FLAXSEED - BENEFITS, SIDE EFFECTS, RECIPES & MORE - NEWSHA

Common Name: Flax, Flaxseed

Scientific Name: Linum usitatissimum L.

History and Origin

Flax is one of the oldest cultivated crops, with evidence of its cultivation dating back thousands of years ⁽¹⁾ (approximately 10,000 BC). ⁽²⁾ Sometime between 4000 and 2000 BC, flax cultivation became a common practice in countries bordering the Mediterranean Sea and in regions of the Middle East. ⁽²⁾ Flax has been cultivated since antiquity in the Mediterranean coastal lands, Asia Minor, Egypt, Algeria, Tunis, Spain, Italy, Greece, ⁽¹⁾ and China.⁽²⁾

Its origin is uncertain. Some consider it to be indigenous to localities between the Persian Gulf, the Caspian and Black seas, while others ascribe its origin to India. ⁽¹⁾ The initial use of flax has also been debated. Based on archeological evidence, it was proposed that flax was used first for fiber of stem. ⁽³⁾

Today, it is cultivated all through the world mainly for the purpose of oil and ⁽¹⁾ mucilage ⁽⁴⁾ of seeds and fiber of stem. ⁽¹⁾ Canada has the highest area and production of flax in the world, followed by China, the USA, India, and the EU. ⁽³⁾

Flax has been divided into three types: oil flax, fiber flax, and oil-fiber flax, based on their agronomic traits and practical use. ⁽⁵⁾ Flax varieties grown for human consumption are different from flax varieties grown to produce fiber; ⁽⁶⁾ according to some sources, flaxseed is used to describe flax when eaten by humans, while linseed is used to describe flax when it is used for industrial purposes.⁽²⁾ Ordinarily utilized types of flaxseed for human use are entire flaxseed, flaxseed oil, ground flaxseed, and somewhat defatted flaxseed. ⁽⁷⁾

The botanical name of flax is Linum usitatissimum L. ⁽¹⁾ The generic name “Linum” comes from the Celtic word lin means thread and the species name “usitatissimum” given by Carl Linnaeus, means very useful. So, it directly refers to its multiple applications and their importance in ancient times. ⁽⁸⁾ The plant was useful as a source of fiber for weaving, oil from the seeds, and feed from the meal. It is nature’s miraculous plant. Today, this oilseed has been classified as superfood, ⁽¹⁾ and demand for it has been increased ⁽⁹⁾ because it provides numerous health benefits ⁽¹⁾ in addition to having a unique nutrient profile, particularly omega-3 fatty acid, lignans, and fiber. ⁽⁹⁾

In 2005, approximately 200 new food and personal care products were introduced in the US market containing flax or flax ingredients, which suggests that flax-based products have the highest growth potentials in superfood markets. ⁽³⁾

Flax Plant Structure

Linum usitatissimum is an annual herb growing up to a 60-120 cm height. It belongs to the genus Linum and family Linaceae. ⁽¹⁾ The genus Linum is composed of approximately 230 species, but cultivated flax is the only species of economic importance in the genus, cultivating for its fiber and oil. ⁽⁸⁾

The cultivars grown primarily for the seed/oil purpose are relatively short in height and possess more secondary branches and seed bolls (seed capsule). The cultivars grown for the fiber purpose are tall growing with straight culms and have fewer secondary branches. ⁽³⁾

Its stem, branches, and leaves are thin. The leaves are up to 3.8 cm long, linear, lanceolate, and ovate. It has smooth edge grey-green in color. The blue flowers may be bluish violet or white. The root is short, fusiform, and light yellow in color.

Fruit is an almost globular in shape, 6-8 mm long capsule on an erect or slightly bent stem. They have 5 cells, each containing 2 seeds. ⁽¹⁾ The seeds are glossy, flat, oval with a pointed tip, 4 - 6 mm in length. ⁽⁶⁾

There are two assortments of flaxseed dark colored brown and brilliant gold ⁽⁷⁾ or yellow. ⁽¹⁾ Flaxseeds have a hard shell that the color ranges from deep amber (yellowish-brown) to reddish-brown depending upon whether the flax is of the golden or brown variety. ⁽¹⁰⁾

According to a study, there were no significant nutritional or safety-related differences between flaxseeds of different colors. Brown flaxseed is rich in ω-3 fatty acid alpha-linolenic acid (ALA). Yellow flaxseed is one of these two types: the first one, a U.S.-developed variety named Omega, is as rich in ALA as brown flax. The second type is entirely different flax called Solin (trade name Linola), which is low in ALA. ⁽⁴⁾

Flax flowers have five petals, usually bluish violet but sometimes white. When the flowers dry, they produce seed pods (seed capsule).

Fig. 1 The photo of flax plant

Flaxseeds in a wooden spoon. Fruit is a 6-8 mm long capsule with an almost globular shape on an erect or slightly bent stem. The capsule has 10 seeds.

Fig. 2 The photo of flax capsules & seeds

Flax Health Benefits

1. Improving Cardiovascular System Function

Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are important nutrients through the life cycle. Evidence from human and animal studies indicates the beneficial role of ω−3 fatty acids in the prevention and management of cardiovascular diseases.⁽¹¹⁾

Flaxseed has recently gained attention in the area of cardiovascular disease primarily because it is one of the richest known sources of both ALA fatty acid ⁽¹⁰⁾ (a precursor for the synthesis of other omega-3 polyunsaturated fatty acids including EPA and DHA ⁽³⁾) and the phytoestrogen, lignans, as well as being a good source of soluble fiber. ⁽¹⁰⁾

Human studies have shown that flaxseed can modestly reduce serum total and low-density lipoprotein cholesterol concentrations, reduce postprandial glucose absorption, decrease some markers of inflammation and raise serum levels of the omega-3 essential fatty acids, ALA and EPA.

