Beetroot Juice Lowers Blood Pressure in Older Adults, New Study Shows

Key Points:

• Nitrate-rich beetroot juice supplementation increased beneficial oral bacteria and reduced harmful ones in younger and older study participants
• In older study participants only, nitrate-rich beetroot juice lowered blood pressure.

High blood pressure (hypertension) is a key modifiable risk factor for heart problems as people age. Elevated levels of harmful mouth bacteria and lower levels of beneficial ones have been associated with hypertension. Along those lines, although modifying the oral bacterial composition has been proposed to lower blood pressure, exactly how to do so has undergone scant research.

Now, as published in Free Radical Biology and Medicine, Jones and colleagues from Exeter Medical School in the UK show that taking a shot of nitrate-rich beetroot juice twice daily was associated with changes in the oral microbe composition, namely, a reduced prevalence of bacteria associated with the breakdown of nitrates. Moreover, the nitrate-rich beetroot juice increased blood nitrate concentrations. Additionally, the nitrate-rich beetroot juice lowered blood pressure in older participants but not younger ones. These findings suggest that supplementing with shots of nitrate-rich beetroot juice could serve as a way to reduce oral bacteria, which break down nitrates, to increase blood pressure-lowering nitrates in the blood and lower blood pressure.

Enzymes in Vascular Cells Convert Nitrates to Nitric Oxide

The study and its findings relate to the conversion of nitrates in blood to nitric oxide, a molecule that improves vascular cell function and can help lower blood pressure. As people age, the enzymes present in vascular cells that convert nitrates to nitric oxide become less efficient, resulting in lower blood nitric oxide levels and an increased risk of hypertension. On top of that, oral bacteria, such as Prevotella, have been shown to increase with age. These bacteria break down nitrates to the compound ammonia, which severely inhibits nitrate conversion to nitric oxide as people age.

Results from the study showing that nitrate-rich beetroot juice reduces oral bacteria, like Prevotella, suggest that targeting oral microbes in addition to using other ways to supplement nitrates may work against hypertension. Since the enzymes that convert nitrates to nitric oxide lose their functional capacity with age, reducing oral bacteria that break down nitrates could be especially important, because research suggests that oral bacteria and their byproducts often enter circulation. Interestingly, Jones and colleagues’ study suggests that supplementing with nitrate-rich beetroot juice increases blood nitrates, likely through the absorption of nitrates in the gut and through the reduction of oral bacteria like Prevotella.

“We know that a nitrate-rich diet has health benefits, and older people produce less of their own nitric oxide as they age,” said study author Anni Vanhatalao in a press release. “They also tend to have higher blood pressure, which can be linked to cardiovascular complications like heart attack and stroke. Encouraging older adults to consume more nitrate-rich vegetables could have significant long-term health benefits. The good news is that if you don’t like beetroot, there are many nitrate-rich alternatives like spinach, rocket, fennel, celery, and kale.”

The Nitrate-Rich Juice Lowers Blood Pressure in Older Adults

To conduct their human trial, Jones and colleagues separated study participants into two groups: a younger group consisting of 39 adults below age 30 and an older group of 36 adults in their 60s and 70s. Individuals in these groups were given nitrate-rich beetroot juice, mouthwash, or a nitrate-depleted beetroot juice placebo twice daily for two weeks, followed by 14 days without treatment before treatments resumed for a total of three cycles.

To find whether nitrate-rich beetroot juice alters the oral microbe composition, Jones and colleagues used a bacterial gene sequencing method to analyze which bacteria were present in the mouth before and after each condition. In both younger and older adults, the oral microbe composition changed after consuming nitrate-rich beetroot juice; however, these changes differed between the groups.

Accordingly, the older group exhibited a significant decline in the mouth bacteria Prevotella after consuming the nitrate-rich juice. The older group also displayed a significant increase in bacteria believed to confer physiological benefits, Neiserria. Such findings support the notion that nitrate-rich beetroot juice modifies the oral microbe composition, lowering potentially harmful and increasing possibly beneficial bacteria.

Because nitrates in the blood are converted to nitric oxide and higher concentrations of nitrates are believed to increase blood nitric oxide to potentially lower blood pressure, Jones and colleagues measured blood nitrate levels. In that regard, Jones and colleagues measured nitrates in the blood after two weeks under each experimental condition. Interestingly, the nitrate-rich beetroot juice significantly increased blood nitrate concentrations in the older group compared to the other conditions. These findings suggest that nitrate-rich beetroot juice more effectively raises blood nitrates in older individuals.

To measure whether nitrate-rich beetroot juice affects blood pressure, Jones and colleagues measured blood pressure after two weeks under each experimental condition. The older group had a higher average blood pressure at the beginning of the study, which declined after taking the nitrate-rich beetroot juice but not after mouthwash or placebo conditions. No significant blood pressure changes were found for younger participants who took nitrate-rich beetroot juice. These results suggest that nitrate-rich beetroot juice lowers blood pressure in older adults only.

Other Nitrate-Rich Foods that May Lower Blood Pressure

The study’s data suggest that taking shots of nitrate-rich beetroot juice or other supplements or foods containing high levels of nitrates may serve as a way to lower blood pressure, especially in older adults. Jones and colleagues’ study is the first human trial to suggest that modifying the oral microbe composition may be one way that nitrate-rich beetroot juice lowers blood pressure in older people.

Future human trials should examine whether other nitrate supplements or foods containing nitrates are as effective at lowering blood pressure in older adults as nitrate-rich beetroot juice. The effectiveness of nitrate-containing supplements and foods in lowering blood pressure may relate to their ability to modify the oral microbe composition by reducing Prevotella, which breaks down nitrates. Along those lines, it may be the case that other foods containing high concentrations of nitrates, such as spinach, celery, and kale, work similarly to modify the oral microbe composition and lower blood pressure. In the meantime, until more data comes forth, it may work best to hedge one’s bet on consuming nitrate-rich beetroot juice, which Jones and colleagues’ study provides some evidence for, to counteract hypertension.

Accordingly, the beetroot juice that Jones and colleagues used contains a high concentration of dietary nitrates—400 milligrams per 70 mL serving, making it a benchmark for high nitrate levels. This value is roughly equivalent to a 6.45 mmol concentration. Other standard beetroot juice products contain roughly a 4.84 mmol concentration of nitrates. This means that the nitrate-rich beetroot juice product used for the study has about a 30% higher nitrate concentration than other products. Thus, when considering a nitrate-rich beetroot juice product, it may be worthwhile to search for those that have high nitrate concentrations, along the lines of 6.45 mmol.