 fluid ounces daily). Those consuming juice lost more weight, consumed more Vitamin C, potassium, and dietary vegetables than individuals who were in the group that only received diet counseling (p < 0.05).ConclusionThe incorporation of vegetable juice into the daily diet can be a simple and effective way to increase the number of daily vegetable servings. Data from this study also suggest the potential of using a low sodium vegetable juice in conjunction with a calorie restricted diet to aid in weight loss in overweight individuals with metabolic syndrome.

The use of a commercial vegetable juice as a practical means to increase vegetable intake: a randomized controlled trial

BackgroundRecommendations for daily dietary vegetable intake were increased in the 2005 USDA Dietary Guidelines as consumption of a diet rich in vegetables has been associated with lower risk of certain chronic health disorders including cardiovascular disease. However, vegetable consumption in the United States has declined over the past decade; consequently, the gap between dietary recommendations and vegetable intake is widening. The primary aim of this study is to determine if drinking vegetable juice is a practical way to help meet daily dietary recommendations for vegetable intake consistent with the 2005 Dietary Guidelines and the Dietary Approaches to Stop Hypertension (DASH) diet. The secondary aim is to assess the effect of a vegetable juice on measures of cardiovascular health.MethodsWe conducted a 12-week, randomized, controlled, parallel-arm study consisting of 3 groups of free-living, healthy volunteers who participated in study visits at the Ragle Human Nutrition Research Center at the University of California, Davis. All subjects received education on the DASH diet and 0, 8 or 16 fluid ounces of vegetable juice daily. Assessments were completed of daily vegetable servings before and after incorporation of vegetable juice and cardiovascular health parameters including blood pressure.ResultsWithout the juice, vegetable intake in all groups was lower than the 2005 Dietary Guidelines and DASH diet recommendations. The consumption of the vegetable juice helped participants reach recommended intake. In general, parameters associated with cardiovascular health did not change over time. However, in the vegetable juice intervention groups, subjects who were pre-hypertensive at the start of the study showed a significant decrease in blood pressure during the 12-week intervention period.ConclusionIncluding 1-2 cups of vegetable juice daily was an effective and acceptable way for healthy adults to close the dietary vegetable gap. Increase in daily vegetable intake was associated with a reduction in blood pressure in subjects who were pre-hypertensive at the start of the trial.Trial RegistrationClinicaltrials.gov NCT01161706

Multiple Measures of Magnesium Status Are Comparable in Mild Asthma and Control Subjects

Magnesium (Mg) may be a significant factor in asthma management. There is debate about how to best assess Mg status. We evaluated multiple indices of Mg status and lung function in 52 people with mild to moderate asthma and 47 controls. Mg measures included serum total, ionized and erythrocyte Mg, intravenous Mg load retention and dietary recall. Methacholine challenge and pulmonary function tests were used to assess diagnosis and severity of asthma. Mg status was similar in asthma and controls, and was not correlated to lung function. Total serum Mg closely reflected ionized Mg and offers a useful clinical diagnostic monitor.

Obesity: food intake

This article discusses some of the changes in our food environment that have encouraged overeating and some research that underlies successful weight loss and maintenance of weight loss. The discussion of these topics will help in the guidance of patients to develop personalized eating plans and reduce energy intake, in part by recognizing the contributions of fat, concentrated carbohydrates, and large portion sizes.

Response to “Salt: The Dying Echoes of the Food Industry”

