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.

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Does Protein Supplement Timing Matter?

Posted May 15, 2018 by Dr. Steve Chaney

How Do You Gain Muscle Mass & Lose Fat Mass?

Author: Dr. Stephen Chaney

 

protein supplement timingMost of what you read about protein supplements on the internet is wrong. That is because most published studies on protein supplements:

  • Are very small
  • Are not double blinded.
    • Both the subjects and the investigators knew who got the protein supplement.
  • Are done by individual companies with their product.
    • You have no idea which ingredients are in their product are responsible for the effects they report.
    • You have no idea how their product compares with other protein products.
    • There is no standardization with respect to the amount or type of protein or the addition of non-protein ingredients.

Because of these limitations there is a lot of misleading information on the benefits of protein supplements timing and maximal benefit. Let’s start by looking at why people use protein supplements. Let’s also look at what is generally accepted as true with respect to the best supplement timing.

There are 4 major reasons people consume protein supplements:

  • Enhance the muscle gain associated with resistance training: In this case, protein supplements are customarily consumed concurrently with the workout.
  • Preserve muscle and accelerate fat loss while on a weight loss diet: In this case, protein supplements are customarily consumed with meals or as meal replacements.
  • Provide a healthier protein source. In this case, protein supplements are customarily consumed with meals in place of meat protein.
  • Prevent muscle loss associated with aging or illness. There is no customary pattern associated with this use of protein supplements.

How good are the data supporting the customary timing of protein supplementation? The answer is: Not very good. The timing is based on a collection of weak studies which do not always agree with each other.

The current study  (J.L. Hudson et al, Nutrition Reviews, 76: 461-468, 2018 ) was designed to fill this void in our knowledge. It is a meta-analysis that compares all reasonably good studies that have looked at the effect of protein supplement timing on weight gain or loss, lean muscle mass gain, fat loss, and the ratio of lean muscle mass to fat mass.

How Was The Study Done?

The authors started by doing a literature search of all studies that met the following criteria:

  • The study was a randomized control trial with parallel design. This means that study contained a control group. It does not mean that the investigators or subjects were blinded with respect to which subjects used a protein supplement and which did not.
  • The subjects were engaged in resistance training.
  • The study lasted 6 weeks or longer.
  • Reliable methods were used to measure body composition (lean muscle mass and fat mass).
  • The subjects were healthy and at least 19 years old.
  • There was no restriction on the food the subjects consumed.

The authors started with 2074 published studies and ended up with 34 that met all their criteria. They then separated the studies into two groups – those in which the protein supplements were used with meals and those in which the protein supplements were used between meals.

Both groups were diverse.

  • Group 1 included subjects who consumed their protein supplement with their meal and those who consumed their protein supplement as a meal replacement.
  • Group 2 included subjects who consumed their protein supplement concurrent with exercise (usually immediately after exercise) and those who consumed their protein supplement at a fixed time of day not associated with exercise.

Does Protein Supplement Timing Matter?

 

protein supplement timing workoutsBecause the individual studies were very diverse in the way they were designed, the authors could not calculate a reliable estimate of how much lean muscle mass was increased or fat mass was decreased. Instead, they calculated the percentage of studies showing an increase in lean muscle mass or a decrease in fat mass.

When the authors compared protein supplements consumed with meals versus protein supplements consumed between meals:

  • Weight gain was observed in 56% of the studies of protein supplementation with meals compared to 72% of the studies of protein supplementation between meals. In other words, protein supplements consumed with meals were less likely to lead to weight gain than protein supplements consumed between meals.
  • An increase in lean muscle mass was observed in 94% of the studies of protein supplementation with meals compared to 90% of the studies of protein supplementation between meals. In other words, timing of protein supplementation did not matter with respect to increase in muscle mass.
  • A loss of fat mass was observed in 87% of the studies of protein supplementation with meals compared to 59% of the studies of protein supplementation between meals. In other words, protein supplements consumed with meals were more likely to lead to loss of fat mass.
  • An increase in the ratio of lean muscle mass to fat mass was observed in 100% of the studies of protein supplementation with meals compared to 87% of the studies of protein supplementation between meals. In short, protein supplements consumed with meals were slightly more likely to lead to an increase in the ratio of lean muscle mass to fat mass.

The following seem to suggest protein supplement timing matters:

The authors pointed out that their findings were consistent with previous studies showing that when protein supplements are consumed with a meal they displace some of the calories that otherwise would have been consumed. Simply put, people naturally compensate by eating less of other foods.

