Overview
nitric oxide
The signalling molecule released by endothelium to relax vessel walls and increase blood flow.atherosclerosis
Inflammatory plaque formation within the artery wall, driven largely by cholesterol particles entering the wall.Interesting facts
- • The endothelium is only one cell thick everywhere in the body, yet collectively weighs more than the liver.
- • Nitric oxide's role in vessel dilation was such a fundamental discovery that it won the 1998 Nobel Prize — and it is the mechanism behind nitrates for angina and the drugs developed for erectile dysfunction.
- • Almost all exchange of oxygen, nutrients and waste happens in capillaries; arteries and veins are purely transport.
- • Veins hold the majority of your blood volume at rest, functioning as a reservoir the body can draw on by constricting them.
- • Arterial stiffness measured as pulse wave velocity predicts cardiovascular events independently of blood pressure, and is now considered a genuine marker of vascular age.
Common misconceptions
- Arteries clog up like a blocked drain, with fat sticking to the wall.
Atherosclerosis develops inside the artery wall, not as a coating on its surface. It is an inflammatory process in which cholesterol particles enter the wall and immune cells respond — closer to a boil than a blockage. - Heart attacks happen when a narrowing becomes complete.
Most heart attacks occur when a modest, non-obstructive plaque ruptures and triggers a sudden clot. This is why severity of narrowing predicts angina better than it predicts heart attack. - Varicose veins are purely cosmetic.
They reflect genuine venous valve failure, and can progress to skin changes, swelling and ulceration. Most are manageable, but calling them cosmetic understates the condition. - Supplements can clean out your arteries.
No supplement reverses established plaque. What is proven to reduce events is lowering LDL cholesterol and blood pressure, stopping smoking, and physical activity — chelation therapy in particular has been tested and failed. - Crossing your legs causes varicose veins.
Genetics, pregnancy, prolonged standing and age are the established drivers. Leg crossing is not a meaningful cause.
Anatomy & how it works
Three vessel classes with sharply different wall structures, all sharing a common endothelial lining.
Endothelium
The single-cell inner lining present in every vessel — a metabolically active organ regulating tone, clotting and permeability.
Elastic arteries
Large vessels like the aorta with elastin-rich walls that stretch with each beat and recoil to maintain flow between beats.
Muscular arteries and arterioles
Smaller vessels with prominent smooth muscle; arterioles are the main site of resistance and therefore the primary determinant of blood pressure.
Capillaries
Single-cell-thick exchange vessels, present in enormous numbers, where all gas and nutrient transfer occurs.
Venules and veins
Thin-walled, high-capacity return vessels that hold most of the circulating volume.
Venous valves
One-way flaps preventing backflow in the limbs; their failure is the basis of varicose veins and chronic venous insufficiency.
Glycocalyx
A gel-like carbohydrate layer coating the endothelium, protecting it and sensing shear stress; its degradation is an early step in vascular disease.
endothelium
The single-cell-thick lining of all blood vessels, functioning as an active organ regulating tone, clotting and permeability.nitric oxide
The signalling molecule released by endothelium to relax vessel walls and increase blood flow.endothelium
The single-cell-thick lining of all blood vessels, functioning as an active organ regulating tone, clotting and permeability.Primary functions
- • Distributing oxygenated blood from the heart to every tissue
- • Enabling exchange of oxygen, nutrients and waste in capillary beds
- • Returning deoxygenated blood to the heart against gravity
Secondary functions
- • Regulating blood pressure by adjusting arteriolar resistance
- • Controlling body temperature by shunting blood toward or away from the skin
- • Storing a reserve of blood volume in the venous system
- • Controlling which immune cells leave the bloodstream and where
- • Maintaining the balance between clotting and fluidity
Across a lifetime
- Development
- Vessels form by both sprouting from existing ones and assembling from precursor cells; this second capability is largely lost after birth, which is why adults regrow vessels poorly.
- Childhood
- Fatty streaks — the earliest stage of atherosclerosis — are already present in the arteries of many children and adolescents, though they are reversible at this stage.
- Adulthood
- Arterial stiffness and plaque burden accumulate quietly through the thirties and forties; most people with substantial coronary plaque have no symptoms whatsoever.
- Later life
- Large arteries stiffen substantially, raising systolic pressure and pulse pressure; venous valve failure and small vessel disease in the brain both become common.
