***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background —A nutrient-wide approach may be useful to comprehensively test and vali date associations between nutrients ( derived from foods and supplements ) and  blood pressure ( BP )  in an unbiased manner . Methods and Results — Data from 4680 participants aged 40 to 59 years in the cross-sectional International Study of Macro/Micronutrients and Blood Pressure ( INTERMAP ) were stratified r and omly into training and testing sets . US National Health and Nutrition Examination Survey ( NHANES ) four cross-sectional cohorts ( 1999–2000 , 2001–2002 , 2003–2004 , 2005–2006 ) were used for external validation . We performed multiple linear regression analyses associating each of 82 nutrients and 3 urine electrolytes with systolic and diastolic BP in the INTERMAP training set . Significant findings were vali date d in the INTERMAP testing set and further in the NHANES cohorts ( false discovery rate < 5 % in training , P<0.05 for internal and external validation ) . Among the vali date d nutrients , alcohol and urinary sodium-to-potassium ratio were directly associated with systolic BP , and dietary phosphorus , magnesium , iron , thiamin , folacin , and riboflavin were inversely associated with systolic BP . In addition , dietary folacin and riboflavin were inversely associated with diastolic BP . The absolute effect sizes in the validation data ( NHANES ) ranged from 0.97 mm Hg lower systolic BP ( phosphorus ) to 0.39 mm Hg lower systolic BP ( thiamin ) per 1-SD difference in nutrient variable . Inclusion of nutrient intake from supplements in addition to foods gave similar results for some nutrients , though it attenuated the associations of folacin , thiamin , and riboflavin intake with BP . Conclusions —We identified significant inverse associations between B vitamins and BP , relationships hitherto poorly investigated . Our analyses represent a systematic unbiased approach to the evaluation and validation of nutrient-BP associations The Trial of Antihypertensive Interventions and Management is a multicenter r and omized trial design ed to examine the diastolic blood pressure response of various combinations of pharmacological and dietary interventions in the treatment of mild hypertension ( diastolic blood pressure 90 - 100 mm Hg ) . Eight hundred and seventy-eight participants at 110 - 160 % of ideal weight were r and omly allocated to nine drug/diet treatment groups receiving either a placebo , chlorthalidone ( 25 mg ) , or atenolol ( 50 mg ) , combined with a usual , a weight loss , or a low sodium/high potassium diet The primary outcome was diastolic blood pressure change from baseline to 6 months . Seven hundred and eighty-seven participants had follow-up data . The mean baseline diastolic blood pressure  was 93.8 mm Hg ; 55.9 % of the participants were male , and the weight loss diet group lost an average of 4.7 kg . Multiple comparisons were accounted for in the analysis . A significantly greater lowering of diastolic blood pressure ( 12.4 mm Hg ) was achieved in the atenolol group compared with either the low sodium/high potassium diet group ( 7.9 mm Hg , p=0.001 ) or weight loss group ( 8.8 mm Hg , p=0.006 ) . Adding weight loss to chlorthalidone significantly enhanced blood pressure lowering ( 15.1 mm Hg ) when compared with the diuretic alone ( 10.8 mm Hg , p=0.002 ) , but adding a low sodium/high potassium diet ( 12.2 mm Hg , p=0.029 ) did not In the short-term treatment of mild hypertension where diastolic blood pressure is the sole consideration , drugs outperform diet , and weight loss is beneficial , especially with diuretics To clarify the mechanism by which potassium ( KCl ) protects against the blood pressure rising action of sodium ( NaCl ) , we studied the effects of KCl loading in patients with idiopathic hypertension who , after a period of NaCl restriction , partook of a high NaCl diet . Eleven patients who had taken the KCl supplement ( 96 mEq/day ) during the high NaCl period showed lesser mean blood pressure ( MAP ) rise with changes in NaCl intake from 25 to 250 mEq/day than 12 patients who had not taken the KCl supplement ( p less than 0.001 ) . With a high NaCl diet , the KCl-supplemented patients retained less NaCl , gained less weight , and showed a lesser increase in plasma volume and cardiac output than the non-KCl-supplemented ones . Overall , the increase in blood pressure