Issue:
115
Page: 37-38
New Buzz about Beets: Enhancing Sports Performance and Cognitive Function
by Karen Raterman
HerbalGram.
2017; American Botanical Council
Hyped by athletes and sports physiologists, beets (Beta
vulgaris, Chenopodiaceae) have emerged as a trendy and promising sports
performance supplement ingredient. A growing body of evidence suggests that
beetroot, the taproot of the beet plant, has the potential to improve athletic
performance and endurance. New research aims to pinpoint its mechanisms of
action, and how it may help support body systems and impact blood pressure,
heart health, and even cognitive function.
Beetroot contains a variety of health-promoting compounds,
including betaines, resveratrol, and quercetin. However, studies of the
potential sports performance benefits of beets have focused primarily on
nitrates, which have been shown to play a role in blood pressure regulation,
cardiovascular function, and mitochondrial energy production.
Exercise Performance
Research supports certain exercise performance benefits of
dietary nitrate supplementation. Several studies in recent years have shown
that supplementation can decrease the oxygen cost of submaximal exercise
(exercise conducted at an intensity less than the maximum of which the
individual is capable), increase high-intensity exercise tolerance in
recreational athletes, and increase oxygen efficiency in submaximal cycling
exercise.1-4
More recently, research is honing in on how and when
performance is affected by consumption of beetroot. One 2017 study, led by
Oliver Shannon at the Institute for Sport, Physical Activity and Leisure at
Leeds Beckett University in the United Kingdom, sought to determine the effects
of dietary nitrate supplementation on physiological functioning and exercise
performance in trained runners and triathletes during short- and long-distance
time trials. The authors measured plasma nitrites, resting blood pressure, and
maximal oxygen consumption of eight trained male runners or triathletes. The
subjects completed four exercise performance tests, each consisting of a
10-minute warmup followed by either a 1,500-meter or 10,000-meter treadmill
time test.5 Three hours prior to each test, the athletes received either 140 mL
of concentrated nitrate-rich beetroot juice or 140 mL of nitrate-depleted
beetroot juice. Researchers found that nitrate-rich beetroot juice
supplementation significantly enhanced performance in the 1,500-meter time
trial but not for the 10,000-meter trial.
The findings, the authors wrote, suggest that beetroot juice
supplementation may be ergogenic (i.e., performance-enhancing) during
shorter-distance time trials at a high work rate, but not during
longer-distance time trials at a lower work rate. The authors also noted that the
effects of nitrate supplementation are highly variable, and that these results
cannot be easily generalized to other populations or conditions and, as such,
further study is warranted.
Previous research on beetroot has focused on endurance, but
one new study from 2017 examined the impact of beetroot on high-intensity or
intermittent-type exercise.6 The double-blind, placebo-controlled crossover
study, led by Jean Nyakayiru of the Department of Human Movement Sciences at
NUTRIM School of Nutrition and Translational Research in Metabolism at
Maastricht University Medical Centre in the Netherlands, investigated whether
six days of nitrate-rich beetroot juice supplementation would improve exercise
performance in trained soccer players. Soccer players were chosen because the
sport requires multiple bouts of high-intensity running and a heavy reliance on
type II muscle fibers, which are thought to be the muscle group most impacted
by nitrates.
The subjects (N = 32), of similar age, height, weight, and
playing experience, ingested two 70-mL doses of beetroot juice (140 mL per day)
containing 800 mg of nitrates or two 70-mL doses of a placebo beverage (with
similar taste and appearance but depleted of nitrate) for six days.6 The final
dose was ingested three hours prior to the exercise test. Subjects then
completed two days of high-intensity intermittent running performance using the
Yo-Yo intermittent recovery level 1 (YoYo IR1) test, which simulates
soccer-specific activities in a controlled setting.
