Several supplements have clinical evidence supporting their ability to improve blood flow, and they work through different mechanisms: widening blood vessels, reducing blood thickness, or improving the flexibility of artery walls. The most effective options target nitric oxide production, the body’s primary way of relaxing and opening blood vessels. Here’s what the research actually shows for each one.
L-Citrulline and L-Arginine
L-arginine is the direct building block your body uses to produce nitric oxide, the molecule that signals blood vessels to relax and widen. Enzymes in your blood vessel walls convert L-arginine into nitric oxide and, as a byproduct, L-citrulline. That byproduct matters because your body can recycle L-citrulline back into L-arginine, keeping the cycle going.
This is why many experts now recommend L-citrulline over L-arginine for supplementation. L-arginine taken orally gets heavily broken down in the gut and liver before it reaches your bloodstream. L-citrulline bypasses that breakdown, gets absorbed intact, and then converts to L-arginine where it’s needed most. The result is a more sustained rise in nitric oxide.
Clinically effective doses of L-citrulline range from 2.4 to 6 grams per day, taken for at least one to two weeks. At these doses, studies show increased nitric oxide production, reduced arterial stiffness, and lower blood pressure. In one trial, 5.6 grams daily for just 7 to 14 days reduced arterial stiffness in healthy, overweight middle-aged men. Higher doses of 10 grams daily for four weeks improved the ability of arteries to expand in response to blood flow in postmenopausal women with high blood pressure. For L-arginine, 3 to 12 grams daily has been shown to reduce both systolic and diastolic blood pressure in people with mild hypertension.
Beetroot Juice and Dietary Nitrates
Beetroot juice works through the same end goal as citrulline, boosting nitric oxide, but takes a completely different route. The nitrates in beets are converted by bacteria in your mouth into nitrites, which then become nitric oxide in your bloodstream. This pathway operates independently of the enzyme-driven process that L-arginine uses, which means the two approaches can complement each other.
One of the strongest advantages of beetroot juice is speed. Blood pressure reductions and improved vessel dilation occur within about three hours of a single dose, and this effect persists with daily use for at least 15 days. The effective range is roughly 200 to 1,000 milligrams of nitrate, typically delivered in 70 to 250 milliliters of concentrated beetroot juice.
The blood pressure reductions linked to dietary nitrate are meaningful. A systematic review found that drops of 5 to 12 points in systolic pressure and 5 to 6 points in diastolic pressure are associated with a 14 to 38% reduction in stroke risk and a 9 to 16% reduction in death from coronary heart disease. Those aren’t small numbers for something you can drink with breakfast.
Omega-3 Fatty Acids
Omega-3s from fish oil improve blood flow through a different mechanism entirely. Rather than widening vessels, they make the blood itself flow more easily. A placebo-controlled, double-blind study found that omega-3 supplementation in increasing doses improved red blood cell flexibility and reduced blood viscosity, essentially making blood less thick and sticky. After 21 days, plasma viscosity dropped significantly. By 56 days, overall blood viscosity decreased further and red blood cells became measurably more deformable, meaning they could squeeze through tiny capillaries more efficiently.
Omega-3s also reduce platelet aggregation, the tendency of blood cells to clump together. This is relevant for circulation because platelet clumping is one of the early steps in blood clot formation. When combined with aspirin, omega-3s produced significantly greater reductions in platelet aggregation and prolonged bleeding time compared to aspirin alone. That’s worth knowing if you’re already on blood-thinning medication, since the combined effect could increase bleeding risk.
Curcumin
Curcumin, the active compound in turmeric, targets endothelial function, which is how well the inner lining of your blood vessels responds to changes in blood flow. When endothelial function is poor, arteries can’t expand properly, and circulation suffers.
In a double-blind, placebo-controlled trial in young, healthy adults, 200 milligrams of a bioavailable curcumin form taken daily for eight weeks improved flow-mediated dilation by 3.0% compared to placebo. A lower 50-milligram dose showed a 1.7% improvement, though that result wasn’t statistically decisive. A 1% or greater improvement in flow-mediated dilation is considered clinically meaningful, so the higher dose cleared that bar comfortably. The odds ratio for clinical benefit at the 200-milligram dose was 546 to 1 in favor of benefit over harm.
