Dietary Nitrate – an Unrecognised Nutrient.

Background: Hypertension (high blood pressure) is a major risk factor for cardiovascular disease such as stroke, NICE [1]. Dietary nitrate supplements, including beetroot juice, may have positive effects on health: for example by reducing blood pressure (BP) Siervo et al. [2] and improving exercise tolerance in peripheral arterial disease Allen et al. [3]. However, nitrate is a strictly controlled, environmental contaminant and not regarded as a nutrient essential for health. Plasma [nitrate] and [nitrite] increase following ingestion of nitrate containing supplements, but few studies have used whole, nitrate-rich vegetables to supplement a normal diet. The purpose of this study was to assess the effects of supplementation with high- and low-nitrate vegetables on plasma [nitrate], [nitrite], and BP. Method: Following ethical approval, fifteen non-smoking, physically active males of 18-40 years of age were recruited between January 2011 and March 2012. In a randomised, balanced, cross-over design, participants received high- or low-nitrate vegetables for a 2- week period and, after a 2-week wash-out, participants received the remaining diet (lowor high-nitrate) for a 2-week period. Data were analysed using repeated-measures ANOVAs. Results: There were significant main and interaction effects by diet on plasma [nitrate] (P<0.05) and plasma [nitrite] (P<0.05). Post hoc tests revealed that high-nitrate diet significantly increased plasma [nitrate] (pre: 29.5±20.0 μM; post: 129.4±87.1 μM, P<0.05) and plasma [nitrite] (pre: 118.9±35.2 nM; post: 226.5 ± 89.3 nM, P<0.05). There were significant inverse correlations between changes in plasma [nitrate] and systolic BP (r =– 0.49, P<0.05), plasma [nitrate] and the mean arterial pressure (r =–0.44, P=0.05) and plasma [nitrite] and diastolic BP (r =–0.56, P<0.05). No significant changes were observed in these variables after the low-nitrate diet. Discussion: This is the first study to compare whole, fresh, high-nitrate and low-nitrate vegetables as a dietary intervention with potential to reduce BP. It was shown that increases in plasma concentrations of nitrate and nitrite were associated with a reduction in BP. These findings are comparable to previous studies using high-nitrate supplements, such as natural or concentrated beetroot juice or sodium nitrate (Siervo et al. [2]. Conclusion: The present findings support the hypothesis that increasing dietary nitrate intake in the form of nitrate-rich vegetables reduces BP, with major public health implications for dietary interventions to reduce hypertension. A population wide promotion of normal BP could substantially reduce the risk of stroke (Seshadri et al. [4].

Por que siguen siendo tan altas las tasas de mortalidad por malnutricion grave? / Why have mortality rates for severe malnutrition remained so high?

La revisión de las publicaciones que han aparecido en los últimos cinco decenios revela que la mediana de la tasa de letalidad de la malnutrición grave no se ha modificado en ese período y que suele oscilar de 20 a 30%, con los mayores porcentajes (50 a 60%) atribuibles a los casos de malnutrición edematosa. Una causa probable de la persistencia de la mortalidad elevada es el tratamiento inapropiado de los casos. Según una encuesta de centros de tratamiento en distintas partes del mundo (n = 79), es común que a los niños con enfermedad aguda se les prescriban dietas inadecuadas con un alto contenido de proteínas, energía y sodio y un bajo contenido de micronutrientes. Se encontró que ciertas prácticas que podrían acarrear consecuencias funestas, como la prescripción de diuréticos para el edema, estaban ampliamente difundidas. También se comprobó que muchos de los manuales de instrucción eran anticuados y encerraban contradicciones. Ya que se pueden lograr tasas bajas de mortalidad por malnutrición con los tratamientos apropiados, es preciso formular y aplicar pautas terapéuticas actualizadas, de carácter práctico y prescriptivo más que descriptivo, como parte de un programa integral de capacitación.

A review of the literature that has appeared over the past five decades indicates that the median case fatality from severe malnutrition has remained unchanged over this period and is typically 20­30%, with the highest levels (50­60%) being among those with edematous malnutrition. A likely cause of this continuing high mortality is faulty case-management. A survey of treatment centres worldwide (n = 79) showed that for acutely ill children, inappropriate diets that are high in protein, energy and sodium and low in micronutrients are commonplace. Practices that could have fatal consequences, such as prescribing diuretics for edema, were found to be widespread. Evidence of outmoded and conflicting teaching manuals also emerged. Since low mortality levels from malnutrition can be achieved using appropriate treatment regimens, updated treatment guidelines, which are practical and prescriptive rather than descriptive, need to be implemented as part of a comprehensive training programme.