Fish Oil Health Benefits and Side Effects

Written by: Christopher Karam ｜ ✔️ Medically Reviewed by: Dr. Riad M., M.D - G.P and Micheal B., M.D ｜ Last Updated: 2020 April 27

What Is Fish Oil?

Fish oil is one of the most effective and consumed dietary supplement in North America. It contains polyunsaturated omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Fish oil does not contain alpha-linolenic acid (ALA), as ALA is mostly found in plant-based foods.

The health benefits of taking fish oil supplements regularly can help with weight loss, as well as physical, cardiovascular, and cognitive improvements.

Fish oil is obtained by extracting the concentrated oil of multiple different oily fish. The oily fish that are especially rich in healthy fats, including omega-3 fatty acids, are the following:

• Mackerel oil

• Herring oil

• Cod liver oil

• Salmon oil

• Tuna oil

• Anchovies

Many studies also show how fish oil can lower blood pressure, improve brain health, cognitive functioning, as well as improve triglycerides and cholesterol levels.

History and Background

A 1989 study showed a 29% reduction in fatal cardiac arrhythmias in subjects taking fish oil supplements once per day for 3 weeks. This was most effective in people who had a recent heart attack (myocardial infarction).

Another scientific study found a similar reduction in the number of death of people who’ve suffered from cardiac arrest-related death, non-fatal heart attacks, and strokes. These participants also took one fish oil supplement that’s high in omega-3 every day.

Fish oil has been a crucial part of the human diet since fishing was created, around the 14th century. The Greenland Eskimo civilization was one of the first groups of people to consistently consume fish.

That civilization suffered low heart disease mortality rates and reduced cardiovascular risk factors by having fish meat and fish oil be the main part of their diets, as compared to the Danes and Americans at that time.

Fish oil has been used as a natural supplement since the 1950s, and in medicinal remedies since around 400 B.C. Fish oil and dolphin liver oi is mentioned by the Greek physician Hippocrates as well as by the Roman military commander Pliny the Younger.

The historic mentions of fish oil tend to focus on dolphin liver oil, cod liver oil, tilapia, and catfish. Mostly mentioning the omega-3 benefits of cod liver oil and dolphin oil.

Both Northern Europe and Northern Scotland used to consider cod liver oil a delicacy, it was also used to fuel their lamps at night. In those regions, it was also given to people who have poor mental health and physical health, as all types of fish oil have strong anti-inflammatory properties.

The anti-inflammatory properties of fish oil come from its antioxidants, healthy omega-3 fatty acids, and polyunsaturated fatty acids.

The composition of fish oil does not contain the omega-3 alpha-linolenic acid (ALA), ALA is obtained by omega-3 rich plant-based foods such as:

• Perilla seed oil (63g of ALA per 100g of oil)

• Flaxseeds and flaxseed oil (60g per 100g)

• Canola (rapeseed) oil (8g per 100g)

• Walnuts and walnut oil (7g per 100g)

• Soybeans, tofu, and soybean oil (6g per 100g)

• Corn (maize) oil (0.7g per 100g)

• Olive oil (0.6g per 100g)

• Safflower oil (0.4g per 100g)

• Sesame oil (0.3g per 100g)

• Peanut oil (0.2g per 100g)

• Palm oil (0.2g per 100g)

• Cocoa powder (0.1g per 100g)

• Coconut oil (0.1g per 100g)

When looking to get high-quality fish oil, you need to look at the nutrition facts, ingredients list, and the optimal ratio of EPA to DHA, to determine the best fish oil supplement. The optimal EPA to DHA ratio is 3:2.

Fish oil supplements are all FDA approved and have had many studies showing the multiple health benefits of consuming fish oil regularly.

Healthy fats help lower triglycerides levels, stabilize blood sugar levels, improve heart health, and reduce the risk of cardiovascular disease.

Cooking With Fatty Fish

Fish oil can be consumed in many ways, most people get their daily intake through eating fatty fish 2 to 3 times per week, while a majority take a supplement through a capsule of mixed fish oils every day.

