Dietary nitrate does not affect physical activity or outcomes in healthy older adults in a randomized, cross-over trial

Abstract

Although dietary nitrate (NO) ingestion appears to enhance exercise capacity and performance in young individuals, inconclusive findings have been reported in older people. Therefore, we conducted a double-blind, crossover randomized clinical trial using beetroot juice in older healthy participants, who were classified as normal weight and overweight. We tested whether consumption of beetroot juice (a rich source of NO) for 1 week would increase nitric oxide bioavailability via the nonenzymatic pathway and enhance (1) exercise capacity during an incremental exercise test, (2) physical capability, and (3) free-living physical activity. Twenty nonsmoking, healthy participants between 60 and 75 years of age and with a body mass index of 20.0 to 29.9 kg/m were included. Presupplementation and postsupplementation resting, submaximal, maximal, and recovery gas exchanges were measured. Physical capability was measured by hand-grip strength, time-up-and-go, repeated chair rising test, and 10-m walking speed. Free-living physical activity was assessed by triaxal accelerometry. Changes in urinary and plasmaNOconcentrations were measured by gas chromatography-mass spectrometry. Nineteen participants (male-to-female ratio, 9:10) completed the study.Beetroot juice increased significantly both plasma and urinary NOconcentrations (P<.001) when compared with placebo. Beetroot juice did not influence resting or submaximal and maximal oxygen consumption during the incremental exercise test. In addition, measures of physical capability and physical activity levels measured in free-living conditions were not modified by beetroot juice ingestion. The positive effects of beetroot juice ingestion on exercise performance seen in young individuals were not replicated in healthy, older adults. Whether aging represents a modifier of the effects of dietary NOon muscular performance is not known, and mechanistic studies and larger trials are needed to test this hypothesis.

Dietary nitrate intake is associated with muscle function in older women

“…When this experiment was repeated in healthy adults ( n = 12, mean age 36 years), similar improvements were observed for knee extension power (6%) and velocity (11%) . Alternatively, in a small randomized controlled trial of older adults ( n = 19), large acute doses of beetroot concentrate supplemented over 7 days (~12 mmol/day of nitrate) only resulted in a trend for improved time‐to‐exhaustion ( P = 0.10) on an incremental cycle ergometer test . No improvements in other functional tests (e.g.…”

“…12 Alternatively, in a small randomized controlled trial of older adults (n = 19), large acute doses of beetroot concentrate supplemented over 7 days (~12 mmol/day of nitrate) only resulted in a trend for improved time-to-exhaustion (P = 0.10) on an incremental cycle ergometer test. 39 No improvements in other functional tests (e.g. grip strength and TUG) were recorded.…”

A single dose of dietary nitrate increases maximal muscle speed and power in healthy older men and women

“…This includes studies of the effects of NO3ingestion on the responses to aerobic exercise in older individuals (19,20). To date, however, no study has determined the influence of dietary NO3on muscle contractile function in older humans.…”

Natural Product Chemistry for Nitric Oxide Based Therapeutics

“…In fact there are several clinical trials showing remarkable efficacy of inorganic nitrate in the treatment of hypertension,, peripheral artery disease, heart failure with reduced ejection fraction (HFrEF), heart failure with preserved ejection fraction (HFpEF), non‐ischemic dilated cardiomyopathy, vascular function in hyperlipidemia patients and even a rare form of muscular dystrophy with little or no unwanted side effects. Interesting, though there are a number of human clinical studies showing no response or improvement using inorganic nitrate . This should be expected given the requirements needed for metabolic nitrate activation to nitrite and nitric oxide.…”

“…Interesting, though there are a number of human clinical studies showing no response or improvement using inorganic nitrate. [21][22][23][24][25][26] This should be expected given the requirements needed for metabolic nitrate activation to nitrite and nitric oxide. Inorganic nitrate is inert in humans since humans lack a functional nitrate reduction gene.…”