Spruce Lignans
Also known as: 7-HMR, Spruce lignans, Norway spruce lignans, HMR lignans, 7-hydroxymatairesinol
Overview
Spruce lignans, primarily 7-hydroxymatairesinol (7-HMR), are bioactive polyphenolic compounds extracted from the knotwood of the Norway spruce (Picea abies). These plant lignans are chemically classified as dibenzylbutyrolactone lignans and are considered phytoestrogens and antioxidant compounds. 7-HMR constitutes a significant portion of the knotwood, making it a rich natural source. They are primarily used as dietary supplements for managing menopausal symptoms, particularly hot flashes, and show promise in cancer chemoprevention, especially for prostate cancer, and potentially for cardiovascular health. The key characteristic of 7-HMR is its bioavailability and subsequent metabolism by gut microbiota into enterolactone, a mammalian lignan that exhibits both estrogenic and antioxidant effects. Research on spruce lignans is at a moderate maturity level, with existing clinical trials and preclinical studies, though large-scale systematic reviews or meta-analyses are currently limited.
Benefits
Spruce lignans offer several evidence-based benefits, primarily due to their conversion to enterolactone. The most notable benefit is the reduction of menopausal hot flashes. A small pilot randomized controlled trial (RCT) involving 20 participants demonstrated a significant 53% reduction in hot flush frequency (from 4.3 to 2.0 flushes/day) with 50 mg/day of 7-HMR lignan over 8 weeks, indicating a clinically meaningful effect. This benefit is particularly relevant for postmenopausal women. Another significant area of benefit is prostate cancer inhibition, supported by animal studies. In prostate cancer xenograft models, dietary 7-HMR supplementation led to a substantial 259% reduction in tumor volume and a 360% increase in apoptotic indices at higher doses. While these are preclinical findings, they suggest a strong potential for anticancer effects in aging men. Additionally, there is potential for cardiovascular benefits linked to increased circulating enterolactone levels, although direct clinical evidence specifically for spruce lignans in this area is still limited. The time course for benefits, such as hot flush reduction, has been observed within 8 weeks of consistent use.
How it works
Spruce lignans, particularly 7-HMR, exert their effects primarily through their metabolism by gut microbiota into enterolactone. Enterolactone is a mammalian lignan that acts as a phytoestrogen, meaning it can interact with estrogen receptors (ERα and ERβ) in the body. This selective estrogen receptor modulating activity contributes to its ability to alleviate menopausal symptoms by modulating hormonal pathways. Beyond its estrogenic effects, enterolactone also possesses significant antioxidant properties, which may contribute to its potential cardiovascular benefits and overall cellular protection. In the context of cancer, 7-HMR and its metabolites are believed to induce apoptosis (programmed cell death) in cancer cells, as observed in preclinical prostate cancer models. Oral 7-HMR is bioavailable, with detectable plasma levels and metabolites confirming systemic exposure, and its conversion to active metabolites is dependent on a healthy gut microbiome.
Side effects
Spruce lignans are generally well tolerated, with human studies reporting minimal adverse effects. Unlike some other lignans, such as flax lignans, which can cause gastrointestinal symptoms, spruce lignans have not been associated with common side effects (defined as >5% incidence) in clinical trials. No uncommon (1-5%) or rare (<1%) side effects have been reported. There are no documented drug interactions, but caution is advised when used concurrently with hormone-sensitive conditions or medications due to its phytoestrogen activity. Spruce lignans are likely contraindicated in individuals with hormone-sensitive cancers unless under strict medical supervision, given their potential to interact with hormonal pathways. Safety in specific populations such as pregnant or breastfeeding women and children has not been established, and therefore, use in these groups is not recommended without further research.
Dosage
The recommended dosage for spruce lignans, specifically 7-HMR, is based on current human pilot data and pharmacokinetic studies. For menopausal symptom relief, an approximate minimum effective dose is 25-50 mg/day of 7-HMR. Optimal dosage ranges observed in clinical and pharmacokinetic studies are typically between 36-72 mg/day. The maximum safe dose has not been definitively established, but no toxicity has been reported at the doses studied. Spruce lignan supplements are generally administered once or twice daily, often with meals, to optimize absorption. Standardized extracts containing around 70% 7-HMR are commonly used. The bioavailability of 7-HMR is confirmed, and its conversion to active metabolites like enterolactone is dependent on the activity of gut microbiota. No specific cofactors are identified as necessary for its absorption or efficacy.
FAQs
Is spruce lignan safe for long-term use?
While short-term human studies indicate good safety, long-term human data on spruce lignans are currently limited. Continued research is needed to fully assess long-term safety.
How quickly do benefits appear?
Improvements in menopausal symptoms, such as hot flashes, have been observed within 8 weeks of consistent daily supplementation with spruce lignans.
Can it replace hormone therapy?
Spruce lignans are not established as a replacement for hormone therapy. They may offer an alternative for managing mild menopausal symptoms, but consultation with a healthcare provider is essential.
Are there side effects?
Spruce lignans are generally well-tolerated with minimal reported side effects in clinical trials. They are considered better tolerated than some other lignans, such as those from flax.
Does it affect hormone-sensitive cancers?
Preclinical studies show anticancer potential, particularly for prostate cancer. However, due to its phytoestrogenic activity, caution is advised, and medical supervision is recommended for individuals with hormone-sensitive conditions.
Research Sources
- https://pmc.ncbi.nlm.nlm.nih.gov/articles/PMC3877914/ – This RCT investigated the pharmacokinetics, safety, and compliance of 7-HMR lignan in humans. It found that 7-HMR and its metabolite enterolactone were bioavailable in plasma after oral administration, with detectable levels up to 72 hours. The study reported no significant adverse events, indicating good safety and tolerability, though it was limited by its small sample size and short duration.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7411943/ – This analytical study characterized the lignan content and localization within Norway spruce knotwood. Using advanced microscopy and chromatography, it identified 15 different lignans, with 7-HMR being the predominant one. This research provides a strong chemical basis for the biological activities observed in spruce lignans but does not include clinical data.
- https://www.nutraingredients.com/Article/2007/11/12/norway-spruce-lignans-cut-hot-flushes-by-53-per-cent-study/ – This article reports on a small pilot RCT that investigated the effect of 7-HMR on menopausal hot flashes. The study, involving 20 participants, showed a statistically significant 53% reduction in hot flush frequency over 8 weeks with 50 mg/day of 7-HMR. While promising, the study's small size and lack of detailed placebo control limit its generalizability.
- https://www.lifeextension.com/magazine/2008/1/report_lignans – This article summarizes an animal study using a mouse xenograft model to evaluate 7-HMR's effect on prostate cancer. The study demonstrated that dietary 7-HMR supplementation led to a dose-dependent reduction in tumor volume and increased apoptosis in cancer cells. These preclinical findings suggest a strong potential for 7-HMR as an anticancer agent, though human confirmation is needed.
Supplements Containing Spruce Lignans
Recommended Articles
Hormone-Balancing Ingredients: What You Need to Know
Certain natural ingredients and dietary supplements can significantly influence hormone levels, with both potential benefits and risks.
Plant vs Fish Omega-3s: A Comprehensive Comparison
While fish oil offers direct EPA and DHA, plant-based omega-3s provide ALA, which the body can convert to EPA and DHA, albeit less efficiently.
Top Omega-3 Supplements of 2025: A Third-Party Tested Guide
In 2025, brands like Nordic Naturals, Life Extension, and Viva Naturals lead in producing the highest-quality, third-party tested Omega-3 supplements.