Flaxseed oil benefits and dangers

Flaxseed oil has long been known to gourmets. Its subtle taste is used in salads around the world.

Today, it is entering the dietary supplement section. Particularly rich in alpha linolenic acid, it seems to offer exceptional biochemical properties. Its virtues for the body are at the center of much scientific research. Focus on this ghost.


Flaxseed oil contains very interesting amounts of alpha-linolenic acid.

Flaxseed and its oil have been used in Asian medicines for a very long time. Its exceptional richness in omega 3,
especially in alpha-linolenic acid, gives it many medicinal properties. Today, scientists are rediscovering it and gradually highlighting the benefits of linseed oil.


Flax has been cultivated since time immemorial. Historically, humans have used fiber from the stems of the plant to make tissue. However, the nutritional and pharmaceutical qualities of both flax seed and its oil have also been known since the dawn of time.

In ancient Egypt, flax was already used for its fiber, its medicinal properties and its nutritional qualities. Pliny the Elder also mentioned more than 30 remedies based on linseed or linseed oil. More recently, it was Dr Catherine Kousmine who put it in the spotlight. Even today, flax, in the form of seeds or oil, is part of the Chinese pharmacopoeia, but also Ayurvedic. Classical western veterinary medicine also uses it as an anti-inflammatory.

It was at the start of the 20th century that flaxseed oil made its triumphal entry into Europe. At the time, it was only marketed in small glass containers and consumed quickly. However, during the 1920s, Europe industrialized rapidly. The oils become refined and are sold in large containers. This is hardly suitable for linseed oil, which is particularly fragile.

By the middle of the 20th century, flaxseed oil had virtually disappeared from the market. It is not considered profitable enough by the industry which is abandoning it in favor of more stable products. However, the renewed interest of the West in Asian medicines has brought this little treasure of nature up to date. Since the 2000s, cold-pressed, unrefined flaxseed oil has found its way into health food stores and some grocery stores.

For a very long time deemed unfit for marketing, it was again authorized under certain conditions.


Flaxseed oil is known for its richness in polyunsaturated fatty acids. They represent about 70% of the total weight of the seed.

The complete composition of linseed oil is:

omega 3,
omega 6,
vitamins A,

vitamin B,

omega 9,
vitamin K,
vitamins E,

From a nutritional point of view, it provides around 900 kcal per 100 ml, like all oils. Its richness in alpha linolenic acid is however exceptional with 56 g per 100 ml of finished product.


The roles of linseed oil are intrinsically linked to those of alpha linolenic acid, which it is particularly well endowed with.

From a purely biological point of view, ALA is a precursor of the two other omega 3 fatty acids essential for the proper functioning of the body, namely eicosapentaenoic acid and docosahexaenoic acid.

These two other omega 3 fatty acids can be found in oily fish, but are generally very insufficiently consumed and therefore require supplementation of alpha linolenic acids.

Omega 3 fatty acids from flaxseed oil have favorable effects on the human body. They interact in particular on the composition of cell membranes and on biological and biochemical processes essential for the proper functioning of the body.

The biochemical processes on which alpha linolenic acid mainly acts are:

  • anti-inflammatory reactions,
  • regulation of blood pressure,
  • platelet aggregation,
  • immune reactions,
  • elasticity of blood vessels.

Properties and virtues

Scientists have established the benefits of flaxseed oil primarily from the established benefits of omega 3 fatty acids and primarily alpha linolenic acid. However, in certain aspects, specific studies have been carried out using omega 3 from flax.

A study, dating from 20181‌, and published in a reputable medical journal, sheds light on the anti-inflammatory role of flaxseed oil. It shows that its regular consumption decreases markers of inflammation in people with heart problems.

This 3-month study was carried out on more than 40 patients. She demonstrated that after regular consumption of flax, the various volunteers had an improvement in the dilation of the arteries and markers of inflammation.

It is therefore a substance that can be administered both to patients at risk and to those who have already developed a heart disease. However, due to the small patient sample, additional homework must be performed in order to establish the most effective dosages and therapeutic procedures to be applied.

