Are There Health Benefits of Beetroot Juice for Athletes?

Written by Dr. Steve Chaney on . Posted in current health articles, Exercise, Food and Health

Should You Add Beetroot Juice To Your Training Diet?

Author: Dr. Stephen Chaney

 

health benefits of beetroot juiceWhen I saw the headline “Beetroot Juice May Boost Aerobic Fitness For Swimmers” I did a double take. Could something as simple as eating more beets actually improve exercise performance? Are there real health benefits of beetroot juice for athletes?  So I looked up recent papers on the topic.  But, before I review those I should give you a little science behind the idea that beetroot juice might affect performance.

The Science Behind Beetroot Juice And Exercise

Nitric oxide is a colorless, odorless gas that serves as an important signaling molecule in the human body. Among its many beneficial effects is increased blood flow to muscle. This increased blood flow appears to be preferentially distributed to the type 2 muscle fibers which support moderate to high intensity exercise. Thus, nutrients that enhance nitric oxide levels might be expected to improve moderate to high intensity exercise.

There are two naturally occurring pathways for producing nitric oxide in the body. The first pathway utilizes arginine, an amino acid found in dietary protein. The second pathway utilizes nitrates, which are found in fruits and vegetables. The best dietary sources of nitrates are beetroot, spinach and other leafy green vegetables.

Arginine has been widely used in sports supplements for some time to enhance performance. However, clinical studies on arginine have been mixed, with some showing small enhancements in performance and others showing no significant effect. Most experts now think that the benefits of arginine are primarily seen with untrained or moderately trained athletes (people like you and me) – not for highly trained or elite athletes.

It is logical that natural sources of nitrates, such as beetroot juice, would have a similar beneficial effect on exercise, but it is only in the last couple of years that scientists have started to evaluate that possibility. I looked up six recent publications for this review.

Does Beetroot Juice Improve Exercise Performance?

Study # 1: In this study (Bailey et al, J. Appl. Physiol., 107: 1144-1155, 2009) untrained men (aged 19-38) were given beetroot juice or a placebo for 6 days and then put through a series moderate-intensity and severe-intensity step exercise tests on days 4-6. The amount of oxygen required to support the moderate intensity exercise was decreased by 19% in the beetroot juice group. For severe intensity exercise, the amount of oxygen needed to support the exercise was decreased by 23% and the time to exhaustion was increased by 16% in the beetroot juice group. Those effects were statistically significant.

Study # 2: In this study (Kelly et al, Am. J. Physiol. Regul. Integr. Comp. Physiol., 304: R73-83, 2013) untrained older adults (aged 60-70) were given beetroot juice or a placebo for 3 days and then put through a treadmill exercise test. Resting blood pressure and oxygen uptake kinetics during exercise were significantly improved in the beetroot group.

Study # 3: In this study (Breese et al, Am. J. Physiol. Regul. Integr. Comp. Physiol., 305: R1441-14505, 2013) physically active subjects were given beetroot juice or a placebo for 6 days and then put through a double step exercise protocol involving a transition from stationary to moderate intensity exercise followed immediately by a transition from moderate intensity to severe intensity exercise. No significant differences were observed between the beetroot juice group and the placebo group during the transition from stationary to moderate intensity exercise. However, for the transition from moderate intensity to high intensity exercise both efficiency of oxygen utilization and endurance were increased by 22% in the beetroot juice group.

does beetroot juice improve exercise performance

Study # 4: In this study (Pinna et al, Nutrients, 6: 605-615, 2014) moderately trained male master swimmers were given beetroot juice for 6 days. Swimming tests were conducted at the beginning and end of the 6 day period. After 6 days of beetroot juice supplementation, the workload was increased by 6% and the energy cost was decreased by 12% when the swimmers were performing at their maximal capacity.

Studies # 5 & 6: These studies (Lanceley et al, British Journal of Sports Medicine, 47: doi: 10.1136/bjsports-2013-093073.8; Hoon et al, Int. J. Sports Physiol. Perform., 9: 615-620, 2014) were both done with highly trained athletes and no significant improvement in performance was observed. This is fully consistent with previous studies utilizing arginine supplements.

