endurance exercise Archives - Health Tips From The Professor

Do Omega-3s Benefit Athletes?

March 11, 2025 by Dr. Steve Chaney

What Do These Recommendations Mean For Non-Athletes?

Author: Dr. Stephen Chaney

I have been following the research on omega-3s for athletes. But I have been reluctant to review that research in “Health Tips From the Professor” because:

Most of the studies are small.

Each study measures the effect of omega-3 supplementation on different aspects of exercise and fitness.

The dose of omega-3s used in the studies varies widely.

To the casual observer, the studies appear to come to conflicting conclusions.

I have been waiting for a respected organization to do an in-depth analysis of the published studies before commenting. The International Society of Sports Nutrition (ISSN) has just published such a study (R Jager et al, Journal of the International Society of Sports Nutrition, Issue 22 (1), 2441775, 2025) and have provided a position statement on the use of omega-3 supplements by athletes and active adults.

I would add that the ISSN is regarded as a trusted source of nutrition information for athletes.

Do Omega-3s Benefit Athletes?

The position of the ISSN is summarized below. What I like is they give the best recommendations based on current data and summarize the strength of the data behind each recommendation.

Statement 1: Athletes may be at higher risk of omega-3 insufficiency, and diets rich in omega-3s, including supplements, are effective for increasing omega-3 levels. In this category, they reported three key findings:

Omega-3s (ie EPA and DHA) are conditionally essential nutrients.

Fatty fish and omega-3 supplements are both effective in raising omega-3 levels.

Athletes belong to the groups at higher risk of omega-3 inadequacy.

My Comments:

- This conclusion was primarily based on studies with Division I college football players. More research is needed for high-level athletes in other sports.

- The reason for this omega-3 insufficiency was not discussed. However, I suspect it has to do with the recognition that high-level athletes need extra protein, and that fish is not usually included as a recommended source of additional protein for athletes.

- The average Omega-3 Index for the football players was 4.4% which is considered at high risk for heart disease. The authors of the ISSN report noted that previous studies have shown that around 1.4 g/day of EPA + DHA is recommended to increase the Omega-3 Index to an optimal 8%.

Statement 2: Omega-3 supplementation, particularly EPA and DHA, has been shown to enhance endurance capacity and cardiovascular function during aerobic-type exercise. In this category, they reported three key findings:

Omega-3s can improve cardiovascular dynamics during and after exercise as evidenced by enhanced red blood cell deformability, endothelial function, and heart rate recovery after exercise.

The incorporation of omega-3s into skeletal muscle membranes has been found to result in changes in muscle omega-3 composition, particularly in the sarcolemma, which is essential for muscle remodeling and/or regeneration after endurance exercise.

While these changes may help the heart pump more efficiently during exercise and muscle recover quicker after exercise, their direct impact on endurance performance remains inconsistent. More studies are needed.

My Comments:

- These studies should be interpreted through the lens of your desired outcome. High-intensity exercise is hard on the heart.

- If your goal is increased endurance the role of omega-3s is uncertain.

- If your goal is to have your heart operate more efficiently during aerobic exercise, omega-3 supplementation may be beneficial.

Statement 3: Omega-3 supplementation in combination with resistance training may improve strength in a dose- and duration-dependent manner. Specifically, they reported.

The incorporation of omega-3s into muscle cells may take a minimum of four weeks, and this is dose-dependent. It takes longer to optimize the omega-3 content in muscle cells at lower doses.

Once the omega-3 content of muscle cells has been optimized, it may take another three to six months until the improvement in strength plateaus.

My Comment:

- In short, don’t expect immediate results, but omega-3 supplementation may help increase muscle strength over the long haul.

Statement 4: Omega-3 supplementation may not confer a hypertrophic benefit in young adults. [In plain English they are saying that omega-3s may not stimulate any increase in muscle mass beyond that due to exercise alone for young adults.] They went on to say:

More high-quality research is warranted to investigate the effects of omega-3 supplementation on body composition.