The principal lignan present in the flaxseed (SDG) reduced high-fat diet-induced visceral and liver fat accumulation and improved hyperlipidemia, hypercholesterolemia, hyperinsulinemia, and hyperleptinemia (hyperleptinemia increases body fat content and stimulates appetite) in the blood. These effects may prevent obesity and may reduce cardiovascular risk factors associated with lifestyle diseases, such as diabetes, atherosclerosis, and hypertension. ⁽¹⁰⁾

According to a 2006 study, consuming flaxseed oil can increase the plasma EPA level by 60%. ⁽¹²⁾

2. Anticoagulant

Activated protein C (APC) is a natural anticoagulant. ⁽¹³⁾ In a study, it was reported that flaxseed oil could prevent thrombosis by 40% increase in APC ratio. ⁽³⁾ Complications of thrombosis can be life-threatening, such as a stroke or heart attack. ⁽¹⁴⁾ Also, the process of metabolizing ALA to EPA is effective in reducing platelet aggregation and coagulation. Flaxseed oil is rich in ALA, which is metabolized in part to EPA. EPA produces prostaglandin E3 (PGE3) and prostaglandin I3 (PGI3), both of which reduce platelet aggregation. ⁽¹⁵⁾

3. Regulating Blood Fat Levels

In human studies, 15 g/d of flaxseed administered for three months was associated with reduction in serum TG and LDL cholesterol without any alteration of high-density lipoprotein (HDL) cholesterol. It has also been reported that consumption of 50 g flaxseed/day for four weeks lowered the plasma LDL cholesterol by 8% in young healthy adults. ⁽¹⁶⁾

In 2012, researchers examined the effect of consumption of 5 g of flaxseed fibers (3/day) for 1 week in the form of bread and drinks on blood lipids and fecal excretion of fat in young healthy adults. The subjects consumed flaxseed fibers:

1. As powders mixed with water and blackberry syrup for immediate consumption 30 minutes prior to all three main meals.

2. Baked into breads as part of all three main meals.

Both flaxseed drink and flaxseed bread resulted in decreased plasma total and LDL-cholesterol and increased fat excretion, but the food type and/or processing may be of importance. Fecal excretion of fat increased by 50% with flaxseed drink consumption. Flaxseed bread and flaxseed drink reduced the total & the LDL-cholesterol by 7 & 9 and 12 & 15 %, respectively. ^{(17, 18)}

These experimental findings support the hypothesis that flaxseed consumption has a positive effect on suppressing the development of atherosclerosis. ⁽¹⁶⁾

4. Regulating Blood Pressure

Flaxseed contains ω-3 fatty acids, lignans, and fiber that together may provide benefits to patients with cardiovascular disease. In a 2013 study, hypertensive patients were fed a variety of foods that containing 30 g of milled flaxseed each day over 6 months. It was demonstrated that both systolic (SBP) and diastolic (DBP) blood pressure significantly reduced in the patients.

The researchers found that plasma levels of the ω-3 fatty acid α-linolenic acid (ALA) and lignans increased 2- to 50-fold in the flaxseed-fed patients. The ALA and lignan content of flaxseed provides this antihypertensive effect.

Inflammation and free radicals have been implicated in the genesis of blood pressure. The anti-inflammatory action of ALA and the antioxidant action of lignan may explain flaxseed antihypertensive action.^{(16, 19)}

According to a 2007 study, also dietary supplementation with flaxseed oil, rich in ALA, lowers blood pressure. ⁽²⁰⁾

5. Regulating Blood Glucose Levels

Dietary fibers, lignans, and ω-3 fatty acids present in flaxseed have a protective effect against diabetes risk. ⁽¹⁷⁾

In studies, flaxseed was incorporated in recipes, which resulted in a reduction in the glycemic index of the food items. ⁽²¹⁾ Low GI (<55) foods produce gradual rises in blood sugar and insulin levels. Low GI diets also reduce insulin resistance and the risk of diabetes. ⁽²²⁾

In addition, there is some evidence that eating flaxseed can reduce blood sugar levels after a meal and increase insulin levels because of its high content of soluble fiber. ⁽²³⁾These observations prompted researchers to investigate the efficacy of flaxseed supplementation in type 2 diabetics. ⁽²¹⁾

They found that supplementation of the diet of type 2 diabetics with 10 g of flaxseed powder for a period of 1 month reduced fasting blood glucose by 19.7 % and glycated hemoglobin (HbA1c) by 15.6 %. It could be due to the lower content of glycemic carbohydrates and higher content of dietary fibers of flaxseed. ⁽¹⁷⁾

Glycemic carbohydrates are digested and absorbed in the human small intestine. These include starch and sugars that give rise to an increase in blood glucose. ⁽²⁴⁾

In another study, diabetic females were provided 15 and 20 g/day of flaxseed powder for a period of 2 months. Postprandial blood glucose levels were found to be decreased by 7.9 and 19.1 %, respectively. ⁽¹⁷⁾

Also, it has been found that the flaxseed principal lignan (SDG) is effective in retarding the development of diabetes in rats. ⁽¹⁰⁾

6. Improving Liver Function

In 2016, researchers investigated the flaxseed supplementation effect on non-alcoholic fatty liver disease. 50 patients with non-alcoholic fatty liver disease (NAFLD) were assigned to take either a lifestyle modification (LM) or LM +30 g/day brown milled flaxseed for 12 weeks.

