You can open your blood vessels, a process called vasodilation, through a combination of regular exercise, specific foods, heat exposure, and staying well hydrated. Your blood vessels widen and narrow constantly throughout the day in response to signals from the cells lining their walls. The good news is that many of these signals are under your direct influence.
How Blood Vessels Open and Close
The inner lining of every blood vessel produces a molecule called nitric oxide, which is the primary signal that tells the surrounding muscle layer to relax. When that muscle relaxes, the vessel widens and more blood flows through. Nitric oxide works by triggering a chain reaction inside the vessel wall: it activates an enzyme that produces a second messenger molecule, which then causes the muscle fibers to release their grip. The whole process takes seconds.
Anything that increases nitric oxide production or reduces signals that constrict vessels will effectively “open” them. That’s the basic principle behind every strategy on this list, whether it’s a dietary change or a prescription medication.
Exercise Is the Strongest Natural Stimulus
When you exercise, blood moves faster through your arteries. That faster flow creates a physical shearing force against the vessel lining, which directly stimulates nitric oxide release. Over time, your vessels adapt: they become more elastic, produce nitric oxide more efficiently, and experience less oxidative damage that would otherwise stiffen their walls.
The key factor appears to be cumulative volume rather than intensity. Training five to seven days per week provides the repeated stimulus needed to fully develop these vascular adaptations. Even moderate aerobic activity like brisk walking or cycling counts. The vessels essentially “learn” to stay more relaxed at baseline when they’re exposed to regular bouts of increased flow. Resistance training helps too, but aerobic exercise produces the most consistent improvements in vessel flexibility and dilation capacity.
Foods That Boost Nitric Oxide
Certain vegetables are rich in dietary nitrates, which your body converts into nitric oxide. Beetroot, arugula, spinach, and celery are among the highest sources. Beetroot juice has become popular specifically because of its concentrated nitrate content, and it has been studied extensively for its effects on blood pressure and blood flow in people with hypertension.
Beyond nitrate-rich vegetables, foods high in omega-3 fatty acids improve how well your vessels dilate on demand. A meta-analysis found that omega-3 supplementation increased flow-mediated dilation (a direct measure of how well arteries open in response to blood flow) by about 0.9% compared to controls. That may sound small, but in vascular medicine, even modest improvements in dilation capacity translate to meaningful reductions in cardiovascular strain over years. Fatty fish like salmon, mackerel, and sardines are the best dietary sources, along with walnuts and flaxseed.
Citrulline Outperforms Arginine for Blood Flow
Two amino acid supplements are commonly marketed for blood vessel support: L-arginine and L-citrulline. Both serve as raw materials for nitric oxide production, but they aren’t equally effective. In a controlled crossover study, citrulline-based supplements produced significantly greater increases in both vessel diameter and blood flow volume compared to arginine-based supplements during exercise. Blood flow increased by roughly 58 to 63 mL/min above baseline with citrulline, while arginine actually showed a slight decrease.
The reason is absorption. Much of the arginine you swallow gets broken down in the gut and liver before it ever reaches your bloodstream. Citrulline bypasses that breakdown, gets absorbed intact, and then your kidneys convert it into arginine where it can be used to produce nitric oxide. So citrulline is essentially a more efficient delivery system for the same end product. Doses in studies typically use around 1.5 to 3 grams of citrulline.
Heat Exposure Redirects Blood Flow
Saunas and hot baths cause widespread vasodilation as your body attempts to cool itself. During a sauna session, your circulatory system redirects roughly 50% to 70% of blood flow from your core to your skin to facilitate sweating and heat loss. This redistribution forces your vessels to practice dilating under real physiological demand, which may improve their long-term function.
There’s an important distinction, though. Whole-body heating primarily increases blood flow to the skin, not to muscles or internal organs. If your goal is improving circulation to a specific limb, local heating (like a warm compress or heating pad) is more effective at increasing muscle blood flow in that area. For people with peripheral arterial disease, a specific type of thermal therapy called Waon therapy has shown decreases in pain scores and improvements in walking distance and blood flow measurements.
Hydration Affects How Easily Blood Flows
Even perfectly dilated vessels won’t deliver blood efficiently if the blood itself is too thick. Dehydration increases blood viscosity, which means your heart has to work harder to push blood through the same vessel diameter. Research on exercising individuals found that adequate hydration normalized blood viscosity, effectively reducing the resistance that blood encounters as it moves through the vascular system. Drinking enough water won’t make your vessels open wider, but it removes a barrier that can negate the benefits of vasodilation. For most adults, this simply means drinking water consistently throughout the day, especially before and during exercise or heat exposure.
When Vessels Need to Be Opened Mechanically
Sometimes blood vessels are narrowed not by muscle tension but by physical blockages, typically plaque buildup from atherosclerosis. No amount of dietary nitrate or exercise will dissolve a calcified plaque that’s blocking 70% of a coronary artery. In these cases, doctors may recommend angioplasty, where a small balloon is threaded into the artery and inflated to compress the plaque, often followed by placing a metal stent to keep the vessel propped open.
The clearest benefit of stenting is during an active heart attack, where restoring blood flow quickly saves heart muscle. Outside of emergencies, the picture is more nuanced. Stenting reliably reduces chest pain and improves quality of life, and it cuts the need for repeat procedures. But for stable blockages, even significant ones, several large trials have found that stenting does not consistently reduce the risk of future heart attacks or death compared to medication alone. When the burden of reduced blood flow to heart muscle exceeds about 10% of the heart’s tissue, early intervention does appear to improve survival. Below that threshold, medications that relax vessels and reduce plaque progression often perform just as well.
Prescription Vasodilators
Several classes of medication work by opening blood vessels through different mechanisms. ACE inhibitors block the production of a hormone that constricts arteries. Calcium channel blockers prevent calcium from entering vessel wall muscles, keeping them relaxed. Nitrate medications, like nitroglycerin, directly increase nitric oxide in the vessel wall, with a particularly strong effect on veins. Phosphodiesterase inhibitors prevent the breakdown of the relaxation signal inside the vessel muscle, prolonging dilation after it starts.
Each class targets a different step in the constriction process, which is why doctors sometimes combine them. The choice depends on the underlying condition: high blood pressure, angina, pulmonary hypertension, or peripheral artery disease each respond best to different vasodilator types.