There are over 8,000 polyphenolic compounds in the plant world (62). Berries, green tea, coffee, cocoa, some spices and even red wine  all contain  polyphenols and have strong antioxidant properties.

Polyphenols in plants protect them from harmful UV radiation as well as attacks from harmful pathogens.

Polyphenols are also powerful micronutrients that our bodies use to stay healthy . They have numerous health benefits that may offer protection from the development of cancers, cardiovascular disease, osteoporosis, and diabetes.  (62) All polyphenols have various bioavailability which will depend on the type of polyphenol as well as the colon microflora.

While it’s ideally best to get these nutrients through our diet, sometimes an unbalanced diet prevents us from getting as much as we need. 

Polyphenols are grouped in 4 major classes: phenolic acids, flavanoids, stilbenes and lignans. 

Nordic Sunn’s Norwegian Spruce Extract contains several lignans sourced from spruce trees in Scandinavia.

Lignans were first discovered in trees over 100 years ago. The norwegian spruce extract, collected from the knotwood of the tree (Picea Abies) is thought to be one of nature's highest concentration of lignans available (50) (38) 

Knots in trees have been shown to have 5-10% dry weight of lignans, much higher than ordinary stemwood, with the Norwegian Spruce containing 6-24% of lignans, this being 50 to 100 times higher than in normal wood (54)

Flaxseed is also known to have the highest concentration of lignans in the plant world, however Chromatographic analysis of lignans shows that Norwegian Spruce knotwood extract has between 10 and 20 times more lignans than flaxseed (50)(61). 

Norwegian Spruce knotwood lignans are primarily composed of 7-hydroxymatairesinol (HMR).   But is also possesses a large amount of other lignans as well

Using more recent measurements techniques, it was found that HMR is also the major lignan source in wheat, oat, barley and bran, but still in much smaller amounts than those found in Norwegian Spruce. (53)

As seen previously, norwegian spruce knotwood and flaxseed are both major sources of lignans in nature.

Norwegian Spruce knotwood contains mostly the lignan hydroxymatairesinol (HMR).  Hydroxymatairesinol then gets converted to matairesinol (MAT) through hydrogenolysis and then mostly into enterolactone (ENL) and some enterodiol (ED) through bacteria in the gut.  (56)  Norwegian Spruce knotwood also contains secoisolariciresinol (SECO), matairesinol (MAT) and lariciresinol (LARI). (50) The chemical structure of HMR is closely related to MAT, and, therefore provides an efficient precursor of ENL. (13)

We live in a world where free radicals can come from many sources and contribute to the deterioration of health. Sources of free radicals include pollutants, drugs, metal ions, radiation, and high intakes of polyunsaturated fatty acids, and also strenuous exercise, mitochondrial dysfunction, and smoking. (87)

One of the benefits of  lignans is thought to be due to antioxidant activity, primarily as an efficient hydroxyl radical scavengers.  (96)  Research done on various wood species, and especially knotwood and bark showed its strong anti-oxidant potential.  (37)

Some research shows the mammalian lignan metabolites (enterodiol and enterolactone) may actually have greater or different activity than the parent lignan. (103)

SECO, ED and ENL were all found to be 4.5 to 5 times more powerful than Vitamin E as a direct antioxidant.  (87)

HMR, the lignan found in the Norwegian Spruce knotwood,  is also known to be a powerful antioxidant.  When comparing to Trolox (the reference for anti-oxidation)  HMR ranked higher than SECO, the major lignan in flaxseed, as an anti-oxidant. (106)

The behavior of the phytoestrogen lignans depends on the biological levels of estradiol . It is thought that at normal estradiol levels, the lignans act as estrogen antagonists, but in postmenopausal women (and thus low estradiol levels) they can act as  weak

estrogens. (61)  (87) This could lead lignans to have both estrogenic and anti-estrogenic effects and benefits..

In women going through menopause, the hormonal balancing impact of phytoestrogens have been shown in various studies to help with menopause symptoms such as hot flashes. (101) (102)

In one study, Japanese women have historically shown low incidence of menopause symptoms compared to Canadian women. (67)  This is presumed to be due to the Japanese diet being high in phytoestrogens through soybean consumption.  In a collaborative studies phytoestrogens soy and flaxseed both had strong positive effects on hot flashes and vaginal dryness. (68)

In a study specifically done using a norwegian spruce extract , researchers found that supplementation led to a 50% decrease in hot flashes (9), while another study showed the hormonal balancing effects of HMR supplementation. (40)

Epidemiological studies have shown that Asian populations with a higher intake of phytoetrogens had a lower incidence of various hormonal related cancers than Western populations. (63)  This had led to much research on the benefits of various foods with health protective properties.

