This systematic review and meta-analysis aimed to investigate the effects of beetroot (BR) or nitrate supplements on body composition indices. A systematic search was conducted for randomised controlled trials (RCT) published up to August 2022 among online databases including Scopus, PubMed/Medline, Web of Science and Embase. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCT. A total of twelve RCT met the inclusion criteria for this meta-analysis. The pooled effect size of included studies indicated that BR or nitrate supplementation did not change body weight (weighted mean differences (WMD): –0·14 kg, 95 % CI –1·22, 1·51; P = 0·836; I2 = 0 %), BMI (WMD: −0·07 kg/m2, 95 % CI −0·19,0·03; P = 0·174, I2 = 0 %), fat mass (WMD: –0·26 kg, 95 % CI –1·51, 0·98; P = 0·677, I2 = 0 %), waist circumference (WMD: –0·28 cm, 95 % CI –2·30, 1·74; P = 0·786, I2 = 0 %), body fat percentage (WMD: 0·18 %, 95 % CI –0·62, 0·99; P = 0·651, I2 = 0 %), fat-free mass (WMD: 0·31 kg, 95 % CI –0·31, 1·94; P = 0·703, I2 = 0 %) and waist-to-hip ratio (WMD: 0, 95 % CI –0·01, 0·02; P = 0·676, I2 = 0 %). Subgroup analyses based on trial duration, BR or nitrate dose, study design, baseline BMI and athletic status (athlete v. non-athlete) demonstrated similar results. Certainty of evidence across outcomes ranged from low to moderate. This meta-analysis study suggests that BR or nitrate supplements cannot efficiently ameliorate body composition indices regardless of supplement dosage, trial duration and athletic status.

Beetroot juice (BRJ) has been demonstrated to decrease blood pressure (BP) due to the high inorganic nitrate content. This pilot randomized crossover trial aimed to investigate the effect of two different high nitrate vegetable juices on plasma nitrate concentrations and BP in healthy adults. Eighteen healthy volunteers were randomized to receive 115 ml of BRJ or 250 ml of green leafy vegetable juice for 7 d which contained similar amounts of nitrate (340 mg) daily. Blood samples were collected, and clinic BP measured at baseline and at the end of each juice consumption. Daily home BP assessment was conducted 2 h after juice consumption. Nitrate and nitrite concentrations were analysed using a commercially available kit on a Triturus automated ELISA analyser. Hills and Armitage analysis was used for the two-period crossover design and paired sample t-tests were performed to compare within-group changes. Plasma nitrate and nitrite concentrations significantly increased and there was a significant reduction in clinic and home systolic blood pressure (SBP) mean during the BRJ period (P-values 0⋅004 and 0⋅002, respectively). Home diastolic blood pressure (DBP) reduced significantly during green leafy vegetable juice consumption week (P-value 0⋅03). The difference between groups did not reach statistical significance during the formal crossover analysis adjusted for period effects. BRJ and green leafy vegetable juice may reduce SBP or DBP, but there was no statistically significant difference between the two juices, although this was only a pilot study.

Beetroot (BR) is a rich source of nitrate (NO3-) that has been shown to reduce blood pressure (BP). Yet, no studies have examined the vascular benefits of BR in whole-food form and whether the effects are modified by age. This study was a four-arm, randomised, open-label, cross-over design in twenty-four healthy adults (young n 12, age 27 ± 4 years, old n 12, age 64 ± 5 years). Participants consumed whole-cooked BR at portions of (NO3- content in brackets) 100 g (272 mg), 200 g (544 mg) and 300 g (816 mg) and a 200-ml solution containing 1000 mg of potassium nitrate (KNO3) on four separate occasions over a 4-week period (≥7-d washout period). BP, plasma NO3- and nitrite (NO2-) concentrations, and post-occlusion reactive hyperaemia via laser Doppler, were measured pre- and up to 5-h post-intervention. Data were analysed by repeated-measures ANOVA. Plasma NO2- concentrations were higher in the young v. old at baseline and post-intervention (P < 0·05). All NO3- interventions decreased systolic and diastolic BP in young participants (P < 0·05), whereas only KNO3 (at 240–300 min post-intake) significantly decreased systolic (–4·8 mmHg, −3·5 %, P = 0·024) and diastolic (–5·4 mmHg, −6·5 %, P = 0·007) BP in older participants. In conclusion, incremental doses of dietary NO3- reduced systolic and diastolic BP in healthy young adults whereas in the older group a significant decrease was only observed with the highest dose. The lower plasma NO2- concentrations in older participants suggest that there may be mechanistic differences in the production of NO from dietary NO3- in young and older populations.

