The American Heart Association Scientific Statement on salt sensitivity of blood pressure: Prompting consideration of alternative conceptual frameworks for the pathogenesis of salt sensitivity?

The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise

INTRODUCTION

The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota.

AREAS COVERED

Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected.

EXPERT OPINION

The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.

Review Article on Molecular Mechanism of Regulation of Hypertension by Macro-elements (Na, K, Ca and Mg), Micro-elements/Trace Metals (Zn and Cu) and Toxic Elements (Pb and As)

Hypertension (HT) is a medical condition arising due to increase in blood pressure (BP) prevalent worldwide. The balanced dietary intakes of macro-elements and micro-elements including Na, K, Ca, Mg, Zn, and Cu have been described to maintain BP in humans by regulating the osmolarity of blood, cells/tissues, prevention of generation of oxidative and nitrosative stress (OANS), and endothelial damage through their functioning as important components of renin-angiotensin-aldosterone system (RAAS), antioxidant enzyme defense system, and maintenance of blood vascular-endothelial and vascular smooth muscle cell (VSMC) functions. However, inadequate/excess dietary intakes of Na/K, Ca/Mg, and Zn/Cu along with higher Pb and As exposures recognized to induce HT through common mechanisms including the followings: endothelial dysfunctions due to impairment of vasodilatation, increased vasoconstriction and arterial stiffness, blood clotting, inflammation, modification of sympathetic activity and higher catecholamine release, increased peripheral vascular resistance, and cardiac output; increased OANS due to reduced and elevated activities of extracellular superoxide dismutase and NAD(P)H oxidase, less nitric oxide bioavailability, decrease in cGMP and guanylate cyclase activity, increase in intracellular Ca2+ ions in VSMCs, and higher pro-inflammatory cytokines; higher parathyroid and calcitriol hormones; activation/suppression of RAAS resulting imbalance in blood Na+, K+, and water regulated by renin, angiotensin II, and aldosterone through affecting natriuresis/kaliuresis/diuresis; elevation in serum cholesterol and LDL cholesterol, decrease in HDL cholesterol due to defect in lipoprotein metabolism. The present study recommends the need to review simple dietary mineral intervention studies/supplementation trials before keeping their individual dietary excess intakes/exposures in consideration because their interactions lead to elevation and fall of their concentrations in body affecting onset of HT.

Dietary factors and hypertension risk in West Africa: a systematic review and meta-analysis of observational studies

BACKGROUND

Contrary to North America and Europe, the prevalence of hypertension is rising in West Africa. Although diet is implicated as a contributor to this trend, nutritional guidelines in West Africa are not tailored to address this concern. This study aimed to address this limitation by investigating dietary factors common to West Africa and evaluating their association with hypertension.

METHODS

PubMed, Scopus, Web of Science, and Medline were searched to identify studies that investigated diet and hypertension in West African adults. All meta-analyses used a generic inverse-variance random effects model, with subgroup analyses by age, BMI, and study location, and were performed in R.

RESULTS

Three thousand, two hundred ninety-eight studies were identified, of which 31 ( n  = 48 809 participants) satisfied inclusion criteria - all cross-sectional. Meta-analyses of the association between dietary factors and hypertension included dietary fat [odds ratio (OR) = 1.76; 95% confidence interval (95% CI) 1.44-2.14; P  < 0.0001], red meat (OR = 1.51; 95% CI: 1.04-2.18; P  = 0.03), junk-food (OR = 1.41; 95% CI: 1.19-1.67; P  < 0.0001), dietary salt (OR = 1.25; 95% CI: 1.12-1.40; P  < 0.0001), alcohol (OR = 1.17; 95% CI: 1.03-1.32; P  = 0.013), and 'fruits and vegetables' (OR = 0.80; 95% CI: 0.24-1.17; P  < 0.0001). Subgroup analyses suggested that 'fruit and vegetable' consumption is less protective in the elderly.

CONCLUSION

High consumption of dietary salt, red meat, dietary fat, junk food, and alcohol are associated with increased odds of hypertension, whereas high fruit and vegetable appear protective. This region-specific evidence will support the development of nutritional assessment tools for clinicians, patients, and researchers aiming to reduce hypertension in West Africa.

