Umezawa M, Hosokawa M, Kohno A, Ishikawa S, Kitagawa K, Takeda T
Department of Nutrition, Koshien University, Hyogo, Japan.
J Nutr. 1993 Nov;123(11):1905-12. doi: 10.1093/jn/123.11.1905.
The effects of replacing dietary casein with soybean protein on mean life span, mean life span of the last one-tenth of a group, grading scores of senescence and deposition of senile amyloid were investigated in senescence accelerated mice (SAM-P/1) compared with a control strain (SAM-R/1). SAM-R/1 mice fed the soybean protein-containing diet had mean life spans of 618 +/- 42 d (males) and 578 +/- 62 d (females), 58% (males) and 44% (females) longer than those of corresponding casein fed mice (P < 0.01). Similarly, in SAM-P/1 mean life-spans were 265 +/- 16 d (males) and 307 +/- 23 d (females) in the soybean diet group, 27% (males) and 30% (females) longer than in the casein diet groups (P < 0.01). The mean life span of the last one-tenth of each group fed soybean protein was significantly longer than the corresponding group fed casein. In SAM-R/1 mice, pathological studies revealed that severe secondary amyloid deposition (amyloid A protein) in the kidneys, spleen, stomach and liver was significantly suppressed, in males only, by replacing casein with soybean protein (P < 0.01). The occurrence of contracted kidneys caused by the infiltration of amyloid A protein was suppressed in SAM-R/1 mice fed the soybean protein-containing diet (P < 0.05). The deposition of senile amyloid in SAM-P/1 mice with aging was retarded by replacing casein with soybean protein (P < 0.01). These results indicate that dietary protein source is important in modulating the advance of senescence in SAM mice.
