Creatine & IGF-1

Here's a study that included vegans & vegetarians about how creatine causes the body to create more natural growth hormone IGF-1.
It basically shows that all exercise increases the hormone (as you'd expect), but adding creatine increases it more (whether you're a meat-eater, veggie or vegan the increase is the same).

Quote :

Int J Sport Nutr Exerc Metab. 2008 Aug;18(4):389-98.
Effect of creatine supplementation and resistance-exercise training on muscle insulin-like growth factor in young adults.

Burke DG, Candow DG, Chilibeck PD, MacNeil LG, Roy BD, Tarnopolsky MA, Ziegenfuss T.
Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada.
The purpose of this study was to compare changes in muscle insulin-like growth factor-I (IGF-I) content resulting from resistance-exercise training (RET) and creatine supplementation (CR). Male (n=24) and female (n=18) participants with minimal resistance-exercise-training experience (=1 year) who were participating in at least 30 min of structured physical activity (i.e., walking, jogging, cycling) 3-5 x/wk volunteered for the study. Participants were randomly assigned in blocks (gender) to supplement with creatine (CR: 0.25 g/kg lean-tissue mass for 7 days; 0.06 g/kg lean-tissue mass for 49 days; n=22, 12 males, 10 female) or isocaloric placebo (PL: n=20, 12 male, 8 female) and engage in a whole-body RET program for 8 wk. Eighteen participants were classified as vegetarian (lacto-ovo or vegan; CR: 5 male, 5 female; PL: 3 male, 5 female). Muscle biopsies (vastus lateralis) were taken before and after the intervention and analyzed for IGF-I using standard immunohistochemical procedures. Stained muscle cross-sections were examined microscopically and IGF-I content quantified using image-analysis software. Results showed that RET increased intramuscular IGF-I content by 67%, with greater accumulation from CR (+78%) than PL (+54%; p=.06). There were no differences in IGF-I between vegetarians and nonvegetarians. These findings indicate that creatine supplementation during resistance-exercise training increases intramuscular IGF-I concentration in healthy men and women, independent of habitual dietary routine.