A small randomised double-blind crossover study published in Free Radical Biology and Medicine links beetroot juice with lower blood pressure in older adults. The study is preliminary and the cohort was small, but the findings are promising for heart health and future interventions.
Do you need to start juicing? Here are the answers.
What did the study find?
Across three two-week trial periods, separated by two-week washouts, study articipants were assigned to one of three protocols: drink nitrate-rich beetroot juice twice daily, drink a placebo beetroot juice twice daily or use a mouthwash twice daily for 30 seconds. On the final day of each period they completed one last drink or rinse. Those in the juice arms did not use mouthwash during their allocated period.
Researchers enrolled two groups: younger adults aged 18 to 30 (n=42) and older adults aged 67 to 79 (n=36), for a total of 78 participants. The aim was to analyse whether shifts in the oral microbiome influence blood pressure.
Participants did not have pulmonary, cardiovascular or metabolic conditions, ulcerative colitis, renal disease or active oral disease and did not wear dentures. Smokers, people with stage 2 hypertension and anyone who had taken antibiotics in the previous three months were excluded.
Testing began after an overnight fast and 24 hours without strenuous exercise, alcohol or caffeine. Apart from their assigned protocol—70 mL beetroot juice or placebo morning and evening or the twice-daily mouthwash—participants maintained their usual diet and activity.
After comparing the three periods, researchers concluded that beetroot juice may help lower blood pressure in older adults, “likely by changing the composition of bacteria in the mouth,” says cardiologist Dr Padma Shenoy. “This blood pressure-lowering effect was not seen in younger people.”
More specifically, beetroot juice was associated with “a decrease in certain bacteria such as Prevotella and an increase in others like Neisseria and Rothia that are better at converting dietary nitrate into nitric oxide, a compound that helps blood vessels relax,” explains dietitian Elizabeth Adrian.
How nitrate, beetroot juice, the oral microbiome and blood pressure are connected
Nitrates occur naturally in the environment, vegetables and some preserved meats. With help from mouth bacteria, dietary nitrates convert to nitric oxide, which can support heart health by relaxing blood vessels and improving blood flow, say Dr Shenoy and Adrian. Nitrates also feature in some blood pressure medicines, Dr Shenoy adds. “That’s why diets high in nitrate-rich vegetables such as spinach, rocket and beetroot are consistently linked with better vascular health,” Adrian says.
The open question is the role of the oral microbiome, but it appears to matter. “We are still learning about the connection between the oral microbiome and blood pressure, but it is possible that certain bacteria in the mouth turn nutrients into substances that lower blood pressure,” Dr Shenoy explains.
You may have heard concerns about excess nitrate intake and cancer risk. Most concerns relate to processed meats and some water supplies where nitrates or nitrites are added to prevent bacterial growth and affect colour and flavour. Naturally occurring nitrates in vegetables are considered safe to eat.
Will drinking beetroot juice really lower your blood pressure in two weeks?
“According to this study, only older adults experienced a slight drop in blood pressure from drinking beetroot juice and more studies are needed to explore who will respond,” says Dr Shenoy. “Eating more vegetables like beetroot may help heart health, but it is just one part of a healthy lifestyle. Other components include following a varied diet, limiting sodium and exercising regularly. More research is needed before making strong recommendations to use beetroot as a blood pressure-lowering therapy.”
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