My Comments:

- We need to remember that the ISSN recommendations are for serious athletes and may not apply to the rest of us.

- For example, the authors state that omega-3 supplementation may enhance an increase in muscle mass…

- - When protein intake is suboptimal.

- - For older adults who are experiencing age-related loss of muscle mass.

- - For people who have previous been inactive and are just beginning an exercise program.

- In other words, omega-3 supplements may help a lot of us non-athletes who are exercising to retain or increase muscle mass and strength.

Statement 5: Omega-3 supplementation may decrease subjective measures of muscle soreness following intensive exercise. In this category, they reported three key findings:

Omega-3 supplementation may attenuate indirect measures of muscle damage following intense exercise.

- For example, when muscles are damaged, they release muscle-specific enzymes such as creatine kinase and lactate dehydrogenase into the blood. Some studies have shown that omega-3s reduce the release of these muscle enzymes following intense exercise.

Omega-3 supplementation is equivocal in decreasing subjective measures of muscle soreness following intense exercise.

Omega-3 supplementation does not decrease measures of inflammation following exercise-induced muscle damage.

My Comments:

- Don’t count on omega-3 supplementation for reducing muscle soreness. But if you experience a decrease in muscle soreness, count it as an unexpected side benefit.

- The lack of an effect of omega-3s at reducing inflammation post exercise may be a good thing. Some experts think that the inflammatory response plays a role in stimulating muscle repair following exercise.

Statement 6: Omega-3 supplementation can positively affect various immune cell responses in athletic populations. In this category, they reported three key findings:

Many athletes develop a compromised immune system due to the stress of high training volumes, which can increase the likelihood of developing acute respiratory infections that negatively impact their ability to train and compete.

Omega-3 supplementation can affect various immune cell responses in non-athlete, clinical, and athletic populations.

Many clinical studies conducted in athletic populations have indicated that omega-3 supplementation can influence the production and regulation of various inflammatory cytokines, which may lead to physiological benefits for the athletes [An example would be a reduction in exercise-induced asthma].

My Comments:

- These recommendations are based on the effect of omega-3s on blood markers of immune health and inflammation. Clinical studies looking at the effect of omega-3s on exercise-induced respiratory infections or asthma are either nonexistent or conflicting.

- So, if you experience decreased respiratory infections or exercise induced asthma when you add omega-3s to your exercise regimen, consider it an unexpected side benefit.

Statement 7: Omega-3 supplementation may offer neuroprotective benefits in athletes exposed to repeated head impacts. In this category, they reported three key findings:

Omega-3s are crucial for optimal brain development and functioning.

Omega-3 supplementation can increase membrane fluidity, neurotransmitter synthesis and release, and cerebral blood flow.

In humans, a limited amount of evidence suggests that omega-3 supplementation may offer neuroprotective benefits in athletes following repeated head impacts.

My Comments:

This is an important recommendation. Long-term cognitive decline, associated with repetitive traumatic brain injuries, is a serious concern for many high-impact sports. And there are no established protocols to prevent cognitive decline from occurring.

I have covered this in more detail in a previous issue of “Health Tips From the Professor”.

Statement 8: Omega-3 supplementation is associated with improved sleep quality. In this category, they reported three key findings:

Omega-3 supplementation has been linked to improved sleep quality in some studies.

Omega-3 supplementation may help sleep quality due to anti-inflammatory properties and effects on neurotransmitters like dopamine and serotonin, a precursor of melatonin, which helps regulate sleep-wake cycles.

However, inconsistency of results indicates more research is needed to fully understand the relationship between omega-3 supplementation and sleep.

My Comment:

If you experience improved sleep when you add omega-3s to your exercise regimen, consider it an unexpected side benefit.

Summary Of ISSN Recommendations

A strength of the ISSN recommendations is that they acknowledge where there is good agreement in the studies supporting their recommendations and where the data are scanty or conflicting. Based on the studies behind each recommendation, I would divide their recommendations into three categories.