Certain types of fatty fish are highly used in cooking and most high-end recipes. Sardines and anchovies are the most popular fish of choice for cooking. They’re easily broken down into a paste and mixed into various foods and ingredients, such as:

• Cooking oils including extra virgin olive oil, coconut oil, sesame oil, vegetable oil, canola oil, corn oil, sunflower oil, and peanut oil

• Herbs and spices including yellow mustard, mustard seeds, parsley, basil, spinach, dill, rosemary, chives, garlic, salt, black pepper, cumin, ginger root, tarragon, cinnamon, summer savory, paprika, chilli, garam masala, curry leaves, oregano, and thyme

• Vegetables including white, red and green onions, carrots, mushrooms, bell peppers, hot peppers, olives, celery, potatoes, sweet potatoes, cabbage, broccoli, zucchini, turnips, green beans, artichoke, cauliflower, and green peas

• Fruits including tomatoes, lemon juice and zest, lime juice and zest, coconut milk, capers, grapefruit, and pomegranates

• Carbohydrates including white and brown rice, lentils, beans, vegetables, and crackers

• Vinegars including apple cider vinegar, balsamic vinegar, and red wine vinegar

• Dairy including cheeses, sour cream, and butter

• Eggs

Fatty fish can also be mixed into healthy salad dressings, sandwiches, or used as a pâté, while fish stock can also be used in soups as well as risotto.

Fish have a strong fishy scent and flavor. To avoid overpowering your food, mix your fish with cooking oils or acidic ingredients such as lemon, lime, or vinegar. If you mix multiple ingredients into your recipes, it will lessen the fishy odor and flavor.

Cooking with fish is the cheapest way to consume adequate EPA and DHA fatty acids regularly. Fish oil pills are made using oily fish, such as:

• Salmon

• Trout

• Cod

• Tuna

• Anchovies

• Herring

• Sardines

• Mackerel

Having 2 to 3 servings of fatty fish per week will significantly improve the health of your heart, liver, brain, and digestive system. EPA and DHA fatty acids are where most of the health benefits of fish oil reside.

Nutritional Information

Fish oil is a pure liquid fat from fish, which means it has no fiber, carbohydrates, protein, or vitamins and minerals. They solely contain omega-3 fats.

Although ALA is an essential fatty acid that’s missing from fish, it’s found in many different types of plants. ALA is not biologically active until the body converts it into EPA and DHA fats, which are essential to the human body.

The plant-based foods that include ALA fats include seaweed and algae, chia seeds, hemp seeds, nuts, flax seeds, and soybeans.

Some people don’t like eating fish, which makes fish oil supplements even more effective. Additionally, there are plant-based foods that also contain omega-3 fatty acids, such as:

• Chia seeds

• Brussel sprouts

• Leafy greens

• Cruciferous vegetables

• Algal oil

• Berries

• Hemp seeds

• Walnuts

• Beans

• Flax

• Perilla oil

Popular in Japanese cuisines, soybeans contain a lot of ALA and omega-3 fats, this includes tofu and edamame. Walnuts also provide a large serving of omega-3 fats in the form of ALA and can be eaten anytime.

Ground flaxseeds may be used to sprinkle on cereal, salads and other dishes to provide essential fatty acids.

The leading cause of death worldwide is from heart disease. Studies have shown that people who eat fish or consume fish oil regularly have much lower rates of heart disease.

Fish oil is thoroughly studied and has many scientifically proven health benefits. Multiple research studies have found that fish oil helped with many different physiological systems of the human body.

Some benefits include mood regulation and clarity, which will help you quit smoking, improve heart health, and reduce symptoms of arthritis.

Fish oils may also help those with liver disease. Healthy fats and natural fatty acids prevent inflammation in the liver, benefiting everyone but is much more effective in people suffering from liver-related disorders.

The fatty acids contained in fish oil, known as EPA and DHA, are not manufactured by the human body. The body is also unable to make EPA from DHA and therefore requires ingestion.

All heart disease risk factors are reduced when taking fish oil supplements. In all types of fish oil supplements, the optimal ratio of EPA to DHA is 3:2 respectively, which is 300 mg of EPA for every 200 mg of DHA.

Fish oil can also prevent the formation of plaques in the arteries, as well as make existing plaques softer for easier removal. Some studies also found that fish oils reduced symptoms of both schizophrenia and bipolar disorders.

Fish oil is also used to treat many kidney-related problems including kidney disease, kidney failure, kidney cancer, as well as other complications.

Consuming fish oil regularly has also been used for preventing heart disease, strokes, clogged arteries, chest pain, irregular heartbeat, bypass surgery, heart failure, rapid heartbeat, preventing blood clots, and high blood pressure after a heart transplant.

1. Lowers Risk of Heart Disease

Multiple scientific studies found that taking 1 fish oil capsule daily had a significantly reduced risk of coronary heart disease, cardiovascular diseases, arrhythmia, and heart failure. Taking 2 capsules per day had an additional 15% to 20% improvement.

A study conducted with 22,000 healthy males and 84,688 healthy women found that taking daily fish oil supplements daily improved the health of red blood cells.

These people were at risk of arrhythmia and myocardial infarctions (MI), their risk of contracting these complications was reduced by 70%.