Continuous ingestion of sodium chloride solution promotes allergen absorption and may exacerbate allergy symptoms on ovalbumin-induced food allergy in mice

Various studies have reported relationships between salt intake and diseases, such as hypertension, cardiovascular disease, stroke, gastric cancer, and bronchial asthma. However, no reports exist on the relationship between salt intake and food allergies. In this study, we investigated the effect of continuous ingestion of sodium chloride (NaCl) on allergy symptoms using a mouse model of food allergy. BALB/c mice were divided into four groups of 6-8 animals each. The control-water group (CW) and sensitization-water group (SW) groups were provided free access to water, and the control-1% NaCl group (CS) and sensitization-1% NaCl group (SS) groups were provided a 1% NaCl solution. The SW and SS groups were sensitized with 50 µg ovalbumin (OVA) at 2 timepoints by intraperitoneal injection. After oral administration of OVA, anaphylactic response was measured and blood was collected. The mice were sacrificed, and serum levels of OVA and anti-OVA immunoglobulin (Ig)E and IgG1 were measured by enzyme-linked immunosorbent assays. The sodium ion (Na⁺) concentrations in duodenal and jejunal extracts were measured using a Na⁺ ion meter. The results suggested that continuous ingestion of a 1% NaCl solution for 36 days promoted allergen absorption and may have aggravated allergy symptoms in the mice. However, NaCl ingestion did not affect Na⁺ concentrations in the small intestine or OVA-specific antibody production.

Collectrin (Tmem27) deficiency in proximal tubules causes hypertension in mice and a TMEM27 variant associates with blood pressure in males in a Latino cohort

Collectrin (Tmem27), an angiotensin-converting enzyme 2 homologue, is a chaperone of amino acid transporters in the kidney and endothelium. Global collectrin knockout (KO) mice have hypertension, endothelial dysfunction, exaggerated salt sensitivity, and diminished renal blood flow. This phenotype is associated with altered nitric oxide and superoxide balance and increased proximal tubule (PT) Na+/H+ exchanger isoform 3 (NHE3) expression. Collectrin is located on the X chromosome where genome-wide association population studies have largely been excluded. In the present study, we generated PT-specific collectrin KO (PT KO) mice to determine the precise contribution of PT collectrin in blood pressure homeostasis. We also examined the association of human TMEM27 single-nucleotide polymorphisms with blood pressure traits in 11,926 Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Hispanic/Latino participants. PT KO mice exhibited hypertension, and this was associated with increased baseline NHE3 expression and diminished lithium excretion. However, PT KO mice did not display exaggerated salt sensitivity or a reduction in renal blood flow compared with control mice. Furthermore, PT KO mice exhibited enhanced endothelium-mediated dilation, suggesting a compensatory response to systemic hypertension induced by deficiency of collectrin in the PT. In HCHS/SOL participants, we observed sex-specific single-nucleotide polymorphism associations with diastolic blood pressure. In conclusion, loss of collectrin in the PT is sufficient to induce hypertension, at least in part, through activation of NHE3. Importantly, our model supports the notion that altered renal blood flow may be a determining factor for salt sensitivity. Further studies are needed to investigate the role of the TMEM27 locus on blood pressure and salt sensitivity in humans.NEW & NOTEWORTHY The findings of our study are significant in several ways: 1) loss of an amino acid chaperone in the proximal tubule is sufficient to cause hypertension, 2) the results in global and proximal tubule-specific collectrin knockout mice support the notion that vascular dysfunction is required for salt sensitivity or that impaired renal tubule function causes hypertension but is not sufficient to cause salt sensitivity, and 3) our study is the first to implicate a role of collectrin in human hypertension.