#1: Recommendations backed by a limited number of strong studies. Confidence in these recommendations can be improved with more studies, but the recommendations are strong. These include:

Statement 1: Athletes are at higher risk of omega-3 insufficiency, and diets rich in omega-3s, including supplements, are effective for increasing omega-3 levels.

Statement 4: Omega-3 supplementation in combination with resistance training may improve strength in a dose- and duration-dependent manner.

#2: Recommendations where the evidence is weak for athletes, but valuable for non-athletes. I will discuss those in more detail below. These include:

Statement 2: Omega-3 supplementation has been shown to enhance endurance capacity and cardiovascular function during aerobic-type exercise.

Statement 3: Omega-3 supplementation may not confer a muscle hypertrophic benefit [increase in muscle mass] in young adults.

#3: Recommendations that are weak and/or conflicting. These fall in the category of “don’t count on it. But if you do experience it, consider it an unexpected side-benefit of omega-3 supplementation”. These include”

Statement 5: Omega-3 supplementation may decrease subjective measures of muscle soreness following intense exercise.

Statement 6: Omega-3 supplementation can positively affect various immune cell responses in athletic populations.

Statement 8: Omega-3 supplementation is associated with improved sleep quality.

Finally, the effect of omega-3 supplementation on preventing the cognitive consequences of repeated head trauma (Statement 7) is a very important topic. I have covered this in more detail in a previous issue of “Health Tips From the Professor”.

What Do These Recommendations Mean For Non-Athletes?

As their name (International Society of Sports Nutrition) suggests, their recommendations are meant primarily for athletes. But what about those of us who are not athletes but work out on a regular basis for fitness, weight management, maintaining muscle mass as we age, or other reasons?

In general, the recommendations apply equally well for athletes and non-athletes with a couple of caveats:

1) Dosage: Some of the studies with athletes were done with 3 to 6 grams/day of omega-3s. However, in most cases similar results were obtained 1-2 grams/day. Since 1-2 grams/day is enough to increase omega-3 levels to optimal for 90% of the population, I would recommend this dosage rather than the higher doses used in some of the studies with athletes.

2) Different Priorities for athletes and non-athletes: As I described earlier, this applies to two of the ISSN recommendations, namely:

Statement 2: Omega-3 supplementation has been shown to enhance endurance capacity and cardiovascular function during aerobic-type exercise. As I said above:

- Young athletes are primarily interested in endurance, and the evidence for an endurance benefit for omega-3 supplementation is weak.

- However, the rest of us are more interested in how efficiently our heart is functioning during high-intensity exercise, especially as we age. And the evidence for that benefit is strong.

Statement 3: Omega-3 supplementation may not confer a hypertrophic muscle benefit [increase in muscle mass] in young adults.

- That is a true statement for young, high-performance athletes who are consuming high protein diets. For the rest of us, we need to remember the authors of the ISSN report stated that omega-3 supplementation may enhance an increase in muscle mass:

- - When protein intake is suboptimal.

- - For older adults who are experiencing age-related loss of muscle mass.

- - For people who have previous been inactive and are just beginning an exercise program.

The Bottom Line

The International Society For Sports Nutrition (ISSN) is recognized as a trusted source of nutrition advice for athletes. They recently reviewed the literature on the value of omega-3 supplementation for athletes and released a position paper with eight statements (recommendations).

I have divided these recommendations into 3 categories:

Recommendations backed by strong data.

Recommendations backed by weak data.

Recommendations that have different significance for high-performing athletes and the rest of us.

For more details about the ISSN recommendations and what they mean for you, 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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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Is The Keto Diet Best For Endurance Exercise?

October 27, 2020 by Dr. Steve Chaney

Where Do Food Myths Come From?

I don’t need to tell you that the keto diet is popular right now. It is touted for weight loss, mental sharpness, and improved health. I discuss the accuracy of those claims in my book, “Slaying the Food Myths”.

