High salt intake is associated with hypertension, which is a major modifiable risk factor for cardiovascular disease and chronic kidney disease. International guidelines recommend a large reduction in sodium intake to reduce blood pressure, organ damage, and mortality. However, if you want to find out the relationship between high salt intake and blood pressure, be sure to read this text until the end.
Effects of salt intake on blood pressure
In response to a high salt intake, healthy individuals are generally resistant to salt-induced hypertension because they quickly excrete salt and retain such a small amount that their blood volume does not increase and thus blood pressure does not rise.
However, impaired elimination of sodium during a high salt intake directly expands the volume of extracellular fluid, which promotes increased blood pressure. In addition, in the general population, genetic variants associated with decreased sodium transporter activity in the renal tubules contribute to resistance against hypertension, promoting increases in salt excretion and a decrease in external saline balance.
An observational study implied a high sodium intake in the development of hypertension. In addition, intervention studies showed that a low salt intake was associated with a decrease in blood pressure. These intervention studies suggested the absence of a significant antihypertensive reaction, even when salt intake was reduced to at least 6.5 g/day.
One of the best scientific studies on salt and blood pressure
One study reported that a salt intake of less than 5.6 g/day was necessary to maintain normal blood pressure after stopping antihypertensive medications. Based on these findings, Western country guidelines recommend a salt intake of 6.0g/day or less, while WHO (general) guidelines in 2012 recommend a salt intake of 5g/day or less.
One study investigated the effects of sodium on blood pressure among three groups of patients: those with mild or severe hypertension and normotensive. No significant changes in blood pressure or aldosterone were observed in normotensive individuals. On the other hand, reductions in blood pressure and aldosterone concentrations were detected in patients with mild and severe hypertension, which were attributed to reduced plasma renin activity in patients with hypertension than in normotensive patients.
Plasma renin activity is sensitive to volume changes and affects blood pressure. Therefore, blood pressure in normotensive individuals receiving a low-sodium diet can be maintained due to aldosterone secretion. Patients with essential hypertension on a low-sodium diet were unable to maintain blood pressure due to suppressed aldosterone secretion because they had lower plasma renin activity. In addition, patients with hypertension excrete less sodium in the urine than normotensive individuals, and this reduction was associated with the severity of hypertension.
Clinical practice
High salt intake is associated with hypertension, which is a major risk factor for cardiovascular disease and chronic kidney disease. NGAL testing may be a useful biomarker for detecting renal tubular injury caused by a high salt intake at an early stage before the progression of chronic kidney disease.
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Article: High salt intake
– Hosohata K. Biomarkers of high salt intake. Adv Clin Chem
. 2021;104:71-106. doi:10.1016/bs.acc.2020.09.002