Inverse Salt Sensitivity of Blood Pressure Is Associated with an Increased Renin-Angiotensin System Activity

High and low sodium diets are associated with increased blood pressure and cardiovascular morbidity and mortality. The paradoxical response of elevated BP in low salt diets, aka inverse salt sensitivity (ISS), is an understudied vulnerable 11% of the adult population with yet undiscovered etiology. A linear relationship between the number of single nucleotide polymorphisms (SNPs) in the dopamine D₂ receptor (DRD2, rs6276 and 6277), and the sodium myo-inositol cotransporter 2 (SLC5A11, rs11074656), as well as decreased expression of these two genes in urine-derived renal proximal tubule cells (uRPTCs) isolated from clinical study participants suggest involvement of these cells in ISS. Insight into this newly discovered paradoxical response to sodium is found by incubating cells in low sodium (LS) conditions that unveil cell physiologic differences that are then reversed by mir-485-5p miRNA blocker transfection and bypassing the genetic defect by DRD2 re-expression. The renin-angiotensin system (RAS) is an important counter-regulatory mechanism to prevent hyponatremia under LS conditions. Oversensitive RAS under LS conditions could partially explain the increased mortality in ISS. Angiotensin-II (AngII, 10 nmol/L) increased sodium transport in uRPTCs to a greater extent in individuals with ISS than SR. Downstream signaling of AngII is verified by identifying lowered expression of nuclear factor erythroid 2-related factor 2 (NRF2), CCCTC-binding factor (CTCF), and manganese-dependent mitochondrial superoxide dismutase (SOD2) only in ISS-derived uRPTCs and not SR-derived uRPTCs when incubated in LS conditions. We conclude that DRD2 and SLC5A11 variants in ISS may cause an increased low sodium sensitivity to AngII and renal sodium reabsorption which can contribute to inverse salt-sensitive hypertension.

Inverse Salt Sensitivity of Blood Pressure: Mechanisms and Potential Relevance for Prevention of Cardiovascular Disease

PURPOSE OF REVIEW

To review the etiology of inverse salt sensitivity of blood pressure (BP).

RECENT FINDINGS

Both high and low sodium (Na⁺) intake can be associated with increased BP and cardiovascular morbidity and mortality. However, little is known regarding the mechanisms involved in the increase in BP in response to low Na⁺ intake, a condition termed inverse salt sensitivity of BP, which affects approximately 15% of the adult population. The renal proximal tubule is important in regulating up to 70% of renal Na⁺ transport. The renin-angiotensin and renal dopaminergic systems play both synergistic and opposing roles in the regulation of Na⁺ transport in this nephron segment. Clinical studies have demonstrated that individuals express a "personal salt index" (PSI) that marks whether they are salt-resistant, salt-sensitive, or inverse salt-sensitive. Inverse salt sensitivity results in part from genetic polymorphisms in various Na⁺ regulatory genes leading to a decrease in natriuretic activity and an increase in renal tubular Na⁺ reabsorption leading to an increase in BP. This article reviews the potential mechanisms of a new pathophysiologic entity, inverse salt sensitivity of BP, which affects approximately 15% of the general adult population.

Mechanism-based strategies to prevent salt sensitivity and salt-induced hypertension

High-salt diets are a major cause of hypertension and cardiovascular (CV) disease. Many governments are interested in using food salt reduction programs to reduce the risk for salt-induced increases in blood pressure and CV events. It is assumed that reducing the salt concentration of processed foods will substantially reduce mean salt intake in the general population. However, contrary to expectations, reducing the sodium density of nearly all foods consumed in England by 21% had little or no effect on salt intake in the general population. This may be due to the fact that in England, as in other countries including the U.S.A., mean salt intake is already close to the lower normal physiologic limit for mean salt intake of free-living populations. Thus, mechanism-based strategies for preventing salt-induced increases in blood pressure that do not solely depend on reducing salt intake merit attention. It is now recognized that the initiation of salt-induced increases in blood pressure often involves a combination of normal increases in sodium balance, blood volume and cardiac output together with abnormal vascular resistance responses to increased salt intake. Therefore, preventing either the normal increases in sodium balance and cardiac output, or the abnormal vascular resistance responses to salt, can prevent salt-induced increases in blood pressure. Suboptimal nutrient intake is a common cause of the hemodynamic disturbances mediating salt-induced hypertension. Accordingly, efforts to identify and correct the nutrient deficiencies that promote salt sensitivity hold promise for decreasing population risk of salt-induced hypertension without requiring reductions in salt intake.

