Several supplements and foods can meaningfully increase blood flow, primarily by helping your body produce more nitric oxide, a molecule that signals blood vessels to relax and widen. The most effective options backed by research include L-citrulline, beetroot juice, omega-3 fatty acids, garlic, cocoa, and capsaicin from hot peppers. Each works through a different mechanism, so understanding them helps you choose what fits your situation.
L-Citrulline and L-Arginine
Your body uses the amino acid L-arginine to produce nitric oxide, which directly relaxes blood vessel walls. The intuitive move would be to supplement with L-arginine itself, but roughly 70% of oral L-arginine gets broken down during digestion before it ever reaches your bloodstream. Only about 30% makes it into general circulation.
L-citrulline, another amino acid, takes a more efficient route. Nearly all of it survives digestion intact and converts into L-arginine once it reaches your kidneys. In head-to-head comparisons, citrulline supplementation raises blood arginine levels about 35% more than taking arginine directly. Its only job in the body is to become arginine, so very little goes to waste. For this reason, most sports nutrition and cardiovascular research now favors L-citrulline over L-arginine as the better supplement for boosting nitric oxide.
Typical study doses of L-arginine range from 2 to 6 grams per day. If you choose L-citrulline instead, doses of 3 to 6 grams daily are commonly used in research. L-citrulline malate, a bound form often sold for exercise performance, is also widely available.
Beetroot Juice and Nitrate-Rich Foods
Beetroot juice works through an entirely different pathway. It’s loaded with dietary nitrate, which bacteria on your tongue convert into nitrite, and then your body further reduces into nitric oxide. About 25% of beetroot juice’s content is nitrate, making it one of the most concentrated food sources available.
After drinking beetroot juice, plasma nitrate levels spike by roughly 550% within one to two hours, and nitrite levels rise about 400% over two to three hours. That nitric oxide then triggers blood vessel walls to relax, lowering resistance to blood flow. The effect is strong enough that multiple clinical trials have shown measurable reductions in blood pressure in people with hypertension.
Other vegetables with similarly high nitrate concentrations (over 250 mg per 100 grams) include spinach, arugula, watercress, lettuce, celery, and radish. Eating these regularly gives your body a steady supply of raw material for nitric oxide production. One important note: antiseptic mouthwash kills the oral bacteria responsible for the first step of nitrate conversion, which can blunt the benefits.
Omega-3 Fatty Acids
Fish oil improves blood flow through a mechanism most people don’t expect. The omega-3 fatty acids EPA and DHA get incorporated into the membranes of red blood cells, making them more flexible and deformable. Stiffer red blood cells have trouble squeezing through small capillaries, so when they become more pliable, blood flows more easily through narrow vessels.
In studies using 3 grams of omega-3s daily, researchers found a significant increase in red blood cell deformability and a corresponding drop in whole blood viscosity, essentially making the blood less thick. Plasma viscosity and red blood cell count stayed the same, confirming the effect came specifically from changes in cell membrane flexibility rather than blood thinning. Fatty fish like salmon, mackerel, and sardines are the richest dietary sources, with fish oil and algae-based supplements as alternatives.
Garlic
Garlic promotes blood vessel relaxation through hydrogen sulfide, a signaling molecule your body uses alongside nitric oxide. When you crush or chew raw garlic, it releases allicin and related sulfur compounds. These polysulfides interact with cells lining your blood vessels and generate hydrogen sulfide, which causes the smooth muscle around arteries to relax.
Research published in the Proceedings of the National Academy of Sciences confirmed that garlic’s ability to relax blood vessels directly parallels how much hydrogen sulfide its compounds produce. The sulfur molecules are fat-soluble, so they can pass through cell membranes and create a sustained, localized dose of hydrogen sulfide that’s more potent than a quick burst. This relaxation likely works by activating potassium channels in smooth muscle cells. Aged garlic extract is the form most commonly studied in supplement form, though raw garlic provides the same precursor compounds.
Cocoa Flavanols
Dark chocolate and cocoa powder are rich in flavanols, plant compounds that stimulate nitric oxide production in blood vessel walls. A single high-flavanol cocoa drink containing about 900 mg of flavanols produced a measurable, temporary spike in nitric oxide levels in healthy people, along with improved blood vessel dilation.
Even small daily amounts appear effective over time. In one study, just 6.3 grams of chocolate daily (containing 30 mg of polyphenols) increased circulating nitric oxide markers in people with elevated blood pressure after 18 weeks. Two-week studies using 100 grams of dark chocolate showed improved vessel dilation in people with hypertension. The key is flavanol content, not chocolate quantity. Heavily processed or “Dutch process” cocoa has most flavanols stripped out, so look for minimally processed cocoa powder or dark chocolate with high cacao percentages.
Capsaicin From Hot Peppers
The compound that makes chili peppers hot also opens blood vessels. Capsaicin activates a receptor called TRPV1, the same receptor responsible for sensing heat, which is present not only on nerve endings but also on the cells lining your blood vessels. When capsaicin activates this receptor on endothelial cells, it triggers a cascade that increases nitric oxide production, causing the surrounding smooth muscle to relax.
Animal research has shown that regular dietary capsaicin improves blood vessel relaxation and lowers blood pressure in hypertensive models. The effect works through at least two pathways: a direct action on blood vessel lining cells that boosts nitric oxide, and a secondary release of a nerve-signaling peptide that relaxes vessels through a separate mechanism. Cayenne pepper, chili flakes, and hot sauces are all practical sources.
Curcumin
Curcumin, the active compound in turmeric, improves endothelial function, meaning it helps the cells lining your blood vessels work better at regulating dilation. A meta-analysis of five randomized clinical trials found that curcumin supplementation significantly improved flow-mediated dilation (a standard measure of how well arteries expand in response to increased blood flow) compared to placebo. The challenge with curcumin is absorption. Standard turmeric powder delivers very little curcumin to the bloodstream, so formulations designed for better absorption, often combined with black pepper extract or lipid carriers, are more practical choices.
How These Options Compare
Each of these works through a different mechanism, which means combining certain ones could offer additive benefits:
- Nitric oxide production: L-citrulline, beetroot juice, cocoa flavanols, and capsaicin all increase nitric oxide, but through different biochemical steps.
- Hydrogen sulfide signaling: Garlic works through a parallel vasodilation pathway independent of nitric oxide.
- Blood viscosity: Omega-3s reduce the physical thickness of blood, improving flow regardless of vessel diameter.
- Vessel lining health: Curcumin supports the long-term function of the endothelium itself.
Beetroot juice produces the fastest noticeable effect, with nitrate levels peaking within one to two hours. L-citrulline also acts relatively quickly as a single dose. Omega-3s and curcumin, on the other hand, require consistent daily intake over weeks to produce measurable changes.
Safety Considerations
Anything that effectively increases blood flow can interact with medications that do the same thing. Supplements that boost nitric oxide have documented interactions with common blood pressure medications and erectile dysfunction drugs like sildenafil and tadalafil. Combining them can cause blood pressure to drop too low, leading to dizziness, fainting, or worse. If you take any blood pressure or cardiovascular medication, check with your prescriber before adding these supplements.
On their own, the options listed here are generally well tolerated at typical doses. Niacin (vitamin B3) does cause vasodilation, but it works by triggering flushing in small skin blood vessels, producing an uncomfortable burning and itching sensation that limits its usefulness as a circulation supplement. Beetroot juice can turn urine and stool red, which is harmless but startling if you’re not expecting it. High-dose fish oil can increase bleeding time, which matters if you’re on blood thinners or heading into surgery.