It was recognized many years ago that fish oil has a dose-dependent effect on lowering blood pressure (1). So how does it do it? There are a lot of different ways.
The first is the ability of the omega-3 fatty acids in fish oil to alter the levels of a group of hormones known as eicosanoids (2,3). These are the hormones that cause blood vessels to contract, thereby increasing the pressure needed to pump blood through the arteries. The omega-3 fatty acids, especially eicosapentaenoic acid (EPA), inhibit both the synthesis and release of the omega-6 fatty acid arachidonic acid (AA) that is the molecular building block necessary to produce those eicosanoids that cause constriction of blood vessels.
The second way that fish oil helps reduce blood pressure is to accelerate weight loss. When you lose excess weight, blood pressure invariably decreases. A recent trial has indicated that when you add fish oil to a calorie-restricted diet, there is greater weight loss (4). This study was followed by an additional trial that indicated when adding fish oil to a weight-reduction diet, there was a further effect on lowering blood pressure (5). So how does fish oil help you lose excess weight? The answer lies in the ability of the omega-3 fatty acids in fish oil to reduce cellular inflammation in the fat cells (6). It's that cellular inflammation that makes you fat and keeps you fat. Reducing that cellular inflammation in the fat cells is the key to weight loss.
Finally another cause of increased blood pressure is increased stress. It was shown in 2003 that high levels of fish oil reduce the rise of blood pressure induced by mental stress (7).
Of course, the best way to reduce blood pressure is to follow an anti-inflammatory diet rich in omega-3 fatty acids. That means a diet rich in fruits and vegetables with adequate levels of low-fat protein and low levels of omega-6 and saturated fats. It's also commonly known as the Zone diet.
- Morris MC, Sacks F, and Rosner B. “Does fish oil lower blood pressure? A meta-analysis of controlled trials.” Circulation 88: 523-533 (1993).
- Sears B. “The Zone.” Regan Books. New York, NY (1995).
- Sears B. “The OmegaRx Zone.” Regan Books. New York, NY (2002).
- Thorsdottir I, Tomasson H, Gunnarsdottir I, Gisladottir E, Kiely M, Parra MD, Bandarra NM, Schaafsma G, and Martinez JA. “Randomized trial of weight-loss diets for young adults varying in fish and fish oil content.” Int J Obes 31: 1560-1566 (2007).
- Ramel A, Martinez JA, Kiely M, Bandarra NM, and Thorsdottir I. “Moderate consumption of fatty fish reduces diastolic blood pressure in overweight and obese European young adults during energy restriction.” Nutrition 26: 168-174 (2010).
- Sears B. “Toxic Fat.” Thomas Nelson. Nashville, TN (2008).
- Delarue J, Matzinger O, Binnert C, Schneiter P, Chiolero R, and Tappy L. “Fish oil prevents the adrenal activation elicited by mental stress in healthy men.” Diabetes Metab 29: 289-295 (2003).