From salt to hypertension, what is missed?

Excess salt intake is viewed as a major contributor to hypertension and cardiovascular disease, and dietary salt restriction is broadly recommended by public health guidelines. However, individuals can have widely varying physiological responses to salt intake, and a tailored approach to evaluation and intervention may be needed. The traditional sodium related concepts are challenging to assess clinically for two reasons: (1) spot and 24-hour urine sodium are frequently used to evaluate salt intake, but are more suitable for population study, and (2) some adverse effects of salt may be blood pressure-independent. In recent years, previously unknown mechanisms of sodium absorption and storage have been discovered. This review will outline the limitations of current methods to assess sodium balance and discuss new potential evaluation methods and treatment targets.

Characterization of the Renin-Angiotensin-Aldosterone System in Young Healthy Black Adults: The African Prospective Study on the Early Detection and Identification of Hypertension and Cardiovascular Disease (African-PREDICT Study)

[Figure: see text].

No evidence of racial disparities in blood pressure salt sensitivity when potassium intake exceeds levels recommended in the US dietary guidelines

On average, black individuals are widely believed to be more sensitive than white individuals to blood pressure (BP) effects of changes in salt intake. However, few studies have directly compared the BP effects of changing salt intake in black versus white individuals. In this narrative review, we analyze those studies and note that when potassium intake substantially exceeds the recently recommended US dietary goal of 87 mmol/day, black adults do not appear more sensitive than white adults to BP effects of short-term or long-term increases in salt intake (from an intake ≤50 mmol/day up to 150 mmol/day or more). However, with lower potassium intakes, racial differences in salt sensitivity are observed. Mechanistic studies suggest that racial differences in salt sensitivity are related to differences in vascular resistance responses to changes in salt intake mediated by vasodilator and vasoconstrictor pathways. With respect to cause and prevention of racial disparities in salt sensitivity, it is noteworthy that 1) on average, black individuals consume less potassium than white individuals and 2) consuming supplemental potassium bicarbonate, or potassium rich foods can prevent racial disparities in salt sensitivity. However, the new US dietary guidelines reduced the dietary potassium goal well below the amount associated with preventing racial disparities in salt sensitivity. These observations should motivate research on the impact of the new dietary potassium guidelines on racial disparities in salt sensitivity, the risks and benefits of potassium-containing salt substitutes or supplements, and methods for increasing consumption of foods rich in nutrients that protect against salt-induced hypertension.

Prior exposure to placental ischemia causes increased salt sensitivity of blood pressure via vasopressin production and secretion in postpartum rats

OBJECTIVES

Women with a history of preeclampsia exhibit increased salt sensitivity of blood pressure at postpartum, which might be responsible for their increased risk of future cardiovascular diseases. However, it is unclear whether preeclampsia can cause increased salt sensitivity at postpartum. Vasopressin may play a role in the pathogenesis of preeclampsia and salt-sensitive hypertension. Therefore, the aim of this study was to determine whether the exposure to preeclampsia, as elicited by placental ischemia, causes increased salt sensitivity at postpartum, and if so, whether vasopressin is involved in its process.

METHODS AND RESULTS

We used a reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. Pregnant Sprague-Dawley rats were categorized into the following two groups: RUPP-operated and sham-operated (SHAM) control groups. A 1-week-long high-salt diet was initiated at 3 weeks postpartum. The high-salt diet-induced increase in mean arterial pressure was significantly greater in the RUPP group than in the SHAM group. In addition, the plasma levels of copeptin, a substitute for plasma vasopressin, increased and serum osmolality decreased in the RUPP group. Double immunostaining revealed that the expression of c-Fos, a marker of neural activity, in vasopressin-producing neurons and presympathetic neurons in the hypothalamic paraventricular nucleus was significantly elevated in the RUPP group. The oral administration of conivaptan, the dual V1a/V2 vasopressin receptor antagonist, during high-salt diet abolished the enhanced increase in mean arterial pressure in RUPP rats.

CONCLUSION

Prior exposure to placental ischemia causes increased salt sensitivity of blood pressure at postpartum probably due to enhanced vasopressin production and secretion.

