Alginate Enhances Excretion and Reduces Absorption of Strontium and Cesium in Rats

Abstract

Alginate (ALA), which is an intercellular polysaccharide associated with brown algae, is used as a food additive, a health food and a medicine. Here, we first examined the adsorption of strontium (Sr) and cesium (Cs) by ALA in vitro, and then evaluated the effects of ALA on absorption and excretion of Sr and Cs in rats, in order to evaluate its potential usefulness for minimizing radiation damage from materials released after a nuclear accident. Both Sr and Cs were concentration-dependently adsorbed by sodium alginate (ALA-Na) in vitro. In rats given diet containing either ALA-Na or calcium alginate (ALA-Ca) for two weeks, the plasma concentration of Sr gradually decreased compared with the controls (normal diet); however, in the case of Cs, the plasma concentration was decreased only in the ALA-Ca group, but not the ALA-Na group. Moreover, we examined the effect of preadministration of diet containing either ALA-Na or ALA-Ca on absorption of Sr and Cs administered orally as the chloride salts to rats. Absorption of both Sr and Cs was reduced in the ALA-Ca group, while absorption of only Sr was reduced in the ALA-Na group. Safety assessments indicated that ALA-Ca is safer than ALA-Na. These results indicate that ALA-Ca reduces absorption and promotes excretion of both Sr and Cs, while ALA-Na does so only for Sr.

Relationship between Physical Parameters of Various Metal Ions and Binding Affinity for Alginate

“…20) Both additives increased the excretion of Sr, though Cs concentration was significantly reduced only in the Ca-Alg group. There have been some reports describing the capacity of Alg for metal binding and the order of affinity between Alg and metals.…”

“…Accordingly, the International Atomic Energy Agency (IAEA) has recommended Na-Alg intake for persons exposed to large amounts of radioactive Sr. 19) We have compared the effects of Na-Alg and Ca-Alg in promoting excretion and decreasing absorption of Sr and cesium (Cs) in rats. 20) Both additives increased the excretion of Sr, though Cs concentration was significantly reduced only in the Ca-Alg group. There have been some reports describing the capacity of Alg for metal binding and the order of affinity between Alg and metals.…”

Cholesterol-Lowering Effect of Calcium Alginate in Rats

“…7,8) We have compared the effects of sodium alginate (Na-Alg) and calcium alginate (Ca-Alg) in promoting excretion and decreasing absorption of Sr and cesium (Cs) in rats. 9) Both additives increased the excretion of Sr, though Cs concentration was significantly reduced only in the Ca-Alg group. We also measured the plasma concentration of cholesterol in that study, and interestingly found that Ca-Alg has a greater cholesterol-lowering effect than Na-Alg.…”

“…We also measured the plasma concentration of cholesterol in that study, and interestingly found that Ca-Alg has a greater cholesterol-lowering effect than Na-Alg. 9) At present, Na-Alg is widely used as a food additive (thickening agent) and as a health food to decrease blood cholesterol and inhibit weight gain. [10][11][12] However, sodium intake is associated with hypertension, 13) and Ca-Alg may be preferable to Na-Alg, if it has an equivalent pharmaceutical effect.…”

Facile Synthesis of Fe3O4-N-[(3-Trimethoxysilyl)propyl]ethylenediamine Triacetic-acid Trisodium Salt and Adsorption of Sr 2+

“…Calcium alginate also carries plenty of carboxyl like TMS [27]. It has a great potential for the removal of strontium [28][29][30]. Carboxyl has strong binding forces with strontium and calcium.…”