The evidence is mixed as to whether beetroot juice (also known as beet juice) improves exercise endurance or performance. At best, beetroot juice modestly improves some aspects of exercise endurance or performance, especially in people who are not trained athletes, and when the exercise is more physically challenging than to what one is accustomed.
Beetroot juice is a rich source of dietary nitrate, which, when converted in the body into nitrite and nitric oxide, can improve blood flow to muscles, and help muscles use oxygen more efficiently during exercise (Bailey, J Appl Physiol 2009; Bailey, J Appl Physiol 2010). These effects may be less beneficial in trained, elite athletes whose bodies have already undergone physiological changes that make their use of energy and oxygen more efficient (Christensen, Scand J Med Sci Sports 2013; Porcelli, Med Sci Sports Exerc 2015). (See our article "Nitric Oxide Supplements for Bodybuilding and Athletic Performance"). For most people, however, research suggests beetroot may help improve some measures of exercise performance.
A review of 17 controlled trials on the effects of nitrate supplementation in younger, healthy active adults, including 11 studies which used beetroot juice, concluded that nitrate supplementation was associated with a moderate improvement in exercise endurance. Doses of beetroot juice in the studies ranged from 4.7 oz to 25 oz per day (providing between 300 mg to 600 mg of nitrate), which were taken one to three hours before exercise, or on a daily basis for up to 15 days (Hoon, Int J Sport Nutr Exerc Metab 2013). A more recent review of the available research on nitrate supplementation concluded that a dose of nitrate between 310 mg to 537 mg is likely to improve exercise economy (i.e. how efficient the body uses oxygen during exercise), but to improve exercise performance, a dose of more than 527 mg of nitrate may be necessary (Jones, Annu Rev Nutr 2018). Unfortunately, as discussed below, many beetroot juice products do not list amounts of nitrate and amounts found in products vary considerably.
Some, but not all studies have found that beetroot juice can improve exercise endurance in older adults, including those with cardiovascular diseases such as heart failure and peripheral artery disease, or other conditions (Stanaway, Nutrients 2017). For example, a study among 20 adults (average age 69) with heart failure found that a daily dose of Beet It Sport (2.4 oz of beetroot juice containing 380 mg of nitrate) for one week improved aerobic exercise endurance by an average of 24% compared to placebo, although a single dose had no effect (Eggebeen, JACC Heart Fail 2016). A study among 24 men and women (average age 69) with peripheral artery disease and intermittent claudication (leg cramping and pain due to poor blood flow) who participated in an exercise program (walking on a treadmill) three times per week for three months, found that consuming 2.4 oz. of Beet It (containing 262 mg of nitrate) three hours before each exercise session, rather than an placebo drink, improved blood flow in the legs and allowed people to walk, on average, two minutes longer without pain and cramping, and 32 yards farther (Woessner, Circ Res 2018).
However, a study in healthy older adults taking double the dose of Beet It (4.7 oz. daily, providing 700 mg of nitrate) for one week found no improvements in measures of strength and endurance, including a walking test, a hand-grip strength test, an up-and-go test, or a repeated chair raising test (Siervo, Nutr Res 2016).
Differences in beetroot juice supplements:
The amount of nitrate in a product may affect how well it works, but, as mentioned above, many products do not list their nitrate content. An analysis of 24 four beetroot juice products by researchers at Purdue University found the nitrate content per serving varied 50-fold (Gallardo, Int J Sport Nutr Exerc Metab 2018). Among the products, the amount of nitrate per serving ranged from 27 mg in a beetroot powder (4 grams of RediBeets, AIM International) to 1,164 mg of nitrate in a bulk beetroot juice (16 oz. of Lakewood Organic Beetroot Juice). Only five of the products listed an amount of nitrate on the label.
Nitrate content varied by an average of 30% when different samples of the same products were tested. Only five products (Beet It, Beet It Organic Beetroot Shot, Beet It Sport ProElite Shot concentrates, and Knudsen and Sons and Lakewood Organic beetroot juices) consistently provided at least 310 mg of nitrate per serving.
Among beetroot powders, the two products that contained the highest amount of nitrate per suggested serving were PureClean Powder by PureClean (159 mg per 10-gram serving) and BeetElite by HumanN (134 mg per 10-gram serving), while Redibeets by AIM Nutrition provided the lowest amount (27 mg per 4-gram serving).
Beetroot mixed drinks that contained the highest amounts of nitrate were Ginger Beet Juice by Makomas (414 mg per 11 oz. serving) and Beet Performer with Passion Fruit by CAJ Foods (246 mg per 8.5 oz. serving). The mixed drink that contained the lowest amount of nitrate per suggested serving was Beet-Power by H2Bev (63 mg per 8.5 oz. serving).
Beetroot concentrates with the highest amounts of nitrate were Beet It Sport ProElite Shot by James White Drinks (397 mg per 2.4 oz. serving) and Beet It Organic Beetroot Shot (368 mg per 2.4 oz. serving). The concentrate claiming the highest amount of nitrate per serving on its label, Red Rush by AIM Nutrition, actually contained the lowest (148 mg per 2.5 oz. serving — much less than the 499 mg claimed).
Among bulk beetroot juices, the highest amounts of nitrate per 16 oz. serving were found in Lakewood Organic Beetroot Juice (1,164 mg) and Knudsen and Sons (777 mg). In comparison, Love Beets beetroot juice contained just 208 mg per 16 oz. serving.
Beetroot juice may slightly lower blood pressure, so be cautious if you have low blood pressure or take blood-pressure lowering medications.
Beetroot can turn urine and stools red; gastrointestinal discomfort and headaches have also been reported.
Individuals with a history of calcium oxalate kidney stones should be aware that beetroot juice can contain high amounts of oxalate (60 mg to 70 mg per 3.4 oz. serving) (Sierer, J Food Compost Anal).