Benefits of Fish Oil on Blood Pressure

Fish oil is good for the heart, helping to lower triglycerides, reduce the risk of heart attack and stroke and can even lower blood pressure, according to the Mayo Clinic. A study highlighted by the American Heart Association (AHA), Morris et al, showed that fish oil reduced blood pressure by 3.4/2 mm Hg. Another study by Appel et al found an even more significant reduction of 5.5/3.5mm Hg in people who had untreated hypertension.

How Does it Work?

• More benefits have been from fish sources than plant-based sources.

  The Mayo Clinic says that the lowering effect found in the studies comes from the omega-3 fatty acids that are found in fish oil. It contains docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The DHA seems to have more of an effect on lowering blood pressure than EPA.

  Omega-3 fatty acids can also be found in vegetarian sources like vegetable oils and English walnuts. This strand is known as alpha-linolenic acid (ALA). According to the Mayo Clinic, similar benefits have been suggested for ALA, but the evidence isn't as convincing, and the benefits are not as prominent.

How Much is Needed?

• Talk to your doctor before starting supplementation.

  The studies that show a reduction in blood pressure used a very high dose of fish oil. The Morris et al study used a dose of 5.6 grams per day. To put this in perspective, the Mayo Clinic states that with the average western diet people consume only 1.6 grams of omega-3 fatty acids daily. Most of these, about 1.4 grams, come from the vegetarian source ALA, leaving only about 0.1 grams from the beneficial fish oils.

  The AHA recommends that healthy adults eat two servings of fatty fish per week. The World Health Association recommends between 0.3 to 0.5 grams per day of omega-3 fatty acids and 0.8 to 1.1 grams per day of the plant-based ALA.

  The U.S. Food and Drug Administration states that consuming up to 3 grams of fish oil per day is "generally regarded as safe." This is particularly important because the Appel et al study saw the blood pressure lowering effect with less than 3 grams daily.

Safety Considerations

• Fish oil can be consumed through pills or fish meat.

  The high doses required to lower blood pressure in the Morris et al study can have some harmful side effects. According to the Mayo Clinic, doses that high can cause an increased risk of bleeding. Thus, supplementation that high should be done only under the watchful eye of a medical professional.

  Also toxins, specifically methylmercury, have been found in some fish species. However, according to the Mayo Clinic, toxins collect more in fish meat than in fish oil. Thus, it says that fish oil supplements seem to have no signs of mercury. But people who are susceptible to heavy metals, such as young children and women who are nursing or pregnant should be particularly careful when consuming fish or considering fish oil supplements.

  The Mayo Clinic says that other less harmful side effects include gastrointestinal upset, burping and a fishy aftertaste. To reduce these effects, take the fish oil supplement with a meal or at night right before bed.