Flaxseed oil vs fish oil: the complete guide

Flaxseed oil vs fish oil: the complete guide
July 13, 2015 6:51 AM

If you were looking for benefits of flaxseed oil and fish oil supplements then you are in the right place. This post is a complete guide comparing benefits, uses and side effects of flaxseed oil and fish oil.

Use of the oil supplements is becoming a popular thing now. But, what are these supplements? What are they needed for? Well, supplements are the nutrients added to diet to enhance its nutritional value. Supplements are needed only when our daily diet starts lacking nutrients that are inevitable for the normal functioning of the body.

No doubt this modern technologically revolutionized era has showed us the way to improve our living standards, but at the expense of our precious health. The processed and instant foods we are addicted to today seem to be delicious and easy to prepare, but they lack the basic essential nutrients. And now we are facing consequences of this so called modernization as these artificially prepared foods have increased the incidence of obesity, hypertension and heart diseases over the past few years. Our body needs all essential nutrients in a balanced proportion to keep its systems running. Eating less nutritious foods means we are depriving our body of essential nutrients that disturbs the body’s natural balance and makes us prone to morbid and serious health problems. Therefore, to overcome the nutritional deficiencies, supplements are added to diet. These supplements are supposed to fortify the diet with essential nutrients and help restore the body’s natural balance.

Fish oil and flaxseed oil are perfect supplements, containing the essential antioxidant nutrients, which help meet up the body’s nutritional requirements and in turn provide protection against a number of diseases. In this article, a detailed comparison of these two supplements will be done, giving you a clear overview about their health benefits, side effects, safety and drug interaction.

Flaxseed oil

Flaxseed plant or Linum usitatissimum is the plant of historical origin that is grown worldwide due to its healing benefits. Flaxseed oil, extracted from the seeds of flaxseed oil plant, has got a number of health benefits due to its rich content of omega 3 fatty acid. Flaxseed oil contains an abundant amount of an essential omega 3 fatty acid named as alpha linolenic acid (ALA). This potential fatty acid helps reduce inflammation in the body that makes it highly beneficial for the prevention of chronic inflammatory diseases. Apart from its high omega 3 content, flaxseed oil is enriched with a number of other nutrients including proteins, carbohydrates, calcium, magnesium, phosphorus, iron, zinc, potassium, sodium and vitamin B complex. Flaxseed oil is considered to be the richest source of ALA amongst all other plant based oils because 1 tablespoon of this oil contains about 7 gram of alpha linolenic acid (ALA), which is much higher in amount than other oil supplements. Alsor, its sugar and calorie content is lower than other supplements, which makes it a choice for people on calorie restricted diet. Due to its anti inflammatory effect and high nutritional value, flaxseed oil is supposed to be an efficacious supplement for imparting relief from a number of inflammatory diseases.

How flaxseed oil works?

To understand the health benefits of flaxseed oil, one must know about the role of omega 3 fatty acids in the body.  Omega 3 fatty acids are the derivates of polyunsaturated fatty acids that are required for the normal functioning of the body.  These potential fatty acids are not produced in the body so they have to be taken through diet to improve the body functions. These omega 3 fatty acids are the essential components of cell membranes and they help to stabilize the cell membranes by strengthening them. Apart from healing and strengthening the cell membranes, these omega 3 fatty acids help in regulating the immune functions of the body. Omega 3 fatty acids control the production of immunemediators and boost the overall immunity of the body. Nature has blessed omega 3 fatty acids with an amazing antioxidant potential. Due to their antioxidant nature, they tend to fight those mediators or chemicals that are produced as a result of inflammation. Thus, they help reduce inflammation by reducing the synthesis of inflammatory mediators. Their ability to regulate immune system and reduce inflammation makes their use effective in the prevention of inflammatory diseases.

Flaxseed oil is enriched with abundant amount of Alpha linolenic acid (ALA), an essential omega-3 fatty acid. ALA is converted by body to other essential omega 3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).  These two are the main essential fatty acids that are necessarily required for keeping the body functions tuned. These highly effective antioxidant omega 3 fatty acids protect the body cells from harmful effects of inflammation causing chemicals and help to keep the inflammation suppressed. As they bestow anti inflammatory and antioxidants effects to the body, these omega 3 fatty acid supplements are quite helpful in preventing chronic diseases like heart diseases, arthritis, diabetes and cholesterol problems.

