Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Alexandra V Goldberg, Registered Dietitian
Many people take fish oil to support heart health—but have you ever heard someone say their blood pressure dropped after taking it?
Fish oil does more than just protect your heart. It can improve blood vessel flexibility, calm your nervous system, and reduce inflammation—all of which can affect your blood pressure.
In this article, we’ll walk through 4 key ways fish oil may help with blood pressure—no complicated science, just what you need to know.
If you’re already on blood pressure meds or just watching your numbers, this could give you a new way to think about support.
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1｜Relaxing Your Arteries: How Fish Oil Boosts Nitric Oxide
If your high blood pressure is of the vascular type—such as age-related arterial stiffness, metabolic hypertension, or if you have mild arteriosclerosis or abnormal lipid levels—it’s recommended to choose fish oil products that are high in EPA.
One of the core problems behind hypertension is the loss of vascular elasticity. Under normal conditions, our blood vessels adjust automatically to body demands—expanding during physical activity and contracting during rest, much like an elastic hose.
This regulatory ability is driven by a key substance released by endothelial cells: nitric oxide (NO).
It acts as a “natural relaxation signal” for blood vessels, helping them dilate, reduce resistance, and maintain normal blood pressure.
However, when we’re under chronic stress, inflammation, or metabolic dysfunction, the function of vascular endothelium is compromised, and NO production is reduced. As a result, vessels become “less responsive,” failing to relax when needed. Blood flow is restricted, causing pressure to build up.
Omega-3 fatty acids in fish oil, especially EPA (Eicosapentaenoic Acid), may help increase nitric oxide production and improve vascular elasticity—supporting more stable blood pressure at the root level.
In a 2022 study published in Atherosclerosis , researchers found in an inflammatory model that: EPA upregulates the expression of eNOS (endothelial nitric oxide synthase) and activates a range of intracellular antioxidant proteins. This process helps endothelial cells maintain NO production, restores the vessels’ ability to relax, promotes smoother blood flow, and may reduce hypertension risk.
Although this study was conducted in animal and cellular models and has not yet been validated in large-scale human trials, it offers a mechanistic explanation: Supplementing with EPA may support healthy blood pressure by improving endothelial function and increasing nitric oxide levels.
Fish oil is not a blood pressure drug, and its effects are not immediate.
But in the long run, it can help restore vascular flexibility and gently support more stable blood pressure control.
For those already on medication, it can also serve as a safe complementary strategy.
2｜Relieving Nervous Tension: Less Stress, Lower Blood Pressure
If your high blood pressure is stress-related (such as white coat hypertension or blood pressure spikes during work stress), it is recommended to choose fish oil with a high DHA content. Combine it with relaxing activities such as stretching, meditation, or deep breathing for better blood pressure stability.
Have you ever noticed that sometimes, just thinking about “taking your blood pressure” is enough to make you feel anxious?
We often say we're “under a mountain of stress,” but did you know? This kind of stress isn't just emotional—it can directly affect your blood vessels and blood pressure.
When we're anxious, rushed, or emotionally tense, our body activates the sympathetic nervous system—like stepping on the gas pedal, speeding up the heart rate, constricting blood vessels, and raising blood pressure. While short-term activation helps us tackle challenges, chronic overactivation keeps the body in a state of constant tension, making high blood pressure harder to control.
This is where Omega-3s, especially DHA (Docosahexaenoic Acid), may come in handy.
Mechanistically, DHA is a key structural component of brain and nerve cell membranes, influencing how neural signals are transmitted and integrated. It can also modulate the body’s "brake system"—the vagus nerve—and improve our ability to recover from stress.
When DHA levels are sufficient, sympathetic nervous activity can be toned down, so the body is less likely to “overreact” to stress, helping blood pressure remain stable.
In a 2013 randomized controlled trial published in the American Journal of Physiology, researchers recruited 67 healthy adults. One group received daily high-dose fish oil supplements (containing DHA 1.1g + EPA 1.6g) for 8 weeks.
Results: During stress testing, the supplement group showed a 60.7% reduction in sympathetic nerve activity and a 20% decrease in heart rate, while the control group showed no significant changes.
Although there was no significant difference in blood pressure between the two groups over 8 weeks, the research team emphasized that modulation of the nervous system response suggests DHA may have important long-term benefits for managing stress responses and lowering chronic hypertension risk.
03｜Can Fighting Inflammation Lower Blood Pressure? A Key You Might Have Overlooked
If your high blood pressure is linked to inflammation, abnormal lipids, fatty liver, or obesity, a high-purity EPA fish oil supplement could be a powerful tool to ease the burden and help stabilise blood pressure.
High blood pressure isn’t caused by a single factor. One often overlooked contributor is chronic low-grade inflammation. If your blood pressure fluctuates a lot—especially after stress, sleep deprivation, or greasy meals—your body may be dealing with a persistent inflammatory response.
So, how does fish oil come into play?
A 2024 review published in Clinical Nutrition ESPEN summarised a decade of clinical research on Omega-3 fatty acids, focusing on their anti-inflammatory role in non-communicable chronic diseases.
The review found that EPA and DHA modulate multiple inflammation-related pathways, including reducing inflammatory cytokines (e.g., TNF-α, IL-6), lowering oxidative stress, and improving insulin resistance. All of these mechanisms are closely linked to better blood pressure control.
In people with metabolic syndrome, high cholesterol, obesity, or early-stage atherosclerosis, the anti-inflammatory effects of fish oil go beyond "general health support"—they may help reduce vascular tension, lower peripheral resistance, and enhance endothelial function. In other words, rather than simply "suppressing" blood pressure, fish oil helps create a more stable vascular environment that’s less prone to problems.
The review also noted that EPA/DHA supplementation may result in several key benefits:
- Reduction in plasma triglycerides (TG)
- Lower levels of inflammatory markers like C-reactive protein (CRP)
- Improved liver enzymes, reduced oxidative stress, and better mitochondrial function
- Lower risk of sudden cardiovascular events due to ruptured arterial plaques
While this doesn’t mean fish oil will lower blood pressure for everyone overnight, for those with chronic metabolic hypertension, it’s certainly a nutritional strategy worth considering and one that’s often underestimated.
Final Thoughts: What You Can Do
Different types of hypertension have different underlying mechanisms. Identifying your blood pressure triggers and choosing the right type of Omega-3 is the key to using fish oil effectively and getting real results.
