Lignans are known to be a phenolic compound present in fiber-rich plants like Flax or Linum usitatissimum. Flax is rich in SDG, metaraminol, and SECO, and Colon bacteria convert SDHG into mammalian lignans enterodiol and enterolactone. Flax seeds are of different colors, from dark brown to yellow, flat seed, and pointed tip. The composition of flaxseed is such that it contains oil content (40-50%) with 20-30% protein, 23% to 34% protein, 4% ash, 5% viscous fiber (mucilage), and lignan precursors (9 to 30 mg/g of the defatted meal), Flaxseed consists of biological products as a result of which researchers are more interested in evaluating more about its beneficial health role. (oil containing approximately 59% a-linolenic acid) and the presence of plant lignan secoisolariciresinol glycoside (SDG;).
It has many potential health benefits as it helps decrease the risk of cardiovascular diseases (Craig, 1999) helpful in decreasing the risk of cancer diseases (Craig, 1999) specifically mammary. Prostate gland cancer (Craig, 1999) also performing a role as an anti-inflammatory (Ziegler et al., 2004) increased menopausal symptoms and osteoporosis. (Kurzer & Xu, 1997) So in UK, Flaxseed and flaxseed meals are consumed in food like cookies, bread, and salad. It is very profitable in reducing the vaginal symptoms of menopause in women when taken with a phytoestrogen supplement. It mutates the original cells, hence reducing the vaginal dryness. (Brzezinski & Debi, 1999) Reduces the risk of breast cancer as reported in many studies, the excretion of phytoestrogen in higher amount, also lower the chances of prostate cancer in Asian men to the North American men comparatively.
Lignins are formed when two conifer alcohol residues combine (Jenab et al., 1999) (Ford et al., 1999) Ground and whole flax contain 0.7% to 1.9 % SDG. Flax oil is available with added lignins, including 0.1% SDG.
There are some other food sources also like seeds, legumes, vegetables, berries, alcoholic beverages.
How does the plant lignin convert to metabolic lignins(role of bacteria)?
Plant lignin is converted to END and ENL by incubating lignin with the bacteria present in the stool: but this process is irreversible. In in vitro studies, it has been found that flaxseed in fecal, when incubated with END it converted to ENL. But this was impossible with sterile culture. Hence human gut bacteria are responsible for this. (Wang et al., 2000) flaxseed can evaluate END and ENL levels to check the plant lignin uptake by the person.
How to get a Better intake and better results:
Due to the tiny size, flaxseed is likely to escape from the body through the digestive tract, but the nutrient would remain unabsorbed. So, a person should uptake it after grinding in a coffee-bean grinder. And Flaxseed can be consumed by mixing with yogurt, oatmeals, baked flaxseeds into muffins and quick bread. It can be consumed as a substrate with breadcrumbs.
In cancer prevention:
In a study, lignin is bounded to ER, suggesting its relationship with ER. Also, it is found in MCF-7 tumors. This relation of lignin is ER-mediated; this indicates that it could be beneficial to prevent breast cancer. (Adlercreutz et al., 1992) (Saarinen et al., 2005)
Another in vivo study suggested that it is highly preferable to prevent DNA damage in mice. Some studies indicate that it is due to the antioxidant machinery of the lignin, but the exact one is not known. (Kitts et al., 1999))
In Colon and skin cancer prevention:
Thompson and Morris demonstrated that flaxseeds are also helpful in inhibiting skin and colon cancer.
A study performed in athymic mice suggested that a 10 mg/kg dose of enterolactone, by subcutaneous injection three times per week, reduced colon 201 human colon cancer cells(some studies indicated that it is based on the apoptosis and decreased proliferation of cancerous cells. However, some clinical studies need to confirm the flaxseed function in preventing cancer in the human population.
A study reported that the higher the portion of enterolactone levels in prostate fluid, the lesser the chances of prostate cancer. Hence Lignan, enterodiol, and enterolactone are responsible for lowering the cases of prostate cancer.
In another study, the person consumes flaxseed for 30g/day and found out to be the decreased proliferation of cancerous cells and increased apoptosis.
Another study proved that consumption of a low-fat diet helps prevent prostate cancer (Demark-Wahnefried et al., 2004)
It is preventing diabetes.
Low-glycemic-index foods reduce insulin content. Some components of flaxseed like soluble fiber, help reduce insulin secretion by maintaining the glucose-plasma interaction. (Cunnane et al., 1993). A study reported that the daily consumption of 50 g/d ground flaxseed for four weeks by a female reduced the blood sugar level of the female. Also, the bread with 25% flaxseed lowers the glycemic content by 28% comparative to non-flaxseed bread (Jenkins et al., 1999)
Effect on Blood pressure:
It positively affects the systolic blood pressure, that is, the pressure of blood in arteries. In a study, the consumption of flaxseed for 24 weeks decreased the blood pressure from 155 to 140. And author concludes that regular consumption can reduce the complete removal of hypertension and cardiovascular risks.
Benefits to the bone:
A study found lignin, a plant-based estrogen, helps overcome menopause-like bone loss and decreases the risk of osteoporosis. Consumption of flaxseed recovers the counter bone loss in aged women. Still, some clinical studies are needed to be done. Antioxidant: many phenolic compounds can be subjected to show the antioxidant property, and their activity can be evaluated for a decreased medical level or to assess the product formation. (Decker et al., 2005)The antioxidant property is helpful in cancer and lupus nephritis due to the ability of SDG to scavenge OH radicals. For flaxseed, it has been shown that the antioxidant property of flaxseed lignans and metabolites is active against AAPH-induced oxidation). Other advantages are that it reduces hypercholesterolemia, atherosclerosis, and diabetes (Prasad, 2000)
Along with beneficial effects, there is some negative influence on health and well-being. The negative factors are cyanogenic glycosides and lining. They act as an anti-pyridoxine factor. In a study, Cyanogenic glycosides found in flaxseed are located in the plant, including brassica vegetables; studies showed that cassava was toxic to animal and human beings. Also, cyanogenic glycosides, trypsin inhibitor, lining, and phytic acid and there was low Trypsin inhibitor activity (TIA) was observed in flaxseed.
Phytohormones like lignin play a potential role in preventing cancer and helpful in replacing hormonal treatment therapy. The gut microbiota metabolizes plant lignans into mammalian lignans. The antioxidant property of flaxseed is beneficial in various healthcare benefits so that it can be used as a natural antioxidant. More clinical studies are in vivo studies that need to be performed to evaluate their role in health benefits better.