Health benefits of flaxseed oil

Flaxseed is packed with rich amount of potent anti inflammatory and antioxidant omega 3 fatty acids that impart protection against inflammation. Therefore, the use of flaxseed oil might be helpful in following health conditions:

High cholesterol

Cholesterol is required for normal physiological function of the body as it is an integral part of cell membrane. But, the level of cholesterol higher than safe limit can wreak havoc upon your body. Cholesterol is obtained from animal dietary sources and is also produced by liver in some amount. However, the concentration of this cholesterol is tightly regulated in the body through lipoproteins. There are two lipoproteins of significant importance that help regulate the cholesterol level, including HDL (high density lipoprotein) and LDL (low density lipoprotein. HDL carries cholesterol from peripheral body tissues and transports it to liver from where it is excreted out of the body. That is why HDL, is also named as “good cholesterol” because it keeps the level of cholesterol low in the blood and tissues. On the other, LDL is considered to be the “bad cholesterol” because it transports cholesterol to the peripheral body tissues and causes their deposition in the blood vessels and body tissue. Higher concentration of this bad cholesterol in the body ends up in increased risk of obesity, hypertension and heart diseases. But, flaxseed oil helps to reduce these risks by lowering down the concentration of cholesterol in the body. The antioxidant omega 3 fatty acids in flaxseed oil resist the piling of bad cholesterol in blood vessels and award protection against heart diseases and high blood pressure.

However, the flaxseed alone cannot cause significant lowering of bad cholesterol until or unless the dietary consumption of cholesterol is restricted. So, if you want to get better results with flaxseed oil, you may need to cut down high cholesterol foods in your diet (1).

Cardiovascular diseases

Research studies have proved that increased dietary intake of ALA tends to reduce the risk of heart diseases and high blood pressure. As flaxseed oil is the richest source of ALA, its daily consumption can give you better control over your blood pressure and make you less vulnerable to heart problems (2). Flaxseed oil provides protection against cardiovascular diseases in a variety of ways. First, it lowers the level of LDL and prevents its collection in the heart blood vessels. Once LDL gets deposited into the blood vessels, it gets oxidized and reactive oxygen species are produced that initiate a series of inflammatory reactions in the blood vessels. This ends up in the formation of atherosclerotic plaque, which occludes the blood vessels and reduces the blood supply to the heart, leading to heart attack. Flaxseed oil prevents this from happening by resisting the accumulation and oxidation of LDL particles in the blood vessels. Secondly, this highly potential anti inflammatory oil tends to suppress the formation of an inflammatory protein, C reactive protein, which is one of the main triggers for causing heart attack. Apart from lowering the LDL level, flaxseed oil also improves the blood circulation by preventing platelet aggregation and clot formation in the vessels.

Type 2 diabetes

In type 2 diabetes mellitus, the defect is not in insulin production because insulin production is normal in such people. The main culprit in type 2 diabetes is insulin resistance, a condition in which tissues become non responsive to the action of insulin. The purpose of insulin is to increase the utilization of glucose by cells and store the extra glucose in the form of fats. In insulin resistant patients, the cells become unable to utilize glucose due to insulin resistance, which results in raised blood sugar level. High blood glucose level is considered as a threat by insulin, so it starts converting this glucose to fats which are then deposited in the body tissues. This insulin mediated deposition of fats in the body causes further inflammation of tissues and makes them more resistant to the action of insulin. Due to high fat deposition in the tissues, type 2 diabetic patient either get overweight or obese. Most of the times, the obesity itself is the triggering factor of type2 diabetes in obese people because the more they get fat, the more will be the tissue resistance to insulin and higher will be risk of diabetes.

Flaxseed oil contains antioxidant omega-3 fatty acid, Alpha linolenic acid, which helps to improve the type 2 diabetes by reducing insulin resistance. These omega-3 fatty acids fight against the inflammation of insulin resistant tissues and make them responsive to the action of insulin. Above all, flaxseed oil also helps in regulating the disturbed lipid metabolism in these patients.  ALA present in flaxseed oil tends to lower the cholesterol and triglycerides deposition in the body tissues, which further improves the tissue resistance. Thus daily supplementation of flaxseed oil along with dietary restriction of high carbohydrate foods proves to be quite helpful in reducing insulin resistance in type 2 diabetic people (3, 4).

