April 2016 Issue

Fitness Foods: Boost Performance With Beets
By Clare Tone, MS, RD
Today's Dietitian
Vol. 18 No. 4 P. 16

"Eat your vegetables!"

This is perhaps the most common refrain from dietitians and parents alike. We say it for the fiber, vitamin C, and host of B vitamins; we say it for the potassium, calcium, polyphenols, and bioflavonoids. But for athletes, there's yet another reason to invoke this mantra: nitrates.

Nitrates are naturally occurring in all vegetables but are particularly high in beets, which research has shown can improve athletic performance. Nitrates ingested through the diet are converted to nitrite in the body, ultimately increasing nitric oxide levels. Nitric oxide is a potent vasodilator with anti-inflammatory and antiplatelet aggregation properties.1,2 Studies looking at the effects of beetroot juice on athletic performance consistently reveal a reduced use of oxygen during exercise, so researchers are now focused on whether that translates to improved time to exhaustion and race times for athletes.

Exercise Tolerance and Athletic Performance
Most studies looking at dietary nitrates as a potential ergogenic aid for elite and recreational athletes have used beetroot juice as the nitrate source. Much research has looked at exercise tolerance, measuring 15% to 25% improvements in time-to-exhaustion in cycling and treadmill running.3-5 A 2014 review article published in Sports Medicine found consensus among research that dietary nitrates reduced the oxygen cost of submaximal exercise and in some cases enhanced exercise tolerance.3 In 2015, the European Journal of Applied Physiology published a double-blind, randomized crossover study of 16 male team-sport players who received 140 mL of beetroot juice daily for seven days and were asked to perform intermittent cycling. The beetroot juice was found to significantly enhance repeated sprint performance along with improving reaction time.6

When it comes to real-world competition, most athletes are more interested in improvements in performance and the time it takes to complete an event. The question of whether beetroot juice can improve exercise performance, not just tolerance, has been examined in studies looking at timed trials. In 2011, Medicine and Science in Sports and Exercise published a study of nine nonelite but competitive male cyclists. The study was a crossover design in which the athletes were given 500 mL of beetroot juice or a nitrate-depleted placebo and asked to complete 4- and 16-km timed cycling events. The cyclists receiving the beetroot juice completed both distances 2.7% faster than the cyclists who received the placebo.7 A similar study showed a 1.2% reduction in time to complete a 10-km cycling trial following six days of beetroot juice supplementation.4 However, benefits aren't reserved solely for competitive athletes willing to consume large doses of beetroot juice. In 2012, the Journal of the Academy of Nutrition and Dietetics published a double-blind, placebo-controlled crossover trial in which 11 recreationally fit men and women completed a 5-km running trial on the treadmill 75 minutes after consuming roasted beets. Not only did the beet-eaters run at a faster velocity but also their perceived level of exertion was significantly lower.8

Some studies looking at the effects of beetroot juice on highly trained endurance athletes conflict with those that examined nonelite athletes, which may relate to the way nitric oxide is generated in elite vs nonelite competitors. For example, a study of highly trained cyclists completing a 50-mile time trial showed an inverse correlation between beetroot juice and time to completion.3 In another study, trained cyclists didn't cover more distance in one hour of cycling following beetroot juice ingestion compared with placebo.3 In normal conditions, when there's ample oxygen present in body tissues, enzymes convert the amino acid arginine to nitric oxide. But when oxygen levels are low—as may be the case during exercise among less trained athletes—the production of nitric oxide relies on conversion from dietary nitrates. It's hypothesized that athletes training at the elite level may have higher capillary delivery of oxygen to their tissues, allowing nitric oxide to be made from arginine rather than dietary nitrates,3 thereby preventing them from benefiting directly from beetroot juice intake in these studies.

Recommendations for Athletes
For potential ergogenic benefits of dietary nitrates, study doses of beetroot juice varied between 140 mL and 500 mL per day for several days before the event. Studies in which athletes received beetroot juice for three days or fewer before the event didn't show consistent gains in exercise tolerance or performance. On event day, beetroot juice should be consumed 1½ to three hours ahead of the event to most closely match the dosing schedule used in studies. So far, research suggests events between five and 30 minutes in duration may see the best gains from dietary nitrates, and recreational athletes may benefit more than highly trained endurance athletes.

