Researchers tested whether fish oil capsules containing omega-3 fatty acids and other natural compounds could improve blood circulation in people with high blood pressure. In this small 3-week study, 64 people took either fish oil capsules or placebo pills. The fish oil group showed improvements in how blood flowed through one of the heart’s main arteries, though blood pressure itself didn’t change much. While the results are promising, the study was short and small, so more research is needed before doctors recommend this treatment widely.
The Quick Take
- What they studied: Whether taking fish oil capsules with added nutrients could improve blood circulation in people with high blood pressure
- Who participated: 64 adults with high blood pressure, split into two groups of 32 each. One group took fish oil capsules, the other took corn oil (placebo) for 3 weeks
- Key finding: The fish oil group showed better blood flow measurements in the heart’s main artery, with improvements of about 2-3% in specific flow measurements. However, overall blood pressure didn’t improve, and circulation in the brain and skin showed no changes
- What it means for you: Fish oil supplements may help blood move more smoothly through the heart’s arteries in people with high blood pressure, but this is early-stage research. Don’t replace blood pressure medications with supplements—talk to your doctor first
The Research Details
This was a carefully controlled experiment where researchers divided 64 people with high blood pressure into two equal groups. One group received fish oil capsules containing omega-3 fatty acids, resveratrol, astaxanthin, and CoQ10—all substances known to reduce inflammation. The other group received corn oil capsules that looked identical but had no active ingredients (placebo). Neither the participants nor the researchers knew who got which treatment until the study ended, making it “triple-blind.” Everyone took 2 capsules daily for 3 weeks.
The researchers measured blood circulation in three different areas: the heart (using ultrasound), the skin (using laser technology), and the brain (using MRI scans). They tracked specific measurements of how fast blood was moving and how much resistance it faced in the arteries.
This study design is important because it eliminates bias—people can’t change their behavior based on knowing they’re getting a real treatment, and researchers can’t unconsciously treat groups differently. The triple-blind approach makes the results more trustworthy. Measuring circulation in multiple organs helps show whether the supplements work throughout the body or just in one area.
This is a pilot study, meaning it’s designed to test whether an idea is worth studying more deeply, not to prove something works. The sample size of 64 people is relatively small, and the 3-week duration is quite short. These limitations mean the results are preliminary. However, the study used objective measurements (ultrasound, lasers, and MRI) rather than relying on what people reported, which strengthens the findings. The use of a placebo group and blinding also increases reliability.
What the Results Show
The most important finding was that fish oil improved blood flow in the left anterior descending artery, one of the heart’s major blood vessels. Specifically, two measurements improved: the speed of blood at the end of the heartbeat increased by about 1.95 units, and the peak speed during relaxation increased by about 2.95 units. Both of these changes were statistically significant, meaning they’re unlikely to have happened by chance.
Another measurement called the resistance index showed a trend toward improvement in the fish oil group, but the improvement wasn’t quite strong enough to be considered statistically significant. This suggests the effect might be real but needs more study to confirm.
Surprisingly, blood pressure itself didn’t improve in either group during the 3 weeks. This suggests that while fish oil may help blood flow more smoothly, it doesn’t necessarily lower the pressure at which blood pushes against artery walls.
The researchers also measured blood circulation in the brain and skin, but found no significant differences between the fish oil and placebo groups in these areas. This suggests that if fish oil helps circulation, the benefit might be specific to the heart rather than a whole-body effect. The lack of change in blood pressure measurements was notable—even though blood flow improved, the actual pressure readings remained similar in both groups.
Previous research has shown that omega-3 fatty acids, resveratrol, astaxanthin, and CoQ10 each have anti-inflammatory properties and may benefit blood vessels. This study is one of the first to test a combination of these compounds specifically in people with high blood pressure. The finding that heart circulation improved aligns with what scientists expected based on earlier research, but the short duration and small size mean this study adds preliminary evidence rather than definitive proof.
Several important limitations should be considered. First, 3 weeks is a very short time—health changes often take longer to develop. Second, with only 64 participants, the results might not apply to larger populations. Third, the study only measured one specific artery in the heart, not overall heart function. Fourth, the lack of improvement in blood pressure and brain/skin circulation raises questions about how widespread the benefits might be. Finally, this is a pilot study designed to test feasibility, not to prove the treatment works—larger, longer studies are needed for stronger evidence.
The Bottom Line
Based on this preliminary research, fish oil supplements may help blood flow in the heart’s arteries, but the evidence is not yet strong enough to recommend them as a treatment for high blood pressure. If you have high blood pressure, continue taking prescribed medications and consult your doctor before adding supplements. The confidence level for these findings is low to moderate due to the small sample size and short duration.
People with high blood pressure might be interested in this research, as well as those looking for ways to support heart health. However, this study is too preliminary to guide treatment decisions. People taking blood thinners or those with fish allergies should avoid fish oil supplements without medical approval. Anyone considering supplements should discuss them with their healthcare provider first.
This study only lasted 3 weeks, so we don’t know how long benefits might take to appear or how long they might last. Real-world benefits could take weeks or months to develop. More research over longer periods is needed to understand the realistic timeline for seeing improvements.
Want to Apply This Research?
- If a user wants to track fish oil supplementation, they could log daily capsule intake and monitor resting heart rate weekly as a simple proxy for circulation health. Track: date, capsules taken, and morning resting heart rate (measured after sitting quietly for 5 minutes)
- Users could set a daily reminder to take fish oil capsules at the same time each day (e.g., with breakfast) and log completion in the app. They could also track any changes they notice in energy levels or how they feel during exercise, though these are subjective measures
- Over 8-12 weeks, users could track consistency of supplement use, resting heart rate trends, and any changes in exercise tolerance or fatigue. They should also continue monitoring blood pressure if they have high blood pressure, as this study showed supplements didn’t lower pressure readings
This research is preliminary and should not replace medical treatment for high blood pressure. Fish oil supplements can interact with blood thinners and other medications. Always consult with your healthcare provider before starting any supplement, especially if you have high blood pressure, take medications, or have fish allergies. This study lasted only 3 weeks in 64 people, so results may not apply to everyone or over longer periods. Do not stop taking prescribed blood pressure medications based on this research.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.