Effect of protein restriction on messenger RNA of insulin-like growth factor-I and insulin-like growth factor-binding proteins in liver of ovariectomized rats

The relationship between dietary intake and stunting among pre-school children in Upper Egypt

OBJECTIVE

Linear growth is controlled by several factors, malnutrition is one of the leading causes of stunted child growth. The objective of this study was to determine the dietary intakes associated with stunting among pre-school children in rural Upper Egypt.

DESIGN

Community-based cross-sectional study.

SETTING

Data were collected by interviewing the children's caregivers in the rural household setting.

PARTICIPANTS

The study included 497 pre-school children aged 2-5 years in rural Upper Egypt. Food intake data were estimated using 24-h recall method. Anthropometric measurements of children were taken and then converted to z-scores for weight-for-age Z-score, height-for-age Z-score and weight-for-height Z-score.

RESULTS

The study included 497 children of which 19·1 % were stunted, 76·3 % did not meet recommended energetic intake and 13·7 % did not meet recommended protein intake and this was significantly higher than non-stunted children. Children who were stunted significantly consumed poultry, eggs and fruits less often than non-stunted children, by regression; male sex (adjusted odds ratio (aOR) = 1·91), mother's age (0·93), lower socio-economic status (SES); and not meeting recommended protein intake (aOR = 2·26) were found to be associated with stunting.

CONCLUSION

Male sex, younger mothers, lower SES and not meeting recommended energy and protein were statistically associated with stunting. Nutrition education messages encouraging adequate and healthy eating are recommended.

Low calcium-phosphate intakes modulate the low-protein diet-related effect on peak bone mass acquisition: a hormonal and bone strength determinants study in female growing rats

Peak bone mass acquisition is influenced by environmental factors including dietary intake. A low-protein diet delays body and skeletal growth in association with a reduction in serum IGF-1 whereas serum FGF21 is increased by selective amino acid deprivation. Calcium (Ca) and phosphorous (P) are also key nutrients for skeletal health, and inadequate intakes reduce bone mass accrual in association with calciotropic hormone modulation. Besides, the effect of calcium supplementation on bone mass in prepubertal children appears to be influenced by protein intake. To further explore the interaction of dietary protein and Ca-P intake on bone growth, 1-month-old female rats were fed with an isocaloric 10%, 7.5%, or 5% casein diet containing normal or low Ca-P for an 8-week period (6 groups). Changes in tibia geometry, mineral content, microarchitecture, strength, and intrinsic bone quality were analyzed. At the hormonal level, serum IGF-1, fibroblast growth factor 21 (FGF21), PTH, 1,25-dihydroxyvitamin D3 (calcitriol), and FGF23 were investigated as well as the Ghr hepatic gene expression. In normal dietary Ca-P conditions, bone mineral content, trabecular and cortical bone volume, and bone strength were lower in the 5% casein group in association with a decrease in serum IGF-1 and an increase in FGF21 levels. Unexpectedly, the low-Ca-P diet attenuated the 5% casein diet-related reduction of serum IGF-1 and Ghr hepatic gene expression, as well as the low-protein diet-induced decrease in bone mass and strength. However, this was associated with lower cortical bone material level properties. The low-Ca-P diet increased serum calcitriol but decreased FGF23 levels. Calcitriol levels positively correlated with Ghr hepatic mRNA levels. These results suggest that hormonal modulation in response to a low-Ca-P diet may modify the low-protein diet-induced effect on Ghr hepatic mRNA levels and consequently the impact of low protein intakes on IGF-1 circulating levels and skeletal growth.

Effect of protein supplementation during a 6-mo strength and conditioning program on insulin-like growth factor I and markers of bone turnover in young adults

BACKGROUND

Exercise is beneficial for bone when adequate nutrition is provided. The role of protein consumption in bone health, however, is controversial.

OBJECTIVE

The objective was to ascertain the effect of high protein intake on insulin-like growth factor I (IGF-I) and markers of bone turnover during 6 mo of exercise training.

DESIGN

Fifty-one subjects aged 18-25 y (28 men, 23 women) received a protein supplement (42 g protein, 24 g carbohydrate, 2 g fat) or a carbohydrate supplement (70 g carbohydrate) twice daily. Exercise consisted of alternating resistance training and running 5 times/wk. Plasma concentrations of IGF-I, insulin-like growth factor-binding protein 3, serum bone alkaline phosphatase, and urinary N-telopeptide collagen crosslink (NTx) concentrations were measured at 0, 3, and 6 mo after 24 h without exercise and a 12-h fast.

RESULTS

Three-day diet records indicated no difference in energy intake between the groups. Average protein intakes after supplementation began in the protein and carbohydrate groups were 2.2 +/- 0.1 and 1.1 +/- 0.1 g/kg, respectively (P < 0.001). The increase in plasma IGF-I was greater in the protein group than in the carbohydrate group (time x supplement interaction, P = 0.01). There were no significant changes over time or significant differences by supplement in plasma insulin-like growth factor-binding protein 3 (44 and 40 kDa). Serum bone alkaline phosphatase increased significantly over time (P = 0.04) and tended to be higher in the protein group than in the carbohydrate group (P = 0.06). NTx concentrations changed over time (time and time squared; P < 0.01 for both) and were greater in the protein group than in the carbohydrate group (P = 0.04). Men had higher NTx concentrations than did women (74.6 +/- 3.4 and 60.0 +/- 3.8 nmol/mmol creatinine; P = 0.005).

CONCLUSION

Protein supplementation during a strength and conditioning program resulted in changes in IGF-I concentrations.

Dietary restriction of single essential amino acids reduces plasma insulin-like growth factor-I (IGF-I) but does not affect plasma IGF-binding protein-1 in rats

The effects of dietary restriction of a single essential amino acid (EAA) on insulin-like growth factor-I (IGF-I) and IGF-binding protein (IGFBP)-1 were investigated in rats. Rats were fed experimental diets containing amino acid (AA) mixtures in which the concentrations of all EAA were at levels recommended by the National Research Council (control), in which a single EAA was restricted to 20% of that of the control diets (Leu(-), Lys(-), Met(-) or Thr(-)), or in which the diet was devoid of amino acids (AA(-)). To eliminate the effect of differences in energy intake, rats were fed the mean amount of food as consumed by the AA(-) group on the previous day. Growth was significantly retarded in rats fed diets restricted in just one EAA compared with that of rats fed the control diet, and further growth retardation was observed in rats fed the AA(-) diet. On the other hand, the plasma IGF-I concentrations in the groups with a single EAA restriction or in the AA(-) group were 66% (P: < 0. 05) and 50% (P: < 0.05) of that of the control group, respectively. The effect of any single EAA restriction was not significantly different from that of total AA deprivation. The plasma IGFBP-1 concentration in the control group did not differ from that of rats fed diets with the single EAA restrictions except for methionine restriction, but it was approximately 6-fold greater in the AA(-) group. Differences in plasma IGFBP-1 concentration under these conditions could be explained by differences in hepatic IGFBP-1 mRNA contents. Based on these results, we conclude that restriction of single EAA does not affect IGFBP-1 synthesis in vivo, although the deprivation of a single EAA has been reported to increase IGFBP-1 production in hepatocyte cultures. Our results also indicated that a single EAA restriction decreased IGF-I production but did not affect IGFBP-1 production. The present study suggests that not only plasma IGF-I, but also IGFBP-1, affects the magnitude of growth retardation in vivo.