Standard curcumin is poorly absorbed, so formulation matters. Look for versions designed for better bioavailability, often labeled as containing piperine, phospholipid complexes, or nano-formulations.
Aged Garlic Extract
Garlic’s effect on circulation centers on arterial stiffness, which is how rigid your artery walls have become. Stiff arteries increase the speed at which pulse waves travel through your vessels, causing pressure waves to bounce back prematurely and raising the workload on your heart.
In a placebo-controlled trial using aged garlic extract, the supplement group saw a 21.6% improvement in arterial elasticity, measured by a standardized index of arterial stiffness. Nearly 70% of subjects in the garlic group responded with measurable reductions in stiffness, compared to no significant change in the placebo group. The stiffness index dropped from a mean of 12.86 to 10.08 over the course of the study.
Aged garlic extract is distinct from raw garlic or standard garlic supplements. The aging process converts harsh sulfur compounds into gentler ones that are easier on the stomach and appear to be more bioactive for vascular health.
Pine Bark Extract (Pycnogenol)
Pine bark extract stands out for its effects on microcirculation, the blood flow through your smallest vessels. These capillaries are where oxygen and nutrients actually reach your tissues, and they’re often the first to suffer when circulation declines.
In a study of 60 people with coronary artery disease, four weeks of pine bark extract supplementation increased the diameter of micro vessels at the fingertips in 53.8% of patients, compared to 32% in the placebo group. Separate research found it reduced resting blood flow resistance in the scalp by 43.5% after six months, roughly double the improvement seen with placebo. In people with early diabetic retinopathy, three months of supplementation improved retinal blood flow by around 30%, reduced retinal swelling by 11 to 25% depending on severity, and improved visual acuity by 21%.
Iron for Oxygen Delivery
Iron isn’t a vasodilator, but it plays a foundational role in how effectively your blood delivers oxygen. Iron is the core component of hemoglobin, the protein in red blood cells that binds and carries oxygen. When iron levels drop low enough to cause anemia, your blood carries less oxygen per unit volume. Your body compensates by extracting more oxygen from each pass of blood, which leaves tissues with lower oxygen saturation overall and causes faster oxygen depletion during any physical demand.
If your poor circulation symptoms include fatigue, cold hands and feet, or shortness of breath with mild exertion, low iron could be a contributing factor. This is especially common in women with heavy menstrual periods, vegetarians, and frequent blood donors. A simple blood test can confirm whether iron deficiency is part of the picture before you start supplementing, since excess iron carries its own health risks.
Capsaicin
Capsaicin, the compound that makes chili peppers hot, activates a receptor called TRPV1 on the inner lining of blood vessels. When this receptor is triggered, it stimulates the production of nitric oxide in endothelial cells, promoting vessel relaxation and lowering blood pressure. Research shows that regular dietary capsaicin intake enhances the activity of the enzyme responsible for nitric oxide production, creating a sustained vasodilatory effect rather than just a temporary flush of warmth.
Capsaicin is available as a supplement in capsule form, which avoids the burning sensation of eating raw peppers. The circulatory benefits appear to come from consistent daily intake rather than occasional use.
Safety With Blood-Thinning Medications
Because many of these supplements affect how blood flows, clots, or passes through vessels, combining them with anticoagulant or antiplatelet medications requires caution. Omega-3s paired with aspirin significantly increase the reduction in platelet aggregation and prolong bleeding time beyond what either does alone. Vitamin E combined with aspirin has a similar amplifying effect on reduced platelet adhesion and prolonged bleeding. Ginseng, sometimes marketed for circulation, has been shown to alter how the body processes warfarin, potentially changing the drug’s effectiveness. If you take any prescription blood thinner, discuss these supplements with your prescriber before adding them.