Breast cancer

Clinical studies were conducted to see the role of flaxseed oil in preventing breast cancers. Studies have proved that flaxseed oil is quite helpful in reducing the risk of breast cancer. High ALA content of flaxseed oil is actually responsible for preventing the breast tumor progression. ALA tends to inhibit the synthesis of those growth factors that are responsible for causing the uncontrolled replication and proliferation of tumor cells. Thus, by suppressing the proliferation of tumor cells, flaxseed oil helps prevent the tumor growth. Apart from its anti proliferative effects on breast cancer, flaxseed oil also helps to settle down the inflammation associated with breast cancer (5).

Colon cancer

Like in breast cancer, flaxseed oil has also proved to be effective in providing protection against colon cancer. ALA acts as a potential antioxidant, which improves the overall gut health and metabolism by reducing inflammation and boosting up the function of gut cells. However, the role of flaxseed oil in colon cancer prevention is through its anti proliferative effects. Alpha linolenic acids suppress the synthesis and release of tumor proliferation causing growth factors. ALA also helps to induce apoptosis or death of tumor cells, which leads to shrinkage of tumor size and prevents its further progression (6).

Rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disorder in which the immune system starts attacking the joint tissues. In rheumatoid arthritis, there is immune mediated inflammation of joints resulting in swelling, redness and pain in joint. With repeated bouts of inflammation, the protective cartilage covering the bones wears off and the bones start rubbing against each other, leading to painful joint movement. With the passage of time, the lubricating synovial fluid in the joint cavity gets thickened, causing the joint fusion and stiffness. Unfortunately, rheumatoid arthritis gets worse with time and medical treatment does not provide complete relief or remission from the disease. However, flaxseed oil due to its anti inflammatory nature can somehow provide relief from symptoms of arthritis. The antioxidant ALA in the flaxseed oil tends to suppress the joint inflammation and helps reduce the severity of joint swelling, stiffness and pain (7).

Sjogren’s syndrome

Sjogren’s syndrome is another autoimmune disorder in which immune system destroys the mucous membranes, salivary glands and lacrimal glands of the body. This results in decreased secretion of saliva and tears. Kertaoconjunctivitis sicca or dry eye is the very common complication of Sjogren’s syndrome because when tear production is reduced, the eyes get dry and eyelids start rubbing against them. This leads to inflammation of eyes conjunctiva, producing a gritty or painful sensations in the eyes on blinking. Flaxseed oil is considered to be highly effective in suppressing the inflammation of conjunctiva because of its high content of ALA fatty acids. Thus, by minimizing the inflammation, flaxseed oil helps to improve the symptoms of dry eyes (8).

Lupus nephritis

Lupus nephritis is the common complication of an autoimmune disorder called systemic lupus erythematosus (SLE). In SLE, antibodies are produced against body organs including heart, brain, lungs, skin and kidneys. These immune mediated antibodies attack the kidneys and cause their inflammation, named as lupus nephritis. Repeated inflammation of kidneys causes significant damage to them and leads to leak of proteins into the urine, causing proteinuria and progressive renal failure. Research studies have proved that daily consumption of flaxseed oil supplements tends to repress this immune mediated inflammation of kidneys and reduces the urinary leakage of proteins. In this way, flaxseed oil helps to improve kidney functions in patients with SLE and slows down the progression of renal failure (9).


Cyclic Mastalgia or breast pain occurs very commonly before menstrual bleeding. In pre menstrual phase, there occur some hormonal changes in the body that also affect the breast tissues. This hormonal imbalance causes inflammatory changes in breast that culminates in breast pain and tenderness. However, this cyclical pain persists for only for 3-4 days before menses and then resolves on its own. But those women who feel uncomfortable due to breast pain, they can surely get benefit from the use of flaxseed oil because this magical oil supplement helps reduce the breast inflammation and diminishes the pain associated with it (10).