HIV-1 proteins and highly active antiretroviral therapy (HAART) have been associated with microvascular endothelial dysfunction. Although nitrate-rich beetroot juice (NR-BJ) consumption has been shown to improve endothelial function in clinical population, its effects in HIV-infected patients has not been addressed. We investigated the effect of a single dose of NR-BJ on muscle oxygen saturation parameters in response to a handgrip exercise in HIV-infected patients. Fifteen HIV-infected patients received NR-BJ or nitrate-depleted beetroot juice (ND-BJ) in a double-blind cross-over design. Near-IR spectroscopy was utilised to assess muscle oxygen saturation parameters during rhythmic handgrip exercise after NR-BJ or ND-BJ supplementation. A significant faster muscle oxygen desaturation rate during exercise (–7·97 (sd 5·00) v. –5·45 (3·94) %/s, P = 0·005) and muscle oxygen resaturation rate during exercise recovery (0·43 (0·24) v. 0·28 (0·24) %/s, P = 0·030) after NR-BJ ingestion was found. However, no significant difference in exercise time until fatigue was observed. Salivary nitrite and urinary nitrate concentration were analysed after NR-BJ or ND-BJ. A significant increase in salivary nitrite and urinary nitrate in NR-BJ was observed compared with ND-BJ (P < 0·05). Our findings suggest that NR-BJ consumption may acutely improve muscle oxygen saturation during exercise and exercise recovery in HIV-infected patients undergoing HAART and who are expected to present microvascular damage. Thus, future studies investigating the chronic effects of NR-BJ are warranted to delineate a better nutritional strategy based on nitrate-rich foods.

In 2010, 7/44 (16%) reported foodborne outbreaks in Finland were linked with raw beetroot consumption. We reviewed data from the national outbreak registry in order to hypothesize the aetiology of illness and to prevent further outbreaks. In the seven outbreaks, 124 cases among 623 respondents were identified. Consumption of raw beetroot was strongly associated with gastrointestinal illness (relative risk 8·99, 95% confidence interval 6·06–13·35). The illness was characterized by sudden onset of gastrointestinal symptoms; the median incubation time was 40 min and duration of illness 5 h. No common foodborne pathogens or toxins were found in either clinical or beetroot samples, but all tested beetroot samples were of poor quality according to total bacterial counts. Beta-haemolytic Pseudomonas fluorescens was detected in several beetroot samples but its effect on human health is unknown. No outbreaks were reported after the Finnish Food Safety Authority Evira advised against serving raw beetroot in institutional canteens.

A number of vegetables have a high nitrate content which after ingestion can be reduced to nitrite by oral bacteria, and further to vasoprotective NO endogenously. In the present study, two separate randomly controlled, single-blind, cross-over, postprandial studies were performed in normotensive volunteers. Ambulatory blood pressure (BP) was measured over a 24 h period following consumption of either four doses of beetroot juice (BJ), 0, 100, 250 and 500 g (n 18), or three bread products, control bread (0 g beetroot), red beetroot- and white beetroot-enriched breads (n 14). Total urinary nitrate/nitrite (NOx) was measured at baseline, and at 2, 4 and 24 h post-ingestion. BJ consumption significantly, and in a near dose-dependent manner, lowered systolic BP (SBP, P < 0·01) and diastolic BP (DBP, P < 0·001) over a period of 24 h, compared with water control. Furthermore, bread products enriched with 100 g red or white beetroot lowered SBP and DBP over a period of 24 h (red beetroot-enriched bread, P <0·05), with no statistical differences between the varieties. Total urinary NOx significantly increased following the consumption of 100 g (P < 0·01), 250 g (P <0·001) and 500 g BJ (P <0·001) and after red beetroot-enriched bread ingestion (P <0·05), but did not reach significance for white beetroot-enriched bread compared with the no-beetroot condition. These studies demonstrated significant hypotensive effects of a low dose (100 g) of beetroot which was unaffected by processing or the presence of betacyanins. These data strengthen the evidence for cardioprotective BP-lowering effects of dietary nitrate-rich vegetables.