New research points to the health benefits of beetroot juice. Bacteria in the mouth and gut help convert inorganic nitrate from vegetables into nitric oxide, which is vital for cardiovascular and cognitive health.
A new study in older adults suggests that drinking beet juice, which is high in inorganic nitrate, promotes the growth of oral bacteria associated with these benefits. These bacteria show promise as a way to reduce age-related declines in cardiovascular and cognitive health. Previous research had already shown that the community of bacteria and other microorganisms that lives in our gut, known as the gut microbiota, can affect our health and well-being in multiple ways, many of which are positive.
However, much of the information about the bacteria that live in our mouths focuses on gum disease and its inflammatory effects throughout the body. Much less is known about the role of oral bacteria in the production of nitric oxide, which benefits cardiovascular and cognitive health.
Good bacteria love beets
Many species of oral bacteria convert inorganic nitrate in vegetables to nitrite. Nitrite is a precursor to nitric oxide, a signaling molecule that dilates blood vessels and transmits messages between neurons in the brain. In the elderly, reduced availability of nitric oxide can contribute to hypertension (high blood pressure) and a decline in cognitive functions. A new study suggests that drinking beet juice, which is high in inorganic nitrate, may alter the balance of bacteria in the mouth in favor of species that promote better cognitive and cardiovascular health.
The results of this study help explain the proven benefits of beetroot juice in lowering blood pressure in people with hypertension. Other vegetables that are high in nitrates, including cabbage, lettuce, spinach, and celery, may provide similar benefits. Scientists from the University of Exeter in the UK led this research, published in the journal Redox Biology. These findings have important implications for healthy aging. Maintaining this healthy oral microbiome over the long term could slow the negative vascular and cognitive changes associated with aging.
Juice with or without nitrate
The study involved 26 people between the ages of 70 and 80. The researchers randomly assigned these participants to one of two groups. While they asked both groups to drink 140 milliliters of beetroot juice daily for 10 days, the experimental group drank a juice high in nitrates, while the control group drank a juice low in nitrates. The smell and taste of both drinks were the same. After a 3-day washout period, the groups switched and participants consumed the other drink for 10 days. The researchers asked the participants not to use mouthwash during the study.
Before, during and after the experiment, they administered a battery of physiological and cognitive tests. They also identified bacterial species by sequencing genetic material in participants’ saliva samples. Compared to the placebo condition, subjects who drank regular beetroot juice had higher numbers of oral bacteria associated with good vascular and cognitive health. Their saliva also contained lower numbers of bacteria linked to inflammation. On average, participants’ systolic blood pressure dropped by 5 millimeters of mercury after 10 days of consuming nitrate-rich beetroot juice.
Additionally, the tests indicated a higher availability of nitric oxide in their blood. Those who drank the nitrate-rich juice also performed better on tests of sustained attention.
Colonies of species of good bacteria
The researchers used a statistical technique to identify two distinct groups of bacterial species that bloomed in participants’ mouths when they drank regular beet juice. These two groups or “modules” (labeled MM5 and MM6) not only tended to coexist in the same mouth, but were also associated with improvements in cognitive function and blood pressure. The authors suggest that these nitrate-sensitive oral bacteria would make suitable probiotics to correct age-related declines in cardiovascular and cognitive health.
A third group of species, which previous research has linked to inflammation, failed to grow in the mouths of participants drinking regular high-nitrate beet juice. This cluster included various pathogenic species, including Clostridium difficile.
Sources
Role of gut microbiota in nutrition and health
Dietary inorganic nitrate: From villain to hero in metabolic disease?