Investigation of the Effects of Calcium Alginate on Blood Sodium Concentration and the Suppression of Blood Pressure Elevation in Rats

The effects of calcium alginate (Ca-Alg) on the suppression of blood sodium (Na⁺) concentration and blood pressure elevation in rats were investigated. In a single-dose administration test, oral administration of a 0.3% sodium chloride (NaCl) solution (5 mg/kg) resulted in a significant increase in the difference in the area under the blood Na⁺ concentration-time curve (ΔAUC). When the finest Ca-Alg particles (8 mg/body, 270 mesh) were simultaneously administered orally under the same conditions, a significant decrease in ΔAUC and a tendency for a decrease in the maximum blood concentration difference (ΔC_max) were observed. In a repeated administration test, rats were allowed to freely ingest a 3.0% Ca-Alg-containing feed for 5 weeks, and an increase in Na⁺ excretion in feces was observed. Furthermore, in spontaneously hypertensive rats (SHR), when the same Ca-Alg-containing feed was freely consumed for 15 weeks, a significant inhibition of blood pressure elevation was observed after 10 weeks. Additionally, blood biochemical tests and renal histopathological examination of these rats confirmed the safety of Ca-Alg. Based on these results, it was concluded that Ca-Alg suppresses Na⁺ absorption and blood pressure elevation in rats.