In short, these studies suggest that beetroot juice is similar to arginine supplements in that:

  • It improves exercise performance at moderate to severe exercise levels, but not at low exercise levels.
  • It improves exercise performance for untrained or moderately trained athletes, but not for highly trained athletes.
  • The effects are modest. However, you should keep in mind that even a 20% increase in endurance during high intensity exercise can result in a significant incremental increase in muscle mass if the exercise is repeated on a regular basis.

What Are The Strengths & Weaknesses Of These Studies?

Strengths: The strengths of these studies are:

  • Most of the studies were double-blind, placebo controlled studies
  • The studies were internally consistent and were consistent with previous studies done with arginine supplements.

Weaknesses: The weaknesses of these studies are:

  • The studies were all very small and were of short duration. Larger, longer term studies are needed to validate the results of these studies.

So, are there health benefits of beetroot juice for athletes?

The Bottom Line:

  1. Nitrates and arginine are both converted to nitric oxide in the body, so it is plausible that they will have similar effects.
  1. Arginine supplements have been around for years and appear to have a modest affect on exercise performance with untrained and moderately trained athletes, but not with highly trained athletes. This is most likely because one of the effects of training is to increase blood supply to the muscles. Thus, highly trained athletes already have enhanced blood flow to the muscles, and the effect of arginine supplementation on blood flow is less noticeable.
  1. Nitrate supplements are just starting to be evaluated for their effects on exercise performance. Most of the research so far has been with beetroot juice, but the results should be similar for any naturally sourced nitrate supplement.
  1. The clinical studies published so far suggest that nitrate supplements are similar to arginine supplements in that they have a modest effect on high intensity exercise in untrained and moderate trained athletes (people like most of us). They appear to have little or no effect for highly trained athletes. Thus, the effect of nitrate supplements on exercise appears to be very similar to the effect of arginine supplements on exercise.
  1. Most of the studies performed to date have been small, short duration studies. They need to be validated by larger, longer term studies.
  1. If the effects of nitrate supplementation published to date are accurate they should be most beneficial for weight training and high intensity exercise because even modest increases in exercise endurance can result in an incremental increase in muscle mass and strength over time.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Trackback from your site.

Leave a comment

Recent Videos From Dr. Steve Chaney

READ THE ARTICLE
READ THE ARTICLE

Latest Article

Is Our Microbiome Affected By Exercise?

Posted November 6, 2018 by Dr. Steve Chaney

Microbiome Mysteries

Author: Dr. Stephen Chaney

is our microbiome affected by exerciseIn a recent post,  What is Your Microbiome and Why is it Important,  of “Health Tips From The Professor” I outlined how our microbiome, especially the bacteria that reside in our intestine, influences our health. That influence can be either good or bad depending on which species of bacteria populate our gut. I also discussed how the species of bacteria that populate our gut are influenced by what we eat and, in turn, influence how the foods we eat are metabolized.

I shared that there is an association between obesity and the species of bacteria that inhabit our gut. At present, this is a “chicken and egg” conundrum. We don’t know whether obesity influences the species of bacteria that inhabit our gut, or whether certain species of gut bacteria cause us to become obese.

Previous studies have shown that there is also an association between exercise and the species of bacteria that inhabit our gut. In particular, exercise is associated with an increase in bacteria that metabolize fiber in our diets to short chain fatty acids such as butyrate. That is potentially important because butyrate is a primary food source for intestinal mucosal cells (the cells that line the intestine). Butyrate helps those cells maintain the integrity of the gut barrier (which helps prevent things like leaky gut syndrome). It also has an anti-inflammatory effect on the immune cells that reside in the gut.

However, associations don’t prove cause and effect. We don’t know whether the differences in gut bacteria were caused by differences in diet or leanness in populations who exercised regularly and those who did not. This is what the present study (JM Allen et al, Medicine & Science In Sports & Exercise, 50: 747-757, 2018 ) was designed to clarify.  Is our microbiome affected by exercise?

