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.

Do Collagen Supplements Build Muscle?

August 24, 2021 by Dr. Steve Chaney

Could Collagen Supplements Make You Leaner?

Author: Dr. Stephen Chaney

Collagen supplements have been considered “vanity products”. Their largest market is people who want to have younger, more beautiful skin. And for many people, collagen delivers on this promise.

However, collagen plays many other roles in the body. It also helps rebuild tendons and ligaments. Many people take collagen supplements to reduce joint pain.

But could collagen supplements coupled with resistance training also build muscle and reduce fat? If so, that would be huge.

A recent study (D Zdzieblik et at, British Journal of Nutrition, 114: 1237-1245, 2015) suggested collagen supplements may do just that. This study showed that a collagen supplement plus resistance training increased lean muscle mass and decreased fat mass in elderly men (average age = 72).

If this finding is duplicated in future studies, it has significant health implications. Both men and women in their 70s lose muscle mass at a rapid rate (a process called sarcopenia). Anything that slows or reverses this process has the potential to extend high quality life and prolong their golden years.

But what about younger adults? Could a collagen supplement plus resistance training also help them build muscle and lose fat? This study (D Zdzieblik et at, International Journal of Environmental Research and Public Health, 18: 4837-4855, 2021) was designed to answer that question.

It was a randomized, placebo-controlled study comparing 15 g of collagen peptides with 15 g of whey protein, and a placebo (silicon dioxide).

How Was This Study Done?

The study recruited 120 middle-aged (average age = 50), overweight (average BMI = 30) men who were untrained (<60 minutes of exercise per week over the previous year). [In other words, the study recruited middle-aged couch-potatoes.]

The participants were asked to fill out a three-day diet analysis at the beginning and end of the 12-week study with the assistance of a nutritionist.

Average caloric intake was 2,600 calories/day.

Average protein intake was 104 grams/day. That is 30% higher than the recommended protein intake for men of that age and weight.

The macronutrient content of the diet was 16% protein, 37% fat, and 43% carbohydrate.

These values were not significantly different between groups and did not change during the study.

All participants participated in a one-hour training program three times per week. The training began with a 10-minute cardio exercise to warm up. That was followed by a three-set program consisting of horizontal leg presses (both legs), reverse crunches, lat-pull exercise, sit-ups, and chest presses with 1 to 2 min rest periods between sets. The intensity of exercise was gradually increased over the 12-week study.

The participants were randomly divided into three groups. After each workout they were given sachets containing 15 g of collagen peptides, 15 g of whey isolate, or 15 g of silicon dioxide (placebo). They were instructed to dissolve the powder in 8 ounces of water and drink it within one hour of the workout. They were also given the same sachets and instructed to take them at the same time of day for the days they were not working out.

Finally, the participants were instructed not to change their diet or physical activity apart from the intake of the powder in the sachets they were given and the one-hour training sessions.

Do Collagen Supplements Build Muscle?

All three groups had statistically significant:

Increases in percent lean muscle mass.

Decreases in percent fat mass.

Increases in leg muscle strength.

No surprises here. If you take a group of middle-aged couch-potatoes and put them in a strength training program, you will see increases in lean muscle mass, decreases in fat mass, and increases in muscle strength.

The real question was what was the effect of the collagen and whey protein supplements? This is where the results got really interesting.

The collagen peptide supplement gave a significantly greater increase in lean muscle mass and decrease in fat mass than the placebo. The increase in leg muscle strength was also greater than the placebo, but this difference was not statistically significant.

The whey protein supplement also increased lean muscle mass and decreased fat mass compared to the placebo, but these differences were not statistically different.

In other words, at the doses used in this study (see next section for discussion), the collagen supplement worked better than the whey protein supplement. Here is the actual data from the study:

Increase in percent lean muscle mass: collagen supplement = 7.4%, whey protein supplement = 5.8%. placebo = 5.0%.

Decrease in percent fat mass: collagen supplement = 15%, whey protein supplement = 11.5%, placebo = 10%.

