Long-term endometrial and breast safety of a specific, standardized soy extract

Abstract

As no case of hyperplasia was diagnosed among the 301 interpretable biopsies at 1 year and there was only one case of simple hyperplasia in the 197 post-baseline biopsies at 3 years, the endometrial safety of this extract has been demonstrated. Furthermore, as demonstrated by the lack of change in endometrial thickness associated with the histologic results, we suggest that this extract does not exert a mitogenic effect on the endometrium. These results suggest that daily administration of 70 mg of a specific, standardized isoflavone extract for 3 years could be a safe treatment for both endometrium and breast.

Soy Isoflavones for Reducing Bone Loss Study

“…Indeed, soy isoflavone tablets easily allow intake in excess of 100 mg isoflavones/d, five times that of isoflavone intake from typical Asian diets 1 . One long-term (3 y) study 2 indicated that soy isoflavone (extract form) intake was safe for the endometrium and breast, another (2 y) study 3 demonstrated that soy hypocotyl isoflavones (80 or 120 mg) did not adversely affect endometrial thickness, and another recent (1 y) study 4 showed that soy isoflavones (60 mg) combined with Lactobacillus sporogenes was safe for the endometrium, mammary glands, and liver function. Indeed, a 2-y study 5 indicated that genistein (54 mg/d), the predominant soybean isoflavone, reduced the mean number of hot flushes/d, but it did not affect the endometrium.…”

A risk assessment-driven quantitative comparison of gene expression profiles in PBMCs and white adipose tissue of humans and rats after isoflavone supplementation

“…Also, it has been shown that the proportions of the more active free isoflavones in the circulation were markedly higher (20-150 times) in rodents than in humans (Setchell et al, 2011). Furthermore, over the past few years human studies have not confirmed the adverse effects found in in vitro and in animal studies, except for a disputable adverse effect related to endometrial thickness (Unfer et al, 2004), which was not confirmed in more recent studies (Alekel et al, 2014;D'Anna et al, 2007;Palacios et al, 2007;Palacios et al, 2010).…”

Preparatory work to support the risk assessment for peri‐ and postmenopausal women taking food supplements containing isolated isoflavones

“…In two studies (Palacios 2010 andColacurci 2013) endometrial and breast safety aspects were the primary endpoint. Khan (2012) specifically investigated breast epithelial cell proliferation, which was presumed to be beneficially influenced by isoflavones.…”

“…No studies were specifically powered for adverse effects on thyroid, endometrium or breast. The study by Colacurci et al (2013) did not report a sample size calculation; the study by Palacios et al (2010) was a prospective open-label study, without control group. This means that it's unclear whether there is sufficient power to detect a difference should there be one.…”