Impact of Intensive Lifestyle Treatment (Diet Plus Exercise) on Endothelial and Vascular Function, Arterial Stiffness and Blood Pressure in Stage 1 Hypertension: Results of the HINTreat Randomized Controlled Trial

Lifestyle modification is an important component of essential hypertension (EH) therapy. The aim of the Hypertension Intensive Nutrition Treatment (HINTreat) parallel, randomized controlled trial was to examine the effect of a 6-month intensive lifestyle treatment (ILT) (diet plus exercise with monthly visits) compared to the usual care. A total of 76 adults with stage 1 EH were randomized (38 in each group). Dietary analysis, anthropometry, physical activity, biochemical and urine profile, blood pressure (BP), asymmetric dimethylarginine (ADMA), central hemodynamics, β-stiffness index and carotid intima media-thickness were evaluated. The dietary inflammatory index (DII) was calculated for each participant from the intake of 29 nutrients/food components. At the end of the trial, participants in the ILT group reduced their 24h urinary Na excretion (p ≤ 0.001), daytime systolic BP (p ≤ 0.048) and mean carotid β-stiffness index (p ≤ 0.005) and ameliorated their lipidemic profile compared to the standard care. Univariate analysis for the total sample showed a strong association between DII and ADMA levels (β = 0.089, p ≤ 0.01). ILT is effective in improving the inflammatory components of the diet and selected cardiometabolic parameters, including arterial stiffness.

Sodium Intake and Hypertension

The close relationship between hypertension and dietary sodium intake is widely recognized and supported by several studies. A reduction in dietary sodium not only decreases the blood pressure and the incidence of hypertension, but is also associated with a reduction in morbidity and mortality from cardiovascular diseases. Prolonged modest reduction in salt intake induces a relevant fall in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ethnic group, with larger falls in systolic blood pressure for larger reductions in dietary salt. The high sodium intake and the increase in blood pressure levels are related to water retention, increase in systemic peripheral resistance, alterations in the endothelial function, changes in the structure and function of large elastic arteries, modification in sympathetic activity, and in the autonomic neuronal modulation of the cardiovascular system. In this review, we have focused on the effects of sodium intake on vascular hemodynamics and their implication in the pathogenesis of hypertension.

Testing Computer Models Predicting Human Responses to a High-Salt Diet

Recently, mathematical models of human integrative physiology, derived from Guyton's classic 1972 model of the circulation, have been used to investigate potential mechanistic abnormalities mediating salt sensitivity and salt-induced hypertension. We performed validation testing of 2 of the most evolved derivatives of Guyton's 1972 model, Quantitative Cardiovascular Physiology-2005 and HumMod-3.0.4, to determine whether the models accurately predict sodium balance and hemodynamic responses of normal subjects to increases in salt intake within the real-life range of salt intake in humans. Neither model, nor the 1972 Guyton model, accurately predicts the usual changes in sodium balance, cardiac output, and systemic vascular resistance that normally occur in response to clinically realistic increases in salt intake. Furthermore, although both contemporary models are extensions of the 1972 Guyton model, testing revealed major inconsistencies between model predictions with respect to sodium balance and hemodynamic responses of normal subjects to short-term and long-term salt loading. These results demonstrate significant limitations with the hypotheses inherent in the Guyton models regarding the usual regulation of sodium balance, cardiac output, and vascular resistance in response to increased salt intake in normal salt-resistant humans. Accurate understanding of the normal responses to salt loading is a prerequisite for accurately establishing abnormal responses to salt loading. Accordingly, the present results raise concerns about the interpretation of studies of salt sensitivity with the various Guyton models. These findings indicate a need for continuing development of alternative models that incorporate mechanistic concepts of blood pressure regulation fundamentally different from those in the 1972 Guyton model and its contemporary derivatives.

Oral Fludrocortisone Test for Salt-Sensitive Screening in Hypertensive Patients: A Randomized Crossover Trial

Background

Salt sensitivity is associated with an increased cardiovascular risk, but the gold standard method (diet cycles) requires 24-h urine samples and has poor patient compliance.