In the words of the authors, “In conclusion, collagen peptide supplementation combined with resistance training was associated with a significantly greater increase in fat free mass and a decrease in fat mass compared with placebo. Resistance training combined with whey protein also had a positive impact on body composition, but the respective effects were more pronounced following the collagen peptide administration.”

Could Collagen Supplements Make You Leaner?

This study leaves lots of questions. Let me handle the main ones here.

What Are The Strengths and Weaknesses Of The Study?

The strengths are obvious. This was a well-design, randomized, placebo-controlled clinical trial, which is the gold standard for determining the efficacy of a treatment.

The weaknesses are also obvious. This was a very small clinical study. There is one previous study that showed the same benefit of collagen in an older age group. However, both studies were published by the same group of scientists. And these scientists were funded by the manufacturer of the collagen product used in the study. More and larger studies performed by other laboratories are needed to confirm this finding.

How Do Resistance Exercise, Whey Protein, And Collagen Stimulate Muscle Growth?

Muscle growth is stimulated by a regulatory pathway called mTOR that (among other things) regulates protein synthesis in muscle cells. For the purposes of this article, I will discuss 3 mechanisms for activating mTOR and increasing muscle protein synthesis.

#1: Resistance exercise (weight training) activates mTOR. That should come as no surprise. The main reason people do weight training is to increase strength and muscle mass. mTOR is the pathway that makes this possible.

#2: Whey protein is rich in the essential amino acid leucine, and leucine also stimulates the mTOR pathway.

Leucine is one of three branched chain amino acids. While all three branched chain amino acids have been traditionally credited with stimulating muscle protein synthesis, recent research has shown that only leucine is needed. The other two branched chain amino acids just play a supportive role. You only need enough of the them to make a complete protein.

While whey protein gets all the attention in the sports world, any complete protein with high levels of leucine has the same effect.

The effect of leucine and resistance training on the mTOR pathway are additive. That is why whey and other leucine-rich proteins enhance the effect of resistance exercise on both muscle mass and strength.

#3: Collagen does not contain enough leucine to activate the mTOR pathway. However, the authors have proposed another mechanism to account for collagen activation of the mTOR pathway.

Most proteins we eat are digested to their individual amino acids before they are absorbed. However, collagen is rich in an unusual amino acid called hydroxyproline that makes collagen resistant to our digestive enzymes.

Thus, collagen is not digested to individual amino acids, but to small peptides that are absorbed from our intestine.

One of these breakdown products, a dipeptide composed of glycine and hydroxyproline, has been shown to stimulate the mTOR pathway.

While this mechanism has not been proven, collagen does appear to enhance the effect of resistance exercise on both muscle mass and strength.

Collagen Only Has 8 Essential Amino Acids. How Could It Stimulate The Synthesis Of Muscle Protein, Which Requires 9 Essential Amino Acids?

The answer is simple. The people in this study were consuming 30% more than the recommended amount of protein in their diet in addition to the collagen supplement. They already had all the essential amino acids needed to synthesize muscle protein. The collagen supplement simply stimulated the rate of muscle protein synthesis by activating the mTOR pathway.

However, there are situations in which the 9^th essential amino acid could become important for muscle protein synthesis. Here are two examples

Vegans and strict vegetarians might not be getting enough protein in their diet. As I pointed out in a previous article vegan “experts” know how to get enough protein from their diet, but many vegan “novices” do not.

Older Americans are also at risk. They need extra protein in their diet to prevent sarcopenia (muscle loss) as they age. And some of them are on restrictive diets, either because of the latest fad or because of loss of income and/or mobility.

Why Did The Collagen Supplement Work Better Than Whey Protein In This Experiment?

Again, the answer is simple. Both collagen and leucine-rich proteins like whey enhance muscle protein synthesis by activating the mTOR pathway (see above). This study used the same amount of protein (15 g/day) for both collagen supplement and the whey protein supplement.