Since the discovery of mammalian lignans  in 1980, it has been suspected they had a beneficial effect on chronic disease.   Produced from plant lignans in the gut, they appear to be anticarcinogenic; lignan metabolites bear a structural similarity to estrogens and can bind to estrogen receptors and inhibit the growth of estrogen-stimulated breast cancer. In particular it was found that urinary excretions of breast cancer patients had lower levels of enterolignans (ED+ENL) as compared to non breast cancer patients.  This led to the hypothesis that enterolignans had a beneficial impact on breast cancer. (44)(95)

Prostate cancer is the second most common cause of cancer among men worldwide. Similar to what is seen with breast cancer, incidence of prostate cancer is highest in North America and Europe, with Asian populations showing lower incidence of the disease. (63) (79) Incidence rate and mortality rates are 60 and 17 times higher respectively when comparing the United States and China . (25)

According to epidemiological studies, as well as in-vitro and in-vivo studies, there is evidence suggesting that iso-flavanoids and lignans, both phytoestrogens,  could be protective against the proliferation of prostate cancer. (63)(70)(116)   ENL was also found to have anti-proliferative properties on prostate cancer cells. (25)  A case-control study conducted in Scotland found that higher serum ENL concentrations were associated with a lower risk of prostate cancer. (118)(61)   In a meta analysis of 11 studies,  increased serum concentration of enterolactone was associated with a significant reduced risk of prostate cancer (80)

In a specific in-vivo study seeking to examine  the effect of 7-hydroxymatairesinol (HMR) on LNCaP tumours in nude mice, HMR from the Norway Spruce was administered.

Animals in receiving HMR  had a reduced tumour take rate, increased percentage of non- growing tumours, and higher tumour cell apoptotic index, compared to a control group (24). 

It is also been researched that ENL is a inhibitor of the enzyme 5α-reductase, the same enzyme that is targeted by finasteride a drug used for benign prostatic hyperplasia.(63)  The inhibition of 5α-reductase could also play a role in inhibiting  the conversion of testosterone to 5a-dihydrotestosterone (DHT). The reduction in DHT concentration has been shown to modify the risk of prostate cancer and benign hyperplasia. (63)(21)

Prostate health is an increasingly important concern for aging men, and lignan supplementation provides some evidence to be supportive for prostate health.

In the mouse liver, the fat-rich diet inhibited regulators of lysosomal biogenesis and autophagy pathways such as the master gene TFEB in parallel to an increase in fat accumulation and the induction of severe steatosis, in line with the observations of Settembre et al.( 36 ) who showed that autophagy is required for lipid degradation via the TFEB pathway. 7-HMR and TEP increased TFEB to levels found in the liver of mice on the LFD (10 % fat), suggesting that the TFEB-regulated pathway may be one of the mechanisms through which lignan can prevent liver steatosis. Amelioration of liver steatosis was also investigated in vitro by using the HEPA 1–6 model.  (30)

A growing amount of research is linking diet, inflammation and cognition.  Similar to other diseases covered, the Western Diet has been associated with higher incidences of neurodegenerative diseases.(124)

In the past several years, several research works demonstrated that dietary polyphenols could have beneficial effects in cognitive functions, by acting against oxidative stress and inflammation. Alteration in the homeostasis of the gut–brain axis has been associated also to neurological disorders and neurodegenerative diseases. (86) This has lead to research on diet, the microbiota-gut-brain axis and its implications in neurological disorders (110)

In terms of general diet, the Mediterranean Diet and Asian Diet have been shown to prevent a variety of pathologies associated with aging. In fact, it is suggested the polyphenols in these diets that are associated with the greatest reduction in neurodegeneration (110)

Polyphenols, as antioxidants, act as free radical scavengers, and thereby afford protection from chronic diseases, such as Alzheimer’s disease and diabetes, in which free radicals play a major role in the pathogenesis. 

There is some evidence that lignans could play a role as an acetylcholinesterase inhibitor, which is shown to have a neuroprotective effect, as acetylcholinesterase breaks down acetylcholine, a neurotransmitter. (81) (86)  Alzheimer’s patients, for example, have been found to have low levels of acetylcholine in their brain.

As a further example, ENL was found to attenuate the degeneration of the striatal dopaminergic terminals in Parkinson’s disease (PD), in the PD rat models (43), while Polyphenols appear to have a positive effect on the gut microbiome, which may decrease inflammation that contributes to the disease. Therefore, a diet rich in polyphenols may decrease the symptoms and increase quality of life in PD patients. (110)

dietary polyphenolic compounds are potentially able to affect the gut–brain axis

via modulation of the gut microbiota, (86)