Researchers find another estrogenic compound in soy.

Jun 15, 2009

Boue, SM, S Tilghman, S Elliott, MC Zimmerman, KY Williams, F Payton-Stewart, AP Miraflor, MH Howell, BY Shih, CH Carter-Wientjes, C Segar, BS Beckman, TE Wiese, TE Cleveland, JA McLachlan and ME Burow. 2009. Identification of the potent phytoestrogen glycinol in elicited soybean (Glycine max). Endocrinology 150:2446-2453.

Another soy compound capable of mimicking estrogen is identified, showing there is still much to learn about what types of compounds soy contains.

Researchers have isolated a new estrogen-like compound in soy called glycinol.  The authors report that glycinol appears to be as potent as other, similar compounds found in the legume and its many food products, such as tofu and soy milk. 

Collectively, these compounds are called isoflavone phytoestrogens. When researchers identify which compounds in soy can mimic estrogen, they take an important step toward understanding how soy can postively or negatively affect health.

Eating a low fat, soy-rich diet is associated with a lower risk of heart disease, cancer and osteoporosis. Asian women have historically had a lower risk of breast cancer than women in industrialized nations. This lower risk has been linked to the soy in their diet but may also result from other foods including fish and leafy green vegtables.

Many of the health benefits of soy foods are attributed to the estrogen-like isoflavones, such as genistein, daidzein and others.  But, because these isoflavones can mimic estrogen in some cases, they are also considered potential endocrine disruptors.  Some scientists have expressed concern that soy compounds could affect development – especially reproductive development – in infants and children fed soy-rich foods such as soy infant formula and soy milk.

Interest in plant compounds with estrogen activity is increasing especially among menopausal women seeking alternatives to hormone replacement therapy drugs. Many phytoestrogens are now also found in dietary supplements.

The research group, based at Tulane University, isolated glycinol and tested its estrogenic actions in a series of experiments.

They found that glycinol is a more effective estrogen mimic than other, more well known isoflavones commonly found in soy foods, including the widely studied isoflavones genistein and daidzein.

Like many other soy isoflavones, glycinol can bind to estrogen receptors and trigger cell actions that are similar to estrogen, according to the authors. For example, it induced cultured breast cancer cells to grow, a common test of estrogen action.

By understanding which compounds in soy can behave like estrogen, researchers can determine the relative safety and potential health benefits of soy food products for different age groups.