Benign prostatic hyperplasia

Prostate is a small gland in males located just below the bladder, surrounding the urethra. In old males this gland, sometimes, gets significantly enlarged in size that causes obstruction of urethra. This in turn leads to urinary retention, urinary frequency and urgency. Flaxseed oil supplements when taken by people having benign prostatic hyperplasia help improve its symptoms and prevent the prostate inflammation (11).

Attention deficit hyperactivity disorder (ADHD)

Attention deficit hyperactivity disorder is a very common psychiatric disorder of childhood characterized by symptoms of behavioral changes, lack of concentration, hyperactivity and poor cognitive function. In ADHD, certain chemical changes occurs in the brain that are responsible for altering the behavioral and cognitive function of children. Sometimes, the lack of essential fatty acids in the diet can further aggravate this condition because a healthy balance of these fatty acids is needed for proper brain function. Thus, adding flaxseed oil supplements in the diet of such children help improve their cognitive functions by overcoming deficiency of essential fatty acids (12).

Dosage and intake methods

Flaxseed oil is a natural supplement enriched with highly beneficial omega-3 fatty acid. But, still these natural supplements must not be taken in more than recommended amount because they do carry some potential health risks. Flaxseed oil supplements are available in both liquid from and soft gel capsule forms. There is no recommended dose of flaxseed oil as the dosage depends on several factors including age, general health of the person and the condition for which he is being treated. However, the generally considered safe dose of flaxseed oil for adults is 1-2 tablespoon or 1-2 capsules per day.

1 tablespoon of flaxseed oil contains about 7grams or 700 mg of alpha linolenic acid (ALA), along with 130 calories.


Keep following precautions in mind while taking flaxseed oil supplements:

  • Flaxseed oil supplements should not be given to children under 12 years of age without physician’s consultation.
  • Keep your flaxseed oil supplements refrigerated to prevent them from turning rancid. Rancid products are not safe to use as they contain toxic elements in them.
  • Always buy good quality flaxseed oil supplements and protect them from heat and moisture as much as you can.
  • In diabetic patients, flaxseed oil can cause sudden lowering of blood glucose. So, diabetic people need to monitor their blood glucose strictly while using flaxseed oil supplements.
  • If you get allergic to flaxseed oil supplements, stop using them immediately.
  • Flaxseed oil slightly tends to increase the risk of bleeding. Therefore, people with bleeding disorders should use it cautiously.
  • Avoid taking flaxseed oil supplements and other medications at the same time as it can cause serious drug interactions.
  • Flaxseed oil supplements are considered to be safe in pregnant and breastfeeding women but it’s better to consult the doctor before using them.

Side effects

Flaxseed oil is very safe to use orally as it only has few side effects. Some mild side effects of flaxseed are:

  • Nausea
  • Stomach upset
  • Bloating or gas

Contact your doctor if you experience following unlikely serious side effects with flaxseed oil use:

  • Signs of allergy including skin itching, rashes, hives, difficulty in breathing or swallowing.
  • Fatigue and weakness
  • Confusion
  • Skin bruising (13)
  • Nosebleeds
  • Black tarry stools
  • Dizziness

Drug interactions

  • Use of flaxseed oil along with other herbal or vitamin supplements should be done cautiously as they can increase the risk of side effects.
  • Flaxseed oil when taken with other anti diabetic medicines can potentiate their glucose lowering effects and result in hypoglycemia.
  • Flaxseed oil should not be used along with blood thinning medication because the chances of bleeding get high when they are used simultaneously.
  • Flaxseed oil also shows mild interactions with non steroidal anti inflammatory medicines and cholesterol lowering drugs.



Fish oil

Fatty fishes, by far, are the richest sources of omega 3 fatty acids, vitamin A and D among all other dietary sources. Fish oil obtained from fatty fishes like tuna, trout, sardines, salmon and mackerel is considered to be of great value. Fish oil is packed with two essential omega 3 fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are required as a fuel for maintaining the body’s normal functions. These essential omega 3 fatty acids are very potent at reducing inflammation and regulating immune system of the body. This makes the use of fish oil highly effective in treatment and prevention of chronic inflammatory diseases like heart diseases, high blood pressure, arthritis and Alzheimer’s disease.

How it works?