Perhaps more surprising has been the adoption of the keto diet by so many endurance athletes. As I point out in my book, there is a kernel of truth for that idea. Fats and ketone bodies are a very efficient energy source for low to moderate intensity exercise, and we have a virtually unlimited source of stored fat that can be converted to ketone bodies.

However, I always add this caveat, “The keto diet is perfect for endurance exercise – as long as you don’t care how fast you get there”. That is because high intensity exercise requires muscle glycogen stores, which come from the carbohydrates we eat. When you cut carbs from the diet, you deplete your glycogen stores.

And, if you are running a marathon and you want to sprint to the finish line, you will need those muscle glycogen stores. Or, if you are in a cycling event and you want to power up a mountain, you will need those glycogen stores.

Of course, you are probably asking, “Why do so many endurance athletes swear by the keto diet?” There is a dirty little secret behind athlete endorsements. I’m not talking about the money that top athletes get paid for endorsements, although that is also a problem.

I’m talking about the testimonials you hear from your friend who runs marathons or your personal trainer. Unfortunately, testimonials from athletes are notoriously unreliable. The problem is that the placebo effect approaches 70% for athletes.

Competitive athletes are strong willed. If they think a diet or sports nutrition product will help them, they will themselves to a higher level of performance. And this happens subconsciously. They aren’t even aware that their mind is influencing their performance.

So, just because your favorite athlete endorses the keto diet doesn’t mean it is the perfect diet for you. Testimonials can be very misleading.

The important question to ask is, “Do clinical studies support the keto diet as the best diet for endurance exercise?” But, before I answer that question, let me frame the question by asking. “Where do food myths come from?” because the belief that keto diets are best for endurance exercise is a classic food myth.

Where Do Food Myths Come From?

I discussed this question at length in my book, “Slaying The Food Myths”. Let me summarize it briefly here.

Secrets Only Scientists Know: First you need to know the secrets only scientists know. Here are the top 2:

#1: Scientists design their studies to disprove previous studies. There is no glory for being the 10^th person to confirm the existing paradigm. The glory comes from being the first to show the existing paradigm might be wrong. While this may seem to be a contrary approach, it is actually the strength of the scientific method.

However, it means that there will be published clinical studies on both sides of every issue.

#2: Every study has its flaws. There is no perfect study.

This is why the scientific community doesn’t base their recommendations on 2 or 3 published studies. We wait until there are 10 to 20 good quality studies and base our recommendations on what 90% of them show.

Now, let me contrast the scientific approach with how food myths are born.

Where Do Food Myths Come From? Food myths usually originate on blogs or websites. Often the articles are written by people with no scientific credentials. But some of them are written by doctors (I will call them Dr. Strangelove to “protect the guilty”). The articles they write have these things in common:

The articles are based on the biases of the author. No effort is made to look at the other side of the story.

The authors “cherry pick” studies that support their bias and ignore studies that contradict them.

They use scientific-sounding mumbo jumbo to make their hypothesis sound credible.

Their articles are usually spectacular. For example, they say things like, “A particular diet, food, or supplement will either cure you or kill you”, and/or “The medical community is hiding the truth from you.”

They never let the facts get in the way of a good story.

Since the idea sounds credible it is picked up by other blogs and websites without any fact checking (social media at its worst). Once it has been repeated often enough, it becomes generally accepted as true. It becomes a food myth. From that point on, studies that disprove the myth are often ignored.

How do you know whether a common belief is true, or just another myth? The only way to be sure is to take a balanced look at all the clinical studies, not just the studies that support the belief.

That is what the authors of a recent review paper (CP Bailey and E Hennessy, Journal of the international Society of Sports Nutrition, 17, Article number: 33, 2020) did for the belief that the keto diet is the best diet for endurance exercise.

Is The Keto Diet Best For Endurance Exercise?

Before I discuss the findings of the review article, there are two things you should know:

#1: There is little scientific research on the effectiveness of the keto diet on endurance exercise. After an exhaustive search of the literature, the authors were only able to find 7 published studies on the topic.

