1.
Is There Association between Altered Adrenergic System Activity and Microvascular Endothelial Dysfunction Induced by a 7-Day High Salt Intake in Young Healthy Individuals.
Stupin, A, Drenjančević, I, Šušnjara, P, Debeljak, Ž, Kolobarić, N, Jukić, I, Mihaljević, Z, Martinović, G, Selthofer-Relatić, K
Nutrients. 2021;(5)
Abstract
This study aimed to test the effect of a 7-day high-salt (HS) diet on autonomic nervous system (ANS) activity in young healthy individuals and modulation of ANS on microvascular endothelial function impairment. 47 young healthy individuals took 7-day low-salt (LS) diet (3.5 g salt/day) followed by 7-day high-salt (HS) diet (~14.7 g salt/day). ANS activity was assessed by 24-h urine catecholamine excretion and 5-min heart rate variability (HRV). Skin post-occlusive reactive hyperemia (PORH) and acetylcholine-induced dilation (AChID) were assessed by laser Doppler flowmetry (LDF). Separately, mental stress test (MST) at LS and HS condition was conducted, followed by immediate measurement of plasma metanephrines' level, 5-min HRV and LDF microvascular reactivity. Noradrenaline, metanephrine and normetanephrine level, low-frequency (LF) HRV and PORH and AChID significantly decreased following HS compared to LS. MST at HS condition tended to increase HRV LF/HF ratio. Spectral analysis of PORH signal, and AChID measurement showed that MST did not significantly affect impaired endothelium-dependent vasodilation due to HS loading. In this case, 7-day HS diet suppressed sympathetic nervous system (SNS) activity, and attenuated microvascular reactivity in salt-resistant normotensive individuals. Suppression of SNS during HS loading represents a physiological response, rather than direct pathophysiological mechanism by which HS diet affects microvascular endothelial function in young healthy individuals.
2.
Dietary Salt (Sodium Chloride) Requirement and Adverse Effects of Salt Restriction in Humans.
Nishimuta, M, Kodama, N, Yoshitake, Y, Shimada, M, Serizawa, N
Journal of nutritional science and vitaminology. 2018;(2):83-89
Abstract
Inevitable sodium loss under sodium restriction must not be construed as evidence for the estimated average requirement (EAR) for sodium (Na) in humans. We conducted human mineral balance studies to determine the EAR for some minerals (Na, K, Ca, Mg, P, Zn, Fe, Cu and Mn). Na concentration in arm sweat was low while those of calcium (Ca) and magnesium (Mg) were high, during relatively heavy bicycle-ergometer exercise under relatively low Na intake (100 mmol/d). This suggests that Na was released from the bone, the sole pool of Na, with Ca and Mg. Additionally, the negative balances of Ca and Mg was observed under a relatively low sodium intake (100 mmol/d) even with the sufficient supply and intake of Ca and Mg into human body. Finally, we found no correlation between the Na intake and the Na balance, while the Na-intake was correlated significantly to the balances of K, Ca and Mg. The Na intake necessary to keep the balances of Ca and Mg positive was calculated to be 68 mg/kg body weight/d. To learn the signs and symptoms of low sodium intake, we compared the results of a metabolic study in which subjects consumed diets with 6 g and 12 g salt/d respectively. The blood pressure decreased only with the 6 g/d group. Fecal moisture contents of the 6 g/d group were lower than for the 12 g/d group, suggesting the fecal Na was strongly reabsorbed with water when the dietary Na was insufficienct. Indiscriminate Na restriction may have adverse effects on health.
3.
The effect of lowering salt intake on ambulatory blood pressure to reduce cardiovascular risk in chronic kidney disease (LowSALT CKD study): protocol of a randomized trial.
McMahon, EJ, Bauer, JD, Hawley, CM, Isbel, NM, Stowasser, M, Johnson, DW, Hale, RE, Campbell, KL
BMC nephrology. 2012;:137
Abstract
BACKGROUND Despite evidence implicating dietary sodium in the pathogenesis of cardiovascular disease (CVD) in chronic kidney disease (CKD), quality intervention trials in CKD patients are lacking. This study aims to investigate the effect of reducing sodium intake on blood pressure, risk factors for progression of CKD and other cardiovascular risk factors in CKD. METHODS/DESIGN The LowSALT CKD study is a six week randomized-crossover trial assessing the effect of a moderate (180 mmol/day) compared with a low (60 mmol/day) sodium intake on cardiovascular risk factors and risk factors for kidney function decline in mild-moderate CKD (stage III-IV). The primary outcome of interest is 24-hour ambulatory blood pressure, with secondary outcomes including arterial stiffness (pulse wave velocity), proteinuria and fluid status. The randomized crossover trial (Phase 1) is supported by an ancillary trial (Phase 2) of longitudinal-observational design to assess the longer term effectiveness of sodium restriction. Phase 2 will continue measurement of outcomes as per Phase 1, with the addition of patient-centered outcomes, such as dietary adherence to sodium restriction (degree of adherence and barriers/enablers), quality of life and taste assessment. DISCUSSION The LowSALT CKD study is an investigator-initiated study specifically designed to assess the proof-of-concept and efficacy of sodium restriction in patients with established CKD. Phase 2 will assess the longer term effectiveness of sodium restriction in the same participants, enhancing the translation of Phase 1 results into practice. This trial will provide much-needed insight into sodium restriction as a treatment option to reduce risk of CVD and CKD progression in CKD patients. TRIAL REGISTRATION Universal Trial Number: U1111-1125-2149. Australian New Zealand Clinical Trials Registry Number: ACTRN12611001097932.