“SuperBeets helps boost your body’s nitric oxide levels, and that helps increase your energy and stamina,” claims a TV ad for the concentrated dried beet powder. “It helps support healthy blood pressure levels, too.”
Beets—like spinach, lettuce, arugula, and some other vegetables—are rich in nitrates. Nitrates? Aren’t bacon, sausage, and other processed meats considered human carcinogens in part because they contain nitrites and nitrates?
Yes, but the nitrates in vegetables may be beneficial. “When you eat nitrates, they are converted to nitrites by bacteria in your mouth,” says Gunter Kuhnle, a professor of food and nutritional sciences at the University of Reading in England. Once the nitrites reach the stomach’s acid, they can turn into either nitric oxide or N-nitroso compounds.
“N-nitroso compounds like nitrosamines are carcinogenic,” explains Kuhnle. “What makes processed meats so ideal for forming N-nitroso compounds is that they have a combination of nitrite and proteins from the meat. And the meat’s heme seems to help convert them into N-nitroso compounds.”
But the vitamin C and polyphenols in vegetables make it harder for nitrosamines to form. You’re more likely to get nitric oxide, which helps blood vessels relax.
Even so, the evidence that beets, beet powder, or beet juice is a “circulation superfood” isn’t quite ready for prime time.
In short-term studies in healthy adults with normal blood pressure, nitrate-rich vegetable juice made from spinach, arugula, or beets lowered blood pressure by about 5 points after a few hours or after people took it daily for a few days or two weeks.1-3
“Some researchers find quite a dramatic reduction in healthy volunteers,” says Mark Gilchrist, a clinical senior lecturer at the University of Exeter Medical School in England.
But evidence in people with high blood pressure isn’t consistent. In one study on 64 people, those assigned to drink 8 oz. of beet juice every day for a month had blood pressures that were nearly 8 points lower than those assigned a placebo drink.4 And pressure started dropping within a week. But a similar study on 27 people found no difference in blood pressure after one week.5
Also disappointing: “In our trials on people with type 2 diabetes, we haven’t seen any effect of beet juice on blood pressure,” says Gilchrist.6,7 He’s not sure why. “Maybe their blood vessels are simply less responsive to the nitric oxide. Or maybe the studies weren’t big enough to detect a difference.”
“The headline finding has been that beet juice reduces the oxygen cost of exercise for a given workload,” says Gilchrist.
“Usually, fitter people use less oxygen to do the same thing as unfit people,” he explains. “That can translate into being able to sustain your exercise for longer or run faster.”
That’s what you see in small studies in healthy, young adults.2,8,9 The evidence is murkier for others.
For example, after three days of drinking beet juice twice a day, 12 healthy older adults didn’t walk farther or use less oxygen than when they drank a placebo.3 And that’s the only study in healthy older adults.
“The results seem to be variable,” says Gilchrist, whose studies on people with type 2 diabetes and COPD (chronic obstructive pulmonary disease) also came up empty.7,10
Until more research is done, why not try beet juice or a beet powder like SuperBeets?
When people drank beet juice for six weeks, “we couldn’t find any nitrosamines in their urine,” says Kuhnle.11 “But we don’t know if beet juice or nitrate supplements increases the risk of cancer. We simply don’t know.”
That doesn’t mean you should avoid beets or other nitrate-rich vegetables. On the contrary, says Gilchrist. “Vegetables contain multiple components, including nitrates, that help lower blood pressure and have other beneficial health effects.”
Just don’t think of beet juice as a panacea.
“You can’t drink beet juice or take other vegetable-based supplements and think that it’s going to make up for eating burgers and fries the rest of the time,” says Gilchrist.
Bottom Line: “We need a long-term study on the potential cardiovascular benefits versus the cancer risk,” says Kuhnle. In the meantime, eat your veggies, but hold off on nitrate and beet supplements.
1 J. Nutr. 146: 986, 2016.
2 Am. J. Physiol. Regul. Integr. Comp. Physiol. 299: R1121, 2010.
3 Am. J. Physiol. Regul. Integr. Comp. Physiol. 304: R73, 2013.
4 Hypertension 65: 320, 2015.
5 Am. J. Clin. Nutr. 102: 368, 2015.
6 Free Radic. Biol. Med. 60: 89, 2013.
7 Free Radic. Biol. Med. 86: 200, 2015.
8 J. Appl. Physiol. 107: 1144, 2009.
9 J. Appl. Physiol. 115: 325, 2013.
10 Nitric Oxide 48: 31, 2015.
11 Am. J. Clin. Nutr. 103: 25, 2016.
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