Ik ben nog niet overtuigd, maar er zitten wel wat interessante tussen!
Epidimiologische onderzoeken geven wisselende aanwijzingen over correlaties tussen zink en IGF-1:
1) In this population of healthy well-nourished men, greater dietary intakes of protein, zinc, red meat, and fish and seafood were associated with higher IGF-I concentrations.
2) Dietary fiber and vitamin A were positively related to IGF-I (p = 0.004 and 0.03), zinc with IGFB-3 (p = 0.0008), and iron with the IGF-I/IGFBP-3 ratio (p = 0.048), but the differences between the bottom and top quartile were less than 10%.
This study detected no ethnic differences in serum IGF-I, but it showed weak associations with dietary variables that require further investigation.
3) IGF-I was positively associated with intakes of protein, magnesium, zinc, calcium, potassium, and phosphorus, and IGFBP-3 was positively associated with energy. The IGF-I/IGFBP-3 ratio was positively associated with intakes of protein, zinc, and phosphorus.
These data suggest that the IGF axis in children is affected by diet. This may provide a mechanism whereby childhood diet could have a long-term effect on risk of chronic disease.
Nog wat onderzoekjes:
These results suggest a direct stimulatory effect of zinc on serum IGF-IGFBP-3, alkaline phosphatase and osteocalcin. Despite improvements in the above parameters, <b>zinc supplementation to children with idiopathic short stature with normal serum zinc levels did not significantly change height or weight SDS during 6-12 months follow-up.</b>
At weaning the remaining eight piglets from every litter were allocated randomly to four dietary treatments with increasing zinc inclusions (Zn100, Zn250, Zn1000, Zn2500). In exp. 2, 48 piglets (six litters of eight piglets) were allocated to four dietary treatments (Zn100, Zn100Cu175, Zn2500, Zn2500Cu175).
Just after weaning feed intake was very low, piglets lost weight and serum IGF-I decreased in exp. 1. However, the piglets fed 2500 ppm of zinc reached pre-weaning levels of serum IGF-I at 14-15 days post-weaning, whereas piglets receiving lower zinc levels showed no changes in serum IGF-I. In exp. 2, <b>additional dietary zinc in weaning diets for piglets was found to be associated with increased feed intake, improved growth rate and increased serum IGF-I.</b> High levels of dietary copper did not affect any of these measurements. Zinc-induced rise in serum IGF-I was partly due to increased feed intake. <b>After correcting for differences in feed intake, zinc significantly increased serum IGF-I.</b>
Chronic highly elevated expression of a growth hormone (GH) transgene enhances overall body growth with minimal adipose accretion, while moderate levels of circulating GH fail to enhance body growth yet promote adipose deposition.
<b>Circulating GH levels in female transgenics were approximately 49, 132, and 750 ng/ml in response to the transgene stimulus at 0, 15, and 25 mM zinc sulfate, respectively.</b> The highest level of circulating GH generated the largest body weight with the smallest fat accrual while the intermediate GH level generated a body weight equivalent to that for the highest GH but the heaviest gonadal fat pads. The lowest GH levels did not increase body size but did enlarge fat depots.
The two highest levels of circulating GH increased all forms of the GH receptor, IGF-I, and hepatic lipoprotein lipase mRNA.