Effects of dietary intervention on IGF-I and IGF-binding proteins, and related alterations in sex steroid metabolism: the Diet and Androgens (DIANA) Randomised Trial.
OBJECTIVE
To assess the effects of a comprehensive change in dietary composition on endogenous hormone metabolism. The specific aim was to examine whether this intervention could lead to favourable changes in insulin sensitivity, levels of IGF-I and IGF-binding proteins (IGFBPs), and total and bioavailable testosterone and estradiol, that would be expected to reduce breast cancer risk.


METHODS
Randomised dietary intervention study; duration of 5 months.


METHODS
From a total of 99 postmenopausal women, who had elevated baseline plasma testosterone levels, 49 women were randomly assigned to the dietary intervention arm and the other 50 to a control group.


METHODS
Main aspects of the dietary intervention were reductions in the intake of total fat and refined carbohydrates, an increase in the ratio of n-3 over n-6 plus saturated fatty acids, and increased intakes of foods rich in dietary fibre and phytooestrogens.


RESULTS
Relative to the control group, women of the intervention group showed a significant reduction of body weight, waist circumference, fasting serum levels of testosterone, C peptide, glucose, and insulin area after glucose tolerance test, and a significant increase of serum levels of sex hormone-binding globulin, IGFBP-1, -2, and growth hormone-binding protein. Serum levels of IGF-I did not change.


CONCLUSIONS
This comprehensive dietary intervention strategy proved to be successful in inducing changes in endogenous hormone metabolism that might eventually result in reduced breast cancer risk. Additional studies are needed to show whether the dietary intervention and related hormonal changes can be both maintained over longer periods, of at least several years.
Kaaks
R
R
Hormones and Cancer Group, International Agency for Research on Cancer, Lyon, France. kaaks@iarc.fr
Bellati
C
C
Venturelli
E
E
Rinaldi
S
S
Secreto
G
G
Biessy
C
C
Pala
V
V
Sieri
S
S
Berrino
F
F
D000368:Aged; D000704:Analysis of Variance; D000886:Anthropometry; D001835:Body Weight / Q000502:physiology; D004032:Diet; D014676:Diet, Vegetarian; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007558:Italy; D008875:Middle Aged; D017698:Postmenopause / Q000378:metabolism; D012016:Reference Values; D018709:Statistics, Nonparametric
D012739:Gonadal Steroid Hormones; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I