Nitrate-rich beetroot juice lowers blood pressure in older adults, found a new study published in Free Radical Biology and Medicine.
“This study shows that nitrate-rich foods alter the oral microbiome in a way that could result in less inflammation, as well as a lowering of blood pressure in older people." said co-author of the study, Andy Jones, Professor of Applied Physiology at the University of Exeter, UK, in a press release.
"This paves the way for larger studies to explore the influence of lifestyle factors and biological sex in how people respond to dietary nitrate supplementation,” he added.
Previous research has shown that supplemental dietary nitrate reduces blood pressure in both young and older adults. Meanwhile, use of chlorhexidine-containing mouthwash, which suppresses oral bacteria, has been shown to raise blood pressure in healthy adults and older people with treated hypertension. The findings suggest that the composition of the oral microbiome may affect an individual’s ability to benefit from ingested nitrate.
Oral bacteria convert nitrate to nitrite, a precursor to nitric oxide, which plays a key role in healthy blood vessel function.
In the current study, researchers investigated whether changes in the oral microbiome from dietary nitrate and antiseptic mouthwash affect nitric oxide bioavailability and vascular function. To do so, they recruited 39 adults aged 18-30 years old and 36 older adults aged between 67 and 79 years for a placebo-controlled crossover intervention. The trial included three 2-week conditions separated by two-week washouts: placebo beetroot juice, nitrate-rich beetroot juice, and an antiseptic mouthwash.
Ultimately, the oral microbiomes of both younger and older adults were affected by nitrate-rich beetroot juice, but not by the placebo or mouthwash interventions. Older adults experienced a significant drop in mouth bacteria Prevotella- increased abundance of which is linked to periodontitis and metabolic disorders- as well as higher levels of beneficial bacteria like Neisseria.
The researchers further found that nitrate-rich beetroot juice reduced arterial pressure in older adults, but not younger adults. Decreased blood pressure in older adults correlated with higher plasma nitrite concentration, which in turn correlated with decreases in certain bacteria Prevotella, P. dentalis, and Crassaminicella.
“Greater blood pressure benefits from supplemental dietary nitrate in older compared to younger people are mediated primarily by the suppression of potentially harmful oral bacteria, that have been associated with ammonia production,” wrote the researchers in their study.
Sources: Free Radical Biology and Medicine, Science Daily, Immunology