Are Carnitine Supplements Good For You Or Bad For You?

What Is The Truth About Carnitine And TMAO?

BodybuilderIf 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

professor owlCarnitine 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.

Question MarkThis 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?

good news bad newsMost 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?

the truth signIs 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 

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?

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.

What Supplements Help Mental Health?

Do Omega-3s Reduce Depression?

Author: Dr. Stephen Chaney

depressionWe are in the midst of a mental health crisis. According to the latest statistics:

·       19% of adults in the United States have some form of mental illness.

·       16.5% of youth ages 6-17 have some form of mental illness.

·       The 5 most commonly diagnosed forms of mental illness are anxiety, depression, post-traumatic stress disorder, bipolar disease, and ADHD.

Even worse, mental illness appears to be increasing at an alarming rate among young people. For example:

·       Between 2005 and 2017 depression increased 52% among adolescents.

·       Between 2002 and 2017 depression increased 63% in young adults.

·       Between 1999 and 2014 suicides have increased 24% in young adults. In the past few years suicides have been increasing by 2% a year in this group.

Much has been written about the cause of this alarming increase in mental illness. The short answer is that we don’t really know. But the most pressing question is what do we do about it?

The medical profession relies on powerful drugs to treat the symptoms of mental illness. These drugs don’t cure drug side effectsthe illness. They simply keep the symptoms under control. Plus, if you have ever listened closely to the advertisements for these drugs on TV, you realize that they all have serious side effects that adversely affect your quality of life.

My “favorite” example is drugs for anxiety and depression. You are told that one of the side effects is “suicidal thoughts”. That means that the very drug someone could be prescribed to prevent suicides might actually increase their risk of suicide. Why would anyone take such a drug?

If drugs are so dangerous, what about supplements? Do they provide a safe, natural alternative for reducing the symptoms of mental illness? Some supplement companies claim their products cure mental illness. Are their claims true or are they just trying to empty your wallet?

How is a consumer to know which of these supplement claims are true and which are bogus? Fortunately, an international team of scientists has scoured the literature to find out which supplements have been proven to reduce mental health symptoms.

How Was The Study Done?

clinical-studyThis was a massive study (J. Firth et al, World Psychiatry, 18: 308-324, 2019.  It was a meta-review of 33 meta-analyses of randomized, placebo-controlled trials with a total of 10,951 subjects. The clinical trials included in this analysis analyzed the effect of 12 nutrients, either alone or in combination with standard drug treatment, on symptoms associated with 10 common mental disorders.

To help you understand the power of this meta-review, let me start by defining the term “meta-analysis”. A meta-analysis combines the data from multiple clinical studies to increase the statistical power of the data. Meta-analyses are considered to be the gold standard of evidence-based evidence.

However, not all meta-analyses are equally strong. They suffer from the “Garbage-In, Garbage-Out” phenomenon. Simply put, they are only as strong as the weakest clinical studies included in their analysis.

That is the strength of this meta-review. It did not simply combine the data from all 33 meta-analyses. It used stringent criteria to evaluate the quality of each meta-analysis and weighted the data appropriately.

What Supplements Help Mental Health?

omega-3 fish oil supplementThe strongest evidence was for omega-3 supplements. In the worlds of the authors:

·       “Across 13 independent randomized control clinical trials in 1,233 people with major depression, omega-3 supplements reduced depressive symptoms significantly.”

o   The average dose of omega-3s in these studies was 1,422 mg/day of EPA.

o   The effect was strongest for omega-3 supplements containing more EPA than DHA and for studies lasting longer than 12 weeks.

o   There was no evidence of publication bias in these studies. This is a very important consideration. Publication bias means that only studies with a positive effect were published while studies showing no effect were withheld from publication. That makes the effect look much more positive than it really is. The fact there was no evidence of publication bias strengthens this conclusion.

o   Omega-3 supplements were more effective when used in combination with antidepressant drugs, but there was some evidence of publication bias in those studies.

·       “Across 16 randomized control clinical trials reporting on ADHD symptom domains, significant benefits were observed for both hyperactivity/impulsivity and inattention.”

·       Omega-3s had no significant effect on schizophrenia or bipolar disorder other than a mild reduction in depressive symptoms.