While 15 g/day appears to be optimal for the collagen supplement, the authors pointed out that previous studies suggest that the optimal dose for whey protein is closer to 20 g/day for middle-aged men.

So, I would ignore the apparent difference in effectiveness of the collagen and whey protein supplements.

The important conclusion is that both collagen and leucine-rich proteins like whey enhance the effect of resistance exercise on lean muscle mass to a similar extent. But they appear to do so by slightly different mechanisms.

What Does This Mean For You?

This study is intriguing. It suggests that collagen may have some tricks up its sleeve we didn’t know about.

It may do more than give you a healthy, youthful looking skin.

It may do more than help with achy joints.

Coupled with resistance exercise it may also help you increase muscle mass and reduce fat mass. It may make you leaner.

The Bottom Line

Collagen supplements have been considered “vanity products”. Their largest market is people who want to have younger, more beautiful skin. And for many people, collagen delivers on this promise.

However, collagen plays many other roles in the body. It also helps rebuild tendons and ligaments. Many people take collagen supplements to reduce joint pain.

But collagen may have other tricks up its sleeve. A recent study suggests that collagen supplements may enhance the effect of resistance exercise on increased muscle mass and reduced fat mass. It may make you leaner.

The study also concluded that both collagen and whey protein enhance the effect of resistance exercise on lean muscle mass to a similar extent. But they appear to do so by slightly different mechanisms.

Let me be clear. I am not recommending you take a collagen supplement to help you build muscle mass. I consider these results as preliminary, and we have good evidence that leucine-rich proteins plus resistance exercise helps build muscle mass.

However, if you are taking a collagen supplement for another reason and are working out, this could be an unexpected benefit.

For more details about this study and how collagen supplements may increase muscle mass, 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.

Are Carnitine Supplements Good For You Or Bad For You?

December 8, 2020 by Dr. Steve Chaney

What Is The Truth About Carnitine And TMAO?

If you are a weightlifter or bodybuilder, chances are you are taking an L-carnitine supplement or a protein shake fortified with L-carnitine. That is because L-carnitine has been promoted for increasing muscle mass and physical performance for so long that most people have come to believe it must be true. Is it true, or is it just another food myth?

If you visit Dr. Strangelove’s website, you may also be told that carnitine supplementation is beneficial for weight loss, migraines, baldness, ADHD and autism, chronic fatigue syndrome, and/or low energy, muscle loss, and cognitive decline in older adults. Are these claims fact or fiction?

On the flip side, recent studies have suggested that the carnitine in red meat might be bad for your heart. Could the same be true for carnitine supplements? Could they also be bad for your heart?

A recent systematic review (AG Sawicka et al, Journal of the International Society of Sports Nutrition, 17: 49, 2020) of L-carnitine supplementation answers these important questions. The authors called their study “The bright and dark sides of L-carnitine supplementation” because they set out to systematically investigate the benefits and potential risks of L-carnitine supplementation.

But before I share the results of this study, I need to give you a little background on L-carnitine. It is time for another Biochemistry 101 segment.

Biochemistry 101: What You Need To Know About Carnitine

Carnitine plays an essential role in human metabolism. It is required for transport of fatty acids into our mitochondria so they can be used to generate energy. Without carnitine we would be unable to utilize most of the fats in our diet as an energy source.

As you might expect, carnitine is essential for any tissues that have mitochondria, but it is particularly important for high energy tissues like skeletal and heart muscle.

For most of us, our liver and kidneys make all the carnitine we need. So, we don’t really need carnitine from food or supplements.

However, we do get significant amounts of carnitine from red meat, much smaller amounts of carnitine from other animal foods, and almost no carnitine from plant foods. Adults consuming diets with red meat and other animal foods get about 60-180 mg of carnitine a day from their diet, whereas vegans only get around 10-12 mg/day.

Uptake of carnitine from the blood into muscle tissues requires insulin. Thus, carnitine uptake into muscle is significantly less on a low-carbohydrate or keto diet than it is on a mixed diet containing carbohydrates.