Distance covered during the test was the primary measure of
performance, although heart rate was measured continuously, and blood and
saliva samples were taken prior to the test. The authors found that
nitrate-rich beetroot juice ingestion improved subject performance by 3.4 ±
1.3% compared to the placebo group. Subjects who consumed the nitrate-rich
beetroot juice had higher plasma and salivary nitrate concentrations as well.
Interestingly, mean heart rates in the beetroot juice group
were lower than in the placebo group during the test. This may have
implications for further study on heart function. The results demonstrate that
nitrate supplementation could represent an effective nutritional strategy to
improve exercise performance in soccer players. Further study, however, is
needed to see if these improvements translate to athletes at different
performance levels.
Cognitive Function
Beetroot juice also may have important benefits beyond
athletic performance that extend to healthy aging of the brain and cognitive
function. A brain-imaging study published in 2016 examined whether beetroot
juice might have a synergistic effect with exercise on neuroplasticity (i.e.,
the ability of the brain to reorganize by forming new nerve cell connections).
Led by Meredith Petrie of Wake Forest University in Winston-Salem, North
Carolina, the study looked at the effects of beetroot juice on the functional
brain network of 26 older men (with a mean age of 65.4 years) who were randomly
assigned to ingest beetroot juice or placebo for six weeks of exercise.7
Using measurements of peak metabolic equivalent capacity and
resting state magnetic resonance imaging, the authors found that the community
structure consistency of the somatomotor cortex (an area of the brain that
controls motor signals to the muscles) was significantly enhanced in the
beetroot juice group compared to placebo.7 They also found significantly
increased secondary connections between the somatomotor cortex and insular
cortex in the beetroot juice group.
Based on these findings, the researchers wrote that subjects
in “the exercise plus beetroot juice group had brain networks that more closely
resembled those of younger adults, showing the potential enhanced
neuroplasticity conferred by combining exercise and beetroot juice consumption.”
Conclusion
Though these studies shed more light on the benefits of
beetroot juice and how dietary nitrates can improve exercise performance and
tolerance, many questions remain. In addition to understanding more about when
and how much nitrate-rich beetroot juice will have an impact, larger studies
with more diverse populations are needed to better understand the potential
exercise advantages and the broader health benefits of dietary nitrates. More
safety data would also be useful to understand the effects of prolonged intake
and the advantages or disadvantages of consuming dietary nitrates from beets
alone, as opposed to obtaining the nitrates from other vegetable sources.
—Karen Raterman
References
- Bailey SJ, Winyard P, Vanhatalo A, et al. Dietary nitrate
supplementation reduces the O2 cost of low-intensity exercise and enhances
tolerance to high-intensity exercise in humans. J Applied Physiol.
2009;107(4):1144-1155.
- Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of
dietary nitrate on oxygen cost during exercise. Acta Physiol.
2007;191(1):59-66.
- Bailey SJ, Varnham RL, DiMenna FJ, Breese BC, Wylie LJ,
Jones AM. Inorganic nitrate supplementation improves muscle oxygenation, O2
uptake kinetics, and exercise tolerance at high but not low pedal rates. J Appl
Physiol 2015;118:1396-1405.
- Cermak NM, Gibala MJ, van Loon LJC. Nitrate
supplementation’s improvement of 10-km time-trial performance in trained
cyclists. Int J Sport Nutr Exerc Metab. 2012;22:64-71.
- Shannon OM, Barlow MJ, Duckworth L, et al. Dietary nitrate
supplementation enhances short but not longer duration running time-trial
performance. Eur J Appl Physiol. April 2017;117(4):775-785.
- Nyakayiru J, Jonvik KL, Trommelen J, et al. Beetroot juice
supplementation improves high-intensity intermittent type exercise performance
in trained soccer players. Nutrients. March 2017;9(3):314.
- Petrie M, Rejeski WJ, Basu S, et al. Beet root juice: An
ergogenic aid for exercise and the aging brain. J Gerontol A Biol Sci Med Sci.
2016. doi: 10.1093/gerona/glw219.
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