An additional DART study conducted on 2033 post-myocardial infarction patients, 3 groups were either a diet high in fiber, polyunsaturated fats, or fish oils.

The group consuming fish oils had a reduced mortality rate of 29%. While another research study found a 73% risk reduction of cardiovascular disease and heart-related deaths.

The healthy fats found in fish oils help lower bad (LDL) cholesterol, triglycerides, blood pressure, and plaques in the arteries. All of which contribute to lower heart-related issues.

Fish oil’s primary health benefit is a drastic improvement of overall heart health, making it highly recommended for people of all ages.

2. Lowers Triglycerides and LDL Cholesterol levels

Triglycerides are fat cells, called lipids, found in your bloodstream. When your body breaks down food, all unused calories are converted into triglycerides and are stored as fat cells for later use, this is the process for the body’s fat storage.

Fish oil supplements help lower triglyceride levels by 14 to 20% while simultaneously increasing both levels of good (HDL) cholesterol and bad (LDL) cholesterol by around 8% each.

Because HDL reduce the effects of LDL cholesterol, the increase in both types of cholesterol may be beneficial, unless you have high cholesterol levels already.

Multiple studies were conducted on type 2 diabetic patients, with one group given fish oil and the other corn oil for 8 weeks. After the 8 weeks, the group given fish oil had seen lowered triglyceride levels by around 18% and increase HDL-2a by 4% and HDL-2b by 9%.

3. Reduces Blood Pressure

Over 31 studies confirmed fish oil’s beneficial effect on blood pressure. This is due to the healthy omega-3s highly benefiting the cardiovascular system.

Blood pressure is measured using systolic pressure over diastolic pressure. Systolic pressure is the pressure in the arteries when the heart pumps out blood.

Diastolic pressure is the pressure in the arteries when the heart is at rest between heartbeats, while oxygenated blood enters the heart.

The length of these controlled studies lasted between 3 and 24 weeks and found an average result of:

• Systolic blood pressure: -4.5 mm, -15 Hg.

• Diastolic blood pressure: -2.2 mm, -0.8 Hg.

Each gram of omega-3 fatty acids contributed to a lowering of -0.66 mm, -0.35 Hg. These results are from healthy individuals, where results were more beneficial to people with a history of cardiovascular issues, hypertensive, diseases, or hypercholesterolemia.

4. Promotes Healthier Skin

The skin is the largest organ in the human body, it’s largely made up of omega-3 fatty acids and collagen, which keeps the skin shining, hydrated, and healthy.

Ageing is the leading cause of skin complications, wrinkles, diseases, and cancer. Consuming foods that are high in antioxidants and omega-3 fatty acids can drastically reduce your risk for any skin disorders.

Fish oil helps reduce the severity and risk of developing skin disorders such as:

• Dermatitis

• Psoriasis

• Eczema

• Acne

• Rosacea

5. Improves Brain Health and Function

Fish oil heavily benefits mental health and may prevent certain mental disorders. Omega-3 fats are essential for proper brain development, function, and memory.

Additionally, the antioxidants help amplify these benefits by also reducing the risk of developing Alzheimer’s disease, depression, Obsessive-compulsive disorder (OCD), bipolar disorder, and schizophrenia.

These healthy fats also make it easier to quit smoking, reduces addictions and cravings, as well as relieve symptoms of anxiety.

A study published by the School of Criminology at the University of Haifa had 48 regular smokers participate, half were given fish oil pills and the other, a placebo.

After 30 days, the group that was given fish oil pills had a naturally reduced rate of smoking by 11%, while no changes were made in the placebo group.

They discovered that omega-3 fats would block endocannabinoid receptors in the brain, which signalled cravings and dopamine release. This also reduced the amount of dopamine released during the activity, making it less desirable.

6. Fish Oil Reduces Inflammation

Inflammation is the immune system's response to fighting infections, foreign agents, and treating injuries. Fish oil helps the body cushion and protect the affected area, this reduces swelling and increases blood flow.

Reducing inflammation helps treat certain mental disorders and improve cognitive function, as your brain is made up of roughly 60% fats, most of which are omega-3 fatty acids.

Omega-3s are essential for proper brain function and health. In many research studies, it's been shown that most individuals who suffer from cognitive decline and disorders have a lower level of omega-3 fats in their diets.

Reducing inflammation helps treat a large variety of symptoms, diseases, illnesses, and chronic disorders. Multiple studies confirm that the anti-inflammatory effects of fish oil relieves chronic inflammation.

