In addition, certain plants can produce chemical compounds that have a similar effect as human estrogens, hence the term "phytoestrogen ", thanks to their structural similarity with estradiol (17-β-estradiol). Vegetable foods with the highest relative phytoestrogen content are nuts and oilseeds, followed by soy products, cereals, breads, and legumes. It has often been assumed that the frequent ingestion of such phyoestrogens contributes to male feminisation (including the condition of Gynecomastia) or the disruption of male reproductivity. It is unclear however under which conditions this may occur (and to which extent), i.e. whether it depends on the daily dose, the age (of the male consumer) or even genetic disposition. A 2010 meta-analysis of fifteen placebo-controlled studies said that "neither soy foods nor isoflavone supplements alter measures of bioavailable testosterone concentrations in men."