Fish Oil or Real Fish, Which is Better for High Blood Pressure
If you have high blood pressure and want to lower it naturally, both fish oil and real fish have been shown to be effective. But is one better than the other, and if so, why? Two new studies tell part of the (fish) story.
Lower your blood pressure with omega-3
Use of fish oil and omega-3 fatty acids for helping heart function, reducing symptoms of osteoarthritis, preventing vision loss, and helping with stroke disability have been reported in the literature for years. When it comes to use of fish oil for treatment of high blood pressure, some of the study results have been mixed.
Before publication of the two new studies, both of which appear in the same peer-reviewed journal and were headed by the same investigator, numerous research teams had reported on the benefits of fish oil in treating high blood pressure (hypertension). As in other studies of fish oil, the benefits are associated with the two main omega-3 fatty acids found in fish, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
DHA and EPA are examples of a long-chain polyunsaturated fatty acid, and in the case of these two fatty acids, they are essential because the body cannot manufacture them and thus they must be obtained from food. In addition to EPA and DHA, another omega-3 called alpha-linolenic acid (ALA), found in plant sources such as walnuts and plant oils, have shorter chains than the fish sources and may be less effective.
In a recent review published in the British Journal of Nutrition, for example, the researchers reported that at least 3,000 mg of omega-3 fatty acids daily was associated with a “significant decrease in blood pressure, especially systolic blood pressure, in older and hypertensive subjects.” However, not all the studies they reviewed yielded the same results.
Now a University of Pennsylvania team, headed by Toshinori Hoshi, PhD, have published two related set of findings regarding fish oil supplements, real fish, and high blood pressure. The focus of their research was on DHA.
First, the team discovered how DHA works to influence blood pressure. Basically, the omega-3 must bind to specific ion channels in smooth vascular (blood vessel) muscle cells. Once they are in place, potassium ions are able to leave these cells, which in turn allows the blood vessel muscles to relax and thus lower blood pressure.
Their second discovery concerned the activity of synthetic DHA, of DHA ethyl ester, which they reported is used in most fish oil supplements. When the DHA ethyl ester was given to mice, it did not trigger the same response in the potassium ions as did natural DHA.
In fact, the researchers noted that real DHA and synthetic DHA compete for the specific binding locations. As an increasing amount of fake DHA achieves those spots, potassium ions are unable to leave the cells, which is detrimental for blood pressure.
The authors concluded that “this finding has practical implications for the use of omea-3 fatty acids as nutraceuticals for the general public and also for the critically ill receiving omega-3-enriched formulas.”
In other words, it’s important to take the real thing when it comes to omega-3 fatty acids and blood pressure. Whether it’s real DHA in your fish oil supplements or real fish on your plate (the American Heart Association recommends 2 servings of fish per week), don’t fake it when it comes to lowering your blood pressure.
Cabo J et al. Omega-3 fatty acids and blood pressure. British Journal of Nutrition 2012 Jun; 107 (Suppl 2): S195-200
Hoshi T et al. Omega-3 fatty acids lower blood pressure by directly activating large-conductance Ca2+-dependent K+ channels. Proceedings of the National Academy of Science USA 2013 Mar 4.
Hoshi T et al. Mechanism of the modulation of BK potassium channel complexes with different auxiliary subunit compositions by the omega-3 fatty acid DHA. Proceedings of the National Academy of Science USA 2013 Mar 4.