- Sex differences
- Women have some vascular protection before menopause and then a rapid convergence of risk; they are also more likely to have heart attacks caused by small vessel disease or plaque erosion rather than a large obstructive lesion, which makes standard testing less reliable.
Body connections
Vascular health is arguably the single most consequential determinant of how well and how long a person lives. Heart attacks, most strokes, vascular dementia, chronic kidney disease, diabetic eye and nerve damage, erectile dysfunction and peripheral arterial disease are all, at their core, diseases of blood vessels. This is why the same handful of interventions — not smoking, controlling blood pressure and LDL cholesterol, staying physically active, managing glucose — reduce risk across so many apparently unrelated conditions. They all act on the same 100,000 km of tissue.
Body connections
How this links to the rest of you
The heart generates pressure and the vessels determine the resistance it works against; the coronary arteries are themselves vessels, so vascular disease is heart disease.
The endothelium determines whether blood remains fluid or clots, making vessel wall health and blood behaviour inseparable.
Stroke and much of vascular dementia originate in blood vessels, and small vessel disease in the brain is a major driver of cognitive decline.
The kidneys both regulate blood pressure and are damaged by it; the glomerulus is a specialised capillary bed exquisitely sensitive to vascular disease.
Retinal vessels are the only ones directly visible, which is why an eye examination can reveal hypertensive and diabetic vascular damage elsewhere.
The feet are at the end of the arterial tree and the bottom of the venous column, making them the first place both arterial insufficiency and venous failure show up.
Calf muscle contraction is the pump that drives venous return; immobility disables it and raises clot risk.
Insulin resistance and high glucose damage the endothelium directly, which is why diabetes is fundamentally a vascular disease.
How lifestyle changes it
Exercise
Among the most powerful vascular interventions available. Exercise increases shear stress, which stimulates nitric oxide production and improves endothelial function measurably within weeks, independent of any weight change.
Nutrition
Dietary pattern strongly influences LDL cholesterol, blood pressure and endothelial function; unsaturated fats, fibre, nitrate-rich vegetables and reduced sodium all have supporting evidence.
Hydration
Dehydration raises blood viscosity and reduces blood volume, lowering blood pressure and impairing tissue perfusion; it also contributes to clot risk.
Sleep
Short and disrupted sleep are independently associated with hypertension and cardiovascular events; obstructive sleep apnoea causes repeated surges in blood pressure and is a treatable cause of resistant hypertension.
Stress
Acute stress causes vasoconstriction and raises blood pressure. Chronic stress is associated with sustained hypertension and, through inflammation, with plaque progression.
Ageing
Arterial stiffening is one of the most consistent features of ageing, raising systolic pressure independently of atherosclerosis and increasing load on the heart, brain and kidneys.
Environment
Air pollution, particularly fine particulate matter, is an established cardiovascular risk factor acting partly through endothelial inflammation. Smoking damages the endothelium directly and is the single most harmful modifiable exposure.
Genetics
Familial hypercholesterolaemia affects roughly 1 in 250 people and causes early heart disease if untreated. Lipoprotein(a) is genetically determined, largely unaffected by lifestyle, and an independent risk factor now increasingly measured.