Objectives

Test the hypothesis that oral fludrocortisone (0.4 mg per day for 7 days) is a good alternative in identifying salt-sensitive patients.

Methodology

We conducted a randomized crossover study with 30 hypertensive individuals comprising the following steps: (1) washout; (2) phase A (low- and high-sodium diet cycles); (3) washout 2; (4) phase B (fludrocortisone test). Phase A and B steps were performed in a random way. Consistent with the literature, we found that 53.3% were salt-sensitive according to the reference test. Using the ROC curve, the fludrocortisone test defined salt sensitivity by a median blood pressure increase of ≥3 mmHg. A good accuracy of fludrocortisone in detecting salt sensitivity was observed (AUC: 0.732±0.065; p<0.001), with 80% sensitivity and 53% specificity.

Conclusion

The fludrocortisone test is a good option for screening salt sensitivity in hypertensive patients. However, the low specificity prevents this test from being an ideal substitute to the labor-intensive diet cycles exam in the definition of salt sensitivity. This clinical trial is registered with NCT01453959.

Salt sensitivity of blood pressure at age 8 years in children born preterm

Preterm birth and low birth weight have been associated with an increased risk of hypertension; postnatal growth and dietary salt intake may contribute to these associations. In adults, the change of blood pressure (BP) in response to modifications in salt intake, i.e., salt sensitivity of BP, has been independently associated with cardiovascular disease. Little is known about salt sensitivity in children. We hypothesize that it may partly explain the association between preterm birth and higher BP in later life. We assessed salt sensitivity of BP at age 8 years in 63 preterm-born children, and explored its association with postnatal growth, sodium intake, and body composition from infancy onwards. BP was measured at baseline and after a 7-day high-salt diet. The difference in mean arterial pressure (MAP) was calculated; salt sensitivity was defined as an increase in MAP of ≥5%. Ten children (16%) showed salt sensitivity of BP, which was associated with neonatal growth restriction as well as with lower fat mass and BMI from infancy onwards. At age 8 years, children classified as salt sensitive had a lower weight-for-age SD-score (-1.5 ± 1.3 vs. -0.6 ± 1.1) and BMI (13.8 ± 1.7 vs. 15.5 ± 1.8 kg/m²) compared to their salt resistant counterparts. Sodium intake was not associated with (salt sensitivity of) BP. Salt sensitivity of BP was demonstrated in preterm-born children at age 8 years and may contribute to the development of cardiovascular disease at later age. Long-term follow-up studies are necessary to assess reproducibility of our findings and to explore clustering with other cardiovascular risk factors.

Functional foods for augmenting nitric oxide activity and reducing the risk for salt-induced hypertension and cardiovascular disease in Japan

High salt intake is one of the major dietary determinants of hypertension and cardiovascular disease in Japan and throughout the world. Although dietary salt restriction may be of clinical benefit in salt-sensitive individuals, many individuals may not wish, or be able to, reduce their intake of salt. Thus, identification of functional foods that can help protect against mechanistic abnormalities mediating salt-induced hypertension is an issue of considerable medical and scientific interest. According to the "vasodysfunction" theory of salt-induced hypertension, the hemodynamic abnormality initiating salt-induced increases in blood pressure usually involves subnormal vasodilation and abnormally increased vascular resistance in response to increased salt intake. Because disturbances in nitric oxide activity can contribute to subnormal vasodilator responses to increased salt intake that often mediate blood pressure salt sensitivity, increased intake of functional foods that support nitric oxide activity may help to reduce the risk for salt-induced hypertension. Mounting evidence indicates that increased consumption of traditional Japanese vegetables and other vegetables with high nitrate content such as table beets and kale can promote the formation of nitric oxide through an endothelial independent pathway that involves reduction of dietary nitrate to nitrite and nitric oxide. In addition, recent studies in animal models have demonstrated that modest increases in nitrate intake can protect against the initiation of salt-induced hypertension. These observations are: (1) consistent with the view that increased intake of many traditional Japanese vegetables and other nitrate rich vegetables, and of functional foods derived from such vegetables, may help maintain healthy blood pressure despite a high salt diet; (2) support government recommendations to increase vegetable intake in the Japanese population.