At the end of the study, body weight, liver enzymes, insulin resistance, hepatic fibrosis, and steatosis decreased significantly in both groups; however, this reduction was significantly greater in those who took flaxseed supplementation. In conclusion, flaxseed supplementation plus lifestyle modification is more effective than lifestyle modification alone for NAFLD management. ⁽²⁵⁾

Flaxseed oil also can ameliorate drug- and alcohol-induced liver injury and NAFLD. Flaxseed oil can ameliorate drug-induced hepatotoxicity due to its intrinsic biochemical/antioxidant properties. ⁽²⁶⁾ Flaxseed oil also can ameliorate alcoholic liver disease via anti-inflammation and modulating gut microbiota. ⁽²⁷⁾ Alpha-linolenic acid (ALA; ω3) increases the ω3 and ω6 polyunsaturated fatty acids (PUFA) and markedly reduces the ω6:ω3 ratio in liver lipids. Thus, ALA is effective in improving non-alcoholic fatty liver disease (NAFLD). ⁽²⁸⁾

7. Relieving Irritable Bowel Syndrome (IBS) Symptoms

According to a 2019 study, flaxseed oil is dually effective in constipation and diarrhea. Flaxseed oil exhibits laxative and gut stimulatory effects, mediated through multiple pathways, including activation of muscarinic and histaminergic receptors. Also, flaxseed oil possesses antidiarrheal and antispasmodic activities, mediated possibly through activation of K+ channels. ⁽²⁹⁾Another study in 2019 indicated that consumption of flaxseed oil could improve intestinal function, associated with the altered gut microbiome and mucosal fatty acid profile. ⁽³⁰⁾

8. Relieving Constipation

Flaxseeds have a laxative effect in both healthy and constipated individuals.

Flaxseed lignans and omega-3 fatty acids may be effective for preventing and reducing colon cancer, modulating constipation and diarrhea through the synergic activity of lignans, fiber, and omega-3 fatty acids. ⁽³¹⁾

In 2018, a study was conducted to investigate the effects of baked flaxseed on the management of constipation. 53 constipated patients received 10 g of flaxseed pre-mixed in cookies twice per day for 12 weeks. According to the findings, in constipated patients, flaxseed cookies used as a snack may be a useful tool for decreasing constipation symptoms. ⁽³²⁾

9. Reducing Appetite

In 2012, a study was aimed to examine the effect of flaxseed dietary fiber supplements on the suppression of appetite and food intake. It was observed that consumption of flaxseed fiber (2.5 g of soluble fibers) increased sensation of satiety and fullness and significantly suppressed appetite and food intake. ⁽³³⁾

Also, in 2013, a study was aimed to examine the effect of flaxseed dietary fibers on reducing appetite in young men. The findings also suggest that flaxseed dietary fibers may suppress appetite. ⁽³⁴⁾

10. Promoting Weight Loss

According to a 2020 study, daily consumption of flaxseed oil for 14 weeks can help a significant decrease in weight and body mass index (BMI). ⁽³⁵⁾

11. Improving Respiratory Tract Function

The lung is an organ particularly susceptible to oxidative stress. ⁽³⁶⁾ Oxidative stress is an imbalance between free radicals and antioxidants in your body.⁽³⁷⁾

According to researchers, flaxseed can be a useful antioxidant nutrient with high concentrations of ω−3 fatty acids and lignans that have anti-inflammatory and antioxidant properties. Hence, in 2006, they evaluated diets with high flaxseed content in murine models of acute lung injury and inflammation. This study investigated that flaxseed can decrease lung inflammation and lipid peroxidation, suggesting a protective and therapeutic role of flaxseed against oxidative stress-induced lung damage. ⁽³⁶⁾

12. Antidepressant Properties

People with depression have elevated levels of cortisol in their bloodstream. Cortisol is a hormone produced by the adrenal glands in response to stress. ⁽³⁸⁾

In a 2013 study, ω−3 fatty acids and polyphenols from flaxseed were evaluated for their anti-depression properties in mice exposed to chronic mild stress (CMS). The researchers found that consuming flaxseed extract, having both polyphenols and omega-3 fatty acid, can decrease serum cortisol concentration significantly. Besides, the extract is able to reduce all the CMS effects, such as depression. ⁽³⁹⁾

In addition, depressive patients have a lower level of EPA, DHA and omega-3 fatty acids, and subjects with a higher level of omega-3 fatty acids consumption have lower odds of depressive disorder. The results of a 2020 study also indicated that consumption of flaxseed oil led to improved mood status in women with depression disorder.

The anti-depressive effect of omega-3 fatty acids consumption may be due to the anti-inflammatory effect of these nutrients. It can also play a role in regulating dopaminergic and serotonergic neurotransmitters, and it is effective on the fluidity of CNS (central nervous system) cell membranes. ⁽⁴⁰⁾

13. Relieving Menopause Symptoms

In a 2007 study, the women who had been having 14 hot flashes per week for at least a month and weren’t taking estrogen to relieve their menopausal symptoms were fed 2 tablespoons of crushed flaxseed twice daily for six weeks. The women halved their number of daily hot flashes while taking flaxseed. The intensity of the women’s hot flashes dropped by 57% too. ⁽¹⁰⁾

Also, in another study on mice, it was found that flaxseed lignan can be an effective treatment for menopausal–induced depression. ⁽⁴¹⁾

14. Improving Nervous System Function

Considerable clinical and experimental evidence now supports the idea that deficiencies or imbalances in certain polyunsaturated fatty acids may contribute to a range of common developmental disorders, including Attention Deficit Hyperactivity Disorder (ADHD).