 

How Was The Study Designed?

is our microbiome affected by exercise studyThis study was performed at the University of Illinois. Thirty-two previously sedentary subjects (average age = 28) were recruited for the study. Twenty of them were women and 12 were men. Prior to starting the study, the participants filled out a 7-day dietary record. They were asked to follow the same diet throughout the 12-week study. In addition, a dietitian designed a 3-day food menu based on their 7-day recall for the participants to follow prior to each fecal collection to determine species of gut bacteria.

The study included a two-week baseline when their baseline gut bacteria population was measured, and participants were tested for fitness. This was followed by a 6-week exercise intervention consisting of three supervised 30 to 60-minute moderate to vigorous exercise sessions per week. The exercise was adapted to the participant’s initial fitness level, and both the intensity and duration of exercise increased over the 6-week exercise intervention. Following the exercise intervention, all participants were instructed to maintain their diet and refrain from exercise for another 6 weeks. This was referred to as the “washout period.”

VO2max (a measure of fitness) was determined at baseline and at the end of the exercise intervention. Stool samples for determination of gut bacteria and concentrations of short-chain fatty acids were taken at baseline, at the end of the exercise intervention, and again after the washout period.

In short, this study divided participants into lean and obese categories and held diet constant. The only variable was the exercise component.

 

Is Our Microbiome Affected By Exercise?

is our microbiome affected by exercise fitnessThe results of the study were as follows:

  • Fitness, as assessed by VO2max, increased for all the participants, and the increase in fitness was comparable for both lean and obese subjects.
  • Exercise induced a change in the population of gut bacteria, and the change was comparable in lean and obese subjects.
  • Exercise increased fecal concentrations of butyrate and other short-chain fatty acids in the lean subjects, but not in obese subjects.
  • The exercise-induced changes in gut bacteria and short-chain fatty acid production were largely reversed once exercise training ceased.

The authors concluded: “These findings suggest that exercise training induces compositional and functional changes in the human gut microbiota that are dependent on obesity status, independent of diet, and contingent on the sustainment of exercise.” [Note: To be clear, the exercise-induced changes in both gut bacteria and short-chain fatty acid production were independent of diet and contingent on the sustainment of exercise. However, only the production of short-chain fatty acids was dependent on obesity status.]

 

What Does This Study Mean For You?

is our microbiome affected by exercise gut bacteriaThere are two important take home lessons from this study.

  • With respect to our gut bacteria, I have consistently told you that microbiome research is an emerging science. This is a small study, so you should regard it as the beginning of our understanding of the effect of exercise on our microbiome rather than conclusive by itself. It is consistent with previous studies showing an association between exercise and a potentially beneficial shift in the population of gut bacteria.

The strength of the study is that it shows that exercise-induced changes in beneficial gut bacteria are probably independent of diet. However, it is the first study to look at the interaction between obesity, exercise and gut bacteria, so I would interpret those results with caution until they have been replicated in subsequent studies.

  • With respect to exercise, this may be yet another reason to add regular physical activity to your healthy lifestyle program. We already know that exercise is important for cardiovascular health. We also know that exercise increases lean muscle mass which increases metabolic rate and helps prevent obesity. There is also excellent evidence that exercise improves mood and helps prevent cognitive decline as we age.

Exercise is also associated with decreased risk of colon cancer and irritable bowel disease. This effect of exercise has not received much attention because the mechanism of this effect is unclear. This study shows that exercise increases the fecal concentrations of butyrate and other short-chain fatty acids. Perhaps, this provides the mechanism for the interaction between exercise and intestinal health.

 

The Bottom Line

A recent study has reported that:

  • Exercise induces a change in the population of gut bacteria, and the change was comparable in lean and obese subjects.
  • Exercise causes an increase in the number of gut bacteria that produce butyrate and other short-chain fatty acids that are beneficial for gut health.
  • These effects are independent of diet, but do not appear to be independent of obesity because they were seen in lean subjects but not in obese subjects.
  • The exercise-induced changes in gut bacteria and short-chain fatty acid production are largely reversed once exercise training ceases.

The authors concluded: “These findings suggest that exercise training induces compositional and functional changes in the human gut microbiota that are dependent on obesity status, independent on diet, and contingent on the sustainment of exercise.”

For more details and my interpretation of the data, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

UA-43257393-1