Finally, our kidneys do an excellent job of regulating blood carnitine levels, with excess carnitine being excreted into the urine. Thus, total body carnitine levels are virtually the same with high-carnitine and low-carnitine diets.

This raises the question: “Are L-carnitine supplements good for you?”

Now, let’s talk about the dark side of carnitine. I have discussed this in a previous issue of “Health Tips From the Professor”. Here is a brief summary:

People who eat a lot of red meat harbor a species of bacteria in their intestine that converts carnitine to trimethylamine (TMA). We don’t know whether this species of gut bacteria is favored by the presence of red meat in the diet or the absence of certain fruits, whole grains, and legumes from the diet of meat eaters.
The TMA is reabsorbed into the bloodstream, and the liver converts TMA to TMAO (trimethylamine N-oxide).
TMAO is associated with an increased risk of heart attack, stroke, and heart failure.

When you think about it, this is a perfect example of double jeopardy. Red meat is high in carnitine, and red meat eaters have gut bacteria that result in carnitine being converted to a compound that may increase the risk of heart disease.

This raises the question: “Are L-carnitine supplements bad for you?”

Let’s look at these two questions. First, I will discuss the recent review. Then I will put the conclusions of that review into perspective by looking at what other health experts say.

Are Carnitine Supplements Good For You Or Bad For You?

Most previous studies of carnitine supplementation have lasted only two or three weeks, which may not be long enough to measure an effect of carnitine supplementation on performance. So, the authors of this review paper selected studies that lasted 11 weeks or more for their review.

The review included 11 studies. They lasted either 12 or 24 weeks. Participants received doses ranging from 1 gm to 4.5 gm of L-carnitine per day. Here are the conclusions of the review:

Participants receiving L-carnitine alone had no increase in muscle carnitine content.

Participants receiving L-carnitine + 80 grams of carbohydrate had around a 10% increase in muscle carnitine content. [To put that into perspective, 80 grams of carbohydrate is roughly equivalent to 2 cups of white rice or two medium potatoes.]

One study compared male vegetarians with male omnivores. The omnivores had no increase in muscle carnitine content, but the vegetarians did. [The study did not analyze the diets of the omnivores and vegetarians, but it is probably safe to assume that the carbohydrate content was higher on the vegetarian diet.]

There was no significant effect of L-carnitine on muscle mass or physical performance. [This is logical, given the minimal effect of L-carnitine supplementation on muscle carnitine levels.

Thus, this review found little evidence that L-carnitine supplementation was good for you. It resulted in little or no increase in muscle carnitine levels or in physical performance.

Two of the 11 studies measured plasma TMAO levels. These studies found that L-carnitine supplementation resulted in a significant increase in plasma TMAO levels.

Thus, this review found some evidence that L-carnitine supplementation might be bad for you.

What Is The Truth About Carnitine And TMAO?

Is carnitine good for you? With respect to this question, the conclusions of this review are similar to the conclusions of other health experts. For example, in their Fact Sheet On Carnitine For Health Professionals the NIH states “Some athletes take carnitine to improve performance. However, twenty years of research finds no consistent evidence that carnitine supplements can improve exercise or physical performance in healthy subjects—at doses ranging from 2–6 grams/day administered for 1 to 28 days. For example, carnitine supplements do not appear to increase the body’s use of oxygen or improve metabolic status when exercising, nor do they necessarily increase the amount of carnitine in muscle.”

The NIH fact sheet goes on to list some diseases causing muscle loss or muscle weakness, for which L-carnitine supplementation is appropriate. However, in these cases, the carnitine supplementation should be recommended by health professionals.

Is carnitine bad for you? The TMAO story is a bit more complicated. As I mentioned above, there is an association between red meat consumption and blood TMAO levels and an association between blood TMAO levels and heart disease.

Is it TMAO that increases the risk of heart disease or is it some other component (saturated fat, for example) of red meat that increases the risk of heart disease? Nobody knows. More research is needed.