Fish oil can benefit people with chronic inflammatory disorders including:

• Joint pain

• Joint stiffness

• Rheumatoid arthritis

• Obesity

• Diabetes

• Asthma

• Peptic ulcers

• Hepatitis

• Inflammatory bowel disease (IBD)

• Crohn's disease

• Tuberculosis

• Periodontitis

• Sinusitis

• Symptoms of depression

• Hay fever

Fish oil’s healthy fats may reduce the production and gene expression of cytokines, which are inflammatory molecules and a part of the immune system’s response.

Supplementing with fish oil helps reduce the production of cytokines, a major contributor to heart disease.

However, there is no conclusive scientific evidence that supports the prevention of heart attacks or strokes and is not medically prescribed to prevent any cardiovascular issues.

More research on cytokines ish needed, but with the potential to help reduce the immunoresponse of releasing cytokines, it’s recommended to take fish oil.

Fish oil supplements also have beneficial effects on patients suffering from rheumatoid arthritis. Multiple studies have shown that fish oil reduces joint pain while lubricating the joints, improving stiffness and movement, as well as bone density.

The average North American diet contains far more omega-6 fatty acids compared to omega-3 fatty acids, omega-6 fats promote inflammation.

The omega-6 to omega-3 imbalance has been shown to increase the risk of low bone density in men and women. Adults with a higher level of omega-3 fatty acids have maintained greater bone density, making fish oil a potential treatment as it’s full of omega-3s.

7. Can Cause Weight Loss

According to the World Health Organization, 33% of children under the age of 12 are classified as obese, while 1.9 billion adults are overweight. Obesity is the leading cause of cardiovascular disease (CVD), heart failure (HF), and coronary heart disease (CHD).

The healthy fats found in fish oils lower insulin levels, which helps induce weight loss. The long-chain fatty acids found in fish increases levels of adiponectin. Adiponectin is a hormone that regulates glucose levels, which increases insulin sensitivity.

Being sensitive to insulin allows you to stay fuller for longer after eating. This lowers the frequency and intensity of cravings and allows you to maintain consistent energy levels throughout the day.

Insulin resistance is when your body doesn’t respond to glucose naturally, reducing the ability for cells to absorb blood sugar for energy. This allows obese and overweight people to lose weight drastically, with a minor change to their diets.

Controlled insulin levels also control blood sugar levels, allowing you to lose bodyweight, lower the risk of heart disease, cancer, hyperglycemia, as well as type 1 and type 2 diabetes.

8. Improves Eye Health

Similarly to the skin and brain, eyes rely on omega-3 fats for proper health and function. Studies have shown that people lacking in omega-3s have an increased risk of eye diseases. Some eye disease includes:

• Cataracts

• Color blindness

• Glaucoma

• Retinitis

• Amblyopia

• Age-Related Macular Degeneration (AMD)

• Crossed Eyes (Strabismus)

• Diabetic Macular Edema

Eye health declines with age, which can lead to age-related macular degeneration (AMD). Omega-3 fatty acids protect the eye from AMD and dryness by keeping the cells moisturized and healthy.

Fish oil has essential fatty acids that facilitate drainage of intraocular fluid, maintaining a healthy pressure in the eye. Proper Intraocular pressure decreases the risk of glaucoma, which is caused by high eye pressure.

Additionally, multiple research studies found that consuming fish oil supplements for 18 weeks improved vision in all AMD patients.

The side effects of fish oil are minimal, almost every harmful effect stems from overconsumption or high mercury levels. The level of mercury differs from brand to brand, depending on which fish is used for making the fish oil pill.

Regarding dosage, it’s not recommended to take more than 3 fish oil pills per day if you’re generally healthy, or 4 pills per day if you’re severely lacking omega-3s in your diet. 2 fish oil pills per day is optimal for most individuals.

Overdosing on omega-3 rich foods while taking fish oil supplements can cause a range of issues such as high blood pressure, diarrhea, acid reflux and heartburn, nausea, digestive pains, and increases your risk of stroke.

Mercury is a very dangerous metal found in many fish, with higher doses in larger and fattier fish. If you ingest too much mercury, it may cause mercury poisoning which amplifies inflammation, headaches, insomnia, as well as other side effects.

Smaller fish such as herring, mackerel, sardines, and anchovies have low concentrations of mercury since they are low in size and fat.

A mackerel's mercury content is 30x smaller than that of a swordfish or shark. The higher the fish is on the food chain the higher the concentration of mercury. Make sure to buy fish oil supplements from trusted brands that extract oil from smaller fish.

1. Fish Oil Negatively Interacts With Medication

Some of the more major side effects of fish oil consumption include an increased risk of bleeding and hemorrhagic strokes. These effects may be due to fish oil’s blood-thinning effects.

