Evaluation of Adding Nitrate Into Foods for Regulating Nitric Oxide Bioavailability in Healthy Individuals

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Whether adding nitrate to commonly eaten foods can improve nitric oxide levels in the body and help lower blood pressure in healthy volunteers will be investigated. Design: An open-label, randomised, crossover trial. Target population: Thirty healthy participants (15 males and 15 females) will be recruited. Experimental intervention: Equal numbers of healthy male and female volunteers, aged 18-60 years, will be recruited. Following recruitment, participants will attend the clinical centre on seven occasions. At baseline, clinic blood pressure will be measured, and plasma, urine, and saliva samples will be collected. Participants will then receive one of the three nitrate-fortified food products according to the randomisation plan. Clinic blood pressure will be measured at 1, 2, 3, and 4 hours post-supplementation. Blood samples will be collected at 0.5, 1, 1.5, 2, 2.5, 3, and 4 hours; urine at 4 hours; and saliva at 3 and 4 hours. At 24 hours post-supplementation, participants will return to the clinical centre for repeat blood pressure measurement and collection of blood, urine, and saliva samples. All human biological samples will be stored for subsequent determination of nitrate and nitrite concentrations. If participants receive nitrate-fortified biscuits during one visit, they will be given either nitrate-fortified porridge or a cereal bar at the following visits, according to the randomisation plan. All participants will eventually receive all three nitrate-fortified food products, each providing approximately 4 mmol nitrate, an amount within the Acceptable Daily Intake (ADI) range. The study will be conducted at the Clinical Research Centre at the William Harvey Research Institute, Queen Mary University of London. Analysis: A two-way repeated measures ANOVA will be used to analyse the differences in \[NO3-\], \[NO2-\] in plasma, urine, and saliva, plasma \[cGMP\] across time and between different NO3--fortified foodstuffs (cereal bar, porridge, and biscuits) and clinic BP. Matching the objectives of comparing the changes in measures following the ingestion of the three food products, the description of the analysis will initially focus on the difference between the three food products and so post-hoc tests (accounting for multiple comparisons) will initially focus on comparing measures at each timepoint. The acceptability of the three different NO3--fortified food products will be analysed using Friedman tests. As this is a crossover study, checks will be conducted for period effect and carry-over effect as part of the statistical analysis plan.