Increasing serum osmolality has recently been linked with acute stress responses, which over time can lead to increased risk for obesity, hypertension, and other chronic diseases. Salt and fructose are two major stimuli that can induce acute changes in serum osmolality. This study investigated the early metabolic effects of sodium and fructose consumption and determined whether hydration could mitigate these effects. Forty-four healthy subjects were divided into four groups: Group 1 (salty soup), Group 2 (salt-free soup), Group 3 (apple juice), and Group 4 (apple juice + water). Both salt and fructose increased serum osmolality, blood pressure, and levels of PRA, aldosterone, ACTH, cortisol, plasma glucose, uric acid, and FGF21. Salt caused greater RAS activation, while fructose caused a greater rise in glucose and FGF21. Hydration prevented the osmolality increase and largely blocked the acute stress response. Acute serum osmolality changes activate the ACTH-cortisol, RAS, glucose metabolism, and uric acid axis, and hydration is responsive to this. Salt and fructose can activate these responses, suggesting hydration may offer benefits despite exposure to these substances. Further research is needed to determine if hydration can mitigate the chronic effects of salt and sugar on disease.

Nuri Baris Hasbal, Cicek Nur Bakir, Said Incir, Dimitrie Siriopol, Laura G. Sanchez-Lozada, Miguel A. Lanaspa, Richard J. Johnson, Mehmet Kanbay