Older people tend to have lower nitric oxide production, associated with poorer vascular and cognitive health. In a study by the University of Exeter, 26 healthy older people (70s to 80s) took part in two ten-day supplementation periods: one with nitrate-rich beetroot juice and another with nitrate-free placebo juice, which they drank twice a day. Participants were healthy, active older people with generally good blood pressure. Beetroot (as well as lettuce, spinach, and celery) are rich in inorganic nitrate, and many oral bacteria play a role in turning nitrate to nitric oxide, which helps to regulate blood vessels and neurotransmission (chemical messages in the brain). After the supplementation period, the results showed higher levels of oral bacteria associated with good vascular and cognitive health, and lower levels of bacteria linked to disease and inflammation. Also, systolic blood pressure dropped on average by five points (mmHg) after drinking the beetroot juice.