There was strong, but not definitive, evidence for folic acid and methylfolate supplements for depression.

·       When used in conjunction with antidepressants both folic acid and methylfolate supplements “…were associated with significantly greater reductions in depressive symptoms compared to placebo, although there was large heterogeneity between trials.”

·       The largest effects were observed with high dose methylfolate. In the words of the authors: “Two randomized control clinical trials examining a high dose (15 mg/day) of methylfolate administered in combination with antidepressants found moderate-to-large benefits for depressive symptoms.” However, to put this into perspective:

o   15 mg/day is 3,750% of the RDA. This is a pharmacological dose and should only be administered under the care of a physician.

o   A smaller dose of 7.5 mg/day is ineffective.

o   No comparison was made with folic acid at this dose, so we do not know whether folic acid would be equally effective.

·       The authors concluded that there is emerging evidence for positive effects of vitamin D (>1,500 vitamin d supplementationIU/day) for major depressive disorders and N-acetylcysteine (2-3 gm/day) in combination with drugs for mood disorders and schizophrenia. The term “emerging evidence” means there have been several recent studies reporting positive results, but more research is needed.

·       The authors did not find evidence supporting the use of other vitamin and mineral supplements (E, C, zinc, magnesium, and inositol) for treating mental health disorders.

·       The authors did not find enough high-quality studies to support claims about the effects of prebiotics or probiotics on mental health disorders.

Do Omega-3s Reduce Depression?

Happy WomanThe evidence supporting the effectiveness of omega-3s in reducing symptoms of depression is strong. In the words of the authors: “The nutritional intervention with the strongest evidentiary support is omega-3, in particular EPA. Multiple meta-analyses have demonstrated that it has significant effects in people with depression, including high-quality meta-analyses with good confidence in findings…”

However, before you throw away your antidepressants and replace them with an omega-3 supplement, let me put this study into perspective for you.

·       Depression can be a serious disease. If you just feel a little blue from time to time, try increasing your omega-3 intake. However, if you have major depression, don’t make changes to your treatment plan without consulting your physician.

·       The best results were obtained when omega-3s were used in combination with antidepressants. This should be your starting point.

·       Ideally, adding omega-3s to your treatment plan will allow your doctor to reduce or eliminate the drugs you are taking. That would have the benefit of reducing side effects associated with the drugs. However, I would like to re-emphasize this is a decision to take in consultation with your doctor. [My only caveat is if your doctor is unwilling to even consider natural approaches like omega-3 supplementation, it might be time to find a new doctor.]

·       Finally, omega-3 supplementation is only one aspect of a holistic approach to good mental health. A healthy diet, exercise, supplementation, and stress reduction techniques all work together to keep your mind in tip-top shape.

The Bottom Line

There are lots of supplements on the market promising to cure depression and other serious mental health issues. Are they effective or are the claims bogus? Fortunately, a recent meta-review of 33 meta-analyses of high-quality clinical trials has answered that question. Here is their conclusion:

·       The evidence is strongest for omega-3s and depression.

o   The average dose of omega-3s in these studies was 1,422 mg/day of EPA.

o   The effect was strongest for omega-3 supplements containing more EPA than DHA and for studies lasting longer than 12 weeks.

·       There is fairly strong evidence for folate/folic acid supplements and depression, although there was large heterogeneity between trials.

·       There is emerging evidence for vitamin D (>1,500 IU/day) and depression and N-acetylcysteine (2-3 gm/day) for depression and schizophrenia.

·       Evidence for other supplements is currently inconclusive.

However, before you throw away your antidepressants and replace them with an omega-3 supplement, let me put this study into perspective for you.

·       Depression can be a serious disease. If you just feel a little blue from time to time, try increasing your omega-3 intake. However, if you have major depression, don’t make changes to your treatment plan without consulting your physician.

·       The best results were obtained when omega-3s were used in combination with antidepressants. That should be your starting point.

·       Ideally, adding omega-3s to your treatment plan will allow your doctor to reduce or eliminate the drugs you are taking. That would have the benefit of reducing side effects associated with the drugs.

·       Finally, omega-3 supplementation is only one aspect of a holistic approach to good mental health. A healthy diet, exercise, supplementation, and stress reduction techniques all work together to keep your mind in tip-top shape.

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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