Lignans are a group of polyphenolic compounds found in plants, particularly in seeds such as flaxseed, as well as in whole grains, legumes, and vegetables. Scientific interest in lignans for breast health comes from their structural similarity to estrogen; lignans are phytoestrogens, meaning they can weakly bind to estrogen receptors in the body. This interaction is thought to potentially modulate estrogen activity, which is relevant because estrogen plays a significant role in the development and progression of certain types of breast cancer.

Several epidemiological studies have investigated the association between dietary lignan intake and breast cancer risk. Some meta-analyses suggest that higher intake of lignans, especially from flaxseed, may be associated with a modestly reduced risk of breast cancer, particularly among postmenopausal women (Buck et al., 2011). Experimental studies propose that lignans may influence breast tissue through anti-proliferative, anti-angiogenic, and pro-apoptotic effects, as well as by altering estrogen metabolism (Dossus & Kaaks, 2014). However, results are not entirely consistent, with some studies finding no significant association.

Overall, the scientific evidence supporting lignans for breast health is promising but not definitive. Most data support their potential benefit in reducing breast cancer risk, rather than direct support for general breast health. More large-scale and long-term clinical trials are needed to clarify their role.