title: Effects of dietary weight loss and exercise on insulin-like growth factor-I and insulin-like growth factor-binding protein-3 in postmenopausal women: a randomized controlled trial.
abstract: High levels of insulin-like growth factor (IGF)-I may increase the risk of common cancers in humans. We hypothesized that weight loss induced by diet and/or exercise would reduce IGF-I in postmenopausal women. Four hundred and thirty nine overweight or obese [body mass index (BMI) ≥ 25 kg/m(2)] women (50-75 years) were randomly assigned to: (i) exercise (N = 117), (ii) dietary weight loss (N = 118), (iii) diet + exercise (N = 117), or (iv) control (N = 87). The diet intervention was a group-based program with a 10% weight loss goal. The exercise intervention was 45 minutes/day, 5 days/week of moderate-to-vigorous intensity activity. Fasting serum IGF-I and IGF-binding protein (IGFBP)-3 were measured at baseline and 12 months by radioimmunoassay. Higher baseline BMI was associated with lower IGF-I and IGF-I/IGFBP-3 molar ratio. Although no significant changes in either IGF-I or IGFBP-3 were detected in any intervention arm compared with control, the IGF-I/IGFBP-3 ratio increased significantly in the diet (+5.0%, P < 0.01) and diet + exercise (+5.4%, P < 0.01) groups compared with control. Greater weight loss was positively associated with change in both IGF-I (P(trend) = 0.017) and IGF-I/IGFBP-3 ratio (P(trend) < 0.001) in the diet group, but inversely with change in IGFBP-3 in the diet + exercise group (P(trend) = 0.01). No consistent interaction effects with baseline BMI were detected. Modified IGF-I bioavailability is unlikely to be a mechanism through which caloric restriction reduces cancer risk in postmenopausal women.
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Mason
authors.forename: Liren
authors.initials: L
authors.lastname: Xiao
authors.forename: Catherine
authors.initials: C
authors.lastname: Duggan
authors.forename: Ikuyo
authors.initials: I
authors.lastname: Imayama
authors.forename: Karen E
authors.initials: KE
authors.lastname: Foster-Schubert
authors.forename: Angela
authors.initials: A
authors.lastname: Kong
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Campbell
authors.forename: Ching-Yun
authors.initials: CY
authors.lastname: Wang
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Alfano
authors.forename: George L
authors.initials: GL
authors.lastname: Blackburn
authors.forename: Michael
authors.initials: M
authors.lastname: Pollack
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
mesh_terms: D000368:Aged; D015992:Body Mass Index; D031204:Caloric Restriction; D004038:Diet, Reducing; D015444:Exercise; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008875:Middle Aged; D015431:Weight Loss
chemical_list: C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I