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KMID : 0385219990090030017
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Korean Journal of Gerontology
1999 Volume.9 No. 3 p.17 ~ p.27
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Kim Hwa-Young
Moon Hye-Mee
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Abstract
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This study was performed to investigate the long-term effect of dietary protein level on calcium and skeletal metabolism. Two-month-old male rats were divided into either 8% casein or 50% casein diet groups. The rats were fed the experimental diets for 1 year and sacrificed in intervals at 3, 6, 12 month. body weight gain was higher in the high protein group. The urinary protein excretion of high protein group was higher throughout the experimental period. Glomerular filtration rate was higher in high protein group until six months. Nitrogen intake, excretion, absorption, and retention were all higher in high protein group than low protein group. For calcium metabolism, calcium intake was not affected by dietary protein level. Fecal and urinary calcium excretion were higher in the high protein group until 6 months, which resulted in lower apparent calcium absorption and calcium balance. However, at 12 months, this tendency was reversed. The Urinary hydroxyproline was higher in the high protein group until 6 months, but decreased by 12 months. The weight, length, strength, and ash, calcium, and magnesium content of femur, scapular, and vertebra were higher in high protein group but the density was lower in high protein group then in low protein group. At 12 months, the differences in bone density disappeared. In conclusion, it seems that the dietary protein level had different effects on growth and Ca metabolism of rat in each experimental period. High protein diet stimulated the bone growth. But it also stimulated the bone calcium resorption due to increased urinary calcium excretion according to high GFR.
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KEYWORD
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dietary protein level, Calcium balance, Skeletal metabolism
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