In 2006, a study was conducted to evaluate the effect of supplementation with flaxseed oil, which is rich in ALA (a polyunsaturated fatty acid), on blood fatty acids composition and behavior in children with ADHD. It was observed that supplementation with flaxseed oil can significantly improve in the symptoms of ADHD in the children. ⁽⁴²⁾

15. Improving Urinary Tract Function

Hypertension is detrimental to several organs, including kidneys. Several studies have indicated that a deficiency of ALA essential fatty acid leads to the development of hypertension, and the supplementation of flaxseed oil reverses the process and normalizes blood pressure. In 2013, a study was conducted on hypertensive rats to evaluate the favorable effects of flaxseed-supplemented diets on kidney function. To test this, functional markers of kidneys including blood urea nitrogen (BUN), uric acid (UA), creatinine, and renin were examined in hypertensive rats fed a flaxseed diet. The results showed that a flaxseed-supplemented diet significantly lowered the plasma levels of BUN, UA, creatinine, and renin.

The data demonstrate the favorable effects of flaxseed in improving kidney function in a hypertensive condition. These effects are likely to be mediated by the ω-3 fatty acid alpha-linolenic acid (ALA) and ω-6 fatty acid linoleic acid (LA) contents of flaxseed oil.

This study suggests that flaxseed has the ability to not only attenuate hypertension but also to exert beneficial effects on hypertension-induced alterations in kidney function. ⁽⁴³⁾

Furthermore, the anti-inflammatory properties of omega-3 polyunsaturated fatty acids (ω-3 PUFA) can protect kidneys from damage. ⁽⁴⁴⁾

16. Anti-Inflammatory

Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today's diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects. ⁽⁴⁵⁾

The current dietary ω-6/ω-3 ratio ranges from 10:1 to 25:1 while Health Canada recommends a ratio of 4:1 to 10:1. ⁽³⁾ A healthy ratio of omega-6 to omega-3 fatty acids appears to be between 1-to-1 and 4-to-1. ⁽⁴⁶⁾ Consuming flaxseed increases ω-3 family intake, which improves the ω-6/ ω-3 ratio. ⁽³⁾

Also, flaxseed oil is a potent anti-inflammatory agent and diminishes signs of inflammation such as swelling, puffiness, sensitivity, eruption and infection. ⁽⁴⁷⁾ According to the studies, flaxseed oil is effective for improving inflammatory diseases such as ulcerative colitis (an inflammatory bowel disease), ⁽⁴⁸⁾ dry eye syndrome, ⁽⁴⁹⁾ lung fibrosis (a condition in which the lungs become scarred). ^{(50, 51)} Also, the oil can improve kidney function and reduce body mass index (BMI). ⁽⁵²⁾

17. Alleviating Arthritis Inflammation

Flaxseed oil has anti-inflammatory, antioxidant and analgesic effects. ⁽⁵³⁾ Topical use of flaxseed oil can be effective in pain relief of patients with knee osteoarthritis, especially in improving the severity of symptoms and functional status of patients. ⁽⁵⁴⁾ Furthermore, topical use of the oil can be effective in the management of mild and moderate carpal tunnel syndrome. ^{(53, 55)}

18. Preventing Skin Aging and Repairing Damaged Skin

According to experts, flaxseed has positive effects on the postponement of ageing. Omega-3, B vitamins, and fibers in flaxseed postpone ageing by keeping cells young. ⁽⁵⁶⁾The seeds can also improve symptoms of acne, rosacea, and eczema. ⁽²³⁾

Supplementation with flaxseed oil can decrease sensitivity, transepidermal water loss (TEWL), skin roughness and scaling, while can increase hydration, firmness and smoothness, significantly. ^{(57, 58)}

Applying flaxseed oil on the facial skin have sebum-reducing effect. There are no obvious differences between the evolution of the seborrhea oleossa (oily seborrhea) and the seborrhea sicca (meaning dry seborrhea). The oil also can produce an improvement in the appearance of the skin, reducing the appearance of scaly skin to complete fade-out. ⁽⁵⁹⁾ Flaxseed oil also has a skin anti-photoaging effect. ⁽⁶⁰⁾

19. Strengthening Hair

Thanks to those handy essential fatty acids such as ALA, flaxseed can make hair shinier, stronger, and more resistant to damage. Also home to B vitamins, it can help reduce dryness and flakiness of the hair and scalp. ⁽²³⁾

According to a 2013 study, topical application of flaxseed oil for 4 weeks has a significant positive effect on hair width. ⁽⁶¹⁾

What Are Flax Side Effects?