In contrast, the authors stated that previous studies have shown that when foods, especially liquid foods, are consumed as snacks (between meals), people are less likely to compensate by reducing the calories consumed in the next meal.

The others concluded: “Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean [muscle] mass.”

What Are The Limitations Of The Study?

Meta-analyses such as this one, are only as good as the studies included in the meta-analysis. Unfortunately, most sports nutrition studies are very weak studies. Thus, this meta-analysis is a perfect example of the “Garbage In: Garbage Out (GI:GO)” phenomenon.

For example, let’s start by looking at what the term “protein supplement” meant.

  • Because the studies were done by individual companies with their product, the protein supplements in this meta-analysis:
    • Included whey, casein, soy, bovine colostrum, rice or combinations of protein sources.
    • Were isolates, concentrates, or hydrolysates.
    • Contained various additions like creatine, amino acids, and carbohydrate.
  • As I discuss in my book, Slaying the Food Myths, previous studies have shown that optimal protein and leucine levels are needed to maximize the increase in muscle mass and decrease in fat mass associated with resistance exercise. However, neither protein nor leucine levels were standardized in the protein supplements included in this meta-analysis.
  • Previous studies have shown that protein supplements that have little effect on blood sugar levels (have a low glycemic index) are more likely to curb appetite. However, glycemic index was not standardized for the protein supplements included in this meta-analysis.

protein supplement timing workout peopleIn short, the conclusions of this study might be true for some protein supplements, but not for others. We have no way of knowing.

We also need to consider the composition of the two groups.

  • Protein supplements used as meal replacements are more likely to decrease weight and fat mass than protein supplements consumed with meals. Yet, both were included in group 1.
  • Some studies suggest that protein supplements consumed concurrent with resistance exercise are more likely to increase muscle mass than protein supplements consumed another time of day. Yet, both are included in group 2. We also have no idea whether the meals with protein supplements in group 1 were consumed shortly after exercise or at an entirely different time of day.

This was the most glaring weakness of the study because it was completely avoidable. The authors could have grouped the studies into categories that made more sense.

In other words, there are multiple weaknesses that limit the predictive power of this study.

What Can We Learn From This Study?

Despite its many limitations, this study does remind us that protein supplements do have calories. This is of relatively little importance for people whose primary goal is to increase lean muscle mass.

However, most of us are using protein supplements to lose weight or to increase our lean mass to fat mass ratio. Simply put, we are either trying to lean out (shape up) or lose weight. And, we want to lose that weight primarily by getting rid of excess fat. For us, calories do matter. With that in mind:

  • If we are consuming a protein supplement immediately after exercise or between meals we probably should make a conscious effort to reduce our daily caloric intake elsewhere in our diet.
  • Alternatively, we could consume the protein supplement with a meal, but time the meal so it occurs shortly after exercise.

 

The Bottom Line:

 

A recent study looked at the optimal timing of protein supplements consumed by subjects who were engaged in resistance exercise. Specifically, the study compared protein supplements consumed with meals versus protein supplements consumed between meals on weight, lean muscle mass, fat mass, and the ratio of lean muscle mass to fat mass. The study reported:

  • Protein supplements consumed with meals were less likely to lead to weight gain than protein supplements consumed between meals.
  • Timing of protein supplementation did not matter with respect to increase in muscle mass.
  • Protein supplements consumed with meals were more likely to lead to loss of fat mass.
  • Protein supplements consumed with meals were slightly more likely to lead to an increase in the ratio of lean mass to fat mass.

The authors pointed out that their findings were consistent with previous studies showing that when a protein supplement was consumed with a meal it displaces some of the calories that would have been otherwise consumed. Simply put, people naturally compensate by eating less of other foods.

In contrast, the authors said that previous studies have shown that when foods, especially liquid foods, are consumed as snacks (between meals), people are less likely to compensate by reducing the calories consumed in the next meal.

As discussed in the article above, the study has major weaknesses. However, despite its many weaknesses, this study does remind us that protein supplements do have calories. This is of relatively little importance for people whose primary goal is to increase lean muscle mass.

However, for those of us who are using protein supplements to lose weight or to increase our lean mass to fat mass ratio, calories do matter.  With that in mind:

  • If we are consuming a protein supplement immediately after exercise or between meals we probably should make a conscious effort to reduce our daily caloric intake elsewhere in our diet.
  • Alternatively, we could consume the protein supplement with a meal, but time the meal so it occurs shortly after exercise.

For more details, 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.

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