#2:Most sports nutrition studies are of poor quality. In general, they are very small studies, are of short duration, and do not use common test procedures to measure a successful outcome. These studies on keto diets were no different. For example:

- The number of subjects in these studies ranged from 5 to 29 (average = 14).

- The duration of time on the diet in these studies ranged from 3 weeks to 12 weeks (average = 5 weeks).

- Tests used to measure the effectiveness of specific diets on endurance exercise were VO2max (the maximum amount of oxygen you can utilize during exercise), Time to exhaustion (how long you can exercise before you are exhausted), Rating of perceived exertion (feeling of fatigue at the end of the exercise), Race time (time required to complete an event), and Peak power output during the event.

- Four studies used a treadmill to simulate endurance exercise. The other three used a stationary bike.

- Five of the studies compared the keto diet to a high carbohydrate diet. Two studies used the keto diet only.

The results were all over the place:

Two studies reported an increase in VO2max for both the keto diet and the high carbohydrate diet. One study reported a decrease in VO2max for both diets. The other studies reported no change in VO2max. In short, there was no difference between the diets for VO2max.

One study reported a decrease in race time for the high carbohydrate diet and a non-significant increase in race time for the keto diet. Two other studies reported no effect of either diet on race time. In short, one study suggested the high carbohydrate diet was more effective at shortening race time. The other two studies found no effect of either diet.

Two studies showed an increase in time to exhaustion for both diets. One study showed a decrease in time to exhaustion for the keto diet (participants got tired more quickly). That study did not include the high carbohydrate diet for comparison. In short, there was no clear difference between the two diets for time to exhaustion.

One study showed that the group on the keto diet reported a higher rating of perceived exertion (were more tired) at the end of the endurance event than the group on the high carbohydrate diet. Another study found no difference between the two diets. In short, one study suggested the high carbohydrate diet was better with respect to perceived exertion (tiredness) at the end of the endurance event. Another study found no difference between the two diets.

One study reported that peak power was significantly greater for the group on the keto diet than the group on the high carbohydrate diet. One of the studies with the keto group reported that peak power decreased for 4 out of 5 subjects on the keto diet. In short, one study suggested that the keto diet was more effective at increasing peak power than the high carbohydrate diet. Another study suggested the keto diet decreased peak power.

The authors concluded: “When compared to a high carbohydrate diet, there are mixed findings for the effect of the keto diet on endurance performance…The limited number of published studies point to a need for more research in this field.” I would add that we need larger, better designed studies, with common measures of exercise performance.

What Does This Mean For You?

You may be wondering why I even bothered to talk about such poor-quality studies and a review that could not provide a definitive answer. In fact, that is exactly my point.

This is characteristic of the kind of “evidence” that Dr. Strangelove and his buddies present to support whatever food myth they are featuring on their website. They don’t know how to distinguish good studies from bad studies, and they “cherry pick” only the studies that support their food myth.

So, if you believe that the keto diet is best for endurance exercise, you can “cherry pick” the one published clinical study that supports your belief. You just need to ignore the other 6 published studies.

And, if you believe that a high carbohydrate diet is better for endurance exercise than the keto diet, you can “cherry pick” two clinical studies that support your belief. You just need to ignore the other 5 published clinical studies.

None of the studies are high-quality studies, and the effect of either diet on endurance exercise in these studies is miniscule.

In short, there is no convincing evidence that the keto diet is best for endurance exercise. Or, put another way, we do not have enough evidence to elevate that belief from a food myth to a recommendation we can confidently make for an endurance athlete.

The Bottom Line

A recent publication conducted an impartial review of the evidence for and against the popular belief that a keto diet is the best diet for endurance exercise. The review found only 7 poor-quality studies on this topic in the scientific literature, and the results of those studies were all over the map.

One study reported the keto diet was better than a high carbohydrate diet for endurance exercise.

Two studies reported that the high carbohydrate diet was better.

The other 4 studies were inconclusive.

None of the studies found a significant effect on endurance performance by either diet.

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.