From the Lab to the Kitchen
With vibrant hues from gold to red, and a mildly sweet flavor to match, it's easy to include beets in the diet. Red and golden beets are a cultivated variety of Beta vulgaris, grown for their edible taproot, thus the common name "beetroot." Perhaps red beets have gotten a bad rap from a related variety, the sugar beet, grown specifically for their taproot rich in natural sugars, which must undergo multiple stages of processing to yield white table sugar—essentially the same as sugar derived from sugar cane.

In contrast, red and golden beets are packed with nutrients. Along with their high nitrate content, a single beet that has a diameter of 2 inches provides 2 g fiber, 266 mg potassium, 64 mg sodium, 89 mg folate, 27 IU vitamin A, less than 6 g sugar, and 35 kcal.9

Beets can be eaten raw, juiced, or cooked. Because of their dark red pigment, beets can be messy to handle. Roasting beets brings out their full flavor while minimizing contact with the deep red pigment. After roasting, simply wrap the cooled beet in a paper towel and rub gently to slip off the skins. Keep roasted beets on hand in the refrigerator for a quick addition to salads like the accompanying recipe.

— Clare Tone, MS, RD, is a freelance writer, high-altitude gardener, and nutrition instructor at Metropolitan State University of Denver.

References
1. Lundberg JO, Carlstrom M, Larsen FJ, Weitzberg E. Roles of dietary inorganic nitrate in cardiovascular health and disease. Cardiovasc Res. 2011;89(3):525-532.

2. Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. J Nutr. 2013;143(6):818-826.

3. Jones AM. Dietary nitrate supplementation and exercise performance. Sports Med. 2014;44(Suppl 1):S35-S45.

4. Jones AM, Kelly J, McDonagh S, Wylie LJ. Dietary nitrate and exercise. Professionals Nutr Exerc Sport. 2013;5(1):1-3.

5. Lansley KE, Winyard PG, Fulford J, et al. Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled study. J Appl Physiol (1985). 2011;110(3):591-600.

6. Thompson C, Wylie LJ, Fulford J, et al. Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise. Eur J Appl Physiol. 2015;115(9):1825-1834.

7. Lansley KE, Winyard PG, Bailey SJ, et al. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011;43(6):1125-1131.

8. Murphy M, Eliot K, Heuertz RM, Weiss E. Whole beetroot consumption acutely improves running performance. J Acad Nutr Diet. 2012;112(4):548-552.

9. Basic report: 11080, beets, raw. USDA Agricultural Research Service website. http://ndb.nal.usda.gov/ndb/foods/show/2863?fgcd=Vegetables+and+Vegetable+Products
&manu=&lfacet=&format=&count=&max=35&offset=&sort=&qlookup=Beets
. Accessed February 8, 2016.

Recipe

Roasted Beet Salad With Goat Cheese and Sherry-Walnut Vinaigrette

Serves 8

Ingredients
10 small red or golden beets, roasted
1/2 cup sherry vinegar
1 tsp Dijon mustard
1/4 tsp agave or honey
1/2 clove garlic, finely chopped
1/2 cup walnut oil
1/4 cup olive oil
11/4 tsp salt
Ground black pepper, to taste
1 lb baby spinach, roughly chopped
5 oz arugula, roughly chopped
1/2 cup toasted walnuts
4 oz crumbled goat cheese

Directions

To Roast Beets:
1. Preheat oven to 400° F.

2. Trim greens to about 1 inch above the root bulb.

3. Wash root bulb and place in covered roasting pan. Alternatively, beets can be wrapped in aluminum foil.

4. Roast beets for about one hour or until easily pierced by a metal skewer or fork.

Vinaigrette:
Whisk together vinegar, mustard, agave or honey, and garlic. Whisk in the oils, salt, and pepper.

Salad:
Cut beets into bite-size pieces and mix with half the vinaigrette. Mix greens with the rest of the vinaigrette. Top greens with beets, walnuts, and goat cheese.

Nutrient Analysis per serving
Calories: 180; Total fat: 14 g; Sat fat: 3.5 g; Cholesterol: 5 mg; Sodium: 240 mg; Carbohydrates: 9 g, Dietary fiber: 3 g; Sugar: 4 g; Protein: 6 g

— Recipe courtesy of Whole Foods Market. Visit wholefoodsmarket.com for more great recipes.
ADVERTORIAL