Lignans are a group of polyphenolic compounds found in plants, especially flaxseed, sesame seeds, and whole grains. Their use for breast lumps—typically referring to benign breast conditions like fibrocystic breast changes—has some scientific basis, though the evidence is limited and not definitive. Lignans are phytoestrogens, meaning they have a weak estrogen-like activity in the body. Several observational studies and small clinical trials have investigated the impact of dietary lignans, particularly from flaxseed, on breast health. Some evidence suggests that lignans may help modulate estrogen metabolism and reduce breast pain and lumpiness in women with benign breast conditions.

A few small randomized controlled trials have shown that flaxseed supplementation can decrease breast pain and improve the overall symptoms of fibrocystic breast disease, likely by altering estrogen metabolism or reducing estrogenic stimulation of breast tissue. However, these studies are generally small, short-term, and sometimes lack rigorous controls. There is also some epidemiological evidence that higher lignan intake is associated with a lower risk of breast cancer, but this does not directly address benign breast lumps.

In summary, while there is some scientific evidence that lignans may support breast health and potentially reduce symptoms associated with benign breast lumps, the data are not robust. More high-quality, large-scale clinical trials are needed to confirm these effects and clarify the mechanisms involved.