A randomized controlled trial of phytoestrogen supplementation, growth and bone turnover in adolescent males

Abstract

Objective: To assess the effect of phytoestrogens on bone turnover and growth in adolescent boys. Design: Randomized double-blind placebo-controlled trial. Setting: Single school in northwest Tasmania. Participants: Adolescent boys (treatment n ¼ 69, placebo n ¼ 59, mean age 16.8 y). Interventions: Six weeks of isoflavone supplementation (Novasoy, 50 mg daily of isoflavone equivalents). Bone turnover markers (bone specific alkaline phosphatase (BAP) and pyridinoline creatinine ratio (PYR)) were measured at baseline and follow-up. Results: Despite marked increases in urinary genistein and daidzein in the treatment arm (both P < 0.001), there were no significant differences in BAP, PYR or short-term height or weight change. This applied to both intention-to-treat and per protocol analysis. Neither was there a significant correlation between urinary genistein and daidzein levels and BAP or PYR. Conclusions: Phytoestrogen supplementation to the level of usual Japanese dietary intake has no measurable effect on bone turnover in adolescent boys. Longer-term studies of bone density may be desirable but it is unlikely that there will be a large effect in either girls or boys given the lower endogenous oestrogen levels in boys.

Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials

“…Our literature search identified 31 RCTs. Twenty-two studies were excluded because of lack of indices of interest (Agnusdei et al, 1997a, b;Gambacciani et al, 1997a, b;Potter et al, 1998;Alekel et al, 2000;Wangen et al, 2000;Clifton-Bligh et al, 2001;Katase et al, 2001;Anderson et al, 2002;Chiechi et al, 2002;Lucas et al, 2002;Chen et al, 2003Chen et al, , 2004Jones et al, 2003;Schult et al, 2003;Atkinson et al, 2004;Harkness et al, 2004;Olsen et al, 2004;Mori et al, 2004a, b), non-randomization (Dalais et al, 1998), lack of a control group (Agnusdei et al, 1997a, b), insufficient original data or baseline values (Gambacciani et al, 1997a, b;Khalil et al, 2002). Thus, nine studies with a total of 432 subjects were included in this meta-analysis, in which five studies had quality score of five; three studies had quality score of four and one study had quality score of three (Morabito et al, 2002;Uesugi et al, 2002;Yamori et al, 2002;Arjmandi et al, 2003Arjmandi et al, , 2005Dalais et al, 2003;Brooks et al, 2004;Mori et al, 2004a, b;Nikander et al, 2004) (Table 1).…”

Phytoestrogens: a review of the present state of research

“…A recent study evaluating the long-term reproductive effects of genistein (0-10 mg/kg per day) during gestation and lactation in mice showed no significant effect on sperm count, the number of motile sperm, or sperm mobility nor was there any effect on testicular gene expression (Fielden et al, 2003). In adolescent boys, isoflavone supplementation showed no significant effect on bone turnover and growth (Jones et al, 2003). Additional studies are needed to further evaluate the risks of phytoestrogen consumption in male development.…”

Feeding brown fat: dietary phytochemicals targeting non-shivering thermogenesis to control body weight

“…No human clinical trial so far included EE or BAT activation as outcome measures. Most reports (152)(153)(154)(155)(156)(157)(158) (supplementary material) focus on anthropometric measures and body composition as surrogates for alterations in energy homoeostasis. The interpretation of human trials investigating the efficacy of isoflavone mixtures or individual compounds is complex as interactive factors such as sex, pre-/postmenopausal state, habitual isoflavone exposure/ethnicity and interindividual variation in metabolising enzymes (hepatic or intestinal, gut microflora) need to be taken into account.…”