If you've never heard of "dietary nitrate," you're far from alone. Only recently has dietary nitrate-and supplements containing it in the form of beetroot-gained serious scientific interest.
The story of dietary nitrate begins with nitric oxide, not to be confused with nitrous oxide-aka laughing gas. The journal Science once declared nitric oxide to be the "molecule of the year," and three scientists earned the Nobel Prize in Physiology or Medicine for their research on this substance. That's an impressive pedigree.
Nitric oxide helps the body's cells talk with each other, and one of its functions is to tell the endothelial cells that line blood vessels to dilate or relax. Because of this property, nitric oxide plays a key role in maintaining normal blood pressure.
Nitric oxide's nutritional precursors include the amino acid L-arginine, but dietary nitrate is also an often overlooked and excellent precursor. Through a series of steps, the body converts nitrate to nitric oxide.
Many fruits and vegetables are good sources of nitrate, and there are significant amounts of nitrate in celery, lettuce, arugula, and spinach. But the hands-down richest source is beetroot and, in particular, beetroot juice and concentrate. (The juice is extracted from the red beetroots you cook with or use in salads, not the sugar beets used for making sucrose.)
How to "Beet" Hypertension with Beetroot Juice
The studies on the benefits of beetroot juice and blood pressure show remarkably consistent benefits. Researchers at Queen Mary University in London asked 68 people with hypertension to drink either 1 cup (150 mL) of nitrate-rich beetroot juice or nitrate-free beetroot juice daily. The drinks were switched so that everyone in the study eventually consumed both types of juice daily for two weeks.
The researchers measured the subjects' blood pressure using three different techniques. All three techniques found a reduction in blood pressure among people drinking the beetroot juice with naturally occurring nitrate.
A separate study by the same researchers involved giving 69 patients a cup of either nitrate-rich beetroot juice or beetroot juice without nitrate daily for six weeks. All of the subjects had elevated cholesterol levels. Using ultrasound, researchers determined that the nitrate-rich beetroot juice led to a 24 percent improvement in blood vessel flexibility and tone. The subjects also had a slight decrease in blood clotting, another sign of improved cardiovascular health. These factors worsened in the placebo group.
Meanwhile, researchers at the Maastricht University Medical Center in the Netherlands tested four nitrate-rich beverages on 11 men and seven women who were in their late 20s. All of the subjects were healthy, had normal blood pressure, and were physically active. The study consisted of a crossover design, so each subject consumed one of the beverages on one day over five weeks.
The four drinks consisted of a concentrated beetroot juice (Beet It), a beverage made from fresh arugula, a beverage made from fresh spinach, and a beverage containing sodium nitrate. Each beverage contained 800 mg of nitrate.
All of the drinks reduced diastolic blood pressure (the lower number) by several points after about two-and-one-half hours, with beetroot concentrate having the greatest effect-7.5 mm Hg lower-and blood pressure remained lower for at least five hours. The drinks lowered systolic blood pressure (the upper number) from 3 to 6 mm Hg after the same time, except for the drink with sodium nitrate.
Reducing Glaucoma Risk
Harvard medical researchers recently reported that eating nitrate-rich vegetables can lower the risk of primary open-angle glaucoma, the most common form of the disease.
Jae H. Kang, ScD, and her colleagues analyzed health data that had been collected every two years, starting in the mid-1980s and continuing through 2012, and that included 63,893 female nurses and 41,094 male physicians as study subjects. She reported that people with the highest daily intake of nitrate-approximately 240 mg, mostly from leafy green vegetables-had a 21 percent lower risk of open-angle glaucoma and a 44 percent lower risk of glaucoma with the early stages of vision loss.
Boosting Athletic Performance
Beetroot juice shots may be transforming both professional and college sports. The Leicester City (England) soccer team won a major title in 2016, and the Auburn Tigers (Alabama) football team had an unexpected winning streak-and both teams attribute a big part of their recent success to using beetroot shots to enhance performance.
Studies conducted in Europe show that concentrated beetroot improves exercise performance and increases tolerance to high-intensity exercise. The studies involved "recreationally fit" athletes and elite athletes training under controlled conditions, such as cycling or running on a treadmill in an exercise laboratory.
The dietary nitrate in beetroot works in a couple of different ways. First, it enables blood vessels to flex (instead of remain stiff) under pressure. Second, the nitrate enables athletes to use less oxygen while exercising at the same intensity. This makes "exercise seem easier, and it should be possible to continue it for longer," says Andrew M. Jones, PhD, a professor and exercise physiologist at the University of Exeter in the United Kingdom.
These studies have found that blood nitrate levels peak two to three hours after consuming beetroot, and that levels remain elevated for six to nine hours. That means the key is to drink beetroot juice three hours before exercising, and to have it daily to maintain higher blood levels of nitrate, according to Jones.
Did you know?
Beetroot-particularly beetroot juice and concentrate-is the richest dietary source of nitrate, a powerful nutrient that may hold the key to blood pressure control.
How to Use Beetroot Juice
You can measure your nitric oxide levels by using saliva test strips from Berkeley Test (berkeleytest.com). Most blood pressure studies have used 180 mg of beetroot juice daily, although more might be helpful to some people. (Beet juice can cause nausea and vomiting, so this amount should be spread over the course of the day in 2-3 doses.) One of the leading 2.4-ounce beetroot "sport shots"-Beet It-provides 400 mg, so half can be taken one day and half the next. A beneficial effect on blood pressure should be apparent within 10 days.
For serious athletes, one or two sport shots daily should be fine. Two shots will saturate the bloodstream and provide maximum benefits, so larger amounts will have no additional effect. An 8.5 ounce bottle of beetroot juice provides approximately 180 mg. Please note that the shots and juice may turn your urine pink, but this is a superficial, not harmful, side effect.