Symptoms & conditions
Common conditions
Rare conditions
- • Vasculitis including giant cell arteritis
- • Marfan and Ehlers-Danlos syndromes affecting vessel integrity
- • Fibromuscular dysplasia
- • Raynaud's phenomenon with digital ulceration
- • Thromboangiitis obliterans (Buerger's disease)
- • Aortic dissection
Acute & chronic problems
- • Deep vein thrombosis and pulmonary embolism
- • Acute limb ischaemia from arterial occlusion
- • Aortic dissection or aneurysm rupture
- • Traumatic arterial injury
- • Superficial thrombophlebitis
- • Atherosclerosis and peripheral arterial disease
- • Hypertension
- • Chronic venous insufficiency and varicose veins
- • Venous leg ulceration
- • Small vessel disease in brain and kidney
- • Abdominal aortic aneurysm
Early warning signs
- • Calf pain that appears after a predictable walking distance and eases with rest
- • Cold, pale or hairless lower legs and feet
- • Aching, heavy legs by the end of the day with ankle swelling
- • Erectile dysfunction, which can precede other vascular disease by years
- • Blood pressure consistently above target on home readings
- • Slow-healing sores on the feet or lower legs
Risk factors
- • Smoking
- • High LDL cholesterol and raised lipoprotein(a)
- • Hypertension
- • Diabetes and insulin resistance
- • Physical inactivity
- • Family history of premature cardiovascular disease
- • Chronic kidney disease
- • Air pollution exposure
Protective factors
- • Not smoking, which begins improving endothelial function within weeks
- • Regular aerobic exercise
- • Blood pressure and LDL cholesterol control
- • Mediterranean-style dietary pattern
- • Maintaining healthy glucose regulation
- • Regular movement during prolonged sitting or travel
Optimise & recover
Prevention
- • Stop smoking — no other single change does more for vascular health, and endothelial function starts improving within weeks
- • Know your blood pressure and LDL cholesterol numbers rather than assuming they are fine; both are silent
- • Accumulate at least 150 minutes of moderate aerobic activity weekly, which improves endothelial function independently of weight loss
- • Reduce sodium and increase potassium-rich vegetables, which lowers blood pressure meaningfully
- • Ask about lipoprotein(a) testing if you have a family history of early heart disease — it is genetic, common and usually unmeasured
- • Treat erectile dysfunction as a possible vascular warning sign rather than an isolated problem
Recovery
- • Supervised exercise therapy is the first-line treatment for claudication and works as well as stenting for walking distance in many patients
- • After a clot, complete the full anticoagulation course and use graduated compression if advised to reduce post-thrombotic syndrome
- • Venous leg ulcers heal with compression — it is the single most effective element of treatment and the one most often under-applied
Vascular rehabilitation is unusually well evidenced. Supervised exercise programmes for peripheral arterial disease produce large improvements in walking distance, partly by developing collateral vessels and improving muscle metabolism rather than by clearing the blockage. Cardiac rehabilitation after a heart attack reduces mortality. In both cases the mechanism is partly endothelial adaptation, which means the benefit is lost if the exercise stops.
Movement library
- Beginner
Ankle pumping during prolonged sitting
Activates the calf muscle pump to maintain venous return and reduce clot risk during travel or bed rest.
- Beginner
Leg elevation
Raising the legs above heart level for periods each day reduces venous pressure and ankle swelling in venous insufficiency.
- Beginner
Supervised walking programme for claudication
Walking to near-maximal pain, resting, and repeating — the best-evidenced treatment for improving walking distance in peripheral arterial disease.
- Beginner
Calf raise training
Strengthens the muscle pump that drives venous return, with evidence for improving venous ulcer healing and symptoms.
- Beginner
Moderate aerobic training
The core intervention for endothelial function and blood pressure; effects appear within weeks and reverse if stopped.
- Beginner
Isometric handgrip training
Short daily isometric holds have reasonable trial evidence for reducing resting blood pressure.
- Beginner
Diaphragmatic breathing and slow breathing practice
Slow-paced breathing has modest but reproducible blood pressure lowering effects in trials.
Massage produces short-term local vasodilation but does not improve vascular health. It is specifically contraindicated over a suspected deep vein thrombosis, where it risks dislodging clot, and should be avoided over acutely inflamed superficial veins.
Habits worth building
- • Get up and move every hour if you sit for long periods — sedentary time predicts cardiovascular risk partly independently of exercise
- • Measure blood pressure at home properly: seated, back supported, arm at heart level, after five minutes of rest
- • Use compression stockings consistently if prescribed; intermittent use does very little
Nutrition, devices & products
Vascular nutrition comes down to a small number of well-supported levers: lowering LDL cholesterol, lowering sodium while raising potassium, and eating enough fibre and unsaturated fat. Dietary nitrate from leafy greens and beetroot is converted to nitric oxide and produces a small, genuine reduction in blood pressure. Replacing saturated with unsaturated fat lowers LDL and cardiovascular events; replacing it with refined carbohydrate does not. A Mediterranean pattern has the strongest randomised trial evidence for reducing cardiovascular events of any dietary approach.