levels during the high Na diet correlated directly either with changes in plasma volume ( p less than 0.05 ) or with changes in cardiac output ( p less than 0.01 ) . The results suggest that KCl may prevent a rise in blood pressure with NaCl loads in hypertensive patients by attenuating the increase in cardiac output , mainly as a result of the natriuresis . Furthermore , plasma norepinephrine was measured to estimate the sympathetic activity , since the sympathetic nervous system is known to control urinary NaCl excretion . From the low NaCl diet to Day 3 of the high NaCl diet , plasma norepinephrine was significantly ( p less than 0.01 ) decreased in the KCl-supplemented patients , whereas it remained unchanged in the non-KCl-supplemented ones . ( ABSTRACT TRUNCATED AT 250 WORDS To determine the effects of potassium on blood pressure and factors affecting blood pressure , we conducted a r and omized , placebo controlled trial of a potassium chloride-based substitute for table salt in 23 patients with mild to moderate essential hypertension . In addition , the effects of potassium chloride on sodium balance were studied in 10 normal subjects .  Potassium loading with 100 mmol/day over five days in these normal subjects caused a cumulative negative sodium balance of 138 + /- 35 mmol , similar in degree to that achieved by severe dietary sodium restriction . However , two weeks of potassium treatment ( 100 mmol/day ) in patients with essential hypertension did not lower blood pressure ( BP ) either in the supine or upright positions ( potassium treatment : mean BP 108 + /- 3 lying and 113 + /- 3 mmHg st and ing ; placebo treatment : mean BP 109 + /- 3 lying and 115 + /- 3 mmHg st and ing ) . Patients found it difficult to tolerate the  potassium-based salt substitute in the dose given . We conclude that it is premature to recommend an increase in potassium chloride intake as treatment for raised blood pressure BACKGROUND / OBJECTIVES The inverse relationships of combined fruits and vegetables intake with blood pressure have been reported . However , whether there are such relationships with salty vegetables has rarely been investigated in epidemiologic studies . We evaluated the relation of combined and separate intake of fruits , vegetable intakes , and salty vegetables , as well as sodium and potassium , with  blood pressure among the middle-aged and elderly population s. SUBJECTS/ METHODS The present cross-sectional analysis of a prospect i ve cohort baseline survey was performed with 6,283 subjects ( 2,443 men and 3,840 women ) and free of hypertension , diabetes , cardiovascular diseases , and cancer .  Dietary data were collected by trained interviewers using food frequency question naire . RESULTS The significantly inverse linear trend of diastolic blood pressure ( DBP ) was found in fruits and non-pickled vegetables ( 81.2 mmHg in the lowest quintile vs 79.0 mmHg in the highest quintile , P for trend = 0.0040 ) and fruits only ( 80.9 mmHg in the lowest quintile vs 79.4 mmHg in the highest quintile , P for trend = 0.0430 ) among men . In contrast , sodium and sodium to potassium ratio were positively related with blood pressure among men ( DBP , 78.8 mmHg in the lowest quintile vs 80.6 mmHg in the highest quintile , P for trend = 0.0079 for sodium ; DBP , 79.0 mmHg in the lowest quintile vs 80.7 mmHg in the highest quintile , P for trend = 0.0199 and SBP , 123.8 mmHg in the lowest quintile vs 125.9 mmHg in the highest quintile for sodium/potassium ) .  Kimchies  consumption was positively related to DBP for men ( 78.2 mmHg in the lowest quintile vs 80.9 mmHg in the highest quintile for DBP , P for trend = 0.0003 ) . Among women , these relations were not found . CONCLUSION Fruits and /or non-pickled vegetables may be inversely , but  sodium , sodium to potassium , and Kimchies  may be positively related to blood pressure among men Background Dietary electrolytes influence blood pressure , but their effect on clinical outcomes remains to be established . We examined sodium and potassium intake in relation to  cardiovascular disease ( CVD ) and mortality in an unselected older population . Methods A case – cohort analysis was performed in the Rotterdam Study among subjects aged 55 years and over , who were followed for 5 years . Baseline urinary sample s were analyzed for sodium and potassium in 795 subjects who died , 206 with an incident myocardial infa rct