HMR lignan (7-hydroxymatairesinol) is a type of plant lignan derived primarily from the Norway spruce. Lignans are phytoestrogens, plant compounds that can have estrogen-like effects in the body. Scientific interest in HMR lignans has focused on their potential role in modulating estrogen metabolism, which is relevant to the female reproductive system. Some studies show that HMR lignan is converted in the gut to enterolactone, a compound associated with a reduced risk of hormone-dependent conditions, such as breast cancer and menopausal symptoms. Clinical and preclinical research indicates that lignans may help support hormonal balance, manage some menopausal symptoms, and promote overall reproductive health in women, though most evidence is from observational studies or small clinical trials rather than large-scale randomized controlled trials.

While the evidence is promising, the degree of scientific validation is moderate. The potential benefits seem to be due to HMR lignan's weak estrogenic and anti-estrogenic activities, which may help buffer fluctuations in endogenous estrogen levels. However, more robust human trials are needed to confirm these effects and to determine optimal dosing and safety. Therefore, while HMR lignan is used to support the female reproductive system and there is a scientific rationale, the overall quality and quantity of evidence currently rates as moderate.