Foods to prioritise
- • Unsaturated fats from olive oil, nuts and oily fish
- • Soluble fibre from oats, legumes, fruit and vegetables, which lowers LDL
- • Nitrate-rich vegetables such as rocket, spinach and beetroot
- • Potassium-rich foods to offset dietary sodium
- • Oily fish twice weekly for omega-3 fatty acids
Foods to limit
- • Sodium, ideally below 6 g of salt daily and lower if hypertensive
- • Trans fats entirely, and excess saturated fat
- • Alcohol, which raises blood pressure dose-dependently
- • Ultra-processed foods, associated with cardiovascular risk beyond their nutrient content alone
| Supplement | Evidence | Note |
|---|---|---|
| Omega-3 (EPA/DHA) | Moderate | High-dose purified EPA reduced events in high-risk patients in one major trial; general low-dose supplementation in the broad population has not shown clear benefit. |
| Dietary nitrate / beetroot juice | Moderate | Consistent small reductions in blood pressure across trials, and modest performance effects; the magnitude is real but not a substitute for medication. |
| Plant sterols and stanols | Strong | Reliably lower LDL cholesterol by around 8–10% at 2 g daily, though hard outcome data are lacking. |
| Vitamin E and beta-carotene | Limited | Antioxidant supplements have repeatedly failed to reduce cardiovascular events, and some trials found harm. |
| Chelation therapy | Limited | Tested in a large randomised trial with no convincing benefit; marketed as artery cleaning without support. |
Devices & wearables
- • Validated upper-arm home blood pressure monitors
- • Graduated compression stockings for venous disease
- • Intermittent pneumatic compression devices for clot prevention and lymphoedema
- • Ankle-brachial index measurement for peripheral arterial disease
- • Optical blood pressure estimation, still poorly validated compared with cuff measurement
- • Wrist devices detecting atrial fibrillation, which is relevant to stroke risk
- • Activity trackers, useful for the sedentary-time reduction that independently affects vascular risk
Professional treatments
- • Duplex ultrasound of arteries and veins
- • CT and MR angiography
- • Coronary angiography with angioplasty and stenting
- • Endovenous laser or radiofrequency ablation for varicose veins
- • Endarterectomy and bypass surgery
- • Endovascular aneurysm repair
- • Compression bandaging for venous ulceration
Educational mention only, not a recommendation: Statins and ezetimibe for LDL reduction, PCSK9 inhibitors and inclisiran for high-risk or statin-intolerant patients, ACE inhibitors, ARBs, calcium channel blockers and thiazide diuretics for hypertension, Antiplatelet therapy for established arterial disease, Anticoagulants for venous thromboembolism and atrial fibrillation.
When to seek medical care
Vascular disease is usually silent until it is not, so the important thing is knowing your numbers — blood pressure, LDL cholesterol and glucose — rather than waiting for symptoms. Leg pain that appears reliably after a set walking distance and eases with rest suggests arterial narrowing and warrants assessment. A swollen, painful calf, particularly after travel or immobility, needs same-day evaluation for clot. Sudden tearing chest or back pain, a cold pale painful limb, or stroke symptoms are all emergencies where minutes genuinely matter.
Seek care promptly if you notice
- • Sudden severe tearing pain in the chest or between the shoulder blades
- • Face drooping, arm weakness or slurred speech — act immediately
- • A limb that becomes suddenly cold, pale, painful and numb
- • Sudden breathlessness with chest pain, particularly with a swollen calf
- • Crushing central chest pain, especially radiating to arm, neck or jaw
- • Sudden painless loss of vision in one eye
- • A non-healing ulcer on the foot or lower leg
Research & frequently asked questions
Current research
- Lipoprotein(a) has moved to the centre of cardiovascular research, with RNA-based therapies that lower it by over 80% now in large outcome trials — the first realistic prospect of treating a previously untreatable genetic risk factor.
1
New England Journal of Medicine · 2018
Primary Prevention of Cardiovascular Disease with a Mediterranean Diet
Randomised trial (PREDIMED) in which a Mediterranean diet supplemented with olive oil or nuts reduced the incidence of major cardiovascular events compared with a reduced-fat control diet.
- Inflammation as an independent treatment target is now established rather than speculative, following trials showing that reducing inflammation lowers cardiovascular events without changing cholesterol.
2
New England Journal of Medicine · 2017
Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease
Trial (CANTOS) showing that targeting interleukin-1β reduced recurrent cardiovascular events without altering lipid levels, establishing inflammation as an independent treatable target.
Emerging therapies
- • siRNA and antisense therapies targeting lipoprotein(a) and PCSK9 with dosing measured in months
- • Anti-inflammatory agents including colchicine for secondary prevention
- • Bioresorbable and drug-eluting scaffolds
- • Gene therapy approaches for familial hypercholesterolaemia
- • Renal denervation for resistant hypertension, with improved trial results after early setbacks
Scientific controversies
- • How aggressively to lower LDL cholesterol continues to be debated, though the accumulated evidence increasingly supports lower targets with no clear floor of benefit.
