Fish-oil supplements slightly lower blood pressure in adults diagnosed with high blood pressure

Campbell F, Dickinson HO, Critchley JA, et al.  A systematic review of fish-oil supplements for the prevention and treatment of hypertension  European Journal of Preventive Cardiology. 2013; 20:1, 107-120

Review question

Are fish-oil supplements effective in preventing and treating high blood pressure?

Background

Regularly eating fish is a part of a healthy diet, and may help contribute to a healthy heart. Many countries worldwide recommend eating several servings of fatty-fish every week. Instead of eating fish, some people choose to take supplements, but it is important to ensure they are safe and effective.  

How the review was done

This review included 17 studies with a total of 1524 participants whose average age was approximately 50 years. Some studies included adults with high blood pressure whereas other studies included adults with normal blood pressure. The studies compared the blood pressure of people who took a fish-oil capsule to people who took a capsule of cooking oil (placebo).

What the researchers found

In people with high blood pressure, taking fish oil supplements for at least 8 weeks effectively lowered both systolic and diastolic blood pressure. While, the reported decrease in blood pressure appears small, it could result in a 10% reduction in stroke mortality, and 7% reduction in mortality associated with ischemic heart disease, among those with high blood pressure.

However, among those with normal blood pressure taking fish oil supplements for at least 8 weeks was not effective at lowering the blood pressure.

Furthermore, taking a higher dose of fish oil was not effective in reducing blood pressure for either those with high blood pressure or those with normal blood pressure.

Conclusion

Fish oil supplements may result in a small but important reduction in blood pressure among those with high blood pressure.