To the Editor: Cappuccio et al.’s letter, “Salt: The Dying Echoes of the Food Industry,”1 concerning our recent article2 does not address our article’s primary data or its analysis or provide any countervailing scientific data to argue against its interpretation. As our data indicated, “human sodium intake, as defined by 24-hour urinary sodium excretion (24-h UNaV), is characterized by a narrow range that is remarkably reproducible over at least 5 decades and across 45 countries.” In fact, several of the letter’s authors’ own reports provided scientific data included in our analysis.2 Furthermore, Cappuccio et al. offer no data to refute the decades of clinical and basic research we cited in support of the 24-h UNaV data characterizing a normal distribution of human sodium intake that is determined by appetite-control circuits in the brain, not the food supply. Instead, the authors extensively cite their many prior opinion pieces, none of which offers scientific data relevant to the concept of a “normal range of human sodium intake.” Their letter focuses primarily on the controversy regarding the effect of sodium intake reduction on cardiovascular disease (CVD) outcomes. Their basic premise is that “the issue is no longer whether reducing sodium (salt) is of public benefit, it is how best to reduce population salt intake.”1 That statement ignores the principle findings of the recent Institute of Medicine (IOM) report Sodium Intake in Populations,3 which challenged the scientific basis of the current US sodium guidelines. Cappuccio et al. suggest that our scientific data and findings, as well as those of the IOM, by inference, represent an ongoing conspiracy by the food industry that has included “biasing research findings, co-opting policy makers and health professionals, [and] lobbying politicians.” That grandiose hypothesis, by necessity in the case of our data, would mean the food industry manipulated the collections of several hundreds of thousands of 24-h UNaV samples from 69,011 individuals in 45 different countries for more than 5 decades. That allegation is, quite frankly, ludicrous. The opinion-based nature of Cappuccio et al.’s letter is evident in their challenges to the following issues, which they incorrectly characterize as “myths.” Issue 1. They offer no scientific data on the evolution of human sodium intake. Instead they cite the long-touted extrapolation of the very low sodium intake of an isolated primitive society with stunted growth, markedly elevated plasma renin activity (PRA) and aldosterone levels, short lifespan, and a history of extreme violence, including cannibalism.4 They provide no data for their contention that higher sodium intake is “recent” and ignore the clearly established findings in societies spanning several thousand years in which salt was a cornerstone of cultural and economic development.5 Issue 2. Cappuccio et al. provide no evidence challenging the cited physiological basis of our finding of a “normal range” for human sodium intake. The extensive evidence provided in our AJH paper— including findings from clinical trials6 and the neurosciences,7 the physiology of the relationship between PRA and 24-h UNaV,8 and documentation of the remarkable cultural diversity of 24-h UNaV clearly support the concept of a “normal range.” They offer no plausible, scientific explanation as to how nearly 70,000 people consuming the unique culinary characteristics of 45 countries observed for over 5 decades could possibly excrete sodium within such a narrow range unless it reflects tight physiologic control. Issue 3. The authors question our definition of the lower range of sodium intake. The 115 mmol/day we noted as representing the lower range of normal was defined by standard statistical analysis where 2 standard deviations defined the lower and upper range of the populations’ intake.2 Further, the “classic” PRA/UNaV data portrayed in Figure 3 of our article was derived directly from scientific data published in the New England Journal of Medicine in 1972.8 Published 40 years earlier, that data predicted, within 3 mmol/day, the mean human sodium intake the data in our article2 estimated. The study that Cappuccio et al. cite9 is most interesting not because it showed that modest sodium reduction in white hypertensive persons was associated with a significant increase in PRA, but for 2 other important points they mentioned in their article but not their letter. First, their recognition of the limited demographic variability in trials of sodium restriction is a critical issue. As noted in the IOM report, there is inadequate scientific data on the effects of Correspondence: David A. McCarron (dmccarron@mccarrongroup.com).

Magnesium Links to Asthma Control

Asthma is a significant public health burden that affects 25.6 million people in the United States [1] and more than 200 million people worldwide [2]. The disease is a major cause of illness and disability. Annual costs due to asthma in the United States have been estimated at more than

No significant relationship between exhaled nitric oxide and body mass index in people with asthma

20 billion in direct costs for medications and physician and hospital visits and in indirect costs such as lost productivity. In 2008, asthma accounted for 14.2 million lost workdays [3]. Asthma is a disease characterized by episodes of reversible narrowing of the airways in response to a wide range of endogenous and environmental triggers. It occurs in individuals who are predisposed to develop the disease as a result of genetic and environmental factors. Symptoms, caused by inflammation and smooth muscle contraction in the bronchioles, can vary from mild chest tightness, shortness of breath, and coughing or wheezing to respiratory failure and death [4]. Currently, there is no cure for asthma. The disease is managed by taking appropriate medication and minimizing contact with environmental triggers such as air pollution, tobacco smoke, pets, dust mites, cockroach allergens, and mold. Other common causes of asthma exacerbations include respiratory infections, stress, and even exercise [5].