Beet the competition

Mardi, Février 19, 2013 - 14:17

A handful of studies performed over the past several years have found that consuming beet juice may lower the oxygen cost of exercise, due to the high concentration of nitrates found in beetroot. As a result, many athletes are consuming beetroot juice as a way to enhance performance. 

So, how does it work?

A compound called 'nitric oxide' (NO) is a compound that is made in the body but can also be made from dietary nitrate. Nitrate is a natural substance found in beetroots and leafy green vegetables.  After beetroots are consumed, some of that nitrate is converted to nitrite by bacteria in the saliva.  The nitrite is then absorbed through the small intestines and into the body where it will be converted to nitric oxide that occurs in the blood and tissues.  Researchers believe that NO is responsible for the endurance benefits that allow muscles to work in a more efficient manner.

Positive effects of beetroot juice:

• improvement in oxygen consumption
• reduction in blood pressure
• contains antioxidants
• improvement in time to exhaustion and lower rate of perceived exertion (RPE)
• or, overall time to complete the exercise

Negative effects of beetroot juice:

• beeturia - the red colouring of urine that comes from eating beetroot (although alarming, it is harmless)
• gastrointestinal upset
• increase in blood glucose levels in individuals with diabetes (beetroot is high in sugar)
• increased risk of kidney stones

What difference does it make?

Studies have reported a 1-3% difference in controlled time trials.  This may not seem like a lot at first glance but for perspective, if you run a 5 km in 20 minutes, a two per cent improvement is 19:36. When many races are won and lost within fractions of a second, this is a big difference.

Preliminary research suggests that beetroot juice supplementation in different athletes can have positive effects on exercise performance, while more research needs to be done to be conclusive, there is little harm in giving beets a try.

References from the SIRC Collection: 

1. Beetroot Juice Seen to Lower BP. Tufts University Health & Nutrition Letter. April 2008;26(2):3.
2. Cermak N, Res P, Stinkens R, Lundberg J, Gibala M, Van Loon L. No Improvement in Endurance Performance After a Single Dose of Beetroot Juice. International Journal Of Sport Nutrition & Exercise Metabolism. December 2012;22(6):470-478.
3. Bordeau T. GOT BEETS?. Rowing News [serial online]. August 2012;19(7):41.
4. Hamilton A. Beat a PB with beetroot juice. Cycling Weekly. February 9, 2012;:37. 
5. JUST BEET IT. Triathlete. September 2010;(317):126.
On the Beetroot Juice. Joe Weider's Muscle & Fitness. October 2010;71(10):32.
6. Volpe S. Does Beetroot Juice Really Help With Endurance Performance?. ACSM's Health & Fitness Journal. January 2013;17(1):29-30.
7. Williams M. Nitrate Supplementation and Endurance Performance. Marathon & Beyond. September 2012;16(5):114-128.