Whole beetroot consumption reduces systolic blood pressure and modulates diversity and composition of the gut microbiota in older participants

Background: Age-associated decline in physiological function has been identified as the main factor increasing disease risk, including cardiovascular (CVD) and gastrointestinal tract (GIT) diseases. Nutritional interventions encompassing dietary inorganic nitrates, such as nitrate rich beetroot may reduce the risk for CVD and GIT. Objective: Assess the impact of whole beetroot on blood pressure (BP), microbiota profile and functional measures (physical and bowel). Design: Thirty-six healthy participants were recruited (mean age 67 ± 6 years; body mass index (BMI) 25 ± 2 kg/m2) and assigned randomly to a beetroot (n = 19) or control group (n = 17). Beetroot group consumed 150 g of whole beetroot and a medium-sized banana and the control group consumed a medium-sized banana every second day for 8 weeks. Resting BP, microbiota profiling, physical activity, urinary nitrate, short-chain fatty acids (SCFA) and Bristol Stool Score (BSS) were measured at 0, 4 and 8 weeks. Plasma nitrate was measured at weeks 0 and 8. Results: The beetroot group had a resting systolic BP reduction of 8.0 mmHg (p = 0.03), lower relative abundance of the phyla Bacteroidetes (p = 0.04), and a higher relative abundance of genus Alistipes (p = 0.03), increased Shannon diversity index (p = 0.03), fibre intake of 7 g/day (p