- • Whether coronary artery calcium scoring should be used routinely to refine risk in intermediate-risk people remains unsettled, with different guidelines reaching different conclusions.
- • The role of revascularisation versus optimal medical therapy in stable coronary disease has been substantially revised by trial evidence showing no mortality advantage to routine stenting.
Blood was thought to be produced by the liver and consumed by the tissues until William Harvey demonstrated in 1628 that it circulates. The endothelium was regarded as inert lining until the 1980s, when Furchgott, Ignarro and Murad identified nitric oxide as the signal by which it controls vessel tone — work that transformed vascular biology and won the 1998 Nobel Prize. The reframing of atherosclerosis from a passive lipid deposit to an active inflammatory disease of the artery wall was a comparable shift, and it is what put inflammation on the treatment agenda.
Frequently asked questions
What is endothelial dysfunction?
It is the earliest detectable stage of vascular disease — the inner lining losing its ability to dilate the vessel and resist clotting, typically decades before any narrowing shows on a scan. It is measurable in research settings and improves with exercise, smoking cessation and treating cholesterol and blood pressure.
Do arteries really get clogged like a pipe?
Not quite. Atherosclerosis develops within the artery wall, where cholesterol particles enter and immune cells create an inflammatory plaque. Most heart attacks happen when a modest plaque ruptures and clots suddenly, not when a narrowing gradually closes.
Can you reverse artery disease?
Plaque can be stabilised and to a modest extent regressed with intensive LDL lowering, and risk falls substantially with treatment. Complete reversal is not realistic, but the difference in outcomes between treated and untreated is large.
Are varicose veins dangerous?
Usually not dangerous, but not merely cosmetic either. They indicate failed venous valves and can progress to swelling, skin changes and ulceration. Compression helps, and modern keyhole treatments are effective if symptoms warrant it.
Why does leg pain when walking matter?
Pain that appears after a predictable distance and eases with rest — claudication — suggests narrowed leg arteries, and it is a marker of arterial disease elsewhere including the heart. It is worth investigating, and supervised exercise therapy is remarkably effective.
Does exercise really improve blood vessels?
Yes, and quite directly. Increased blood flow raises the shear stress the endothelium senses, which stimulates nitric oxide production and improves function within weeks — independent of any weight loss. The effect fades if the training stops.
What is lipoprotein(a) and should I test it?
It is a cholesterol-carrying particle whose level is set almost entirely by genetics and barely affected by diet or exercise. It is an independent risk factor, roughly one in five people have a raised level, and it is worth testing once — particularly with a family history of early heart disease.
Explore further
Keep exploring
Glossary
- Endothelium
- The single-cell-thick lining of all blood vessels, functioning as an active organ regulating tone, clotting and permeability.
- Nitric oxide
- The signalling molecule released by endothelium to relax vessel walls and increase blood flow.
- Atherosclerosis
- Inflammatory plaque formation within the artery wall, driven largely by cholesterol particles entering the wall.
- Claudication
- Leg pain on walking that eases with rest, caused by narrowed arteries limiting muscle blood supply.
- Arterial stiffness
- Loss of arterial elasticity with age or disease, raising systolic blood pressure and cardiovascular risk.
- Chronic venous insufficiency
- Failure of venous valves causing raised leg vein pressure, swelling, skin changes and ulceration.
- Lipoprotein(a)
- A genetically determined cholesterol-carrying particle that independently raises cardiovascular risk.
- Pulse pressure
- The difference between systolic and diastolic pressure; widening with age reflects stiffening large arteries.
Trusted organisations & further reading
- NHS — High blood pressure
- British Heart Foundation
- NHS — Peripheral arterial disease
- Circulation Foundation
- The Cholesterol Wars — Daniel Steinberg. History of how the link between cholesterol and arterial disease was established, and the resistance it met.
- Heart: A History — Sandeep Jauhar. Readable account of cardiovascular medicine's development, with useful chapters on atherosclerosis and intervention.
Medical disclaimer
This page is for general education and does not replace personalised medical advice. If you have concerning symptoms, or before starting a new supplement, medication or exercise programme, speak with a qualified healthcare professional.