Does fish oil lower your blood pressure?

Treatments for high blood pressure include medications and lifestyle changes, including eating a low sodium diet and quitting smoking (if you smoke).

Fish oil is a natural source of omega-3 fatty acids, which can help lower blood pressure. However, like any health supplement, fish oil can produce side effects and may not be suitable for certain people. Your doctor can discuss the benefits and risks of fish oil and whether it’s right for you.

How fish oil affects blood pressure

Fish oil contains omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 

These essential fatty acids have been the subject of extensive research due to their potential cardiovascular benefits, including their effect on blood pressure.

A 2015 review explains that omega-3 fatty acids can help lower blood pressure through several mechanisms:

• Reducing inflammation: Omega-3 fatty acids have anti-inflammatory properties, which can help relax blood vessels and improve blood flow.
• Dilating blood vessels: EPA and DHA can promote the widening of blood vessels. The widened blood vessels reduce blood flow resistance and subsequently lower blood pressure.
• Decreasing blood clot formation: These fatty acids may help prevent the formation of blood clots, thereby decreasing the risk of blockages in the arteries.
• Stabilizing heart rhythm: Omega-3 fatty acids may help stabilize the heart’s electrical activity and make the heart’s resting period longer, which can also help maintain healthy blood pressure levels. 

Which fish oil works best?

According to a large 2022 research review, the optimal dosage for lowering blood pressure is 2–3 grams of omega-3 fatty acids per day. Getting more than this may have additional benefits. 

There are large variations in how much omega-3 fish oil supplements contain. Generally, you can expect a 1,000 milligrams (mg) fish oil supplement to contain around 180 mg EPA and 120 mg DHA, according to the National Institutes of Health.

To find the right fish oil supplement, be sure to review the packaging label. Choose an option that: 

• contains at least 2 grams of omega-3 fatty acids per day dose(s)
• is free from contaminants like mercury
• is third-party tested

You can purchase capsules or liquid fish oil. Some people dislike the oil because of its fishy flavor, while others dislike the capsules as some options can be large and harder to swallow. 

You can ask a pharmacist for recommendations on the right fish oil for you. 

How quickly does fish oil lower blood pressure?

How long it takes for fish oil to lower blood pressure can depend on factors including:

• any lifestyle changes you make, like exercising more or eating differently
• any blood pressure medications you may be taking
• how consistently you take fish oil every day
• your dosage of fish oil
• your overall health, age, and starting blood pressure

A 2022 research review on the effect omega-3 fatty acids have on blood pressure showed that the average study length to monitor effects was 10 weeks.

Your doctor can discuss the expected timeline for your symptoms to improve with fish oil or with blood pressure medications.

You will likely see your healthcare professional for follow-up blood pressure measurements or measure your blood pressure at home. By tracking your progress, you can determine which combination of therapies is working best for you.

How to take fish oil

Follow the dosage directions for the fish oil supplement you have chosen.

Your doctor may recommend taking fish oil supplements with food. A 2019 review noted that the body most efficiently absorbs EPA and DHA when you take them with a meal that includes dietary fat.

Taking a fish oil supplement with food may also help reduce side effects like fishy burps. 

Before starting any supplement, it’s best to consult a doctor. They can advise on the right dosage for you. They can also recommend if you should take other steps to lower your blood pressure, such as lifestyle changes or prescription medications. 

Fish oil side effects

Omega-3 supplements, including fish oil, produce only mild or no side effects, according to the National Center for Complementary and Integrative Health (NCCIH)

Possible side effects of fish oil include:

• foul-smelling breath
• fishy burps
• changed smell of your sweat
• stomach issues like nausea or diarrhea

To minimize these effects, you can try taking fish oil with meals. If you find the side effects of fish oil to be too bothersome, talk with your doctor about other options for lowering your blood pressure.

Does fish oil lower cholesterol?

The American Heart Association explains that it’s important to distinguish between different types of fat in your blood:

• high-density lipoprotein (HDL): known as the “good” cholesterol to improve heart health
• low-density lipoprotein (LDL): known as the “bad” type of cholesterol, as high levels increase the risk of heart disease and stroke
• triglycerides: a type of fat that works as storage for the energy you get from your diet

High triglyceride levels can worsen heart health, particularly when combined with high LDL or low HDL levels. 

A 2022 clinical trial report confirms that omega-3s, such as those in fish oil, can have a positive effect on cholesterol levels. Specifically, fish oil may reduce total cholesterol, LDL, and triglycerides while also improving HDL. 

When not to take fish oil

Fish oil is not suitable for everyone. 

According to the NCCIH, you should avoid fish oil supplements if you: 

• have allergies to fish or seafood
• take medications for blood clotting 

Talk with your doctor about any other potential risks of fish oil supplements in the context of your individual health.

Summary

Fish oil rich in omega-3 fatty acids, may reduce blood pressure and cholesterol levels.

Evidence suggests you need to take fish oil containing at least 2–3 grams of omega-3 fatty acids per day to see these beneficial effects. 

Fish oil is generally safe to take and is available over the counter. 

Still, if you have high blood pressure, it’s best to consult a doctor for individual treatment advice. Besides fish oil, they may recommend other treatment options like lifestyle changes or prescription blood pressure medications.