1. When taken by mouth: Flaxseed is LIKELY SAFE for most adults when taken by mouth in recommended amounts. ⁽⁶²⁾However, when taken in large amounts and with too little water, it can cause bloating and gas. ⁽⁶³⁾

2. Digestive Problems: For people who are not used to eating a lot of fiber, incorporating flaxseeds too quickly can cause mild digestive problems, including bloating, gas, abdominal pain, nausea, ⁽⁶⁴⁾ and constipation. ⁽⁶⁵⁾ It is best to start with small doses. ⁽⁶⁴⁾This can also occur when a high fiber intake is paired with inadequate hydration since water is essential to helping fiber pass through the digestive system. ⁽⁶⁵⁾

Furthermore, adding flaxseeds to your diet may also increase bowel movement frequency, as flaxseeds are a natural laxative. ⁽⁶⁴⁾When consumed in limited quantities, it prevents constipation and ensures regular and healthy bowel movements. However, an excess of flaxseeds can even lead to diarrhea in some cases and IBS. Those who already are suffering from IBS should avoid flaxseeds. ⁽⁶⁶⁾

Patients suffering from abnormal constrictions of the gastrointestinal tract, diseases of the cardia (the part of the stomach that is closest to the esophagus), or megacolon (an abnormal dilation of the large intestine) should consult a doctor before consuming flaxseed. ⁽⁶⁷⁾

However, for most people, negative symptoms from high fiber intake can be prevented by increasing fiber intake slowly and drinking plenty of water. ⁽⁶⁵⁾

3. Gastrointestinal (GI) Obstruction: People with a bowel obstruction, a narrowed esophagus, an inflamed (swollen) intestine ⁽⁶²⁾ or paralysis of the intestine ⁽⁶⁷⁾should avoid flaxseed. The high fiber content of flaxseed might make the obstruction worse. ⁽⁶²⁾

Those with difficulty swallowing or any throat problems should exercise extra caution when eating them.

Each single dose (10 – 15 g flaxseed) should be taken with at least 150 ml of water or similar aqueous fluid. Taking it without adequate fluid may cause it to swell and block the throat or esophagus and may cause choking. ⁽⁶⁷⁾

4. Pregnancy: Taking flaxseed by mouth during pregnancy is POSSIBLY UNSAFE. Flaxseed can act like the hormone estrogen. Some healthcare providers worry that this might harm the pregnancy. But there is no reliable clinical evidence about the effects of flaxseed on pregnancy. ⁽⁶²⁾

5. Breast-feeding: There are possible non-significant side effects that affect lactation or a baby. Although devoid of toxicity, its estrogenic effects make its use during lactation should be moderate, avoiding prolonged use. ⁽⁶⁸⁾ Consult with your physician or other health care professional before taking flaxseeds.

6. Children: The use is not recommended in children below 12 years old due to the estrogenic effects of flaxseed. ⁽⁶⁷⁾

7. Diabetes: There is some evidence that flaxseed can lower blood sugar levels and might increase the blood sugar-lowering effects of some medicines used for diabetes. There is a concern that blood sugar could drop too low. If you have diabetes and use flaxseed, monitor your blood sugar levels closely.

8. High blood pressure (hypertension): Flaxseeds might lower diastolic blood pressure. Theoretically, taking flaxseeds might cause blood pressure to become too low in individuals with high blood pressure who are taking blood pressure-lowering medication.

9. Low blood pressure (hypotension): Flaxseeds and flaxseed oil might lower diastolic blood pressure. Theoretically, taking flaxseeds and flaxseed oil might cause blood pressure to become too low in individuals with low blood pressure.

10. Hormone-sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Because flaxseed might act somewhat like the hormone estrogen, there is some concern that flaxseed might make hormone-sensitive conditions worse. However, some early laboratory and animal research suggests that flaxseed might actually oppose estrogen and might be protective against hormone-dependent cancer. Still, until more is known, avoid excessive use of flaxseed and flaxseed oil if you have a hormone-sensitive condition. ⁽⁶²⁾

11. Prostate cancer: The evidence is mixed as to whether flaxseed or its oil has any effect on the prostate or the risk of prostate cancer. ⁽⁶³⁾The products containing partially defatted flaxseed, the seed with less alpha-linolenic acids content, are also available. Some men choose these products because they have heard that alpha-linolenic acid might raise their risk of getting prostate cancer. It's important to remember that the source of the alpha-linolenic acid is key. Alpha-linolenic acid from dairy and meat sources has been positively associated with prostate cancer. However, alpha-linolenic acid from plant sources, such as flaxseed, does not seem to affect prostate cancer risk. So, men should not worry about getting alpha-linoleic acid from flaxseed. ⁽⁶²⁾ However, if you have prostate cancer or have a high risk of getting it, avoid eating large amounts of flaxseed and flaxseed oil.

12. High triglyceride levels (hypertriglyceridemia): Partially defatted flaxseed (the seed with less alpha-linolenic acid content) might increase blood triglyceride levels. If your triglyceride levels are too high, don't take defatted flaxseed. ⁽⁶²⁾

13. Bleeding disorders: Large doses of omega-3 fatty acids may have blood-thinning effects. ⁽⁶⁴⁾ Therefore, flaxseed and flaxseed oil might slow clotting. ⁽⁶²⁾ If you have a bleeding disorder or are taking blood thinners, consult with your healthcare professional before incorporating flaxseed and flaxseed oil into your diet. ⁽⁶⁴⁾

14. Surgery: Because flaxseed oil might decrease blood clotting, stop using flaxseed or its oil two weeks before having elective surgery. ⁽⁶³⁾

15. Anti-nutrients (nutrient antagonists): Flaxseed is considered as superfood owing to the presence of high-quality protein, ⁽⁶⁹⁾ lignans, ⁽⁷⁰⁾ dietary fiber, and alpha-linolenic acid (ALA), an omega-3 fatty acid. However, the presence of anti-nutritional factors ⁽⁶⁹⁾ such as cyanogenic glycosides,⁽⁷⁰⁾ phytic acid, and oxalate⁽¹⁰⁾ restricts flaxseed's consumption as a food ⁽⁶⁹⁾and may pose adverse health effects. ⁽⁹⁾

a) Cyanogenic glycosides are the major anti-nutrients in flaxseed. ⁽⁷⁰⁾ Many foods, including not only flax but cashews, almonds, some beans, and other plant products, naturally contain very small amounts of cyanide compounds. You’re more likely to ingest these trace amounts of cyanide when such foods are consumed raw, as heat breaks down the compounds.

