Nitrate has been shown to improve exercise performance in healthy adults. Nitrate is metabolized to Nitrite and then Nitric Oxide. Nitric Oxide dilates blood vessels. Nitrate has been shown to reduce blood pressure, inhibit platelet aggregation (clumping) and improving irregularities in constriction and relaxation of blood vessel tissue. Nitrate may also reduce inflammation, make arteries less stiff and stiff. Healthy blood vessels and arteries allow more blood to be delivered to muscles during exercise. There have been a number of new articles on beets as performance enhancers. Beets are rich in anti-oxidants, but they are also high in nitrate. Nitrate can be metabolized to NO, which is a vaso-dilator (relaxes and widens blood vessels.) Nitrate from the diet, or nitrate supplementation may increase the response of type II muscle fibers to exercise.
Does Beetroot juice enhance exercise performance?
Given evidence that nitrate can increase muscle fiber activation, an experiment was undertaken to determine if beetroot juice would have similar effects. The research team compared normal nitrate-rich beet root juice against a beet-root juice that had had its nitrate removed. VO2 kinetics and exercise tolerance were recorded. VO2 max is a measure of the maximum volume of oxygen that an athlete can use. The exercise session was a double-step protocol. The beet root juice supplement resulted in a 22% increase in exercise tolerance and faster VO2 kinetics. This indicates that it is most likely the nitrate that is providing the effect rather than something else in the beet juice. Anti-oxidants for example.
VO2 maxis a measure of the maximum volume of oxygen a person can take in.
Until recently nitrate was thought to be primarily a problem. Nitrate interferes with iodine uptake, so it could contribute to iodine deficiency. There are also associations between high nitrate consumption and cancer. Associations among nitrate and cancers are strongest with nitrate from meat products. It is possible that something else in meat increases cancer rates. Many vegetables, besides beets, contain nitrate too. High vegetable intake is strongly associated with lower risk of cancers, heart disease and early death. If you are thinking of using beets as a performance enhancing vegetable it would be important to know how long it takes
- How long it takes for beets to be digested
- How long it takes for nitrate to be metabolized to NO (nitric oxide)
- When optimal levels are reached in the blood
- What optimal levels are.
There has not been enough research to know how much is enough or how much is too much. We do know that nitrate levels are highest 2-3 hours after a drinking beet juice. Conversion to nitrite and nitric oxide probably happens very quickly. The test subjects in the Breese study took the beet root juice supplement for three days before starting the exercise protocols.
The Power of Walnuts
This is a tougher subject than beets. Walnuts seem to lower inflammation. Less inflammation may mean less pain during endurance exercise. The effects of walnuts on endurance performance has been studied in mice (Kim & Kim 2013). In this study a group of mice was dosed with walnut extract. Mice were given Walnut Extract at 600 and 900 mg/kg. This is probably awful lot of walnuts. Another group was dosed with water and served as controls. All the mice were given a forced swim test. (Not a polite thing to do) Time to exhaustion was recorded. Walnut-dosed mice:
- Got the equivalent of a human eating 42 grams of walnuts once a day for 4 weeks. (About 1/3 of a cup)
- Swam longer
- Had lower lactate levels
- Had lower ammonia levels
- More glutamine
- More liver glycogen.
The conclusion was that walnuts increase endurance
Walnuts and beets may give you a competitive advantage. They may also make you healthier overall.
About the Author:
Andrea Kirk, MSc. PhD is a toxicologist affiliated with the University of Texas at Arlington’s Department of Chemistry and Biochemistry and the University of North Texas Health Sciences Center‘s School of Public Health. Dr. Kirk does research on human exposures to environmental contaminants and micro-nutrient intake and excretion.
Vanhatalo A, Bailey SJ, Blackwell JR, DiMenna FJ, Pavey TG, Wilkerson DP, Benjamin N, Winyard PG, & Jones AM (2010). Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. American journal of physiology. Regulatory, integrative and comparative physiology, 299 (4) PMID: 20702806
Lidder, S., & Webb, A. (2012). Vascular effects of dietary nitrate (as found in green leafy vegetables & beetroot) via the Nitrate-Nitrite-Nitric Oxide pathway British Journal of Clinical Pharmacology DOI: 10.1111/j.1365-2125.2012.04420.x Kim DI, & Kim KS (2013). Walnut extract exhibits anti-fatigue action via improvement of exercise tolerance in mice. Laboratory animal research, 29 (4), 190-5 PMID: 24396383
Breese BC, McNarry MA, Marwood S, Blackwell JR, Bailey SJ, & Jones AM (2013). Beetroot juice supplementation speeds O2 uptake kinetics and improves exercise tolerance during severe-intensity exercise initiated from an elevated metabolic rate. American journal of physiology. Regulatory, integrative and comparative physiology, 305 (12) PMID: 24089377