Atherosclerosis and endothelial dysfunction involve progressive impairment of the inner lining of blood vessels, known as the endothelium. The endothelium regulates vascular tone, nitric oxide signaling, blood flow, platelet activity, immune signaling, and barrier integrity within the circulatory system. When endothelial function becomes impaired, arteries lose elasticity, inflammatory signaling increases, oxidative stress accumulates, and lipid particles are more likely to become trapped within the arterial wall. Over time, these changes contribute to plaque formation, vascular stiffness, impaired circulation, and increased cardiovascular stress. The condition is strongly associated with chronic oxidative stress, inflammatory cytokine activity, metabolic dysfunction, excess refined food intake, elevated blood glucose, low dietary fiber intake, and reduced intake of antioxidant-rich plant foods. Endothelial dysfunction is often observed before advanced plaque accumulation develops and is considered an early biological marker of cardiovascular deterioration. Nitric oxide bioavailability plays a central role in endothelial health. Nitric oxide supports vasodilation, vascular relaxation, blood flow regulation, mitochondrial signaling, and endothelial communication. Reduced nitric oxide production may contribute to vascular constriction, impaired circulation, increased platelet aggregation, and inflammatory activation. Diets low in nitrate-rich vegetables, polyphenols, and antioxidant compounds are associated with reduced endothelial resilience. Atherosclerotic progression also involves activation of inflammatory pathways including NF-κB signaling, oxidative modification of lipoproteins, endothelial adhesion molecule activation, vascular immune cell recruitment, and altered lipid metabolism. Excess oxidative stress may damage endothelial cells and impair mitochondrial function within vascular tissue. Elevated inflammatory signaling can also increase endothelial permeability and contribute to plaque instability. Whole plant foods provide fiber, polyphenols, carotenoids, flavonoids, nitrates, potassium, magnesium, and antioxidant compounds associated with improved endothelial signaling and vascular integrity. Leafy greens, berries, cruciferous vegetables, legumes, garlic, green tea, citrus fruits, tomatoes, flax seeds, and whole grains contain compounds associated with nitric oxide support, oxidative stress reduction, and inflammatory pathway regulation. Dietary patterns emphasizing whole-food plant nutrition are associated with improved vascular flexibility, healthier lipid metabolism, improved endothelial responsiveness, and reduced inflammatory burden. Fiber-rich foods also support microbiome activity and short-chain fatty acid production, which influence vascular signaling and systemic inflammation. Consistent intake of minimally processed plant foods supports circulatory resilience, endothelial communication, vascular repair systems, and overall cardiovascular metabolic balance.