Hair and skin

Linseed oil also helps protect the skin and hair. It deeply hydrates the skin and improves its elasticity. It also contributes to hair health.

Mental health and cognitive functions

The virtues of omega 3 have been repeatedly demonstrated in the fight against both Alzheimer’s disease and senile dementias and for mental serenity.

The PAQUID studies dating from 1988 and the Three Cities studies dating from 1999 have already established that Alzheimer’s disease is due, among other things, to dietary and genetic causes2‌.

Other studies, carried out later, believe that regular consumption of omega-3 fatty acids could slow the progression of Alzheimer’s or even limit its onset3‌‌ 4‌. This finding seems to be shared for all age-related mental dementias5‌.

Mental health also seems to benefit from the properties of flaxseed oil and its omega-3 fatty acids. Indeed, studies have shown that they are useful for relieving or accompanying treatments aimed at fighting depression6‌, schizophrenia7‌ and bipolar disorder8‌.

However, these studies are limited and require further work to establish the real links between omega 3 and mental health. However, it seems that omega 3, particularly present in the brain, can prevent all forms of degeneration.

Laxative action

Flaxseed oil has a laxative action and can therefore help with constipation.

A study in Sao Paulo, Brazil, shows that flaxseed oil is effective in treating constipation in patients on hemodialysis9‌. This 4 week trial was conducted on 50 constipated patients.

He studied the results on the most frequently assessed constipation symptoms. The results showed that it was effective in the treatment of constipation.

Cardiovascular protection

Cardiovascular diseases are among the leading causes of death in the world. They are mainly on the increase in countries opting for a Western lifestyle, particularly poor in omega 3.

Cardiovascular disease is mainly caused by too high levels of cholesterol, triglycerides and sugar, worsened by high blood pressure and lifestyle problems, especially an unbalanced diet.

In 2018, a study conducted at a medical university in Poland concluded that flaxseed oil was effective in increasing HDL 3 cholesterol and lowering blood pressure in patients with moderate hypercholesterolemia10‌.

It was previously believed that flaxseed oil has protective effects. However, its action on hypertension had not yet been proven. The researchers therefore set up a study to confirm its usefulness, on blood pressure and lipid metabolism, in patients who have too high a cholesterol level.

The study was conducted in 150 people with mild to moderate hypercholesterolemia. The volunteers ingested 15 ml of flaxseed oil as a daily dose.

Compared to a group on placebo, the people had a significant decrease in “bad cholesterol” and an increase in “good cholesterol”. Researchers have also observed a decrease in hypertension numbers, whether on diastolic or systolic blood pressure.

This finding is not new, because since the 1950s, researchers have already been well aware of the role of omega 3s in cardiovascular protection11‌ 12‌ 13‌. Numerous studies already demonstrate these facts. However, researchers are still unable to define the specific role of each omega 3 in the protection of the cardiovascular system.

Flax containing a high proportion of alpha linolenic acid, which is itself the precursor of omega 3 EPA and DHA, can be considered as one of the major factors in this cardiovascular protection.

Hormonal regulation

Flaxseed oil is rich in phytoestrogens. Scientists are therefore interested in its possible benefits in hormonal regulation, mainly during premenopause and menopause.

As early as 1998, an Australian study was carried out to discover the effects of dietary phytoestrogens in postmenopausal women14‌. The purpose of this study was to monitor the concentrations of phytoestrogens, bone density, hot flashes and pap smears in postmenopausal women supplemented or not with a diet rich in flax.

The data obtained, over a period of 12 weeks, suggests that the phytoestrogens present in flax may be useful in alleviating some symptoms of menopause.

Anti-cancer properties

The omega 3s contained in flaxseed oil are the subject of numerous studies aimed at demonstrating, or not, their role in the prevention of certain cancers.

Initial results have shown the protective role of omega 3 in the protection of breast cancer15‌. A 2010 Canadian study comes to a similar conclusion16‌. To do this, she studied the evolution of human breast tumors in the presence of oil from flax seeds.

Their observations, carried out in mice, have shed light on the effectiveness of flaxseed oil in reducing the proliferation of certain types of cancerous tumors. The size of the tumor was also reduced.
The findings of the study confirm that alpha linolenic acid does indeed have an anti-tumor effect on certain breast cancers.