There is also a “red herring” that complicates the TMAO story. It turns out that TMAO helps fish survive the high pressures they encounter in the deep ocean. Thus, many fish are high in TMAO, and fish consumption also increases blood TMAO levels.

Are the bad effects of TMAO in fish outweighed by the heart healthy components in fish (omega-3s, for example)? Nobody knows. More research is needed.

To summarize:

There is no reason to take L-carnitine supplements unless directed by your health professional. There is little evidence they will help your physical performance. There is also no good evidence to support the other benefits of L-carnitine you find listed on Dr. Strangelove’s blog or the website of your favorite supplement company.

L-carnitine supplements may be bad for your heart, but much more research will be needed to be sure. [Note: Based on what we know about the role of gut bacteria in TMAO production, vegans could probably take l-carnitine supplements without causing an increase in TMAO levels. However, that is probably a moot point. There is no evidence that L-carnitine is more effective for vegans than it is for omnivores.]

The Bottom Line

On the flip side, recent studies have suggested that the carnitine in red meat might be bad for your heart. Could the same be true for L-carnitine supplements? Could they also be bad for your heart?

A recent review looked at these questions. Here are the conclusions of the review:

Participants receiving L-carnitine alone had no increase in muscle carnitine content.

Participants receiving L-carnitine + 80 grams of carbohydrate had around a 10% increase in muscle carnitine content. [To put that into perspective, 80 grams of carbohydrate is roughly equivalent to 2 cups of white rice or two medium potatoes.]

There was no significant effect of L-carnitine on muscle mass or physical performance. [This is logical, given the minimal effect of L-carnitine supplementation on muscle carnitine levels.

Thus, this review found little evidence that L-carnitine supplementation was beneficial. It resulted in little or no increase in muscle carnitine levels or in physical performance.

This review also found that L-carnitine supplementation resulted in a significant increase in plasma TMAO, a compound that has been associated with an increased risk of heart disease.

Thus, this review found some evidence that L-carnitine supplementation might be bad for you.

The NIH has also issued a fact sheet for health professionals summarizing research on L-carnitine over the past 20 years. The conclusions from their fact sheet can be best summarized as:

There is no reason to take L-carnitine supplements unless directed by your health professional. There is little evidence they will help your physical performance. There is also no good evidence to support the other benefits of L-carnitine you find listed on Dr. Strangelove’s blog or the website of your favorite supplement company.

L-carnitine supplements may be bad for your heart, but much more research will be needed to be sure.

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.

Are Fat Burning Sports Supplements Safe?

November 5, 2013 by Dr. Steve Chaney

It’s Buyer Beware in the Sports Supplement Market

Author: Dr. Stephen Chaney

For many athletes it’s all about being bigger, faster, stronger. That’s what makes the fat burning sports supplements so appealing. If you believe the ads, they will burn fat, increase muscle mass and give you an energy boost. But, are fat burning sports supplements safe? Are they effective?

What Are Fat Burning Sports Supplements?

Simply put, most of the fat burning sports supplements contain metabolic stimulants of some kind. That’s where the energy and fat burning claims come from. The stimulants range from clearly ineffective to downright dangerous.

Are Fat Burning Sports Supplements Effective?

Because sports supplements are considered to be foods rather than drugs, the FDA cannot require sport supplements manufacture to prove that their products are either safe or effective. As a consequence, most sports supplement manufacturers don’t conduct clinical trials to prove the effectiveness of their products. Their claims are based on animal studies and testimonials. However, in most cases there is no objective evidence that their supplements actually work.

Are Fat Burning Sports Supplements Safe?

All stimulants carry some risk. Even small amounts of caffeine can be problematic for some individuals, and many sports supplements contain massive amounts of caffeine. But, it is not caffeine containing sports products that are the most worrisome.

Many sports supplement manufacturers are firm believers in the “better living through chemistry” motto.