ion and 181 subjects with an incident stroke , and in 1,448 r and omly selected subjects . For potassium , dietary data were additionally obtained by food-frequency question naire for 78 % of the cohort . Results There was no consistent association of urinary sodium , potassium , or sodium/potassium ratio with CVD and all-cause mortality over the range of intakes observed in this population . Dietary potassium estimated by food frequency question naire , however , was associated with a lower risk of all-cause mortality in subjects initially free of CVD and hypertension ( RR = 0.71 per st and ard deviation increase ; 95 % confidence interval : 0.51–1.00 ) . We observed a significant positive association between urinary sodium/potassium ratio and all-cause mortality , but only in overweight subjects who were initially free of CVD and hypertension ( RR = 1.19 ( 1.02–1.39 ) per unit ) . Conclusion The effect of sodium and potassium intake on CVD morbidity and mortality in Western societies remains to be established Forty young subjects , aged 18 to 28 years , with mildly elevated blood pressure participated in a double-blind r and omized three-period crossover study of the effect of sodium restriction with and without potassium supplementation on blood pressure .  Dietary sodium intake was restricted for 18 weeks in which the patients received in r and om sequence ' slow-sodium ' ( 90 mmol/day ) , ' slow-potassium ' ( 72 mmol/day ) , and placebo tablets , each for 6 weeks . Mean urinary sodium excretion was 129 mmol/24 h in the slow-sodium period , 57 mmol/24 h during placebo , and 69 mmol/24 h during slow-potassium . Mean supine systolic blood pressure in the sixth week of the slow-potassium period was 3.3 mmHg lower than that at the end of the slow-sodium period ( P less than 0.05 ) . There was no significant difference in systolic or diastolic blood pressure between the placebo and the slow-sodium periods . The fall in systolic blood pressure in the low sodium/high potassium period was accompanied by a fall in cardiac index of 0.4 l/min per m2 body surface area ( BSA ) ( P = 0.03 ) . Our observations suggest a small hypotensive effect of moderate sodium restriction combined with high potassium intake in young hypertensive subjects . Sodium restriction alone has little effect on blood pressure in this group . The combination of a low sodium/high potassium diet may lower blood pressure by affecting cardiac output . Reducing the dietary sodium : potassium ratio may therefore be useful in the management of early primary hypertension It is generally accepted that a significant restriction in sodium intake can lower blood pressure in hypertensive patients and more recently it has also been suggested that a high potassium intake can exert an antihypertensive effect . We have therefore , conducted a double-blind , r and omized , cross-over study to evaluate the antihypertensive efficacy of the combination of a modest dietary sodium restriction and a high potassium intake in hypertensive patients of mild and moderate degrees . During the modest sodium ( 100 mmol/day)/high potassium ( 130 mmol/day ) diet the blood pressure was significantly reduced ( -17/-6 mmHg ) when compared to the normal diet ( 160 mmol Na/day and 80 mmol K/day ) . The blood pressure reduction did not interfere with hemodynamic and humoral responses to dynamic exercise . The modest reduction in sodium intake and increase in potassium content in the diet was well tolerated by the patients Abstract Sixteen patients with mild essential hypertension ( average diastolic blood pressure 90 - 110 mm Hg ) and eight normotensive subjects ( diastolic pressure less than 85 mm Hg ) were 
    Output:
    
The main findings show that , among the r and omized controlled trials review ed , the sodium-to-potassium ratio appears to be more strongly associated with blood pressure outcomes than either sodium or potassium alone in hypertensive adult population s. Recent data from the observational studies review ed provide additional support for the sodium-to-potassium ratio as a superior metric to either sodium or potassium alone in the evaluation of blood pressure outcomes and incident hypertension .
It remains unclear whether this is true in normotensive population s and in children and for related outcomes including the renin-angiotensin system , arterial stiffness , the augmentation index , and endothelial dysfunction .