Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations

Nitrate-rich vegetables are increasingly recognised as a key subgroup of phytochemical-dense foods that have significant potential for preventing and managing chronic diseases. Although dietary nitrates were historically approached with caution due to concerns about nitrosamine formation, contemporary evidence highlights their beneficial effects on vascular, metabolic and cognitive functions. Ageing is characterised by endothelial dysfunction, impaired nitric oxide (NO) synthesis and increased oxidative stress, which elevates cardiovascular risk. In this context, nitrate-rich vegetables offer a natural way to restore NO bioavailability and support cardiometabolic health. This narrative review provides an integrative overview of nitrate-rich vegetables as sources of bioactive phytochemicals with therapeutic relevance. We summarise the biochemical pathways of nitrate and nitrite metabolism, including the enterosalivary nitrate-nitrite-NO cycle, the role of oral microbiota, and red blood cell-mediated nitrite reduction. Particular emphasis is placed on NOS-independent NO production, which becomes increasingly important with age, and on the synergistic interactions between dietary nitrates and other phytochemicals such as polyphenols, vitamin C, flavonoids and betalains. These compounds enhance NO stability, reduce oxidative stress, modulate inflammatory signalling and support mitochondrial function, thereby amplifying the health benefits of nitrate-rich vegetables. Beetroot, with its high nitrate content and distinctive antioxidant profile, is highlighted as a prime example. Clinical and mechanistic studies suggest that nitrate-rich vegetables may lower blood pressure, improve endothelial function and cerebral perfusion, enhance cognitive performance and muscle oxygenation, and increase exercise efficiency, particularly in older adults. Additional benefits include anti-inflammatory effects, modulation of platelet function and improvements in metabolic parameters, all of which are relevant to the prevention of chronic diseases such as hypertension, type 2 diabetes and atherosclerosis. While dietary nitrate is generally considered low-risk for healthy adults, caution is warranted in susceptible populations, such as infants and individuals with impaired renal function. Finally, significant research gaps remain, including the need for long-term, well-controlled trials and personalised strategies that account for variability in microbiota composition and nitrate metabolism between individuals.