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the essential omega 3 fatty acids that cannot be prepared in the body. So, one must take ample amount of these fatty acid through diet to meet the body’s requirement. But, what makes them so essential for our body? A proper balance of omega 3 fatty acids must be maintained in the body to keep the immune system active and well regulated. Omega 3 fatty acids are considered to be powerful antioxidants and anti inflammatory nutrients because they surround the body cells like a guardian that fights against all inflammation causing chemicals attacking the cells. Thus, by inhibiting the synthesis of inflammatory mediators, fish oil helps reduce inflammation associated with various chronic diseases.

Another important affect of omega 3 fatty is to boost immune system of the body. EPA and DHA are the important components of cell membrane. Once these omega 3 fatty acids incorporate themselves into the cell membranes, they regulate immune system and decrease the production of inflammatory mediators, prostaglandins. Prostaglandins are the inflammation causing chemicals that are released at the site of inflammation. These prostaglandins then cause swelling, pain and redness. But, omega 3 fatty acids help prevent all this from happening because they aid in suppressing the release of these harmful prostaglandins. Apart from inhibiting the synthesis of prostaglandins, these omega 3 fatty acids also fight all the reactive oxygen molecules that are produced at the site of inflammation. Reactive oxygen species are highly toxic and they cause aggravation of inflammation. However, omega-3 fatty acids in fish oil tend to eliminate these toxic molecules which further helps in suppressing and alleviating the symptoms of inflammation.

Health benefits of fish oil

Due to the high content of omega-3 fatty acids, fish oil is supposed to be the excellent natural supplement for relieving the inflammation associated with following health conditions:

Heart diseases

Fish oil is an excellent cardio protective supplement. Those who regularly take fish oil are less likely to have heart diseases. Omega-3 fatty acids present in fish oil help to lower bad cholesterol (LDL) level in the body and prevent their build up in the heart blood vessels. Removing the excess cholesterol deposits from heart vessels prevent their occlusion. This way, the blood flow through heart vessels remains adequate and the hearts stays in healthy condition. Hence, it has been proven that regular consumption of this fish oil supplementation keeps your heart active and protects it from the risk of heart attack or angina (14).


With age, the blood vessels get hard and narrow due to clot formation, cholesterol deposition and inflammatory changes. When the blood moves through these hard and narrow blood vessels, the resistance to its flow increases. In order to overcome this resistance, the blood moves with high pressure, which results in hypertension. Fish oil seems to very effective in lowering down the blood pressure in patients having hypertension. Those who take fish oil supplements have better control of their blood pressure. Omega-3 fatty acids prevent hardening of blood vessels by suppressing age related inflammatory changes in the blood vessels.  Furthermore, these healthy fatty acids make the blood less sticky and prevent its clot formation, which makes the blood flow easier through the blood vessels.

Rheumatoid arthritis

Rheumatoid arthritis is a painful inflammatory disease of joint. In this autoimmune disorder, immune antibodies are produced against the body’s healthy joint tissues. These antibodies cause repeated inflammation and destruction of joints.  Fish oil helps in relieving the symptoms of rheumatoid arthritis by suppressing this immune mediated inflammation. Being immune regulators, the omega-3 fatty acids also minimize the production of inflammation causing immune mediators (15).

Alzheimer’s disease

Alzheimer’s disease is an age related degenerative disorder of brain. In this disorder, certain inflammatory degenerative changes occur in brain tissues, which disturb the cognitive and memory functions of the person. Alzheimer’s disease is very common in old age and it tends to progress in slow and insidious manner. However, the progression of these degenerative changes can be slowed through fish oil supplements. Omega-3 fatty acids in fish oil protect the brain tissues by suppressing the inflammatory changes. Thus, fish oil supplements are helpful in improving the cognitive functions in people with Alzheimer’s disease (16).

Attention deficit hyperactivity disorder (ADHD)

ADHD in children causes cognitive dysfunction, behavioral changes and inability to concentrate. This happens due to some neurotransmitter imbalances in the brain tissues. Children suffering from ADHD are unable to concentrate on their studies and have difficulty in understanding new things. Clinical trials have proved that omega-3 fish oil supplements can help improve cognitive function in such children. Omega-3 fatty acids have neuro-protective role because they keep brain tissues protected from toxic inflammation causing chemical and help maintain the neurotransmitter balance as well (17).


