Abstract
This paper was aimed to study the Na+ binding capacity of various dietary fibers (DFs) and their feeding effects on blood pressure in spontaneously hypertensive rats (SHR).
1) The Na+ binding capacity to thirty six DFs or DF-rich food components was measured by equilibrium method in vitro. Acidic polysaccharides having carboxylic group such as alginate (Alg), pectate, carrageenan and gum arabic effectively binded to Na+. Similar property was observed also in phytate and cereal brans. Especially, K+ in Alg easily exchanged to Na+ under excess Na+ condition.
2) In SHR fed 1 % NaGl, concomitant feeding on 5 % K-Alg or 5 % Ca-Alg depressed blood pressure by 6-7 %. Fecal excretion of Na increased by 49-95 % in both Alg-fed animals than the control ones.
3) Present results suggest that the changes of blood pressure in SHR fed on K-Alg or Ca-Alg are due to the Na+/K+ or Na+/Ca2+ ion-exchanges by Alg in gastro-intestinal tracts, and following inhibition of Na+ absorption.
