With older age, the risk of reduced leg blood flow (peripheral vascular disease), increased arterial stiffness—leading to hypertension—and endothelial dysfunction, a condition where the inner lining of the small arteries malfunction, increases exponentially—all the result of reduced nitric oxide (NO) availability.
According to research – Acute Dietary Nitrate Supplementation Improves Flow Mediated Dilatation of Superficial Femoral Artery in Healthy Older Males – which appears in the May issue of the journal Nutrients – “nitric oxide is the primary regulator of vascular tone and it has an essential role in the prevention of platelet aggregation, inhibition of vascular smooth muscle cell proliferation, and the prevention of atherosclerotic plaque formation.”
Older adults, “demonstrate reduced NO bioavailability, which contributes to age-related increases in blood pressure and vascular stiffness, and the associated risk of cardiovascular events. Impairments in NO bioavailability may also lead to a reduction in limb blood flow, possibly through the role of NO in functional sympatholysis, (opposing stimulation of the sympathetic nervous system), and endothelium-dependent vasodilation.”
When you inhibit blood flow in the legs, muscle function and exercise capacity are compromised. Therefore, healthy mechanisms to improve vascular function, enhance blood flow and NO availability may help in the age-associated cardiovascular deficits.
NO is created internally via the amino acid L-arginine obtained from food sources high in inorganic nitrate (NO3), like beetroot, which is converted to nitrite (NO2) by bacteria in the mouth. Then, reduced to NO via, “a wide variety of enzymatic and non-enzymatic pathways.”
Concentrated beetroot juice, “has been shown to acutely improve exercise tolerance in older adults and in patients with peripheral arterial disease.” It’s also been noted in the research that, “increased NO bioavailability through NO supplementation may promote vessel dilation, increasing blood flow, which might contribute to improved exercise tolerance in older adults.”
Australian researchers sought to use flow mediated dilatation (FMD) – an established measure of endothelial function – to determine whether or not, “an acute dose of inorganic dietary NO3 would improve femoral artery FMD, increase passive leg movement hyperaemia (an excess of blood in vessels supplying an organ or other body part), and reduce arterial stiffness.”
Fifty-three men aged 60 to 75, who provided a full medical history, including medication and nutritional supplements, were screened for an absence of blood flow impairments—with appropriate exclusion criteria, such as being a smoker or the presence of CVD, used in candidate selection. However, Participants taking certain low doses of statins were included. Before and after the study period, blood pressure, plasma NO2 & 3, augmented index, carotid-femoral pulse wave velocity, leg FMD, passive leg movement hyperaemia were measured.
Prior to the intake of the test beverage, the participants omitted vigorous exercise, abstained from high NO3 foods, alcohol, and caffeine. Using a double-blind, crossover design, the subjects either received 140 milliliters of concentrated beetroot juice or a similar amount of a placebo-NO3 depleted drink.
The research demonstrated that, “a dose of dietary NO3 improved NO bioavailability and enhanced endothelial function, as measured by femoral artery FMD. These findings provide insight into the specific central and peripheral vascular responses to dietary NO3 supplementation in older adults.”
The researchers reflect that generalizations relative to the response of NO3 supplementation in females needs confirmation and further investigation. There are limitations to the study – among which were some participants were on low dose statins that may improve baseline NO bio-availability.
It’s always important that you check your personal healthcare provider before you embark on any supplementation program—relative to your personal health profile.