Table 1.

Examples of human studies investigating the effect of inorganic nitrate on cerebral blood flow (CBF)

Reference	Participants	Study design	Measures	Dietary intervention/period	Main findings
Presley et al. 2011 [77]	16 healthy older individuals	RCT, crossover	CBF	High nitrate diet vs. low nitrate diet for 2 days	CBF increased with high-nitrate diet
Bond et al. 2013 [78]	12 healthy adults	RCT, crossover	CVRI, BP, TVR and BP measured at rest and at two exercise workloads	500-ml BJ or placebo (orange juice)/single dose	CVRI was decreased after single beetroot juice treatment at rest and at submaximal exercise workloads
Wightman et al. 2015 [79]	40 healthy adults	RCT, double-blind, placebo, parallel	NIRS, cognitive tasks (including 3s and 7s verbal series), BP, HR	450-ml BJ or placebo drink with negligible nitrate content/150 min	Nitrate improved CBF and performance on 3s serial subtractions test but not others

BJ beetroot juice, BP blood pressure, CBF cerebral blood flow, CVRI cerebrovascular resistance index, HR heart rate, NIRS near-infrared spectroscopy, RCT randomised clinical trial, TVR total vascular resistance