Beetroot juice and nitric oxide: what the evidence says about blood pressure and exercise

Nitrates occur naturally in many vegetables, and beetroot is a particularly rich source. Blood Pressure UK explains that beetroot's high levels of inorganic nitrate, which is also found in leafy green vegetables like lettuce and cabbage, helps to relax and widen blood vessels, improving blood flow and reducing blood pressure. A Royal Brompton and Harefield hospitals researcher describes the mechanism: higher levels of nitrate in the blood can increase the availability of nitric oxide, a chemical that helps blood vessels relax, and may increase the efficiency of muscles so that they need less oxygen to do the same work.

The phrase 'nitric oxide supplement' covers several different products, including beetroot juice and powders, concentrated juice shots and nitrate-containing capsules. This page concerns beetroot juice and dietary nitrate, which the sources discuss.

Blood Pressure UK reports a Queen Mary University of London study published in 2015 in which patients with hypertension who drank a 250 ml glass of beetroot juice every day saw an average decrease in blood pressure of 8/4 mmHg, with blood pressure returning to the normal range for many. The trial included 64 patients aged 18 to 85, and those who drank the juice also showed improved blood vessel dilation and reduced arterial stiffness. The charity notes that more research is needed to see whether effects last long term.

The British Heart Foundation takes a more cautious view in its dietitian's article. It says that research, including some funded by the BHF, has linked beetroot juice to reduced blood pressure but that studies so far have only included small numbers of people, and that we do not know if there is something special about beetroot or whether other fruit and vegetables would have the same effect. It describes beetroot juice as not a magic bullet, and says the best way to manage high blood pressure is to take any prescribed medication, keep physically active and eat healthily.

The Royal Brompton and Harefield hospitals reported a study in people with chronic obstructive pulmonary disease (COPD) whose systolic blood pressure was above 130 mmHg. Participants took 70 ml of concentrated beetroot juice containing 400 mg of nitrate once a day, or a placebo that looked and tasted the same but had the nitrate removed. Those taking the nitrate-rich supplement had an average reduction in systolic blood pressure of 4.5 mmHg compared with placebo, less stiff blood vessels, and walked around 30 metres further in six minutes.

The lead researcher noted that there is some evidence that beetroot juice as a source of nitrate could be used by athletes to improve performance, and described the COPD results as very promising but needing confirmation in larger, longer-term studies. That is a statement about the research stage rather than an endorsement of use.

The BHF says that a 150 ml portion of beetroot juice only counts once a day towards your 5-a-day and naturally contains around 10 g of sugar, and that we should limit sugars including those from fruit and vegetable juices to 30 g a day. Concentrated shots often contain more nitrates per millilitre but more sugar too, so check the label. It suggests eating beetroot whole, which adds more fibre, and choosing cooked or ready-prepared beetroot with nothing added; the sugar and salt in pickled beetroot varies, so choose one low in both.

The BHF says to check with your doctor before regularly drinking beetroot juice if you take blood pressure-lowering medication. If you have a long-term condition such as diabetes or kidney disease, or are on a restricted diet, ask your clinician or a dietitian, because juice contains sugar and the BHF notes beetroot also contains potassium.

The BHF is clear that the best-established steps for high blood pressure are taking prescribed medicines, being physically active and eating healthily, with a third of the diet coming from fruit and vegetables. Beetroot can be enjoyed as part of that diet without being relied on as a treatment. Blood pressure should be measured regularly, and any treatment decision belongs with your GP or practice nurse.

Beetroot juice is bought over the counter and is not prescribed. Practice pharmacists and registered dietitians can advise on how it fits with your conditions and medicines. Home blood pressure monitoring, as recommended by your GP, is a sensible way to see whether a change in diet is making a difference.