However, even when flaxseed is eaten raw, the body has a natural capacity to break down a certain amount of these cyanide compounds. A 1994 study found that, in healthy individuals, daily consumption of as much as 60 grams of raw flaxseed —more than eight tablespoons—was safe. ⁽⁷¹⁾ The U.S. government agencies say that 2 tablespoons of raw flaxseed (about 3 tablespoons of flax meal) are safe and probably an “effective dose” for health purposes. ⁽⁷²⁾

Note that inappropriate storage of flaxseed may lead to higher content of cyanogenic glycosides, ⁽⁶⁷⁾and ripe seed contains less glycoside than the immature (unripe) seed. ⁽⁷⁰⁾Taking unripe flaxseed by mouth is POSSIBLY UNSAFE. Flaxseed in these forms is thought to be poisonous. ⁽⁶²⁾

As mentioned, cyanogenic glycosides are heat-labile. ⁽⁷⁰⁾ Therefore, roasting is generally done to remove them. ⁽⁹⁾

b) Flaxseed contains two compounds, phytic acid and oxalate, that bind calcium, copper, iron, magnesium, and zinc to form insoluble complexes in the intestine. ⁽¹⁰⁾ The two compounds interfere with the absorption of the minerals. ⁽⁷⁰⁾

Phytic acid is widely distributed in plant foods; an imbalance in the intake of phytates, calcium, and zinc diminishes growth and decreases bone zinc levels. ⁽¹⁰⁾

16. Allergies: Occasionally, using flaxseed or its oil causes an allergic reaction. ⁽⁶³⁾Signs of an allergic reaction include hives, difficulty breathing, and swelling of your face, lips, tongue, or throat. ⁽⁷³⁾

Generally, every person can have an allergy to certain herbs and spices. This sensitivity must be first diagnosed by the person and secondarily by the physician. However, these allergic reactions do not cause chronic or acute side effects; after identifying the allergenic plant and eliminating it from their diet, allergy-related complications will be gone away.

No company or product can be aware of the allergic reactions of different bodies in advance. The body's incompatibility with one or more specific herbs rarely occurs, but some consumers may encounter it anyway.

Nutritional Information

Nutritional value of flaxseeds per 100 g (source: USDA)

- Energy: 534 Kcal

- Protein: 18.29 g

- Total lipid: 42.16 g

- Carbohydrate: 28.88 g

- Dietary fiber: 27.3 g

- Minerals: calcium (255 mg), iron (5.73 mg), magnesium (392 mg), phosphorus (642 mg), sodium (30 mg), zinc (4.34 mg)

- Vitamins: vitamin C (0.6 mg), thiamin (1.644 mg), riboflavin (0.161 mg), niacin (3.080 mg), pyridoxine (0.473 mg), vitamin E (0.31 mg). ⁽⁹⁾

Flax Daily Dosage

Flaxseed: Generally, your daily diet may include 1 ½ to 3 tablespoons of flaxseeds.

Flaxseed oil:

- Internal: you can include 1 to 2 tablespoons (15–30 ml) of flaxseed oil into your daily diet. Flaxseed oil can be consumed directly or used in salad dressing, smoothies, or juice.

- Topical: You can massage flaxseed oil into joints, stretch marks, and scalp.

The following oral doses also have been recommended:

Decrease platelet aggregation: 1 to 2 tablespoonfuls flaxseed oil daily.

Constipation: 2 teaspoons of whole or bruised (not ground) seed with at least 150 ml of liquid 2 to 3 times daily. ⁽⁷⁴⁾

Breast pain (mastalgia): 25 grams of flaxseed powder has been taken daily for 2 months. Also, a muffin containing 25 grams of flaxseed has been eaten daily for 3 months. ⁽⁶²⁾

Bioactive Compounds

The composition of flaxseed can vary with genetics, growing environment, and method of seed processing. ⁽¹⁰⁾ Based on an analysis conducted by the Canadian Grain Commission, this oilseed containing mucilage is rich in fat, protein, and dietary fiber. ⁽⁹⁾

Protein and amino acid: The total protein content in flaxseed ranges between 20 to 30%. ⁽⁹⁾ However, the protein content of the seed decreases as the oil content increases. The amino acid pattern of flaxseed protein is similar to that of soybean protein, which is viewed as one of the most nutritious plant proteins. Brown flaxseeds contain all nine essential amino acids for humans, including histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, valine, and tryptophan. In addition, the seed is gluten-free, making it a great choice for people who are sensitive to gluten. ⁽¹⁰⁾ Comparing nutritional profiles of various oilseeds, including flaxseeds, chia seeds, sesame seeds, safflower seeds, and sunflower seed kernels, showed that flaxseed contains the second-highest amount of protein, followed by sesame seed, chia seed, and safflower seed. ⁽⁹⁾