Type 2 diabetic patients are prone to develop cardiovascular diseases because they have disturbed lipid metabolism. These people have high blood level of LDL or bad cholesterol which clogs the heart blood vessels and causes heart attack. But, fish oil seems to play a preventive role here. Essential fatty acids in fish oil lower down the LDL level and lessen the risk of heart attack (18).

Cancer prevention

Efficacy of fish oil in treatment of pancreatic cancer has been proven through research studies. Omega-3 fatty help induce apoptosis of cancer cell by inhibiting the synthesis of tumor growth factors. Fish oil also potentiates the effect of chemotherapeutic anti cancer drugs and helps in reducing the tumor size (19).

Miscarriage prevention

Fish oil is very beneficial for pregnant women and can be taken safely without having any adverse effect. Omega-3 fatty acids in fish oil not only help in proper development of baby but, they also prove to be very efficacious in preventing the miscarriage. Women who have history of recurrent miscarriages can take fish oil as it significantly reduces the risk of miscarriage (20).

Mental health

If want to cope with your anxiety and depression then fish oil can help you in doing so. The essential omeg-3 fatty acids in fish oil provide protection to your brain and correct all those neurochemical imbalances that are responsible for giving you depression and anxiety. Fish oil is also helpful in curing other psychiatric illnesses like major depressive disorder, schizophrenia and bipolar disorders (21).

Dosage and intake methods

Like flaxseed oil, fish oil is also available in the form of liquid and soft gel capsules. The safety daily dose of fish oil depends on the condition for which it is being taken. The usual recommended dose of fish oil is 1-2 grams daily. But, for heart diseases and high cholesterol, 2-4 grams can be taken daily in divided doses. For soft gel capsules, the recommended dose is 2 capsules per day.


  • Fish oil supplements are likely safe to be used. But, over dosage of these supplements should be avoided because over dosage can bring you more harm than good.
  • Some fatty fishes like swordfish shark accumulate toxic heavy metals within them. Oil obtained from these fishes should not be used as they can cause heavy metal toxicity.
  • Always buy good quality branded fish oil.
  • Protect fish oil supplements from heat and moisture. Keep them refrigerated to maintain their efficacy for long term.
  • Fish oil supplements increase the risk of bleeding and bruising in patients with bleeding disorder. So, these patients need to be cautious while taking these supplements.
  • Diabetic patients need to carefully monitor their blood glucose level because fish oil can cause hypoglycemia in these people.
  • Fish oil is likely safe to be use in pregnancy but dose adjustment needs to be done with doctor’s consultation to avoid risk of side effects.

Side effects

Some of the common side effects of fish oil are:

  • Indigestion
  • Stomach discomfort
  • Nausea
  • Bloating or gas

Immediately seek medical help if you have following rare side effects;

  • Skin rashes, hives or itching
  • Skin bruises
  • Wheezing or chest discomfort
  • Difficulty in breathing
  • Unusual tiredness
  • Confusion or dizziness

Drug interactions

When taking any supplements one should be aware of possible interactions. The fish oil may interact with the following drugs:
  • Fish oil increases the risk of bleeding when taken along with blood thinning drugs (21).
  • When taken along with other herbal supplements, chances of adverse effects get many folds higher.
  • Birth pill tends to reduce the effectiveness of fish oil. So they should not be used together.
  • Fish oil, when taken in combination with glucose lowering drugs, can lead to hypoglycemia.


Both flaxseed oil and fish oil have got great health benefits and are effective in curing various chronic diseases. Both supplements are safe to use and have fewer side effects. However, fish oil is better than flaxseed because it contains high content of preformed DHA and EPA omega 3 fatty acids. Flaxseed contains only ALA which needs to be converted to EPA and DHA by the body. But, human body is not very efficient in converting ALA to EPA and DHA so higher doses are required to achieve the health benefits.

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Written by: Michal Vilímovský (EN)
Education: Medical student, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
Article resources: See numbered references within the article.
Image resources: Dollarphotoclub.com
Published: July 13, 2015 6:51 AM
Next scheduled update: July 13, 2017 6:51 AM
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