They start with an herbal ingredient that has stimulant properties
They synthesize what they think is the active ingredient
Perhaps they chemically modify it a bit….
..and, Voila! They have a proprietary new sports supplement
They label it a fat burner, prepare their claims and they’re ready to go to market

And, why bother testing it? Unless the product kills or seriously harms people, the FDA can’t step in and tell a manufacturer to take their product off the market.

And, if you think that the manufacturers and sellers of the product are looking after your best interests, think again.

Case Study #1: Jack3D and DMAA

I told you about this story last year, so I’ll just give you a brief recap here.

After a couple of marines died after using Jack3D prior to a workout, the US military ordered that the product not be sold on their bases. The manufacturer continued to make the product. GNC stopped selling it on military bases, but continued to sell it in all its other stores.
Eventually the FDA stepped in and recommended that Jack3D not be sold. The manufacturer claimed that the active ingredient, DMAA, was found in the geranium extract they used in their product. Since that was a food ingredient, they claimed the FDA did not have jurisdiction.
The FDA denied that claim based an extensive testing of geranium extract. At that point the manufacturer stopped making it (They have since resuming making the product with yet another poorly tested stimulant). GNC said they would stop selling Jack3D “as soon as their inventory was used up”.
The FDA finally had to raid the GNC warehouses to get the product off the market.

Case Study #2: OxyElite Pro and Aegeline

In case you thought that was an isolated case, the same sports supplement manufacturer has recently been involved in a second case that sounds all too familiar.

The FDA recently advised consumers to stop using OxyElite Pro after reports of 24 cases of acute non-viral hepatitis (a very rare disease) in users of that sports supplement in Hawaii. Two of those patients required liver transplants, and one of them died.
In this case the manufacturer stopped domestic distribution of the product, but argued that the product is safe. They claimed that counterfeit versions of OxyElite Pro were being sold in the US market.
On October 11, 2013 the FDA sent a warning letter to the manufacturer stating that the active ingredient, aegeline, was not a lawful dietary ingredient. The manufacturer replied that it was a natural constituent of the citrus fruit tree Bael. (I’m not sure why that makes it safe. I don’t know about you, but I don’t eat a lot of Bael fruit.)
As of a few days ago England, Denmark, Spain, Australia & New Zealand have warned consumers in those countries not to use OxyElite Pro.

It’s too early to tell how this story is going to turn out, but my money is with the FDA.

Case Study #3: Craze and DEPEA

And, in case you thought the problem was with a single rogue manufacturer, there is a developing story around yet another popular sports supplement, Craze, made by a different manufacturer.

Researchers from the NSF, Harvard and the National Institute for Public Health in the Netherlands recently published a paper claiming that Craze contained DEPEA, a methamphetamine-like compound.
The manufacturers claimed that the researchers did the chemical analysis incorrectly and their product actually contained a close analog of DEPEA that is found in dendrobium orchids. (Again I’m not sure why that makes it OK. I don’t think people eat a lot of dendrobium orchids either).

Stay tuned. I’m sure this story will have some interesting twists before it’s finished.

The Bottom Line:

1) In the sports nutrition industry, it is buyer beware. There are lots of rogue manufacturers out there who care more for their bottom line than your well being. Do your homework and search for reputable companies with a long track record of product quality and ethical standards. There are some out there.

2) Ignore the outlandish claims, no matter how appealing. Once again, stick with establishing companies with a track record of product integrity. Only use sports supplements that are backed by clinical studies showing that they are both safe and effective.

3) Be particularly cautious about sports supplements that claim to burn fat or give you energy. They generally contain metabolic stimulants, and often those stimulants are poorly characterized. Most have not been proven to be effective, and some have the potential to do more harm than good.

4) Fat burning supplements are often cross marketed as weight loss supplements. They are just as dangerous for dieters as they are for athletes.

5) Don’t assume that just because the ingredients supposedly come from a natural source (geraniums, Bael trees or dendrobium orchids, for example) they are safe.

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.