Fatty acids: Flaxseed has been valued historically for its abundance of fat, which provides a unique mix of fatty acids. Fatty acid composition of flax oil includes omega-3 polyunsaturated fatty acids, ⁽¹⁰⁾ particularly alpha-linolenic acid ⁽⁴⁾ (57%), omega-6 polyunsaturated fatty acids (16%), monounsaturated fatty acids (18%), and saturated fatty acids (9%). ⁽¹⁰⁾ In comparison with other oilseeds, including chia seeds, sesame seeds, safflower seeds, and sunflower seed kernels, flaxseed has the highest amount of polyunsaturated fatty acid. ⁽⁹⁾

Phytosterols: β-Sitosterol is the main phytosterol in flaxseed oil, followed by campesterol, stigmasterol, and Δ 5 – avenasterol. ⁽⁷⁵⁾

Tocopherols: Tocopherols are strong antioxidants ⁽⁷⁶⁾ and a class of fat-soluble compounds with vitamin E activity. ⁽⁷⁷⁾

Gamma-Tocopherol predominates in the tocopherol fraction of flaxseed oil. ⁽⁷⁵⁾ Gamma-tocopherol is an antioxidant that protects cell proteins and fats from oxidation; promotes sodium excretion in the urine, which may help lower blood pressure; and helps lower the risk of heart disease, some types of cancer, and Alzheimer’s disease. ⁽¹⁰⁾

Carbohydrate: Flaxseeds are low in carbohydrates. ⁽¹⁰⁾However, they serve as a good source of both water-soluble and insoluble dietary fiber. It contains 35–45 % of fiber; two-thirds is insoluble fiber, and one-third is soluble fiber. Insoluble fiber consists of cellulose, hemicellulose, and lignin. Most of the soluble fiber of flaxseed appears to be the mucilage of the seed coat. Mucilaginous material consists mainly of water-soluble polysaccharides. ⁽⁷⁰⁾ Flaxseeds contain more fiber than sesame seeds and sunflower seed kernels. ⁽⁹⁾

Minerals: Flaxseed is a good source of minerals, particularly phosphorus, magnesium, calcium, iron, zinc, and very little amount of sodium. ⁽⁹⁾ One tablespoon of milled flaxseed contains 34 mg of magnesium, about the same amount of magnesium found in a 250 mL (8 oz) container of low-fat yogurt with fruit, 30 g (1 oz) of pecan halves, or half a fried chicken breast (140 g).

The potassium content of milled flaxseed is about 66 mg per tablespoon or about the same amount of potassium found in a 175 mL (6 oz) mug of brewed tea or a hard-boiled egg. ⁽¹⁰⁾

Vitamins: Flaxseed contains several water-and-fat-soluble vitamins, ⁽¹⁰⁾ including vitamins A, ⁽⁹⁾ C, E, B vitamins (including B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), biotin (B7), folic acid (B9)), and K (in the form of phylloquinone, which is the plant form of the vitamin).Vitamin K plays an essential role in the formation of certain proteins involved in blood clotting and in building bone. ⁽¹⁰⁾

Phenolic compounds: Many phenolic compounds have anticancer and antioxidant effects in humans. Flaxseed contains at least three types of phenolics viz., phenolic acids (about 1%), flavonoids (35-70 mg/ 100 g), and lignans (1-26 mg/g).

Lignans are part of plant cell wall carbohydrates and are also considered phytoestrogens; they help balance hormone levels, such as estrogen, in the body. They’ve also been found to help reduce menopause symptoms, similar to soy phytoestrogens. Flaxseed contains at least 75 times more lignans than any other plant source. The principal lignan present in the flaxseed is secoisolariciresinol diglucoside (SDG).

Proximate composition of whole flaxseed, milled seed, and flax oil, based on the common measure (tablespoon):

1 Tbsp. of whole seed (11 g): Energy (50 Kcal), total fat (4.5 g), ALA (2.5 g), protein (2.2 g), total carbohydrate (3.0 g), total dietary fiber (3.0 g).

1 Tbsp. of milled seed (8 g): Energy (36 Kcal), total fat (3.3 g), ALA (1.8 g), protein (1.6 g), total carbohydrate (2.3 g), total dietary fiber (2.2 g).

1 Tbsp. of flax oil (14 g): Energy (124 Kcal), total fat (14.0 g), ALA (8.0 g).

*Total carbohydrate includes carbohydrates like sugars and starches and total dietary fiber. ⁽¹⁰⁾

Best Time to Consume

Generally, you can consume flaxseeds at any time of the day. However, the best time depends on why you are using the seeds, too. For example:

Before a meal: Flaxseed fiber seems to make people feel less hungry. So, they might eat less food. ⁽⁶²⁾

After a meal: Eating flaxseed after a meal reduces blood sugar levels and increases insulin levels because of its high content of soluble fiber. ⁽⁷⁸⁾

Possible Drug Interactions

Generally, all bulk-forming laxatives like flaxseed may delay the enteral absorption of concomitantly administered medications. Flaxseed should therefore be taken at least ½ to 1 hour before or after intake of other medicinal products. ^{(67, 74)}

1. Medications that Slow Blood Clotting (Anticoagulant / Antiplatelet Drugs): Flaxseed and flaxseed oil might slow blood clotting. Taking flaxseed along with medications that slow clotting might increase the chances of bruising and bleeding. Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others. ⁽⁶²⁾

