## 1 Introduction  
Dietary nitrate is an inorganic anion which, in the human body, serves as a substrate for the multifunctional signalling molecule nitric oxide (NO) [1]. Dietary nitrate is available from a variety of food sources, but most nitrate in the diet comes from vegetables, with smaller contributions coming from certain herbs, fruits, processed meat, and drinking water [2, 3, 4]. Although dietary nitrate intake can vary considerably between individuals, the average intake tends to be just over 100 mg/d in both healthy (median intake: 108 mg/d) and patient (median intake: 110 mg/d) populations [2]. Early data from observational and animal studies suggested that a high intake of dietary nitrate could be detrimental to health, increasing the risk of methaemglobinaemia and certain types of cancer [5, 6, 7]. Consequently, an acceptable daily intake (ADI) of nitrate was established at 3.7 mg/kg/d [8]. However, other studies have questioned this view [9, 10, 11]. Indeed, recent studies have suggested that consumption of dietary nitrate alone does not cause methaemglobinaemia [4], which, instead, is typically caused following ingestion or inhalation of an oxidising agent [12]. Likewise, some [13], although not all [14, 15], recent investigations have refuted the notion that nitrate intake increases cancer risk. In contrast to this early body of evidence, which tended to focus on nitrate as a potentially harmful dietary compound, research emerging in recent years suggests that increasing dietary nitrate intake (and thus enhancing NO bioavailability) can improve markers of cardiovascular and cognitive function. For example, dietary nitrate supplementation has been shown to reduce blood pressure (BP) by between \(\sim\)2 and 10 mmHg [16; 17; 18; 19; 20], and could represent a potential adjunct to traditional antihypertensive medications. In addition, dietary nitrate supplementation has been shown to improve endothelial function [17; 21], decrease platelet aggregation [17; 19], and, albeit less reliably, enhance cerebral blood flow and cognitive function [22; 23; 24]. Over 100 studies have also been conducted exploring the potential benefits of dietary nitrate for sports performance, with findings from both a recent meta-analysis [25] and Delphi expert consensus [26] suggesting that nitrate can improve performance across a range of exercise modalities and in various populations. Several mechanisms have been proposed to explain these effects, including improvements in the efficiency of muscle contraction [27; 28] and mitochondrial respiration [29], and modulation of tissue blood flow [30; 31]. Interestingly, the health and performance benefits of nitrate are not apparent in individuals who use antibacterial mouthwash, which destroys bacteria in the mouth that play a crucial role in the processing of nitrate in the body [32; 33]. Most studies investigating the health and/or exercise performance effects of dietary nitrate have administered this compound via nitrate-rich supplements, especially concentrated beetroot juice'shots', which are highly enriched in nitrate and for which a nitrate-depleted placebo product is available [17; 25; 34; 35]. For mechanistic research studies, the advantages to the provision of nitrate via concentrated beetroot juice are obvious, which may explain the ubiquity and dominance of this nitrate source in the literature. However, the translation of research that predominantly relies on the use of beetroot juice into the'real world' could be limited if individuals are not willing or able to incorporate this particular product into their habitual diet. Another strategy for increasing/optimising dietary nitrate intake to influence human health and/or exercise performance, which could be used alongside or instead of nitrate-rich supplements in both research and'real world' settings, is the consumption of whole nitrate-rich vegetables [36; 37; 38].