In 2013, a large study concluded to the protective effect of this acid against cancer. Specifically, these omnipresent omega-3s in flaxseed oil may inhibit the development of cancer cells17‌.

The different shapes

Capsules or as an oil

Flaxseed oil is available in food form and in the form of food supplements.

In food form, it is distributed in opaque glass bottles. These are usually small, as flaxseed oil goes rancid quite easily. It should therefore be stored a maximum of a few months after opening in a cool place, away from sunlight.

In the form of dietary supplements, it is usually distributed in gelatin capsules.

Organic linseed oil?

Flaxseed oil can come from organic production and be certified organic.

Health claims

The European authorities recognize the following health claims for flax seeds18‌:

  • contributes to the regularity of bowel function;
  • supports a healthy prostate;
  • facilitates weight loss in addition to dietary measures;
  • supports the proper functioning of the stomach and intestines;
  • has estrogenic properties;
  • offers benefits for menopause.

Dosages and use

Flaxseed oil Dosage

There is currently no official dosage for flaxseed oil supplements. However, given their richness in alpha linolenic fatty acids, the dosages commonly accepted for this omega 3 should be observed.

Currently, scientists believe that a supplement of 2 g of alpha linolenic acid per day is more than sufficient to meet the natural needs of the human body.


Due to its particular richness in omega 3, flaxseed oil is relatively fragile. Whether in food form, or in the form of food supplements, it requires special use to develop its full potential.

In all cases, linseed oil should not be exposed to light or to strong heat. In addition, it should not be consumed during a meal rich in omega 6. It is also interesting to use a food supplement based on linseed oil with an antioxidant diet, that is to say low in iron and copper and rich in vitamins A, C and E.


Precaution for use

Flaxseed oil, in a culinary dose, does not require any use precautions. However, as a precaution, some precautions are necessary when using a supplement.

In the event of suspected or proven pathologies, flaxseed oil is not a substitute for medical treatment. A consultation with a specialist is therefore essential to take stock of your health.
Due to its high omega 3 content, it should be consumed with caution in people who have bleeding disorders or who are taking blood thinners.
People with a thyroid problem should also be careful with the consumption of a flaxseed oil supplement. Professional advice is strongly recommended.
It is also not recommended for women on hormonal treatment.
People being treated for hypertension also seek the advice of a doctor before supplementation.


ANSES has two major contraindications to flaxseed oil supplementation:

the use of flaxseed oil as a dietary supplement is not recommended for children under 3 years old,
it should not be consumed by people with intestinal obstruction.

Side effects

In therapeutic dosage, linseed oil has no side effects. However, at very high doses, and for long periods of time, excess alpha linolenic acid, the main lipid component of flax, can cause gastrointestinal disorders as well as bleeding.


Theoretically, because of its high omega 3 content, flaxseed oil is likely to interact with:

  • certain pro-oxidant substances such as iron or copper taken as a supplement,
  • molecules or plants with a hypotensive or anticoagulant effect,
  • certain treatments for the thyroid gland,
  • estrogen-based hormonal treatments,
  • certain mixtures of plants intended for postmenopausal women which contain in particular soy isoflavones.

Sources in food

Flaxseed oil is only present in the seeds of the same name, from which it is derived.


What is flaxseed oil?

Flaxseed oil has been used in Chinese medicine for a very long time. It is extracted from flax seeds.
Rich in alpha-linolenic acid, it has many medicinal properties.

Why take flaxseed oil?

It has many benefits:
1. Anti-inflammatory action
2. Skin and hair protection
3. Laxative effect
4. Improvement of cognitive functions
5. Protection of the cardiovascular system
6. Hormonal regulation
7. Take part in the fight against cancer

How much flaxseed oil per day?

There is no official dosage for flaxseed oil supplements.
However, the experts recommended a supplement of 2 g of alpha-linolenic acid per day.

What are the dangers ?

Don’t use for children under three years old and for people with intestinal obstruction.
It can interact with a large number of treatments, drugs or plants. Seek medical advice before consuming it.

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