Lignans are a diverse group of plant-derived compounds that can interfere with estrogen metabolism in animals and humans. As phytoestrogens, lignans exhibit both estrogen and antiestrogen activity—the reason behind their hormone-balancing effects. They also have numerous biological properties that benefit human and animal health, including antimitotic, antifungal, and antioxidant activities.
Sources of Plant-Based Lignans
Lignans are abundant in the plant kingdom. You can find them in most unrefined grains; legumes; and vegetables like broccoli, carrots, cauliflower, and spinach. Flaxseed contains high levels of the plant lignan precursor, secoisolariciresinol diglycoside (SDG), and has 75 to 800 times more plant lignans than most other foods found in vegetarian diets.
For those who want to add lignans to your diet, nutrition experts recommend using ground flax or extract-based lignan products, as they are more easily digested and absorbed by the body. Some of the most common types of lignan supplements you can find in the market today are derived from flax hulls (SDG lignans), the knots of Norwegian Spruce trees (HMR lignans), and sesame seeds (sesamin).
Ground Flax vs. Extract-Based Lignans
Each person or animal will respond differently to different lignan types. As you can observe from the table above, ground flax products confer two important benefits that extract-based products do not: they contain fiber and omega-3 fatty acids.
In terms of releasing enterolignans and antioxidants, ground flax and SDG extract both produce a time-release effect, while HMR lignans do not. Ground flax and SDG also produce both enterodiol (ED) and enterolactone (EL), which is valuable as some people (or animals) may respond better to one or the other.
However, for those who cannot tolerate fiber and in cases where Omega 3 supplementation is undesirable, either SDG or HMR extract is recommended.
When choosing between the two extracts, key considerations are whether “time-release” effects are desirable and the relative bio-receptivity of the patient’s body to the two enterolignans (vs. just one of them–EL). SDG lignans produce a time-release effect and contain both ED and EL, while HMR lignans only produce EL.
A Cushing’s treatment study performed by the University of Tennessee noted a difference in response towards ED and EL, although not at a statistically significant level. That said, extensive clinical experience since then has also shown that HMR lignans are effective and work equally well in reducing cortisol levels associated with Cushing's. The University of Tennessee recommends both HMR and SDG lignans for treating Cushing’s disease.
A More In-Depth Comparison of SDG Lignans and HMR Lignans
Both SDG (secoisolariciresinol diglucoside) and HMR (hydroxymatairesinol) are lignans, but they have different properties, characteristics, and benefits to the body.
SDG lignans are glycosides. They are attached to a sugar molecule, affecting their solubility and absorption in the body. HMR lignans, on the other hand, are non-glycosylated lignans. They have better bioavailability and absorption in the body.
SDG lignans need intestinal bacteria to convert them into their active forms (enterolactone and enterodiol) before they can be absorbed into the bloodstream. HMR lignans, on the other hand, can be absorbed directly into the bloodstream and do not require bacterial conversion. This may make HMR lignans a more effective source for individuals with poor gut health or low levels of intestinal bacteria.
Both SDG and HMR lignans have been shown to have health benefits, but their effects may differ. SDG lignans were linked to reduced risk of breast, prostate, and colorectal cancers, as well as improved cardiovascular health and reduced inflammation. HMR lignans have been shown to improve menopausal symptoms, reduce oxidative stress, and improve bone health.
SDG lignans are found in various plant-based foods, such as flaxseed, sesame seeds, and whole grains, while HMR lignans are primarily found in Norwegian spruce trees and are not widely available in food sources.
It is important to note that while both types of lignans have potential health benefits and can be obtained through dietary sources or supplements, the optimal source and dosage may vary based on individual needs and health status. We recommend discussing lignan supplements with a healthcare professional before use to determine the appropriate dosage and source for you or your dog.