Genistein aglycone does not affect thyroid function: results from a three-year, randomized, double-blind, placebo-controlled trial.
OBJECTIVE
Genistein aglycone positively affects postmenopausal symptoms. However, questions about its long-term safety on the thyroid gland still remain.


METHODS
The parent study was a randomized, double-blind, placebo-controlled trial involving 389 osteopenic, postmenopausal women for 24 months. A subcohort (138 patients) continued therapy for an additional year.


METHODS
Patients received ambulatory care.


METHODS
Participants received 54 mg of genistein aglycone daily (n = 71) or placebo (n = 67), plus calcium and vitamin D(3) at therapeutic doses. Circulating thyroid hormones (TSH, free T(3), free T(4)) and autoantibodies (thyroid peroxidase, thyroglobulin, and thyroid microsomal antigen) were assessed in 40 genistein and 37 placebo subjects who completed 3 yr. Thyroid hormone receptor (THRalpha and THRbeta) and retinoid receptor (RARalpha, RARgamma, and RXRalpha) expression from peripheral blood monocytes was also evaluated at baseline, 12, 24, and 36 months in all 3-yr completers.


RESULTS
Genistein administration over 3 yr did not affect serum thyroid hormones or autoantibodies. In addition, there were no differences in THRalpha, THRbeta, RARalpha, RARgamma, or RXRalpha mRNA expression between groups.


CONCLUSIONS
These data suggest that genistein aglycone intake does not significantly increase the risk of clinical or subclinical hypothyroidism at the dose of 54 mg/d.
Bitto
Alessandra
A
Department of Clinical and Experimental Medicine and Pharmacology, Section of Pharmacology, University of Messina, 98125 Messina, Italy.
Polito
Francesca
F
Atteritano
Marco
M
Altavilla
Domenica
D
Mazzaferro
Susanna
S
Marini
Herbert
H
Adamo
Elena Bianca
EB
D'Anna
Rosario
R
Granese
Roberta
R
Corrado
Francesco
F
Russo
Silvia
S
Minutoli
Letteria
L
Squadrito
Francesco
F
D000368:Aged; D015992:Body Mass Index; D004032:Diet; D004311:Double-Blind Method; D005260:Female; D019833:Genistein / Q000009:adverse effects* / Q000097:blood; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating / Q000097:blood; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011988:Receptors, Thyroid Hormone / Q000096:biosynthesis / Q000378:metabolism; D047488:Retinoid X Receptors / Q000096:biosynthesis / Q000378:metabolism; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D018828:Immunoglobulins, Thyroid-Stimulating; D008055:Lipids; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D047488:Retinoid X Receptors; D014284:Triiodothyronine; D013972:Thyrotropin; D019833:Genistein; D013974:Thyroxine