Fish oil is a blood-thinner that makes it harder for your blood to clot, this increases your risk of brain hemorrhage or a hemorrhagic stroke.

Avoid taking fish oil before going on surgical medication, any surgeries, and a few weeks after surgery. A surgeon or nurse will typically ask you if you have taken fish oil, aspirin or any blood thinners before surgery.

If you’ve been taken fish oil, make sure to disclose that to your care provider. Fish oil has negative interactions with multiple medications and drugs including:

• Blood clotting and anticoagulant medication such as Aspirin, Clopidogrel (Plavix), Dalteparin (Fragmin), Dipyridamole (Persantine), Enoxaparin (Lovenox), Heparin, Ticlopidine (Ticlid), Warfarin (Coumadin), and Rivaroxaban (Xarelto).

• Weight loss drugs such as Orlistat (Xenical, Alli), Lorcaserin (Belviq), Phentermine-topiramate (Qsymia), Naltrexone-bupropion (Contrave), and Liraglutide (Saxenda).

• Heart disease, cariovascular disease, and blood pressure medication such as Clopidogrel (Plavix).

• Fish oil does not negatively interact with statins including Atorvastatin (Lipitor) and thyroid drugs such as Synthroid (Levothyroxine, L-thyroxine).

Always consult a medical professional before taking any prescription medication or before adding concentrated fish oil to your diet.

2. Lowers Blood Pressure

Fish oil’s blood-thinning effects can cause a drastic drop in blood pressure, which can be beneficial or harmful. A study conducted on 31 patients who were given either a placebo or 1g fish oil per day for 3 to 24 weeks.

After the research trial was over they found that the placebo group found a 7% decrease in blood pressure, per gram of fish oil consumed. If you already have low blood pressure, adding too many fatty fish to your diet may lead to:

• Fainting

• Dizziness

• Pale colored skin

• Lightheadedness

• Lack of mental focus

• Chest pain

• Blurry vision

• Nausea

• Heart palpitations

• Depression

3. May Cause Acid Reflux

Fish oil is a pure liquid, concentrated set of fats that may cause acid reflux and other digestive side effects. People who have high stomach acidity, Zollinger-Ellison syndrome, or stomach ulcers should seek medical advice before adding fish oil pills to their diet.

As fish are full of omega-3 fats, consuming too much may seriously harm your cardiovascular and digestive system.

Consult a medical professional if you naturally have too much gastric acid. The side effects of taking fish oil with high gastric acid levels may cause:

• Abdominal pain

• Vomiting

• Diarrhea

• Nausea

• Belching

• Heartburn

• Headaches

Fish oil is one of the very few supplements that we would recommend to the majority of the population, as fish oil has many health benefits and few side effects. The optimal dosage for fish oil would be 1 to 2 pills per day, with an EPA to DHA ratio of 3:2.

To avoid any potential side effects, skip taking your fish oil supplements on the days where you're eating fatty fish.

Fatty fish are full of omega-3 fatty acids, EPA and DHA, which are essential for proper immune health, heart health, and for reducing inflammation. The numerous health benefits range from improved blood sugar levels to improved brain function.

Omega-3 fatty acids also significantly lower cardiac risk factors while improving insulin sensitivity. Omega-3s are easy to incorporate into your diet through the use of fish oil, which plays a critical role in most systems in the human body.

Here’s the full list of the health benefits of fish oil:

1. Lowers Risk of Heart Disease

2. Lowers Triglycerides and LDL Cholesterol levels

3. Reduces Blood Pressure

4. Promotes Healthier Skin

5. Improves Brain Health and Function

6. Fish Oil Reduces Inflammation

7. Can Cause Weight Loss

8. Improves Eye Health

Here’s the full list of side effects of fish oil:

1. Fish Oil Negatively Interacts With Medication

2. Lowers Blood Pressure

3. May Cause Acid Reflux

Hundreds of research papers and studies have been conducted on fish oil, all of which have found numerous health benefits when taken regularly.

The most serious side effects of fish oil are through its interaction with medication and other drugs, including:

• Weight loss medication

• Anticoagulant and blood clotting medication

• Heart disease, cardiovascular disease, and blood pressure medication

These issues arise from the concentration of the omega-3 fats in the fish oil pills, you can circumvent these side effects by consuming leaner, whole fish such as tuna, sole, cod, red snapper, halibut, and pike.

Lean fish are quite cheap, while most omega-3 supplements can get expensive. There are some high-quality fish oil and cod liver oil supplements that hover around 0.10$ per pill.

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