Also, avoid using flaxseed and flaxseed oil together with other herbal/health supplements that can also affect blood-clotting. This includes angelica (dong quai), capsicum, clove, danshen, garlic, ginger, ginkgo, horse chestnut, Panax ginseng, poplar, red clover, saw palmetto, turmeric, and willow. ⁽⁷³⁾

2. Medications for Diabetes (Antidiabetic Drugs): Flaxseed and flaxseed oil can decrease blood sugar levels. Diabetes medications are also used to lower blood sugar. Taking flaxseed along with diabetes medications might cause your blood sugar to be too low. So, monitor your blood sugar closely. The dose of your diabetes medication might need to be changed. Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, and Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others. ⁽⁶²⁾

Also, avoid using flaxseed together with other herbal/health supplements that can lower blood sugar, such as alpha-lipoic acid, chromium, devil's claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, and psyllium and Siberian ginseng. ⁽⁷³⁾

3. Blood Pressure Drugs, Herbs, and Supplements: Flaxseed oil might lower blood pressure. So, taking it with drugs, herbs, and supplements that lower blood pressure might lower blood pressure too much.

4. Estrogens: Flaxseed might have an anti-estrogen effect. So, taking flaxseed might decrease the effects of oral contraceptive drugs and estrogen replacement therapy. ⁽⁶³⁾

5. Medications that Inhibit Gastrointestinal Propulsive Motility: Attention is to be paid to interactions between laxative bulk agents like flaxseed and medicinal products that inhibit gastrointestinal propulsive motility, given the risk of ileus (gastrointestinal obstruction) development following concomitant use.

In order to decrease the risk of ileus, flaxseed should be used with caution with medicinal products known to inhibit the peristaltic movement (e.g., opioids, loperamide) and only under medical supervision. ⁽⁶⁷⁾

Also, do not take flaxseed without medical advice if you are using any of the following medications:

- An antibiotic;

- Acetaminophen (Tylenol);

- Furosemide (Lasix), a strong diuretic. ⁽⁷³⁾

Traditional Use

Flax was used as a food source and natural laxative dating back as far as the ancient Greeks and Egyptians. ⁽³⁾

In Tunisia, flaxseed is used in traditional medicine against cough, asthma, and measles. It is also used for the treatment of constipation and gastritis. ⁽⁷⁹⁾

Unani physicians described the Mizaj (Temperament) of flaxseed as Hot and Dry. The Mizaj of oil is described as Hot and Wet. ⁽¹⁾

Flaxseed Tea: Add 2 teaspoons of uncrushed seed into 1 glass of water. Leave it to soak for 20-30 minutes and stir it occasionally. Drain the seeds without squeezing them and drink obtained water by making it slightly tepid.

Clearing out Constipation: Flaxseed is a natural laxative. Put a teaspoon of flaxseed powder into a glass of hot water, brew, and drain it. Drink one cup every day.

Against Bad Cough, Common Cold, or Catching Chill: Boil one tablespoon of flaxseed in 3 cups of water for 10 minutes; leave it to soak for 3-5 minutes, drain, and drink it. Also, the vapor of this tea is inhaled through the nose.

Helping Expel Kidney Stones: One tablespoon of flaxseed, a tablespoon of hollyhock root, and half a teaspoon of licorice are put into one liter of water. It is boiled for half an hour and drained; then 3-4 tepid glasses of this mixture are drunk on an empty stomach.

Good for Stomach Ulcer: 1 kg flaxseed is pounded in press, boiled with 1 kg milk, and taken off the stove when it gains a thick consistency. Take one tablespoon of it half an hour before meals.

Flaxseeds are Recommended for Diabetic Patients: 1 tablespoon of flaxseed is boiled in 1 liter of water until the water gets down to ½ liter. Drink the obtained ferment 3 times a day.

Useful against Dyspnea (Shortness of Breath), Asthma, Dysphonia (Having an Abnormal Voice), Bad Cough, and Bronchitis: Mix 1 tablespoon of roasted and milled flaxseed with honey and eat it one hour before meals. ⁽⁵⁶⁾

For Cystitis (Inflammation of the Bladder): 2 teaspoons of flaxseeds are boiled up with 2 glasses of water, left to settle for 10 minutes, and drunk during the day. ⁽⁶⁷⁾

Some Questions about Flax

How to eat flaxseeds?

For maximum nutrient absorption, most nutrition experts recommend ground over whole flaxseed because the ground form is easier to digest. Whole flaxseed may pass through your intestine undigested, which means you won't get all the benefits. ⁽⁸⁰⁾

How to store flaxseed?

The seeds should be protected from light and stored in a sealed container. ⁽⁷⁴⁾Once flaxseed is ground, it becomes oxidized (rancid) quickly. Rancid flaxseed has a bad smell and taste. Store ground flaxseed in the freezer or refrigerator to prevent it from going rancid quickly. ⁽⁸¹⁾

Is flaxseed enough for daily omega-3 needs?

Consuming flaxseed increases ω-3 family intake, which improves ω-6/ ω-3 ratio. ⁽³⁾ Increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) can suppress the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. ⁽⁴⁵⁾

Is flaxseed good for vegetarians?

The well-known source of ω-3 PUFAs is marine fish, but flaxseeds are an important plant source of ALA (ω-3 fatty acid) as well. Also, the seeds have a low ω-6 / ω-3 ratio.

Moreover, they are useful for maintaining the balance of serum lipid profile.

These seeds can be an appropriate alternative to ω-3 PUFA sources for vegetarians, people allergic to fish, ⁽⁶⁾ and/or populations which do not have large access to seafood. ⁽⁹⁾